Newbie looking for advice on takedown bow

[Brandon B. in PA]

Hi Y'all!  (sorry in advance for the long post and any stupid questions therein)

This is my first post here, so I wanted to go ahead and say hi! I'm still pretty new to bow making, and so far my labors have yielded one darn pretty wall hanging  :p

In my first attempt, I was making an American Flat Bow out of red oak, using a tutorial I found online (by Sam Harper) and some plans I managed to dig up.  After that first bow didn't pan out (had a hinge that gave way while tillering       ), I decided I wanted to try to build a 3-piece takedown bow so that if something else DID happen, I wouldn't be out 100% of the work.  Don't get me wrong, when it broke, instead of thinking "dangit!" I was thinking "ok... next time, I'll get it right".

But with all that said, I came up with some plans for a takedown bow by taking things I liked from bows I saw all over the internet (and guessing on most of the dimensions), and since I still have very little experience with actually making bows, I wanted to see if I could get some feedback on them, like "wow, that thing's gonna snap like a twig" or "there's no way that wood can even DO that!?"

Ideally, I'm going for 64" NTN, and about 45# @ 29" (I'm 6'2").  I'm sure some experimenting will be needed to hone in the poundage, but these numbers are kind of roughly what I saw would give about that.

 

 

 

If the images aren't clear enough, I have a pdf of  them I made from drawing them up in AutoCAD.  I am going to pick up some wood to glue up for the riser today, and I'll probably be using bamboo? for the lams.

[Trux Turning]

Welcome! Pretty nice plans. I've been building a 64" TD recurve that is similar to yours. Mine has a 19" riser with 18 degree pads. Your stack height should put you in the ball park- I'd increase the wedge to 9"s and leave more meat in the grip section. You'll have to post pics of the build!

[Brandon B. in PA]

Thanks! This place seems like probably the coolest and nicest place on the net for trying to build anything like this.

Glad to hear that I'm at least in the ballpark on the poundage, and yeah, I was thinking that the grip might be a little on the skinny side, especially at the base of the handle. I'll 'tweak' it a little with those suggestions in mind.  I figured if I drew it up on the computer, I could just print out a 1:1 of it to have a good reference when I cut the forms from the block.

Like I said, today I'm off to gather up some wood from the sawmill for the riser and wedges, and I'll do my best to post pics of the build.

[NormanDale33]

I am impressed at your tackling of this so far. Looking forward to watching this build.

[Brandon B. in PA]

Thanks Norman, I should be getting some pics up this evening of the riser block.  

I got the wood the other day from Lowes (saw mill fell through :/ ) and glued up the riser block.  Using Oak 2x2's, an oak 1x2, and poplar 1/2 x 2's (for accent strips) and 1.5 ton marine epoxy to hold things together.  I'm expecting to sand it smooth and trace my outline onto it, and maybe do a rough cut of it with the jig-saw if time permits this evening.

[macbow]

Brandon, as a insurance policy. I would add about 1/8 inch  fiberglass or phenolic accent strip either curved or straight through the riser. Binghams bow projects is a,good place to look.

I've had a few all wood risers like that break at full draw, hurts.
Every one after had them.

[Brandon B. in PA]

ouch... that sounds painful indeed.  Unfortunately I already glued it up and cut the side profile out of it, so I'm kind of all-in at this point (I think).  I did choose to beef up the handle a bit by leaving a lot more meat than I had when I designed it... Seeing the actual paper cutout gave me a much better idea of just how thin some spots were.  Wish me luck  :p

[Brandon B. in PA]

OK, time to upload some photos of the riser block as promised!

The glue-up is oak 2x2, poplar 1/2x2, oak 1x2, poplar 1/2x2, oak 2x2.
 

Finally got it glued up and sanded smooth to transfer the design over.
 

After I got the design masked on with masking tape to cut out with the jig-saw.
 

Note to self: next time find someone with a band saw! that little jigsaw blade will wobble all over the place through something so thick!  Luckily I gave myself about 1/4" to 3/8" buffer around my lines for goofs.  (Thank goodness I only made it 1 1/2" thick or i woulda never got it cut out)
 

Good news is that it's sanding out pretty well, so with a little squaring up and stuff, we'll be on our way    :rolleyes:

[dfrois]

Brandon, if you can`t do what macbow suggested, perhaps you should consider adding a reinforcing strip of fiberglass on the back of the bow, from one pocket to another, laminated as the lams on the limbs. I have been down this very same road very recently (building an entire wood riser and matching recurve limbs, second riser I ever built), and I`m still fine tuning the bow, but I have encountered pics of similar risers breaking in the grip/sight window area, so it does happen. Your drawings are marvellous! I wish I knew how to work with Autocad. Your limbs seem, to my inexperienced eyes, to be too straight on the "straight" part. All the recurve limbs that I know have a moderate curve on that long section, and only the old 50´s and 60´s recurves had recurve limbs similar to your drawing, with a perfectly straight profile and then the recurve at the tip. I would imagine they would store a bit less energy that way, but could be wrong. In any case, I wish you the very best of luck with this, and please keep us posted!

DF

[Brandon B. in PA]

Adding a strip of fiberglass to the back of the bow is probably doable!  I'll see what I can get hold of and l'll probably add some to the glue up.  

Just out of curiosity, is it the woods I chose that would make them prone to breaking? Is it just for a what-if? or is it something else I'm missing about all the other risers I looked at when I was planning this out?  I'm not trying to say I know more than anyone (lord knows I don't, I'm just getting started here  :p  ), but I'm genuinely interested in learning as much as I can and preventing as many goofs as possible before I go off and make something that just turns out to be a pretty looking bruise machine, lol.

Oh! and about the limbs... Those were just the best guess I could come up with in my inexperience.  I still have to build a hot-box and make up a limb-forming jig, so any input on limb shape is much appreciated.  I'm planning on cutting the jig to match the back of the limb, and using a rubber strip/aluminum (or steel) bar to distribute the pressure from all the c-clamps I have (about 20 i think) while it cures.

And I use AutoCAD at work, so I get tons of practice with it, but if you have anything you've got dreamed up and want put into a model/drawings to visualize, just hit me up in a pm and I can most probably draw it up for you.  I blew up the profile of mine to 1:1 and traced it onto masking tape with an X-acto knife to make a guide for the one I'm doing now.

[Jon in North Idaho]

I don't usually post on this site, but I thought this was important enough to log on for....  That riser is begging to explode for a variety of reasons.

I apologize beforehand because this post is going to sound very critical, but I'm not sure to say it lightly....

First - the woods.

Poplar is a terrible wood choice for a riser.  Poplar is categorized as a "hard wood", but it is probably the softest of them.  It has a specific gravity of .4, which is on par with pine.  It also grows very fast and does not have a tight cellular structure that we want for building bows.

Red oak is a very strong wood.  That being said, I would never use it without a lot of reinforcement (either fiberglass or phenolic).  I think it's fine to use in a riser, but mostly avoided because it's recognized as a cheap wood.

Next - the riser (particularly the wood layout)

Your Red Oak has a lot of grain runoff.  Every spot where the grain runs off is a weak point for stress.  The strength in your riser will primarily be in the middle oak lamination - which seems to have quite a bit of runoff (at least from the side profile pic).

The vertical stripes are a great way to strengthen a riser - but the poplar won't take that stress.  Look at the riser design - when you draw, all of that stress is going to be on your limb pads.  The stress from that will act like a pry bar, with the central fulcrum being the deepest part of the grip (the throat) - if the oak doesn't shear along the runoff, then the poplar will simply blow up.  The epoxy will hold, but the wood won't.

I'd better stop being critical....   Here's my advice....  Glue up a new riser.  While the glue is curing, you can practice shaping this riser, but don't use it.

If you want to keep the riser shape, your reinforcement/accent stripe should really be curved.  Ideally you want your wood/stripes to be continuous from riser top to riser bottom.  It is far better to use thin strips instead of one thick one.  Even if they are straight - two 1/8" strips will be much stronger than one 1/4" strip.

I would also move that strip forward a little - it's too close to the throat.  You want a little more meat in front of the throat, but not too much.

An I beam layout will be much stronger - basically turn your laminations 90 degrees - so that when you are drawing the bow, you will see the glue joints running vertically.  Does that make sense?

Hope all that helps.  Sorry for being critical - I just don't want the first post after "I mounted the limbs" to be "I'm in the hospital"

[Brandon B. in PA]

Not at all! Like I said, I know I'm new to this and I'd rather have someone steer me clear of doing something stupid than wind up with a body full of splintered wood.  I think I'll take your advice for just chalking this one up as a practice piece.

At the same time though, what kinds of woods would be more ideal? I've seen people using all kinds of fancy woods, but I was looking more for a "this is my first try, so I don't want to risk ruining a $50+ board" kind of setup, hence the trip to the hardware store   .  I was thinking if it'll work for a board bow, surely it'll work for a riser.  I'll definitely be finishing this one out, so at the very least I can do the next one with a little more confidence in my ability to shape it.

I had considered doing the layout you'd mentioned with the laminations rotated so that they're running parallel to the arrow (stacked side to side, not front to back) but changed my mind just based on the pieces of wood I found.

[Jon in North Idaho]

Hickory.  Or Maple.  

Here's an example of what I mean with the laminations - this one also has a curved stripe.
     

One other thing I noticed - you're going to have a really hard time squaring up your limb pads.  You might want to try something like this.
   

I cut the limb pads, squared them up, then ran fiberglass the entire length, then glued on the "horns" as I call them.

[Brandon B. in PA]

WOW! that's a beautiful riser there.  I see what you mean with the lamination running that way.  I hadn't thought about gluing on the horns after putting some glass down like that.  Looks like it's back to the drawing board and time to hit the phone book to see if I can't find somebody in central PA with some maple or hickory.  

It's funny cause before I moved up here from Oklahoma, there were at least 6 places within driving distance I could have gone to get some, but now that I'm up here, I haven't found a single place yet