Building a bow

[Coca Cola]

I think he might have a layer of action boo but I am not sure

[smj]

I assume that your are talking about the ipe bow... Think back about this bow - I broke the tip and then jumped through a few hoops to try to salvage something from what remained... This bow is ipe, action-bamboo, with bamboo backing. The backing was .125 thick, I have thinned it a little since glue up. The action-bamboo is at least .1 thick. I will use a thinner layer in the future when working with action-bamboo. Anyway - since this bow had a severe shock to the limb, I decided to make it a light weight bow rather than a 50 or 60 pounder. Also, when I shortened the limbs I ended up with some nasty hinges, this meant reducing draw weight as well. My goal - 35 pounds at 28 inches. Right now, I think I am at 33 pounds at 27 inches. Since I shortened the limbs I shortened the draw length, too. I aslo thinned the limbs a fair amount, wanting to make sure a crack in the layers did not go back inside the limb along the edge. There is way more bamboo than I'd like at this point, thickness wise, but this bow was originally intended to be ~55 pounds at 28 inches, the belly would have been a lot more thick had that worked out. I just could not bring myself to toss the bow if there was a chance at shooting an arrow out of it. It is quick for the draw weight, I was surprised! I do worry about long term follow, and holding the tiller. It is a fun bow at the point, one that I can polish up my skills a bit on. Every grip you make, the next one ends up just a tad different - in a good way. So, I am seeing the bow through the process is all. I know a non-archer with a short draw length who wants to start shooting a bit, this should work for them. If they out grow this bow, I'll pass it to someone else so long as it holds together! I'd prefer at least a 1 to 3 ratio (or more) bamboo backing to limb thickness - this bow will not even come close! It is a child of its circumstances!!!

Two layers of hickory - you could end up with a really stiff bow! Let me thumb through my notes when I get home and get back to you on this one.

[easternhunter]

PLease do...we'll all learn something here I think(hope).

Since these lams are 3/32" thick, I thought I could glue up both on the back instead of laminated belly(kinda reverse laminated bow).

I'm not sure SMJ...maybe I'll simply use the one backing for now...wonder if I glue on 2 layers, maybe I could taper it toward the tips, but that's tricky in trying to get a nice smooth transition..would likely throw off the tiller badly.

Ahh...nothing wrong with lower weight bows....just a whole lota fun, I say. I really appreciate you hanging with this process for so long too. I've learned alot.

[easternhunter]

Well, I dunno if BT wants to let this thread run or not, but I'll post where I'm at anyhow...if anybody including SMJ wants to chime in with words of wisdom, I'm allll ears.

After splicing my Jatoba billets, I've stepped back and pondered on which way to proceed. I'm not gonna jump in head first like last time for sure.LOL

I've been testing the Jatoba to see what kind of reflex I can force into it. It seems to bend amzingly well(fingers crossed). I don't want to impart such a drastic r/d profile as the maple bow..It may have survived if I hadn't dragged it kickin' & screamin' into such a crazy profile.

This time, as SMJ suggested, I tested a couple of different profiles...nothing drastic and I didn't leave the limbs stressed very long..just enough to shoot some pics. I think I can do abit more reflex, as I suspect I'll loose at least half of it before this ones shot in. Anyhow boys, have a look and I'll describe what I did on these profiles...


This one has mostly a flat limb with 2" of reflex starting from about midlimb to the tip..looks mild and nicely curved all the way to the tip. I'll end the curve about 6" from tip.(wanna keep that area stiff and straight.



This one is at 3" toal reflex, starting from about 1/3rd way out the limb with about 3/8" deflex to deepest part. I know 3" seems alot, but I expect to lose half. So any comments are more than welcome. SMJ? you out there?? This was your idea anyhowLOL.

[smj]

Howdy all - I am here, but have been swamped the last couple of days at work. It seems like the world has crashed on me this past week and I have have been engaged to the point that all I've had time for were a couple quick comments here and there!

Backings - let's talk about those a bit. When I do bamboo, I like a .125 thick backing. Of course, if you add a layer of action bamboo, your overall thickness will increase, but this is another layer so obviously that will happen! I am trying to figure out what action bamboo thickness I want and will let you guys know once I feel I have something that rocks! Trial and error takes a while...

So far as hickory backings go - Here is what the sources say:

Maurice Thompson, Witchery of Archery: 1/3rd inch thick, 1.25 inches wide on a 2 inch wide belly.

Saxton Pope, Hunting with the Bow and Arrow: 1/4 inch thick and 2 inches wide. The example is a cedar belly 1 inch thick and 2 inches wide with a straight-grained hickory backing. (He replys that they used to rely on yew protected by sapwood, but had so many break that they let Ishi talk them in to backing the bows they made... they used rawhide, known as clarified calfskin, about as thick as writing paper.)

The Bowyers Bible - #1: Hickory must be straight grained, do not use wood from a spiral grained tree. It can be applied in three ways, flat ring, edge ring, and bias ring.(Has to do with the edges of the hickory rings on either side of the backing strip: edges on either side, edges showing inside and outside at 90 degrees, rings meet the surface at less than 90 degrees.) Hickory strip should be 3/16th of an inch thick.

The Bowyers Bible #3 : Same wood bows should have thinner backs than belly. Wood tends to handle tension better than compression. Same wood bows should have about 1/3rd backing to 2/3rds belly. With stronger woods, drop that to about a 1/4 of thickness. However, with a very strong backing on a much weaker wood, drop that to as little as 1/6 of overall thickness. For example, 1 to 4 with sugar maple on eastern red cedar, 1 to 6 with hickory on red cedar.

I have found the above directions to work out well.

[BT]

Good to see you smj....dont let the world take you over

[smj]

OK - now on to looking at your photos...

I would suggest somewhere between 3 and 4 inches of reflex. The use of clamps to get just the right flex is OK. My personal preference is to thin the limbs from the grip to the tip to get the flex I want unless you are pulling the limbs below the grip block. An 1/8 inch of taper over all to start with from grip to tip, and then a little more if required along the last half of the limb to achieve the custom looking limb curve that you want. If you go in to recurve, that is a bit different story - I'd stay away from that for now.

I like the last one with 3/8ths deflex. I would thin the last half (or middle third) of the limb a bit more (say 1/32 to 1/16 inch max) to get a bit more distributed flex through the last half of the limb. Don't thin the last 6 inches of the limb any more though! You should be able to pull the limb down for the deflex, and it should curve the way you want from there without extra clamps - or at least be very close to where the clamp does not do much. I find that a natural curve just looks better - clamps tend to hinge things or leave flat spots along the curve.

I think you will find this one much easier to tiller!

[easternhunter]

OK..so what I did last nite was laminate the 2 3/32" hickory slats together, and put them into a reflex of 3" from midlimb out. When I glue this to the belly wood, the reflex will be pulled back abit, depending how much reflex I force into the belly wood.

That being said, I may change my feeble mind at the last minute and go rip out a fill 1/8-3/16" backing instead....the belly wood will be thinned abit more to allow goood curve in the reflex.
Sorry no pics, but not much to show anyhow.......

I think I have the disease now, as I'm already planning for a boo-flooring bow with hickory backing...stay tuned!

[smj]

While pulling together the info dump on hickory backings - I stumbled on to something else in one of the Bowyers Bibles...

One guy did several laminates glued one by one. He changed the reflex for each glue up so that the reflex put into the limb gained a bit more for each layer. If you'd like, I think I can find the example again and give a better explaination!

By the way - did my post above answer your questions, or did I miss anything?

[easternhunter]

Nope...your post was very helpful. I have TBB vol. 1 &2, maybe I should look it up myself huh?

I'm gonna do a dry fit once I get this backing trimmed to shape. I'm aiming for the profile No.2
if I think it'll be too stiff, then I'll go rip another backing strip. I don't want much deflex, and a bit of reflex, so the tillering will go smoother..