Author Topic: Robin bamboo build along  (Read 554 times)

Offline Sam Harper

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Re: Robin bamboo build along
« Reply #25 on: July 18, 2014, 12:11:00 PM »
I went back and forth on whether I should have a power lam or not.  On the last one-like-this, I used a power lam, but it turned out to be unnecessary.  Look how much the Osage tapers from the handle to the end of the power lam here.

 

I think I could've gotten away without a power lam.  But the starting Osage is slightly thinner on this one than on the last one, so I figured it's better to have a power lam and not need it than to need it and not have it.  Besides, it looks good, and going with tradition, I decided to make one out of walnut this time, too.

The original power lam was 15", but I made this one 13.5" because it fit more neatly between the blade and the throat of my bandsaw.  I'm going to make the glued on handle part 9", so that power lam will extend 2.25" past the handle on either end.

Here's the power lam all nice and tapered so you can see how thin I got those ends.

 

As usual, I didn't take any pictures of the glue up because I had glue on my hands and didn't want to handle my iphone.  But basically, I used Smooth On and put glue over all the surfaces, wrapped it in plastic wrap, put masking tape around it in a few places to keep it from sliding around, then put squeeze clamps on it.

I'm not using a form.  It's resting on a couple of pieces of wood near the middle, and I'm letting gravity give it a little bit of deflex.  Having some deflex will make it more stable.  By "stable," I mean less likely to have the tips twist one way or the other when it's under tension, which is harder to prevent with recurves than with longbows because recurves are inherently less stable than longbows, and by "stable," I mean. . . whoa, deja vous.

 

Can you see that string?  I thought maybe if I put a little c-clamp on each tip and tie a string between them, I could keep more of my curve than on the last bow.  Here's a close up of the c-clamp.

 

I used a broken arrow piece as a tourniquet to tighten the string.

 

I put that in the hot box, and I'm going to leave it on for 4 hours and probably not take it out until tomorrow or late tonight.
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Offline Sam Harper

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Re: Robin bamboo build along
« Reply #26 on: July 20, 2014, 12:21:00 AM »
All I did today was clean it up a bit with the bandsaw and belt sander.  Check how much curve it retained compared to the last one.

 

I'm pretty pleased with that.  Now, if only the tips line up.  I'll leave you in suspense about that for now.    :p  

I also went over the back and pealed off all the glue from the bamboo with a pocket knife.

 

It comes off pretty easy because the rind is waxy.  I'm going to take the rind off after I glue on the handle.
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Offline Sam Harper

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Re: Robin bamboo build along
« Reply #27 on: July 20, 2014, 12:34:00 AM »
Oh, here's one more picture to show it has a slight amount of deflex.  Gravity probably wouldn't given it more deflex if not for the string.  But it'll probably gain some deflex during tillering.

 
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Offline takefive

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Re: Robin bamboo build along
« Reply #28 on: July 20, 2014, 01:38:00 AM »
Looking good Sam!  Your bow's going to have some sexy curves, too   :)    I'm always thrilled when reflexed tips hold as well, especially after the bow has been shot in.
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Offline bigbob2

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Re: Robin bamboo build along
« Reply #29 on: July 20, 2014, 03:34:00 AM »
Watching with great interest Sam, looks great

Offline Mad Max

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Re: Robin bamboo build along
« Reply #30 on: July 20, 2014, 02:27:00 PM »
Looking good sam
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Offline Sam Harper

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Re: Robin bamboo build along
« Reply #31 on: July 21, 2014, 07:16:00 PM »
Today, I glued on the handle and tip overlays.  Before gluing on the handle, I took a piece of 40 grit sanding paper, wrapped it around a piece of wood, and prepared a place on the belly to glue the handle on.  The 40 grit makes a good gluing surface.

 

I decided to use a piece of pecan for the handle because I happened to have a piece that was just the right size, and I had nothing else to do with it.  Besides, I plan to put a handle wrap on this to cover up the splice on the back, and there's no sense using a pretty piece of wood if I'm just going to cover it up.

Since there was a bit of deflex in the handle, I couldn't just glue the handle straight on.  I had to curve it a little.  If there's a lot of deflex, I'll use the bow to trace a line on the handle piece and use that as a guide to bandsaw it to shape.  But there's just a tiny big of curve to this one, so I just used the belt sander.  Here's the before picture.

 

After some sanding and check and sanding and checking (which can be maddening if you're me), here's the after picture.

 

It's not perfect, but I'm going to rely on clamp pressure to take care of the imperfections.

Preparing a nice flat surface to glue on tip overlays has always been a struggle for me when making recurves.  This is one reason I prefer to make longbows.  But here's how I do it.

 

Sometimes I use the disk sander.  The only way to avoid digging into the limb of the bow on accident is to have that grind go through all layers.  In other words, I don't just sand the surface of the bamboo.  I sand all the way through to the belly wood.

 

Here's the handle and tip overlays all glued up.

 

I used Smooth On, but I'm not going to stick it back in the oven this time because I did that last time, and the Osage developed cracks on the belly.

 

I filled those with superglue and after hundreds of shots, it's never been a problem.  But I'd still rather not have them in my bow if I can avoid it.  I wonder if I could avoid this problem by wrapping the whole bow in plastic before putting it in the hotbox so it doesn't lose as much moisture.  I don't know.  But I'm just going to let this one cure at room temperature.

Perhaps I will post more tomorrow.
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Offline Sam Harper

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Re: Robin bamboo build along
« Reply #32 on: July 22, 2014, 12:55:00 AM »
There's a couple of things I forgot to mention.

First, I used Ipe for tip overlays just because I already had some tip overlay sized pieces ready to go.

Second, whenever I use c-clamps on bamboo, I use some kind of padding because if you don't, the c-clamps will put dents in the bamboo.  I use thick leather for padding.  Squeeze clamps don't have that problem.

Third, before gluing on the handle, I draw an arrow indicating the top limb.  I sometimes don't decide on a top limb until near the end of tillering, but I had to in this case because that splice is off-set with the intention of having most of it be under the thick part of the handle, and the arrow shelf being above it.  Drawing that arrow keeps me from making a booboo later on.  Or at least that's what it's meant to do.

 

Fourth, I forgot to show you the tip alignment.

 
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Offline bubby

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Re: Robin bamboo build along
« Reply #33 on: July 22, 2014, 01:10:00 AM »
sam I use a high quality super glue for my overlays, just hold it for a few seconds, no clamps, no problems

Offline Sam Harper

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Re: Robin bamboo build along
« Reply #34 on: July 22, 2014, 01:15:00 AM »
bubby, can you give me an example of a high quality superglue?  Like a specific brand, and preferably a link to it on Amazon?
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Offline takefive

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Re: Robin bamboo build along
« Reply #35 on: July 22, 2014, 03:01:00 AM »
This is what I like to use and I've heard it recommended by quite a few others.  The bond is amazing.  Just make sure that your pieces are aligned where you want them, 'cuz you only have a couple of seconds of working time.  

 http://www.amazon.com/Loctite-LOC1364076-Super-Glues/dp/B004MEXDH2/ref=sr_1_7?ie=UTF8&qid=1406012031&sr=8-7&keywords=loctite+super+glue
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Offline Sam Harper

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Re: Robin bamboo build along
« Reply #36 on: July 22, 2014, 10:08:00 AM »
Thanks takefive!
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Offline Sam Harper

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Re: Robin bamboo build along
« Reply #37 on: July 22, 2014, 12:40:00 PM »
This morning, I cleaned the bow up some more with the belt sander, got the handle and tip overlays flush with the rest of the bow.

Then I cut out the fades.  I really wanted to use this Bowie knife I'm working on to trace the fades because then I could tell people, "This fade matches the curve on my Bowie knife!" but because the handle is going to be so short on this bow, I wanted the curves to go up faster.

 

"Faster"?  That's not my usual way of putting things.  I suppose 2000 years from now, scholars may look at this and say, "Faster" is not a typical Samine way of wording this description; therefore, this build along must be pseudonymous.  (For those who didn't get the joke, I'm poking fun at how some modern scholars dismiss some of Paul's letters as being inauthentic.)

Where were we?  Oh yeah, the fade.  So I just drew a straight line where I wanted the fades to be, and cut that out with a bandsaw.

 

Then I shaped it a little with the elbow of the belt sander, being careful not to dig into the limb.

 

And that's all I had time to do this morning.

"But wait a minute, Sam, if you had time to update this build along, you had time to work on the bow some more."

Well, I did work on the bow some more.  I just meant that I didn't have time to do anymore updating on this build along.  I'll have time later today.
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Offline Sam Harper

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Re: Robin bamboo build along
« Reply #38 on: July 22, 2014, 03:24:00 PM »
Except for the fades, I leave the handle square while tillering so it sits in the tiller thingy better.  I'm going to go ahead and cut an arrow rest since I've already designated the top limb.

I'm just getting the bow ready to tiller at this point.  I rounded the tips overlays, too, but didn't fully shape them.  I'm going to cut string grooves and not fully shape them until the end.

I also remove the waxy rind before I tiller.  I've used various methods to do this with--a pneumatic drum sander, a piece of sand paper wrapped around a t-shirt wrapped around a piece of wood, and a cabinet scraper.  I've gotten to where I really like the cabinet scraper.  I didn't used to like it as much, probably because I wasn't very good at sharpening them.  Let me explain the procedure I use to sharpen my cabinet scraper.

First, I want to get the edge perfectly square and smooth, so I lay a piece of 320 grit sand paper on a slab of granite (glass would also work), lay the scraper on it flat, and move it around in a circular motion.

 

I do that on both sides, and I also do it on the edge.

 

You don't want to lean it when you're doing the edge because the idea is to get it square, like this:

 

Don't press down too hard when you're doing the edge because you don't want to deform it.  After I do the 320 grit, I do the same thing with 400 grit.  Lighten up on the pressure again when doing the edge.  You can go to 600 grit, too, and that might improve things a little, but 400 grit is good enough.

Then I clamp it in a vice and use a burnishing tool (a screwdriver would work), and rub it along the edge.  

 

Be sure to hold the burnishing tool perpendicular because you want to cause the sides to flare like this:

 

That's why you want to get it perfectly square to begin with and use a fine grit, so it'll create a good sharp edge when you burnish it.  If it's not good and square and good and smooth, it won't make a good edge.

I can't tell you how much pressure to use or how many times to stroke it.  You just have to figure that out by experimenting.

Once you've got a little edge (and you can feel it by pinching the scraper between your thumb and finger and pulling up to the edge), then tilt your burnishing tool and burnish a little more.

 

That makes your edge hook down a little like this:

 

Yeah, it's not the best drawing, but you know what I'm talking about.
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Offline Sam Harper

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Re: Robin bamboo build along
« Reply #39 on: July 22, 2014, 04:12:00 PM »
I used that scraper to remove the rind.  I saw a thread somewhere where James Parker questioned why people remove the rind.  I look up to James Parker as kind of a bamboo guru, and it sounded like he doesn't remove the rind. I still remove it, though, for a couple of reasons.

First, you saw how easy it was to remove Smooth On from the rind with a pocket knife.  Obviously, things stick to it very well.  It doesn't take a stain as well, and it doesn't take a finish as well.

But the rind actually has two layers.  The top layer is thin and waxy.  Right below that, it's white and not waxy.  I suppose you could just lightly sand the whole back, get rid of that waxy surface, and leave the white stuff.  It'll take a finish and a stain.  But I remove it (or most of it) anyway because. . .

Second, I believe the bow is less likely to break if you remove the rind.  There are no fibers running through the rind.  The fibers are in the layer directly below the rind.  The rind is kind of brittle, and if you leave it there, your bamboo will be more likely to lift a small splinter which will turn into a big break.

When you remove that white rind, it's a little darker underneath.

Since this build along is meant to be a review of this bamboo that Robin Tan sent me, I want to talk a little bit about it and compare and contrast it with the usual stuff I get at Franks or wherever.

This bamboo smells different than other bamboo I've tried.  Other bamboo I've tried smells like hay, but this stuff smells kind of funky.  I don't know what to compare it too.  Maybe a pot that's been left on the stove too long.

The rind of this bamboo has a consistency very much like the early growth layers of Osage.  If you've ever chased a ring on an Osage stave, you know what I'm talking about.  It's that kind of porous crusty layer that's easy to scratch off.  You can kind of see it in this picture.

 

So I would definitely not want that on the back of my bow.  Whereas I'll sometimes leave a bit of white on my bamboo, I took this completely off with the scraper.  Other bamboo I've used has ridges running along the length that leaves white streaks when you try to sand the rind off, but this was fairly smooth.

It's a little more difficult to remove the rind around the nodes.  The nodes on this bamboo were kind of funky.  On one side, there were two dips before you got to the node, and one dip on the other side of the node.

 

It was like that on all the nodes.  The double dips made it a little difficult to get the rind off.

Once I got the rind completely off, I sanded with the 320 grit, then the 400 grit.  I like the back to be nice and smooth, and if there are any nicks or scratches, I'll sand them out.

Another thing I noticed about this bamboo that is different than other bamboo I've used is that the area immediately beneath the rind is a lot harder than other bamboo.  It was actually easier to remove the rind on this bamboo than other bamboo because there was such a difference in hardness between the rind and the bamboo beneath.  I was basically just scraping crusty stuff off of a hard surface.

I was going to put some kind of cool dye job on the back of this bamboo.  I'm working on a YouTube video right now showing various patterns and techniques, and I was going to add this one to it.  But because it's so dark already and had some interesting colouring, I decided to leave it natural.

 

I'm a little concerned about it because it looks like water damage.  It looks like some spalted pecan I have, and "spalted" is a euphemism for "rotted."  It's pretty, though.

I have to go pick up a friend at the airport in a couple of hours, but I have time to work on the bow some more, so I'll probably post another update later tonight.

I want to say one more thing about the scraper before I go.  You might have to experiment on the angle you hold it at to see where it cuts the best.  It'll depend on how much you brought that edge over with the burnishing tool.  I don't bring mine over that much, so I get the best cuts by holding my scraper nearly perpendicular.  I guess I've got it at maybe a 60-something degree angle to the surface I'm scraping.

When you first start to scrap a roughly sanded surface, don't expect to get those nice little slivers.  You'll just get dust at first and question whether you got the scraper sharp.  Then, once the scraper has smoothed the surface down, you'll start to get those thin slivers, and that's when you'll know your scraper is working properly, and you'll start to enjoy using it.  It leaves the surface so smooth, you barely need sand paper when you're done tillering.  I just use the sand paper to smooth over the ridges from scraping different facets of the belly.

See you later!
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Offline Sam Harper

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Re: Robin bamboo build along
« Reply #40 on: July 22, 2014, 05:34:00 PM »
It's later already!  I'm still getting the bow ready to tiller.  I had to file in some nock grooves.  I used to hold the bow down with one hand and file with the other.  Here's a video showing how I used to do it.

 

That was especially hard to do with a recurve, but now I use a vice, and it's a lot easier.

 

I glued leather padding onto the vice for just such occasions.

I cut an arrow shelf about 1.25" above center.  It curves in at the top of the fade because I don't want to cut into the fade too much and weaken it.

 

People always ask me how far in they can cut and whether they can cut to center.  There are too many variables to give a tidy answer to such questions.  It depends on how thick your handle area is, how wide your handle is, what kind of wood/materials you're using, and how strong your bow is going to be.  Even if I knew all that, I couldn't necessary say.  I used to cut my shelfs really shallow because I didn't know what I could get away with.  I guess over time, I just developed a feel for it.  I have noticed on some of the bows I've made where I waited until the end to cut the arrow shelf that although the bow didn't break, it did cause an alignment problem.  Whereas the string might originally have tracked straight through the center of the handle, after cutting in the arrow shelf, it drifts in the direction of the shelf, which means the cut weakened it a little.  I've used that as a gauge for how far in to cut on subsequent bows.  For this one, it's pretty narrow already, so I didn't want to cut anywhere close to center.

 

I'll remove wood from inside there when I shape it later anyway, and it'll be closer to center but still not there.

I use my disk sander to radius the shelf.

 

I've been doing it that way for a long time because it's quick and easy.

 

I saw somebody somewhere use a template and a router to cut the arrow shelf.  I may try that some day.  I would think it would reduce the amount of work later on when you have to sand and use files to get everything smoothed out.

The last thing I do before tillering is round all the corners on the limbs on all four sides.  First, I run each corner down the elbow of the belt sander.

 

Then, I go over each corner with a piece of sanding belt and a block of wood.  My block of wood is rounded on one side so I can do the inside of the curve on the back of the bow.

 

That's all I do to the belly side, but I want that backing to be nice and smooth, so I use the scraper to smooth out the corners on the bamboo.

 

The belly side will get smoothed out more as I tiller.

No more stalling.  There's nothing left to do but tiller.
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Offline bigbob2

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Re: Robin bamboo build along
« Reply #41 on: July 22, 2014, 06:36:00 PM »
Thanks for posting Sam I'm enjoying your build along.

Offline Sam Harper

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Re: Robin bamboo build along
« Reply #42 on: July 22, 2014, 09:00:00 PM »
Thanks bigbob2.

I'm going to stall just a little bit more.  I was looking it over while ago, and I saw this crack.

 

That could cause a failure, and it looked like it might be too deep to just rasp off, so I put some superglue on it.

 

Superglue is really thin and can wick down into the crack.  I don't know how far it'll go in, though.  I can only hope that it'll work.
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Offline robin

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Re: Robin bamboo build along
« Reply #43 on: July 22, 2014, 10:22:00 PM »
Sam your mid section of the osage in 3/8 thick and the riser fade out seems kind of steep...wont it cause the riser piece to pop off?

Rob

Offline Sam Harper

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Re: Robin bamboo build along
« Reply #44 on: July 22, 2014, 10:29:00 PM »
No, Robin.  The shorter a bow is, the thinner the wood will end up being for a given draw weight.  This bow is pretty short, and 3/8" is plenty of thickness.  Plus, I have that power lam.  The fade will continue past the end of the glued on handle, and the limb probably won't be bending at all near the glued on handle.
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Offline Sam Harper

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Re: Robin bamboo build along
« Reply #45 on: July 22, 2014, 10:30:00 PM »
Of course that depends on how strong you want to make the bow.  I'm going to be shooting for somewhere between 45 and 50 lbs.
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Offline robin

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Re: Robin bamboo build along
« Reply #46 on: July 23, 2014, 12:31:00 AM »
Sam your mid section of the osage in 3/8 thick and the riser fade out seems kind of steep...wont it cause the riser piece to pop off?

Rob

Offline Sam Harper

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Re: Robin bamboo build along
« Reply #47 on: July 23, 2014, 01:41:00 AM »
No, Robin. The shorter a bow is, the thinner the wood will end up being for a given draw weight. This bow is pretty short, and 3/8" is plenty of thickness. Plus, I have that power lam. The fade will continue past the end of the glued on handle, and the limb probably won't be bending at all near the glued on handle.

Of course that depends on how strong you want to make the bow. I'm going to be shooting for somewhere between 45 and 50 lbs.
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Offline takefive

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Re: Robin bamboo build along
« Reply #48 on: July 23, 2014, 01:48:00 AM »
That is a neat trick using your disc sander to radius the shelf, Sam.  I have yet to cut a shelf in, but if I ever do I'll give that a try.

Are splinters pretty common with bamboo backing?  I've only made two bows with the stuff.  One raised a small splinter that I could super glue down, no problems with the other one.  I scrape the top layer off like you have shown and try to sand carefully on the nodes.

Very cool build along    :thumbsup:
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Offline Sam Harper

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Re: Robin bamboo build along
« Reply #49 on: July 23, 2014, 02:30:00 AM »
Splinters haven't been that common for me, but I've had a few raised.  I just sanded the bamboo down until the splinter was gone.
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