I thought about putting this topic in the "bowyer's bench" but chose not to because it was about making a bow with my son more so than how to make a bow. My son will be 5 years old on the 30th of this month...and I want him to have a bow made by "Daddy." I figured some other Dads could appreciate the post.
My son and I made a very light weight form with a very simple method that I have never used before...and I honestly think this is just a cool little light weight form. While I personally use a heavy duty high pressure 2 piece form on my Protege Longbows, the "rubber-band form" certainly is sufficient. I chose to use this simple form this kid's bow form since kid bows generally have less stresses in them (given their low pull weight and short draw).
The coolest thing about the rubber band system form is it is VERY SIMPLE. Being "one piece," it doesn't have to withstand heavy external forces acting upon it...as all stresses in the form are all internal in a rubber band form (counteracting one another) and the form itself doesn't need to be heavily reinforced in order to stay true. In this case, less materials meant simplier and less expensive construction.
That said, this inexpensive and simple form has come out SURPRISINGLY NICE! I must say, I like it a lot and I can see why this type of form is so well liked by some hobbiest bowyers. The total cost to make this form was just a few hours, little materials, and was probably only a $50-60 investment. (In comparison, my other form cost me much more time, more work, as well as several hundred dollars to make).
While I personally wouldn't use a rubber band type form for producing "top shelf" bows or bows with heavy draw weights, I can tell that if it is well crafted it is certainly capable of being a great form and I am sure one could produce excellent bows with such a form.
I will post some pictures of it hopefully this evening with my son being involved in the process. It isn't going to be a "build along" necessarily as we didn't get enough photos to cover that...but we have enough to get the idea across I think. In the end, it was about quality time between a dad (me) and his son (Conner). I hope this topic motivates a few others to make a bow for a kid.
I'd like to see what it looks like. Hap
Do a build along, on the bowyers bench!!
Would love to see it happen.
Johnny/JAG
Look'in forward to the pics and details.
We have a lot of kids in our church shooting and just need more light weight bows. Thanks
Here are a few pictures of my son and I working on the form. Bow pictures will be posted soon when it is completed.
(http://www.protegelongbows.com/ConnerMakingForm.JPG)
(http://www.protegelongbows.com/ConnerMakingFormpic2.JPG)
(http://www.protegelongbows.com/ConnerMakingFormpic6.JPG)
(http://www.protegelongbows.com/ConnersBowGlueUp.JPG)
I'm gonna send you a PM.
Excellent!!! :thumbsup: :clapper:
pretty special, lee. :notworthy:
Thanks guys. Here is one more photo I overlooked. I will post some pictures of the bow soon.
(http://www.protegelongbows.com/ConnerAndDaddyMakingForm.JPG)
Additionally, I want to take the opportunity to clarify something just to prevent any misunderstandings as to my views on this type of form. First of all, I want to say if I thought this type of form was insufficient, I wouldn't use it...not even for a kid bow.
I think the MOST important things in a form are...
1. Good design and
2. Good craftsmanship (general overall precision, balance of design for good tiller, good matching of materials for proper fit/glue up, and of course being square for good tracking to reduce torque).
Both of these things can be obtained with this "simple, inexpensive, and light weight" form. The ONLY reason I believe a heavy duty, highly reinforced form is superior to this type of form is because with a heavily reinforced form one can use a high pressure system for glue up. I BELIEVE a high pressure system is able to obtain tighter glue joints. By "tighter," I am not referring to "fit" (which comes from detailed craftsmanship to match up parts) but simply referring to the amount of pressure applied on the materials during glue up. More pressure shouldn't be how one obtains fit, but it can be used to drive more epoxy into the pores of the materials (which I believe may result in a stronger bond) AND high pressures will likely squeeze out more excess epoxy to the sides (therefore minimizing limb mass). These two minor gains that I BELIEVE are obtained by a high pressure system may be minimal and may not be a real concern, but...I have my own "insecurities" so I tend to side on overkill when in doubt in order to error on the side of caution. Maybe I suffer from ADHD and OCD though. LOL.
On my high pressure 2 piece forms, I tend to glue up at about 100 psi...which means I use a total of about 12,600 pounds of pressure over the entire form (100 psi x 72" long x 1.75" wide). I think 60 psi is about standard for a air hose system, but I was trained to make some modifications in a pressure system form that allows one to go up to 120 psi without any problems...and probably higher should one choose to do so...but I don't. I stop at 100 psi because I feel that is way more than sufficient. To obtain that pressure, I not only clamped my end caps in my hose, but the caps are also permanently epoxied into place as well. A good friend of mine that uses high pressure air hoses professionally informs me that with the hose done this way, one could go up to pressures MUCH HIGHER than this and that there is no safety concerns of and end cap blowing out. For my two piece high pressure form to withstand that pressure, I would say it is way over built. I call it the "back breaker." LOL. It is very heavy plus it is encased in 3/16" of steel from end to end to prevent flex. It wasn't cheap or easy to make...nor is it convenient to use. In other words, it is not nearly as "simple" or "cool."
That is why I LIKE the rubber band system form. It is so easy to use. It can obtain the most important criteria of a form...yet still be user friendly...as it is much easier on the pocket book, much easier to create, and much easier to use. It is a good form and I wouldn't want anyone to think I am saying otherwise. That is why I called it "simple" and "cool."
That's awesome. That will definitely be a special bow for both of you. Thanks for sharing the pics.
Updated "roughed out" pictures...Still need to finish it out and put the grip on it. It is just under 42" NTN.
(http://www.protegelongbows.com/ConnersBowroughedout.JPG)
(http://www.protegelongbows.com/ConnersBowroughedoutpic2.JPG)
Strung up...(the brace height is a little high here, but it illustrates tiller somewhat IMO)
(http://www.protegelongbows.com/ConnersBowroughedoutStrungUp.JPG)
Tip overlays are made from excess limb materials...the part cut off. The portion used for the overlays only consisted of clear glass and bamboo. Not much of an overlay...but plenty for a 15# bow. He will use dynaflight97.
(http://www.protegelongbows.com/ConnersBowlimbtip.JPG)
Very nice
Nice!
grats on the project! That's really special.
Thanks guys. I will make him another one later some time this summer. I definately like the high pressure system more than the rubberband form, but it is indeed capable of making a good bow. When I look closely at it, I can see the belly side has a few VERY SMALL knat sized air bubbles in it. There are only a few, but I have never had that problem with my high pressure form. Of course, that is what "test runs" are for. In the bow above, the belly lams are actually "packing strips" that were tapperred at 0.002" per inch. They had "packing strip" stamped on them on one side (which I turned inside). I don't even know what kind of wood those packing strips are, but they were ground good except on the butt end, so I cut that off, which made them about 24" long by the time I removed the "bad spot." Other than that, they were basically good so I put them in this bow for a "test run" just to test the form. Those packing strips kind of look like yew under the glass (now that they are in the bow), but I am confident they are not yew. I will photo the belly and see if someone can identify that wood. There are no bubbles on the bamboo (back side), which leads me to believe my form is good, and that I only need to increase the pressure during glue up.
Regardless, I am sure this bow is good to go and will be trouble free. There aren't any significant issues really. It just isn't "perfect" so to speak. A few more extra rubber band (inner tube) straps and some C-clamps should solve any "low pressure" issues. I was afraid to put too many straps on the wooden pegs, as I didn't want to break them, but if I keep the straps in close to the form and also use some C-clamps I am sure I can get more pressure on it.
Daddy's boy has to have one that is personalized and perfect...as I want him to keep it as a wall hanger once he outgrows it. 8^)
What a great project for your son.. Thanks for the post :)
:coffee:
Just a question after reading you post about this style of glue up and high poundage bows, what would you consider to be a high poundage bow made from a for like this? In relationship to the high pressure, high dollar form?
I've made all my bows on this type of form, and have no problems getting plenty of pressure. Lee, you are the only bowyer I have ever heard of using that much pressure. How many have you glued up that way? I do believe you can use too much pressure and starve the joint, but I could be wrong. Here is an example of one of mine glued up. I use lots of rubber! I've never broken a dowel, rubber strip, or had a bow failure. I haven't built as many as some have, and the heaviest bow I've built was 75@28.
(http://i121.photobucket.com/albums/o203/Apex-Predator/Bow%20Building/6-12-10-10.jpg)
Stringstretcher,
I do NOT have enough experience with the rubber strap types of forms to comment as to their capabilities or limitations. They very well may be capable of producing a glue up just as solid as a high pressure form. With as much rubber as Marty used, they may have as much pressure in them as a typical air hose/high pressure form. I noticed in Marty's picture you don't see ANY of the belly on that bow. If you look at mine in the hot box, I didn't completely cover the belly with rubber. My fear of limitations on this type of form is NOT from fact, but is a result of MY lack of experience with using one piece forms...but I certainly find their concept very user friendly. Someone such as Apex Predator (Marty) would be much more qualified to address your questions as to what this type of form is capable of. Next time I will use much more rubber. Does it matter that I made that error on that first bow? No, not really. It was educational and I am confident that bow will be fine. It turned out nice, just not perfect...but it isn't something I am selling and it won't have to endure much tension and/or compression since it is only 15#@18" draw. I came out good in the critical areas (the fadeouts and overall limbs). I also noticed a glue line on the bow that is about 0.010" on the curve the glass had to follow on the BELLY side of the riser right next to the grip, but again that would have resulted from not having enough pressure on the bow during glue up. I am being very critical though, as I don't want to see a glue line at all. I have actually seen thicker glue lines on some adult bows that receive regular use to be honest. Given the excellent fit on the backside of the riser and bow, I am confident that the form is good and if I had used as many straps as Marty is using in that picture above, everything would have been better in my son's bow...so again, on the next one I make I will fix that. I also see Marty has a C-clamp on the riser. I ran my belly glass over the belly of the riser, so I might skip the C-clamp aid for now, but I will AT LEAST use much more rubber. I will post some close up photos when I am done to illustrate what I learned...and if you like I will update this thread when I do a "2nd attempt" to see if I solved the issues I observed in my "1st attempt."
As far as "one piece" forms go...I know some EXCELLENT bowyers use them. I believe Chris Cox (Habu bows) and Howard Hill Archery use them (at least they use to) but both used C-clamps instead of rubber. My reason for using rubber instead of C-clamps was because I MYSELF didn't know how hard to twist the clamp in order to obtain a desired pressure on the bow. I didn't want to have INCONSISTENT pressure that resulted in "pressure points" as I feared that might crack the belly glass. Chris Cox, IMO, is probably one of the best bowyers out there but IF MEMORY SERVES ME CORRECTLY he has some way of evenly distributing C-clamp pressures. I think he had 2" blocks on top of 1/4" thick rubber pressure strip, but I am not certain about that...as it has been many years since he and I spoke on that matter. Please do NOT take MY INCOMPETENCE with this type of system to mean/represent the inabilities of this type of form in general. It is just I MYSELF am not versed in them as I am with the high pressure air hose/2 piece form.
Marty,
I have certainly not made as many bows as you have. I only started making bows last October. My reason for becoming a bowyer was motivated by my experience as an archer...as I have come to prefer certain characteristics in a bow...and I wanted it done my way. Not to say my way is the only way or the best way...but it is the best I know of for ME. I wanted a bow that met my criteria, so I asked Gary Sentman to teach me how to make a bow. Gary, my mentor, had about 3 decades as a professional bowyer and he has certainly made a few thousand bows...and MANY bows well over 100#. Remember, he was known for setting the world record 176# bow back in 1975, so many people that wanted heavy bows would call him up. He informed me he generally glued up at 100-120# psi and told me to do the same. He taught me how to reinforce my form and air hose system to sustain such pressures. That said, I actually stop at 100 psi on my form. With a properly assembled air hose and a highly reinforced form that has CONSIDERABLE brackets (not the 1" ones you can get in a kit that by the time a 1/2" hole is drilled into them you only have a 1/4" on each side of the bolt holding thousands of pounds). If these extra steps are made to "beef up" things, then the process goes really well, except for having to move that 100# beast around. I have never had a single air bubble in any of our bows. That is why I called the heavy form the "back breaker." The only problems I see with using this much pressure is one BETTER have a super clean slick surface. If you have a grain of sand on the form, there is a good chance it may leave a mark/dent on the bow and we obviously don't want that. I clean my form and wax it with a paste every time I use it for that reason. Plus, that helps to remove the bow after it is cured.
As far as a "starved" glue joints are concerned...starved to me means empty...an area void of glue...and I would speculate that is a result of either not having enough glue on the bow or actually not having enough pressure on the bow. One of those two. I don't think pressure will squeeze out all the glue. In contrast, I think it can drive epoxy into tiny pores that otherwise might not be penetrated by the epoxy. I think pressure eliminates "pockets" and voids. In other words, I actually think low pressure was the reason I got the few gnat bubbles I got in that youth bow. I think with more pressure, I would have driven the epoxy into all the tiniest pores more efficiently.
Marty and Lee,
I used the rubber band system for many years, many years ago. It's a fine system. However, I found through use, that many clamping systems are a fixed pressure system, meaning that whatever pressure you start with, that degree of force applied to the glue joint isn't adjustable once the glue heats up and gets runny before it starts to cure. C-clamps and such are this type. Rubber band systems actually adjust tension as the glue heats up, but then they lose tension due to heated/softened rubber. The speed at which the epoxy 'sets' is what saves the day most of the time. I prefer a clamping system that applies more pressure as everything heats up and gets soft...ie changing pressure as needed. I get better glue-ups this way. But to each their own, that is what makes it all good.
Also, I found when using the band system, a pressure strip that was slightly narrower than the form allowed more pressure on the glue joint, because you lose pressure from the band as it goes over the edge of the form, creating air bubbles... make the pressure strip about 1/4" narrower than the form so the band can apply more pressure to the middle of the limb....
Sunset,
Do you use an air hose system? You didn't say what you are using now. While you didn't directly mention that the air hose system actually increases pressure when heated, I believe you are referring to that based upon what other option is left that could increase pressure once everything is warmed up?
I have opened my hot box on my personal bows during glue up to see how things were going and have checked the air pressure...because I know heat causes air to expand and I was curious as to how much pressure was gained by the heating of the air hose. I don't remember how much it changed exactly, but if memory serves me correctly the pressure didn't increase as much as I expected it to. I do like the fact that it doesn't reduce pressure though.
Lee,
the air pressure system doesn't increase pressure much because the hose is trapped and can't expand much which is good, because pressure isn't reduced. I use a type of metal spring clamp form, which keeps pressure continually adjusting as components heat up and get soft, the springs clamp down more...essentially the same result as the air hose system....
According to this link... http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=73
A "general rule of thumb" as they put it is for every 10 degrees F change in temp, the psi is altered by only 1 psi. I am sure that isn't an exact correlation, but if it is relatively close that rule would be very simple and convenient to use.
So, if I inflate to 100 psi at 80 degrees...and then "cook" at 160, then the pressure in the hose would increase 8 psi...making it 108 psi total when at 160 degrees.
As I said, I don't remember exactly how much change I saw, but I would say it was probably pretty close to that "rule."
Lee,
I am very convinced that your system works for you and your fine bows. I only wanted to share that the rubber band method can, and does work extremely well for the "hobby" bowyer. I have thought of changing my methods to make things quicker and easier, but always balk at the idea. I'm not a "production" type bowyer, and never will be. Personally, I like to build them one at a time, where no two are the same. The design characteristics are the same for a given model, but I won't build bows in a "quicker and easier" fashion. As a result, I will never be a "big time" bowyer, as I prefer the simpler "hands on" approach to each step. There are many steps that a bowyer can take to save time, and they are not bad, just not for me.
The pressure strip is key in the rubber band type form. I start with a piece of aluminum that I can bend to conform to the fades of the chosen riser, which is either 1/16" or 1/8", depending on the model. I glue rubber to the bottom and a piece of pvc lattice to the top to make sure the epoxy is forced out from the center to the edges. With a pressure strip the full width of your lams, it has a tendancy to bow up in the middle. The narrower lattice prevents this. Here is an example of my pressure strips.
(http://i121.photobucket.com/albums/o203/Apex-Predator/Bow%20Building/4-10-09-1.jpg)
(http://i121.photobucket.com/albums/o203/Apex-Predator/Bow%20Building/4-10-09-2.jpg)
(http://i121.photobucket.com/albums/o203/Apex-Predator/Bow%20Building/4-10-09-3.jpg)
To make money in bowyering, you have to streamline the process. I will probably never make money in this endeavor! :) The guys making money selling bows, are not making much, cause it's still a "labor of love"! :)
Where do you get the rubber for that type of form? I like the concept, but can't think of where the rubber might come from.
I get mine for free at the local bicycle shop. They throw out all the ones they replace. Nothing wrong with them, usually, except a pin hole, which will not affect them for what you need them for. I cut them into length-wise strips. On a fat one I may get three strips, but normally only two. I like them to be around 1 1/4-1 1/2".
As mentioned, my two piece high pressure form weighs about 100# reinforced like it is, so it isn't used for convenience. I use it on my protege longbows though because cumbersome or not...it offers me a great deal of precision and quality and it works perfectly for me.
That said, I would like to use the rubberband system on my "youth bow" form, so your tips on the pressure strip are much appreciated. When I do a second attempt, I am certain those tips will help. They make a lot of sense. Thanks. I will keep you posted...unfortunately it may be a while before I have time to make another personal bow (for the family), as I need to first take care of some custom orders from some much appreciated customers.
Marty,
Is the rubber on your aluminum pressure strip inner tube rubber also, or is it some other type? It looks thicker. I am sure those tips will help me make my son a better bow without going through the trouble of making a high pressure form for his bow's layout. I will post some pictures of my heavy form if you like. It isn't near as simple, but it does work great. Maybe you will see something you can use should you ever decide to go that route.
Marty,
Your form looks really similar to the one I have put together.
I understand that the pressure strip is the key to the "rubber band" method. Where is it you get the aluminum and stick-on rubber?
Do you buy a whole 4X8 sheet of the lattice and take it apart to get those pieces?
I hope you truly beileve that "Imitation is the purest form of flattery" because I am TOTALLY swipeing your glue-up process. I'm never gonna be any competition in the bow market. I just hope mine turn out half as good looking as yours.
OkKeith
The aluminum,lattice, and rubber can be found at Lowe's. The lattice can be bought in singe strips in the trim molding section. The rubber comes in 4' lengths, is about 5-6" wide and is used in tile flooring jobs. I can't remember what it's purpose is but you can find it if you look.
Apex, you just answered the question I have been trying to get at about the "mound" on top. Makes perfect sense to me. My for will be make just like yours and I am sure it will be all I need. Just one question. On the bottom of your form, do you also use a pressure strip with rubber of just glue down directly to the form?
Mine have an aluminum strip glued straight to the form, which averages out any imperfections in the surface of the form. On top of the aluminum I add another piece of hard rubber.
On top of both of my forms (my protege longbow form and my youth bow), I used a piece of formica for the same reason Marrty uses the aluminum/rubber. On my high pressure form I don't use rubber, but I wouldn't object to using a thin piece on the belly side (which wouldn't be on the form). I fear any loss of precision (I believe I am within micrometer accuracy and balance on my form's limbs). I spent a LOT of time and measurements putting extreme precision into my form. I try to keep that as smooth as possible to as I don't like that idea of anything reducing the precision I put into creating my desired profile. I also have a fear that heat strips cause a loss of precision on the form and don't use them for that reason (I use an oven)...but that may be ureasonable on my part. The heat strips are convenient and quick, but I can't help but wonder how "flat" (consistent and even) they are under pressure. That is why I wax my form every time I use it...I want my bows to have a perfect surface.
Thanks for all the help guys!
I have learned quite a bit from these posts.
OkKeith
NICE,,,LOOKS GOOD,,,
Hi , this is old topic. New for me :)
i have two options
first options is
(https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-prn1/q87/s720x720/1238810_662254807118499_1013922770_n.jpg)
second options is
(https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-ash3/q77/s720x720/943598_4969929169230_1781895951_n.jpg)
I want to make bows, but as a hobby. I do not care no more than that. But I'd like to do it well and in the best way, I'm aware that there are many ways and that no one is wrong. But I'd do it in a way that has the least bad side. So I would like to hear advice