Trad Gang
Main Boards => The Bowyer's Bench => Topic started by: Elison on September 29, 2014, 07:51:00 AM
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Hy guys!
So, I was searching something about "how it's made" a Bo Tuff, but I can't find the exactly way to do it.
In some places I saw tips to use fiberglas clothes, in other to use Rooving... :|
The properly resin to use also confuses, because some places people say: " - Use flexibe resin epoxy."
Others: " - Use rigid resin epoxy."
In the worst case, I was saw too: " Mix the flexible and rigid epoxy... " :?
Has anyone tryed to make his own Bo tuff and know what is all the correct way to do it?
Thanks very much!
Cheers!
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Me to, inquiring minds want to know.
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What would be the purpose to building your own glass even if you could get it done???? I remember when I was building black powder rifles that I would buy a 3/16 bolt and turn it down in a lathe to make a specialty bolt I could buy from the supply house for $1.00. Have fun with your project and let us know how it works out. Also maybe you could make some clear glass so we won't have to buy the second (or third) rate glass that Gordon's is producing.
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JamesV, the main motive is because here in Brazil we don't have Gordon's glass...
We can import, sure, but this process is very expansive. For example, for each strip imported we paid almost the double of the original price because of the government tax and shipping. =(
( actually 60% of tax and plus shipping for Brazil)
If would be some way to make our own bo-tuff, even a little worst than Gordon's, will be can progress in archery in our country, because importing is almost inviable.
thanks guys.
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Gentlemen,
I registered just to share this knowledge - so you're in luck!
Gordon's Bo-Tuff is a prestressed, unidirectional weave, fibreglass lam - similar in concept to a prestressed, steel-reinforced concrete beam, only with fibreglass acting as the steel & resin acting as the concrete. My background is largely in composites, so when I started in bowmaking I was naturally inclined toward making my own fibreglass lams and, after a few years of research & experimentation, I've got to a point where I'm producing workable specimens, albeit not quite up to Gordon's standard (yet).
To make your own fibreglass lams you need,
- Unidirectional fibreglass
- Epoxy Resin (an aradur derivative is what I use, but in a pinch any epoxy can be used. Don't use polyester resin as it doesn't have the bonding or bulk strength). This resin, when mixed with a thickening agent, like colloidal silica, also make for excellent glue. Better, or at least as good as, Smooth On.
- A curing procedure. In Brazil, assuming you're in one of the sunnier, hotter parts, this might just be a black cloth wrapped around the item & left in the sun. Basically, you need to get the item as much over 30 deg. C (but no higher than 80 deg. C) to cure the epoxy properly. Many people use hotboxes to cure their glues, which work really well. I've built a digitally controlled hotbox, which is not as good as you might think.
- A fibreglass form. I used a length of C-Section steel, 2m (7', almost) long x 50mm (2") wide with 25mm (1") walls. At either end I have removable plugs with foam rubber feet to grip the fibreglass as it is tensioned & stop the resin from flowing away.
I'm not sure on the policy regarding posting from other archery forums, so this link may need to be removed, but here's some pictures of some of the products I'm using & the finished results - http://www.ozbow.net/phpBB3/viewtopic.php?f=34&t=14869
The process for making this is,
1. Cut 2 to 4 layers of fibreglass to length & width (for a thin 1/16" lam, 2 layers will do, for a 1/8" lam I use 4 layers). I make 6' lengths, so I cut to 6.5' to 7' lengths, to give some purchase for the plugs at either end & the bit to hold onto when you tension it.
2. Clamp one end of the fibreglass in the form with the plug. The rubber foot on the plug really helps here to make sure all the fibres are gripped.
3. Making sure there are no twists in the fibres, remove the thin crossweaves. This makes little structural difference (so if you want, you can skip this step) but it does improve the finished look.
4. Pull the fibres tight along the length of the form and, without removing the tension, clamp the second plug down. It's easier to do this with two people - one holding the tension in the glass, the other operating the clamp. This is the really important part as it allows the glass to really work as the limbs are bent.
5. Mix up your resin. I use 120grams of resin (inc. hardener) for 2 layers of glass, 160grams of resin (inc. hardener) for 4 layers of glass.
6. Pour the resin into the form, or apply with a brush, then roll with a fibreglass/carbon/kevlar steel roller for 10-15 minutes. This is very important! It means that the resin works all the way through the lam and there won't be any dry spots. You may even want to put a layer of resin down between steps 3 & 4, to ensure the resin is all the way through. As the resin works it's way through, you'll see the glass change from white in appearance to clearish.
7. Once adequately rolled, cure for the appropriate period.
8. Remove the plugs at either end & gently pull the lam out from the form. Trim the ends (and if necessary, the edges) then grind with a thickness sander (or similar, but not a thickness planer, that just won't work) to desired thickness.
9. Congratulations, you have a pre-stressed, fibreglass lam!
I would advise that you source your materials from a dedicated composites supplier, which you may find working in boat building services. The resins/glues/fibreglass are commonly used in that sector, so you shouldn't have too much difficulty sourcing it. From a price perspective, it's actually pretty much the same as buying Bo-Tuff, but if you want the flexibility & satisfaction of doing it yourself, this is the way to go.
Hope you have some luck with that! It's taken me a year or so to work this procedure out, I'd love to see how you do with it.
P.S. A big shout out to Sam Harper who inspired me to give this a shot. Cheers, Sam!
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Nezwin,
That is awesome instruction. You should do a build along on here with pics. There was a post of a kid making glass limbs in south or central America on here. He cut out the cloth put it on a form and brushed on the resin, and be damned made a bow. It might have been a youtube video.
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Hy guys!
Nezwin, First I'd like to thank you so much for the amazing response! You really show me the light path.
Second, I'd like to sorry for late response, I taked some time to read and read again until understand all the process. English is not my native language, so it's a little dificult to me translate, reply, etc...
If you can, the idea of KellyG is a good deal, it will be marvelous a build along with pictures.
I can admit that the process is a little simple than I thought! hehehe...
I've saw some videos when It used a process called pultrusion, where they use expensive industrial machines to make laminates apparently equals than Gordon's... but I just never see any of this pultruded laminates in my hand to confirm it.
An example of this kind of process:
https://www.youtube.com/watch?v=D--p7JOhmL4
But looking in the link that you shared, I saw the specs in a Gordon's pdf and they don't tell nothing about pultrusion.
About the materials, I have some of they. :)
My resin epoxy just arrived today ( bought in the internet). Have parts of fiberglass cloth, but it's BD... :(
I will buy a UD and start to make experiences. For sure will share all here with you. :)
One question: Following the idea of pultrusion, it wouldn't be better use rooving in the place of cloth UD?
Thanks again Nezwin!
And thank you guys!
P.S.: A big shout out to Sam Harper too... hehehehe... he always inspire me with the tutorials and videos. ;)
Cheers!
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I believe tha pultrusion is a completely different process than the process of making fiberglass laminations.
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Ola Elison,
I'm afraid I don't speak Portuguese, but my Italian wife speaks Spanish if that's any help?
I would imagine that Gordon's probably use a process similar(ish) to pultrusion, maybe, but for the small scale guys like us, it's not an option. I did speak with a technical representative from Gordon's about a year ago and he was very co-operative in explaining the properties of the Bo-Tuff product. It was through speaking to him that I was able to work out it was pretensioned.
I've used bidirectional cloth to back bows before and it works by stopping splinters lifting. However, it is a completely different way of working than a pre-tensioned lam - indeed, a cloth backing applied directly to a limb won't actually do any "structural work", it only stops splinters lifting. To get a fibreglass lam performing "structural work" you need depth (which is achieved by using the form, which stops the resin flowing away) and appropriate tensioning (achieved by pre-tensioning).
I'll do a build along over the weekend and try to work out how to upload pictures, etc. Is there a thread explaining how to post pictures and things like that?
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Hi Nezwin!
Don't worry about language, english for me is ok. Spanish sounds a bit more similar to portuguese, but I believe I can understand english much more. :)
I didn't saw any post explaining how to post photos here, but I've been using the photobucket as well to post my photos here...
You will need an account there to upload the photos ( or just sign in with facebook). After you upload the photos, you need to select the photo who you will share and click in the field "IMG" inside the area "shared Links". This will copy the entire url to photo inside the tag used by the forum. Then it's just paste here and post... It's quite easy, but if you have some difficult, you can send the photos to me and I'll be glad to share for you.
Nice tip about the bidirectional cloth... I tried use it before, but I didn't had much success... especially in belly, where the fibers broken with the compression.
Are you already tried with rooving?
http://www.fiberglass.name/UploadFiles/200751622220683.jpg
Is there any differences to work between it and uniderectional cloth?
I ask it because I tried to find unidirectional cloth here, but found nothing for now. (Even in internet)
Thank you again!
Cheers
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I think you will have better luck if you search for a unidirectional E-Glass tape if comes in many different widths.
I can see the need to tension the material for lamination it makes sense. I think this can be done in a way that might produce a superior product by using vacuum bagging to form the strips which should eliminate all the tiny air bubbles and reduce streaking/improve clarity. I don't have the solution yet but I'm working on it. Need to work out a form that can hold the strips under tension that will go in a vacuum bag and into the hot box. That should do it.
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Forget the previous, after reading the following I think I'll stick to trying to learn to make bows.
Gordon Glass Profile (http://arrowtrademagazine.com/articles/nov_07/Nov2007-GordonGlassProfile.pdf)
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Thanks for the information on Photobucket, I'll see if I can get it working when I do the buildalong over the weekend.
Bidirectional cloth will eventually breakdown due to internal stresses - basically, the threads rub against one another & the friction breaks them. Using it on the belly would do almost nothing. In fact, using any fibreglass on the belly of a bow will no almost nothing, only the resin will actually perform any work in this instance. Take a length of fibreglass cloth & compress it longitudinally - it will just go limp, like string! The resin though, as a strong plastic, will take the compressive force very well. My advice is that when making belly lams, only use resin. Any fibreglass used will be wasted. Or you can just use a decent timber - something like Ipe or Osage should be able to handle the compression stress from a thin fibreglass backing lam at lower poundages.
The only difference between roving & unidirectional cloth is that the cloth is easier to use. With the roving you'd be required to cut each thread to length before placing it in the form, which would be annoying. Alternatively, you could create a jig to thread the roving through the form which, if done correctly, would work well, although then applying tension would be a further challenge. At a later date I'll lay out some ideas on how that might be done.
As Pago pointed out, unidirectional tape would be good, if you can source it. It makes it easier for cutting to size to fit into the form. Pago is also right about the vacuum bagging, but it would make it very difficult to cure in a hotbox while applying a vacuum... If ambient temperature was high enough (ie, you live in a desert..) that would be fairly achievable.
I didn't read the entirety of the article Pago posted, but looking through it there were some interesting insights - for instance, Gordon's use roving, and they produce their lams 1/3 resin, 2/3 glass. It's given me ideas for an improvement on my current process, but I'll have to test it to see.
I think it's important to stress that what I'm producing, and what I've explained in the process above, is not the same as Gordon's Bo Tuff. It's a pre-stressed fibreglass lam, which had very similar properties to Bo-Tuff, but it is the responsibility of the individual making it to ensure the final result. Ultimately, it would be exceptionally difficult to reproduce the Bo-Tuff product at home (Gordon's have a HUGE amount of dedicated equipment & years of experience) but what I've described would produced a good product that would perform in a similar function.
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Dont get me wrong this is a fun problem to think about. I actually think a person could make a far superior lam at home, but at the cost of time, money, space, energy and lost opportunity to do other things, at least for me.
However if you build a form that can pre tension the material and use lots a wax+release agent pre-lay up (something like milled aluminum), its just a matter of throwing in a heat resistant vacuum bag (already available) and baking in a hot box like we already use for bow lay ups with the vacuum tube hanging out of the box. But then you need a regulated vacuum pump, bags, mylars and all the trimmings. BUT, the lams should come out crystal clear.
I have done similar lay ups before building aiplanes, the vacuum pulls all the air out and leaves a beautiful streak free layup.
My problem is I don't have time to work on bows as is and I would be wondering off in another direction to make a product that is already available and spending a great deal more in resources and money to make it. Doesn't add up for me, but its still fun to think about.
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If you read the linked article above many have tried to do their own and in the end most buy from gordons because of the economy and quality.
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Agreed, Pago - in the end, it's cheaper, quicker & easier to buy the Gordon's product, but, you know, it's fun to make the lam too... I'm pretty short on time, in general, but sourcing Bo-Tuff in the Australia is difficult (there's one guy) and I don't like the idea of not being able to do it myself.
For a form using roving, I was thinking of mounting a series of pins to each end and wrapping the roving around them, end to end, not dissimilar in manner to how a flemish twist jig is used (kinda). With that, you can either tension them yourself as you thread them or, if you want to get technical, you could have a screw mechanism which when turned increases the distance between the pins. A sketch would relay the idea better, but what do you think?
Re: release agent, I've moved away from using wax and had no problem so far. I line my form with sticky tape, which provides a very low friction surface and the lam never sticks.
Re: vacuuming, it's a good idea but a hell of a lot more work & materials! As it is, I'm already at the point where I'm looking at bamboo and thinking "that looks waaaaaay easier"! You're right though, vacuuming would give a great result.
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I feel for you Aussies when it comes to sourcing materials. I wish you all the success in the world. I get your pin idea and think its a good one. The question is how many strands you need in width and how tightly distributed they need to be. You might need two rows of pins on each end slightly offset and experiment to get the right thickness somewhere in the 0.040-0.050 range.
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The expense and scarcity of supplies for bow making is exactly why I mainly make bbb longbows and recurves.
I'll have to try woven fiberglass this summer those results look good
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Never done a buildalong before but here goes...
I'm pretty lazy, so I'm going to copy my original post & add pictures & notes.
To make your own fibreglass lams you need,
- Unidirectional fibreglass
(http://i1372.photobucket.com/albums/ag321/Nezwin1/fibreglassroll_zps6cfb1f51.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/fibreglassroll_zps6cfb1f51.jpg.html)
(http://i1372.photobucket.com/albums/ag321/Nezwin1/fibreglassclose_zps4ee20ba2.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/fibreglassclose_zps4ee20ba2.jpg.html)
- Epoxy Resin (an aradur derivative is what I use, but in a pinch any epoxy can be used. Don't use polyester resin as it doesn't have the bonding or bulk strength). This resin, when mixed with a thickening agent, like colloidal silica, also make for excellent glue. Better, or at least as good as, Smooth On.
- A curing procedure. In Brazil, assuming you're in one of the sunnier, hotter parts, this might just be a black cloth wrapped around the item & left in the sun. Basically, you need to get the item as much over 30 deg. C (but no higher than 80 deg. C) to cure the epoxy properly. Many people use hotboxes to cure their glues, which work really well. I've built a digitally controlled hotbox, which is not as good as you might think. Edit: It's working great!
- A fibreglass form. I used a length of C-Section steel, 2m (7', almost) long x 50mm (2") wide with 25mm (1") walls. At either end I have removable plugs with foam rubber feet to grip the fibreglass as it is tensioned & stop the resin from flowing away.
The process for making this is,
1. Cut 2 to 4 layers of fibreglass to length & width (for a thin 1/16" lam, 2 layers will do, for a 1/8" lam I use 4 layers). I make 6' lengths, so I cut to 6.5' to 7' lengths, to give some purchase for the plugs at either end & the bit to hold onto when you tension it.
(http://i1372.photobucket.com/albums/ag321/Nezwin1/fibreglasscomingapart_zps2caba866.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/fibreglasscomingapart_zps2caba866.jpg.html)
2. Clamp one end of the fibreglass in the form with the plug. The rubber foot on the plug really helps here to make sure all the fibres are gripped.
(http://i1372.photobucket.com/albums/ag321/Nezwin1/glasslayuptensioned2_zps9c89ea5a.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/glasslayuptensioned2_zps9c89ea5a.jpg.html)
(http://i1372.photobucket.com/albums/ag321/Nezwin1/plug_zps61fc41a7.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/plug_zps61fc41a7.jpg.html)
Rubber foot at the top, steel plug at the bottom.
(http://i1372.photobucket.com/albums/ag321/Nezwin1/glasslayuppreresin_zpsc0e2c23c.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/glasslayuppreresin_zpsc0e2c23c.jpg.html)
The lateral weaves have been removed in this picture but no tension has been applied.
3. Making sure there are no twists in the fibres, remove the thin crossweaves. This makes little structural difference (so if you want, you can skip this step) but it does improve the finished look.
(http://i1372.photobucket.com/albums/ag321/Nezwin1/lateralthreads_zpscf73af30.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/lateralthreads_zpscf73af30.jpg.html)
4. Pull the fibres tight along the length of the form and, without removing the tension, clamp the second plug down. It's easier to do this with two people - one holding the tension in the glass, the other operating the clamp. This is the really important part as it allows the glass to really work as the limbs are bent.
(http://i1372.photobucket.com/albums/ag321/Nezwin1/glasslayuptensioned_zpsb77f4a57.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/glasslayuptensioned_zpsb77f4a57.jpg.html)
You can see in this picture that the glass is very much centered - I didn't have anyone to help with the tensioning! After applying some resin & having a think, I loosened the tensioning clamp & spread the fibres evenly over the 2" base of the form, then reapplied the tension.
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5. Mix up your resin. I use 120grams of resin (inc. hardener) for 2 layers of glass, 160grams of resin (inc. hardener) for 4 layers of glass.
(http://i1372.photobucket.com/albums/ag321/Nezwin1/resin_zps1cb48098.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/resin_zps1cb48098.jpg.html)
6. Pour the resin into the form, or apply with a brush, then roll with a fibreglass/carbon/kevlar steel roller for 10-15 minutes. This is very important! It means that the resin works all the way through the lam and there won't be any dry spots. You may even want to put a layer of resin down between steps 3 & 4, to ensure the resin is all the way through. As the resin works it's way through, you'll see the glass change from white in appearance to clearish.
(http://i1372.photobucket.com/albums/ag321/Nezwin1/rollerinfocus_zpsf2e41364.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/rollerinfocus_zpsf2e41364.jpg.html)
This roller is cut down from a larger one & I made my own wire frame from an old coat hanger.
(http://i1372.photobucket.com/albums/ag321/Nezwin1/glassrolled_zps8c159103.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/glassrolled_zps8c159103.jpg.html)
Note the uniform colour with no white streaks. This means the resin has penetrated the whole way through for the entire length.
7. Once adequately rolled, cure for the appropriate period.
(http://i1372.photobucket.com/albums/ag321/Nezwin1/curing_zps5a14538a.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/curing_zps5a14538a.jpg.html)
Few other bits & pieces in there, but the fibreglass form is on the left.
8. Remove the plugs at either end & gently pull the lam out from the form. Trim the ends (and if necessary, the edges) then grind with a thickness sander (or similar, but not a thickness planer, that just won't work) to desired thickness. Only grind the 'rough' side of the lam - the smooth side, the side that was in contact with the form, shouldn't be touched from now on. I will cover it in 2" masking tape prior to using it in a bow layup and leave the tape on as the bow is built.
Very important! When grinding the fibreglass WEAR A RESPIRATOR. The dust is exceptionally fine and very, very nasty if inhaled. You'll also want to be wearing throwaway gloves (like the latex ones doctors use) when handling the resin, and make sure you have plenty of acetone around for cleaning brushes, rollers, etc.
(http://i1372.photobucket.com/albums/ag321/Nezwin1/newlamfresh_zps73a616e8.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/newlamfresh_zps73a616e8.jpg.html)
Fresh out of the form.
(http://i1372.photobucket.com/albums/ag321/Nezwin1/lamgrinder_zps111c2969.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/lamgrinder_zps111c2969.jpg.html)
Improvised thickness sander.
(http://i1372.photobucket.com/albums/ag321/Nezwin1/newlamfinished_zps03c07a00.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/newlamfinished_zps03c07a00.jpg.html)
Beautiful!
(http://i1372.photobucket.com/albums/ag321/Nezwin1/newlamcloseup_zpscf872311.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/newlamcloseup_zpscf872311.jpg.html)
This might look rough & white now, but as soon as more glue or resin is applied, it turns transparent and will show any grain beneath.
9. Congratulations, you have a pre-stressed, fibreglass lam!
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I've been thinking about the roving and I think it could be a better way of doing this... I'm going to mount my form to a piece of timber, then put pegs at either end. I'll tie off a length of roving to a peg, then thread it up & down the form, around each peg, ensuring the tension remains. When I get to the end, I'll turn back and repeat for 2 or 4 layers. The weaves will cross and will be at an angle, but it'll only be 1/8" over 7 feet, so it will be minimal. Once the glass is down, I'll clamp each end with the plugs & proceed as before.
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Wow!!! What a great build along!
Nezwin, you are the guy! :) As the fact that was your first build along, for me it was wonderful!
Your fiberglass lam seems very nice too, if I could make in that quality, I'll be happy. =)
Pago, your tips was very helpful too. I couldn't read that entire article that you shared yet, but I already see that have many good things.
I made some experiences this weekend with the epoxy resin and the cloth that I have, but I did have some difficulties.
One of that is that the resins cures too fast! kkkkk...
I started to mix the resin and the hardener, and at first I've got a very liquid state.
But in the period that I was applying in some layers, the resin changed at a very glued state, almost a gel.
The period time of this change was about a 15 minutes. Is that normal?
My new brush turns like a stone. I tried to dissolve the resin with a kind of thinner, but didn't work. =[
I was thinking too about how to use roving and your idea of a timber with pegs sounds great.
One thing that I was tought in use a slingshot's rubber to make tension, something like this, but with the timber clamped in it:
(http://img.dxcdn.com/productimages/sku_46030_3.jpg)
Just an idea... ;)
Thank you guys!
You guys rocks!
Cheers!
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No problem, Elison :) I'm just glad I can help & get this information out there. I know when I started doing this myself there were very few people able to help, so I know how it is to be in your position.
15 minutes sounds a bit quick for the resin to have gone off (that is the term used for 'setting' - you say "the resin has gone off"), I would imagine you've used a little too much activator/accelerator/hardener and/or you're working in too warm an area. You want to try to be working in an area out of direct sunlight and not too hot. Conversely, an area in direct sunlight & very hot makes a great place to cure resins & glues. My resin takes about an hour or maybe two hours to get to a 'gel' state.
I'm not sure if thinner would do the job to clean the brush, I've always used Acetone, which is like thinner but much stronger. To be honest, I always buy cheap brushes at about 50 cents each when I see them on sale. I get maybe 2 or 3 uses out of each one before I throw it away. It's the nature of the work - you'll go through a lot of brushes.
Here's my thoughts on the roving idea - it's a rough image, so apologies!
(http://i1372.photobucket.com/albums/ag321/Nezwin1/RovingGlassForm_zps0d06517c.jpg) (http://s1372.photobucket.com/user/Nezwin1/media/RovingGlassForm_zps0d06517c.jpg.html)
Basically, tension is made as the roving is threaded. You don't need a huge amount of tension, just enough to ensure the threads are in the same orientation and aren't loose. The pegs I imagine could be something like small nails, or wooden dowels, but nails would be quicker, easier & smaller. I would do a few layers of that threading, then apply the tensioning clamps to either end, then apply the resin. The rubber could work, but there could be a lot of problems arise from it too. I always like to try & keep things simple :)
I've laminated the piece of glass in the pictures above into a bow yesterday. I should be able to get it finished in a week or two, so I'll get a picture up when it's done.
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Nezwin finished your bow? Is that laminated glass works well?
I have a question. What is colloidal silica and where can i get it
ratio between epoxy and colloidal silica?
is it ok to use fiberglass cloth prevent wood splinter and lifting?
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The bow is finished in the sense that it delaminated and rather than fix it, I smashed the hell out of it. I tend to lose it a little when I get frustrated... My fault really, I left the Spotted Gum (local version of Hickory, or close to) lams with a planed finish, so they didn't adhere correctly. I've been playing around with bamboo backing of late, not that I've had a lot of time to commit to bowmaking! It's a shame about that bow though, because the backing came out beautifully. I've done it a few times and it always works very well but on this particular occasion it was exceptionally good. Another time, perhaps. I'm sure you'll see it up on the board here when I do.
Colloidal Silica is ground glass - an exceptionally fine white powder that when mixed with resin acts to thicken it into a glue compound with gap filling properties. It's very dangerous to work with so a respirator must be used. You should be able to source it at any good composites supplier, so wherever you get your fibreglass & resin, assuming you're not buying it from a car repair shop or something like that. I strongly recommend when buying this stuff that you go to a dedicated supplier, as opposed to a commercial shop with a few 'fibreglass packs' for fixing up holes in boats or cars, which just won't do the right job.
As far as ratio of silica to resin, that's up to you. For gluing a tri-lam, I'll mix up about 80 grams of resin (inc. hardener) and then add the colloidal silica to thicken it, adding one spoonful at a time until I'm happy with the consistency. Doing this on the scales, it works out at about 1-2 grams, which isn't much in terms of mass, but it's a fair volume. If you're using an epoxy glue, like Smooth On or something similar (you might be able to buy this at the same place you buy the resin) you won't need the silica to thicken it, it should already be thick enough. I only use the resin as a glue because it's easier than having several different products about the workshop. With the bamboo backed bows I've been making the last week or so I've been using Titebond III which I've always been happy with, especially for non-fibreglass bows.
So to sum up all those points, you don't need colloidal silica for making just the lam. If you're making just the lam, you only need the resin. You should be able to get colloidal silica at a dedicated composite materials supplier and if you do use it to mix with resin into a glue, I add a spoonful at a time until I'm happy. For 80 grams it's about 3-5 spoonfuls, which is about 1-2 grams.
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And as far as fibreglass cloth is concerned, sure, go ahead. It'll work in the same was as any other cloth backing and will, after thousands and thousands of shots, eventually fail, but it's easy to use & very durable. The only point I'd stress is that even though it's fibreglass and it's used as a backing, it's not a fibreglass bow... By using 1 or 2 layers of cloth (I assume you mean cross-weave cloth in this regard, not unidirectional cloth that I've demonstrated above) applied directly to the back of the bow it won't be doing any 'work' when the bow is drawn, it will only be stopping splinters lifting.
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Thank you for your kind reply
Here in Korea there is not much bow building meterial. I can buy epoxy or bo tuff on 3rivers archery or bingham but shipping charge is expensive and delivery period is too long. Besides I like diy.
I want to laminate fiberglass lam and wood lam. I don't have smooth on. I have just normal epoxy resin. Do i need Colloidal Silica?
you said Colloidal Silica makes resin thick and get gap filling properties. Why thickening resin? what is gap filling? what's the advantage of gap filling and thickening?
what is the difference between bow making resin(like smooth on) and normal epoxy resin? concentration(thick) and gap filling?
so your bow delaminated but fiberglass itself works well?
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And I don't have ud cloth but i have single loving
how about make fiberglass lam like this?
http://youtu.be/yVPgw0_sESE
this is compound bow limb but if you see 1:50
they wind up single loving with resin on the frame and press. i want to make this wood
what do you think?
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http://www.google.com/patents/US4735667
(http://cafeptthumb2.phinf.naver.net/20140830_25/dlgusgkrgud_1409333342805i3WN5_PNG/1.png?type=w740)
(http://cafeptthumb4.phinf.naver.net/20140830_254/dlgusgkrgud_14093333432458pG6v_PNG/2.png?type=w740)
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Colloidal Silica and aerosil or fumed silica is same?
http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=000148
in the link someone says Laminating fiberglass to wood it can be used without thickeners, but for wood to wood I would use one of the above agents to prevent gaps. is that true?
and what about epoxy bendability or flexibility?
i find westsystem g-flex epoxy
650-8 G/flex Epoxy
A toughened, versatile, liquid epoxy for permanent waterproof bonding of fiberglass, ceramics, metals, plastics, damp and difficult-to-bond woods. With a modulus of elasticity of 150,000 PSI, it is a bit more flexible than standard epoxies and polyester, but much stiffer than adhesive sealants. This gives G/flex 650 the ability to make structural bonds that can absorb the stress of expansion, contraction, shock and vibration. It is ideal for bonding dissimilar materials. It can be modified with West System fillers and additives, and used to wet-out fiberglass tapes and fabrics. Mixed at a 1:1 ratio, G/flex 650 gives you 45 minutes of working time at room temperature. It reaches an initial cure in 7 to 10 hrs and full cure in 24 hrs. Click for photo. (8 fl. oz. / 236 mL)
i think this epoxy has good properties for bow making if i add sillica on normal epoxy can i make epoxy like g-flex? i heard filler like sillica only increase the viscosity. sillica does other things? except thickening and gap filling properties?
talc is cheaper than sillica can i use talc?
how about milled fiber glass? http://youtu.be/cTuXBt7uIeM
in the video he says milled fiberglass give epoxy strength and flexbility
you said fiberglass cloth won't be doing any 'work' when the bow is drawn, it will only be stopping splinters lifting. but when I added fiberglass cloth, draw weight increased. it just increase draw weight and not increase arrow speed(elasticity)?
you said prestress fiberglass but it looks just straight fiber. pre stress means just lay fiberglass straight? no need to pull or stretch fiberglass strongly? just put fibers straight is enough? something like prestressed concrete?(rodlonq said) or just to hold fibers in the correct plane as the resin is poured(hunterguy1991 said) http://www.ozbow.net/phpBB3/viewtopic.php?f=34&t=14869
most of fiberglass lam is unidirectional but i saw fiberglass lam(Gordon Bo-Tuff E Glass ULS - A continuous unidirectional "E" fiberglass laminate combined with a 50/50 woven fiberglass inlay (scrim) that has high strength and stiffness along the longitudinal (0) axis and provides cross strength (90 degrees to the longitudinal axis). Available in .043 & .050 clear, .040 & .050 black & brown, and .60" black. Sanded 1 side. http://www.gordoncomposites.com/products/TDS/GC-70-ULS.pdf
and
Uni-Weft Glass - A continuous unidirectional "E" fiberglass laminate with 90 degree fiberglass inlay. This combination not only gives high strength and stiffness along the longitudinal (0) axis but also provides cross strength and stiffness 90 degrees to the longitudinal axis. It provides increased limb stability where thin or narrow limb design is used, with the addition of a color stripe through the limb when red or black is used, as viewed from the edge of the bow. Available in red, black, and natural. Sanded 2 Sides.) that add fiberglass inlay 90 degree to improve torsional rigidity. but in the link here
http://www.ozbow.net/phpBB3/viewtopic.php?f=34&t=14869
the woven glass tended to break down due to the friction of the crossed woven fibres against one another resulting in the fibres being severed
what is correct? use only woven fiber cause friction but mix ud fiberglass and woven fiberglass is ok?
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Sorry for the delayed reply, have been having eye surgery and have been partially blinded for a week or two.
Okay, so you've asked a lot of questions and raised a lot of points, I'll do my best to get through them one by one.
"Here in Korea there is not much bow building meterial" - you have plenty of good material in korea! Korea has one of the oldest & strongest archery traditions in the world, I wouldn't discount your local bamboo & timber combinations available.
"Do i need Colloidal Silica?"
"Why thickening resin? what is gap filling? what's the advantage of gap filling and thickening?"
The silica just acts to thicken the resin, otherwise the resin is too thin (like water) and will flow out of the joint. For a long time I didn't use silica and it still worked, but I had a higher failure rate. Gap filling properties refer to the epoxy filling gaps between the surfaces, whether at a micron level or up to fractions of an inch. It just helps the bond make up for any imperfections (even at a very, very tiny size) in your preparation.
"what is the difference between bow making resin(like smooth on) and normal epoxy resin? concentration(thick) and gap filling?"
There is many, many different epoxy resins out there, Smooth On is just one - one that is very strong & very thick/goo-ey. The thickness/goo-eyness is what gives it the gap filling properties. Epoxy Resin tends to be stronger than Polyester Resin, which I wouldn't advise using. While Smooth On is a great product, it's not easy to get everywhere in the world while other epoxies are. Generally speaking, any epoxy compound should be good enough to used at some level, but for high end bows make sure you've experimented with the compound previously. To make it clearer, the difference between an epoxy resin and an epoxy glue is really only the viscosity/thickness/goo-eyness.
"how about make fiberglass lam like this?"
This is, basically, similar to the way I outlined using roving in the post on page 2 with the bad MS Paint picture. I would strongly suggest that if all you have is roving, you give that a try. If I had access to roving easily, I would probably be doing it that way.
Colloidal Silica and aerosil or fumed silica is same?
They fulfill the same purpose in this application, but they're not the same.
in the link someone says Laminating fiberglass to wood it can be used without thickeners, but for wood to wood I would use one of the above agents to prevent gaps. is that true?
Yes, it's basically what I've been saying through this entire thread.
and what about epoxy bendability or flexibility?
It's not the epoxy doing the work, it's the fibreglass & wood. The epoxy is just the glue. Bear in mind that, for bowmaking, the 'flexibility' and 'bendability' are not a big deal, this is more for the aeronautical industry with huge bending wings and things like that.
talc is cheaper than sillica can i use talc?
Maybe? I'm not an expert, I've just experimented with a few things and have some experience in some other industries. I would say it should probably work for this application.
how about milled fiber glass?
This is colloidal silica. Silica = glass, colloidal = ground up very small.
in the video he says milled fiberglass give epoxy strength and flexbility
Kinda, sorta. Yes and no. There's a lot of other variables.
you said fiberglass cloth won't be doing any 'work' when the bow is drawn, it will only be stopping splinters lifting. but when I added fiberglass cloth, draw weight increased. it just increase draw weight and not increase arrow speed(elasticity)?
You've increased the second moment of area of the limb, so yes, you've increased the draw weight. Does this increase the draw weight as much as a proper prestressed lam? No. You could create a limb using only cloth & resin by building up layers of cloth impregnated resin and it would work. When I used the term "Work" in my original post I was referring to "Structural Work", which is an engineering term.
you said prestress fiberglass but it looks just straight fiber. pre stress means just lay fiberglass straight? no need to pull or stretch fiberglass strongly? just put fibers straight is enough? something like prestressed concrete?(rodlonq said) or just to hold fibers in the correct plane as the resin is poured(hunterguy1991 said)
Prestressing means the fibreglass is straight and all in the same direction. It also means that any slack, or looseness, in the fibre is taken up already so that when it is put under load (as the limb bends) it immediately begins storing energy efficiently, like prestressed concrete. Basically, it's what they both said.
what is correct? use only woven fiber cause friction but mix ud fiberglass and woven fiberglass is ok?
A mixture of the two is better than only using woven cloth, but unidirectional on its own would be preferable. To be honest, using fibreglass cloth directly on the timber as a backing is as efficient as using drywall tape, or brown paper bags, or silk, or linen, or something like that. Even rawhide, maybe. The guy who said "the woven glass tended to break down due to the friction of the crossed woven fibres against one another resulting in the fibres being severed" is correct, but you'd need to shoot the now several hundred thousand times for it to be an issue. He tends to have a very high standard for bow construction, despite not building bows himself. He is also very interested in very fine details, which is great for him, but very different to my approach of just getting the job done and learning new techniques.
Going through your posts you seem to be getting a lot of stuff very confused and mixed up. While this composites stuff isn't real easy, it's not real hard either. I do appreciate that English is not your first language though.
If you want to understand about why to prestress the fibreglass do some research into prestressed concrete - the idea of a matrix of concrete/resin and steel/fibreglass are the same principles. Look at some engineering texts or websites on this.
Don't get hung up (a phrase in english that means "interested too much" or "focused a lot") on the details. Ultimately, all these ideas will work, it's just a matter of how well and with what finish at the end. The best advice I can give you is to buy some materials and start experimenting. Or do an Engineering degree. It's cheaper to buy the materials though.
You should also read www.poorfollbows.com. (http://www.poorfollbows.com.) While Sam Harper doesn't make his own fibreglass lams and the only epoxy he uses is smooth-on, his approach to bow building and way of thinking about what he is doing will teach you a lot about how to move forward with your own bow building. I strongly advise you start with something simple, like a simple board bow, and move up to more complicated bows with fibreglass and wood lams, or bamboo backings after you've got the basic skills & understanding of how a bow works correct.
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Sorry for may bad English. I can't express exactly what I want to say...and thank you for reply.
you mean poorfolkbows.com? I know that site already. I learned lot's of information from that site.
By the way I found interesting information about making fiberglass lam on russian archery forum
http://www.bowmania.ru/forum/index.php?board=24.0
you need register
http://www.bowmania.ru/forum/index.php?topic=1480.0
I used russian translator
http://www.youtube.com/user/vasilenkoivanv/videos
youtube videos
part1 - part5
In part2 1:40 he mix something on epoxy resin.what do you think it is? It looks like thinner(acetone?) to me. If it is thinner i have question. thinner makes epoxy resin weaker?
he made many bow with his own fiberglas lam
http://www.bowmania.ru/forum/index.php?topic=7029.msg206104#msg206104
http://www.bowmania.ru/forum/index.php?action=profile;u=5140;sa=showPosts
and this is other question. do you know what is set and string follow?
I searched on the forum but i can't understand exactly. it seems that people has different definition. and why using these terms? what for?
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Interesting thread and I have a bit to add. I have made up pre-stressed carbon laminates for building a bow. I really like the look of 90-90 weave set on a bias and know it adds almost nothing to the performance of the bow. It does add torsional rigidity to the limbs but the resistance to bending along the limb is minimal.
What I did was add CF rovings. The bits were laminated on a waxed glass door to get the smooth look. The rovings were stretched on a jig made from wood with two combs attached to turnbuckles, One comb at either end of the jig and each comb had two turnbuckles. The combs were three rows of finish nails offset to keep the rovings aligned with minimal gaps between threads. The rovings (tow) was 12k.
The weave was braid I slit into a single flat width which was laid down on the glass and wet out. Next, the jig was set into place so the stretched tow was on top of the open braid. The next layer was release film, breather cloth to soak up excess resin and allow the vacuum to be even. The breather also acted as a barrier to keep the edges from piercing the 4 mil. plastic drop cloth used to cover everything. The 4 mil. plastic was held onto the glass door with low grade caulk to seal it in. The vac hose just ran under the 4 mil. The vac held to 22" hg. until the resin (West) was cured. After cure the lam was ripped into1.75" strips using an abrasive cutoff wheel. It came out pretty good and has not yet been used on the bow. Still making the press and will fill you in when it is done.
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It would be nice to see some pics of your setup. Sounds very intresring.
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After the press is built I'll lay up another set of the CF pieces and take photos. The setup is cumbersome as it involves a full sized sliding glass door and my shop is really small.
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Hi guys!!
Let me re-open this ancient thread to show my experiences with fiberglass...
Your help was really decisive. :)
My work its still not good. Some times I have bubbles in the strips other times dry spots, but with time and experience I think could be better.
Let me show a strip that I've made with unidirectional carbon:
https://www.youtube.com/watch?v=IQz3P29z_N4
And here, I shred the bi-directional cloth to get unidirectional fiberglass and I did a bow with it (picture and build-along in video):
(https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xfa1/v/t1.0-9/1175307_913826942002594_2097424826363982382_n.jpg?oh=1f2cb53e1970c0a0b9081ff0c498f3fe&oe=557B2063&__gda__=1435525427_76f8c7cb724c563e4bdfe83c2fd668f1)
https://www.youtube.com/watch?v=8u5EAAd4SrA
Here is one way that I did:
(https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-xft1/v/t1.0-9/11008824_944513865600568_7756016474304800543_n.jpg?oh=615f25a8f8c0a8217c0c95df0fdde35c&oe=55CCE79C&__gda__=1439462166_07bbbf53806033d3ef3f16827f9f3a17)
(https://scontent-gru.xx.fbcdn.net/hphotos-xap1/v/t1.0-9/11173390_944514072267214_5821286329844624697_n.jpg?oh=6582450cbd6688e7f52db1be4bd87993&oe=559F86AE)
(https://fbcdn-sphotos-f-a.akamaihd.net/hphotos-ak-xfp1/v/t1.0-9/11159464_944514478933840_1798746717690705676_n.jpg?oh=9f3ad3e6a7e7b1046c15a461ab7e2dd9&oe=55DC3449&__gda__=1440834240_ac09e5e45c3eea34bf34ab9145642e08)
(https://fbcdn-sphotos-d-a.akamaihd.net/hphotos-ak-xap1/v/t1.0-9/11075719_943848872333734_3116549636291999188_n.jpg?oh=004f74d58606b1a8387963d4129c17d0&oe=55DA3D32&__gda__=1436102126_5bbac2438c8fc65dc160d474c6f65b5b)
(https://fbcdn-sphotos-f-a.akamaihd.net/hphotos-ak-xpf1/v/t1.0-9/1896894_943848902333731_7278383973395514475_n.jpg?oh=6a74be4373bfb8ead2c708648b588096&oe=55D49C29&__gda__=1439365352_a197fcc705f1076d294050d55cb1f52c)
Hope you like... ;)
Cheers!
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I'm assuming you've made bows before? Because that is a really, really well made takedown bow there... Good job!
As far as your laminates are concerned, they seem to be pretty effective. You've certainly got a fairly good finish on your outward facing (ie, back) side of the laminate, that side being the most important for uniformity.
I see you haven't tensioned your carbon - this shouldn't be a problem, as carbon is far less elastic than glass and the way you've made it should have similar properties to using tensioned glass. Or similar enough that I wouldn't worry about it. If you were to use glass I would recommend tensioning it before applying the resin. Also, you might want to aim for a thicker laminate, which would require using more resin in a form with sides to it (so the resin doesn't flow away). The thicker the laminate, the more work the composite materials do.
What's the rest of the bow? They're very nice timbers and you've done a really neat job with it. I'm very impressed!
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Thanks Neil... :)
Yes, I did some bow before, but only english longbows or wood bows... without fiberglass.
I'm working in another one now for me: A recurve with reverse riser.
This one will use the carbon ( those in the video and photo ) as a core-limb to reduce limb weight and get a bit more speed. :)
In the backing and belly I plan use fiberglass ( Gordon's fiberglass - I have a couple waiting for use ) :)
So I'll need sand the both of sides of carbon's strips to glue well.
Take a quick look
Riser:
(https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/11188431_947877191930902_6740254779680209448_n.jpg?oh=950e8c7a37f66a69afcdf3d6796d3589&oe=55D5F961&__gda__=1440159961_2f6d32051eeb0f1d10edd20e89f84a4b)
Form:
(https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-xat1/v/t1.0-9/1907655_947877205264234_747486953395081889_n.jpg?oh=51cae23b2ab890aa37414422048f4e2f&oe=55C0823C&__gda__=1439569791_e240dd59a7fd2f135e7f514feb2f603a)
Limbs:
(https://scontent-gru.xx.fbcdn.net/hphotos-xpt1/v/t1.0-9/11150361_947877351930886_7272056710588524367_n.jpg?oh=28500df0d1694e7c8fa9f842e1abbec6&oe=55DFBCBA)
I didn't used a form this time with Carbon, but in the take-down I made in the same way as you explained. I put the fiberglass in a iron mold with 'U' format with clamps in the tips. :)
I used in riser a wood called here: "Peroba Vermelha"
Link: http://en.wikipedia.org/wiki/Goupia_glabra
And in the limbs: Jatobá;
Edge: Jatobá + Grapia
http://grapia.mmcparket.com/grapia-en.htm
Grapia is a very good wood for limbs too... :)
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G'Day TDonald, your question isn't really within the 'Trad' remit but I'm sure no-one will object.
I've never gone thicker than 1/8" for my lams, nor have I tried using multiple lams in a stack. Doesn't mean you can't though.
The simple equation would be to multiple all my quantities by a factor of 6 (for a 3/4" limb) and lay up in the same manner I do, but I've a feeling it would come out a little thin. That would also be 24 layers of glass cloth, all pretensioned, which could be laborious to say the least. You could use chopped mat in the centre, potentially, as this would bulk out the space between the outer sections (where the work is really done) but I'm not sure I'd want to take a risk with that quantity of material, to be honest. Another option would be to use a flexible core material with high shear strength, but I'm not sure that would be 'compound traditional' - I don't know a whole lot about how they're made. Whatever you do you'll want to use a dye in your resin - at that thickness you won't get a good looking, clear product.
Hope that helps! Your undertaking an ambitious project... I hope you've used composites before...
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Elison.....................
What if I sent you a couple pieces of 1 1/2 X .040
black glass? Would you have to pay the import tax?
James
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Thanks for deleting the posts from TDonald, admin.
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James, In this case ( a physical person sending to a physical person) will be not taxed in products declared under $50. But if I buy for a company ( like bingham, 3rivers, etc ) will be taxed 60% of the product and shipping value.
Supposing a couple cost $40 + $20 (shipping) + $36 (tax)
40 + 20 + 36 = $96
If in this context you apply that here in Brazil the minimum wage is about $233 (month) you'll see thats a little complicated importing to here.
What I made one time was talk to others bowyers here and buy 55 strips together directly from Gordons. It worked fine... for that time. But a few months ago I tried contact to Gordon again to buy about 100 pieces in the same way, but they loose the interest and suggest us to talk to bigham.
So, we got in big trouble. :(
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I'm thinking about having a go at making some unidirectional carbon lams at some point and this thread has been very interesting. Thanks!