My first glass r/d bow (with pics)

[GentlemanArcher]

My first glass bow that has made it out of a form actually.  This is actually my third attempt at using glass.  The first was tossed because of gaps between the riser and lams(not enough pressure on the clamps and poorly shaped riser), the second is still sitting on the shelf to be shaped.  And this one, walnut lams and boo cores.

   

   

I did mess up this one too, not enough glue and/or clamping pressure at some points on the lams so there are "bubbles" between the glass and walnut. Chalk it up as more learning.

It's 45 pounds at 26 inches and flings an arrow pretty good.  I'm happy about that, but I'm not happy about the way the limbs bend right off the riser.  Does the form need more bend?  So a more curvy riser?  Would adding a power lam a few inches longer than the riser help smooth out the bend?

The other thing I noticed was that the fades are pretty short and fat, I could try the same form again but shape the riser with a more gradual fade.

Any input/ideas are appreciated.  I've learned a ton from you all and have enjoyed sharing my adventures (and failures, er, um, "learning opportunities" with you)

Right now, I plan:
redo #1: same form, more gradual fades on riser, thin power lam extending 5 inches past riser

redo #2: deepen back curve of form and riser. And a more gradual fade on riser.  I think this will look better unstrung as well.

redo #3: buy a kit from Bingham or Kenny M like I should have the first time  

Kia Kaha
GA

[Tron]

Looks good sir!  We all fight a constant battle to have enough pressure on our lay-ups.  As to the tiller, since I don't know what your lay-up was, I would say you need either another .002 taper to your lams or you need to narrow up the tips of the bow some.  Either method would yield good results, however you will lose a fair amount of weight should you try to narrow the limb tips on the existing bow.

[GentlemanArcher]

Thanks for the input.  The 2 boo core lams are tapered at .001 each.  I taper the limb width over the last 10 inches from 1.25 down to 1/2.

Good idea for this bow, I can start the width taper closer to the riser.  Losing a little draw weight won't be bad for me anyway.  I don't plan on hunting with this bow, so horse power isn't super important.

Thanks!

[Tron]

My first lam bow came out at 17 pounds so I'd say you're doing great!  I bet she's actually pretty fast with that tiller profile.  Basically you just have a short working limb

[Trux Turning]

Your on to something there!! I think you are on the right track with the riser fades and adding a power lam to push the bend further out. You might also try and start your limb taper at the end of your riser fades to the tip- that may help with the bending on this bow.
What are you using as a clamping system?

[johnny girardi]

Ga Bow looks good. I think instead of power lam maybe make the .001/1 tapers .002/1. Were the walnut lams === or tapers?I guess  ====.002 tapers are thicker at the riser and will bring down the working limb further.I also agree with limb taper start it fades. Good work

[GentlemanArcher]

TruxT....2x6 for the form.  Four c-clamps and two 3-way clamps on the riser.  The form also has dowels every three inches.  So I backed up the clamps on the riser with shrink wrap.  Then shrink wrap the rest of the way out on the limbs.  

I didn't use a pressure strip on the limbs, so the cling wrap was right on the glass (well, glass then the plastic wrap that the whole bow was wrapped in to catch the extra glue)

Johnny G...the walnut lams were parallel.  

Tonight I'll extend the width taper all the way from the riser to the tips. Then take some more pics and remeasure the draw weight.

If the bow still needs some help, I'll add a power lam to the bow.  I have another piece of glass, I'll go 27.5 inches and taper the ends to 0.0

I'll post updates tomorrow.

[Trux Turning]

You need to improve your clamping system. Free tubes (the thrown away ones/bad)can usually be gotten at a local bike shop. Heres a really good build along and tubes being used as a clamping system-  http://tradgang.com/noncgi/ultimatebb.php?ubb=get_topic;f=125;t=002382;p=2
For you limb taper- mark out the width of your nock and taper from there to you fades- Johnny G. makes a good arguement for .003 taper in your stack also.

[Tron]

I definitely agree with Trux.  I use a c-clamp form but i have 17 clamps on mine and pressure strips

[GentlemanArcher]

Update....since I can't adjust the thickness taper on this bow, I went to work on tapering the width.  The first try was 2" past the fades, straight out to the 5/8" tips.  It was better, but needed more.

The second grind was 3" past the fades out to 1/2" tips.  Still needed more.

The last try was 4" past the fades and out to 3/8" tips.  Pretty much stuck at this one.  The tiller needs adjusted.  The lower limb is still a little more stiff than the upper.  You can really see this when the bow is at brace height.  I'm still not happy with the final shape though.  I'll take a little glass off the belly on the last 10" of the limbs.  

There's not more more to do for this bow than that.  The bow started at 46# at 26" and is now 40#.  It seems to draw smoother and still flings an arrow pretty good.

     

For the next bow on this form, I'll use the same stack thickness, but a .004 total taper.  And I'll be WAY more gentle with the fades (much less steep).

Thanks for all your input.

GA

[GentlemanArcher]

Ha...now that I'm looking at that picture again...I think I like the lower limb better.

Geez...I'm at a total loss  

[kennym]

Hi Phil,

On my d/r bows, from 58 to 64" ,I use a .003 total limb taper, and on the shorter bows, a p-lam and tip wedge. Makes the limb bend more in center so you can get a bit more draw length without stack.

A really narrow bow can use more taper since you can't get as much on limb edges.

Hope this helps!

[David Flanrey]

Phil,
I agree with Kenny.  He talked me into the .003 taper a couple years ago.  I make 58-62" d/r bows that are pretty narrow.  I even trap the back about 1/8 inch.  I go with a core that has two pair of lams.  One at .002 taper and one at .001 with a power lam built in.  Kenny calls them "super lams".  I really like them.

Also, when I first started making glass bows, I did not use pressure strips and had the same problem with the air bubbles.  Started using them and air bubbles went away.
David

[johnny girardi]

GA I was talking about next bow. Sorry if mis-understood. I see improovement on last pic. That bow will shoot long time.KennyMs .003 total taper will work as well as .004 total taper.nice bow
J.G.