Author Topic: What Happened? (Read 1054 times)

D.A. Davis · « **on:** May 02, 2015, 02:06:00 PM »

Looking for some input here guys. I've finally got my health problems under control, and got back out in the shop. I've been building a 64" Hybrid longbow, and everything has been going great until today. I had it on wall checking the poundage and tiller when I heard a couple ticks, and it let loose. It doesn't look like the adhesive let loose. All the glue lines were pulled apart by pulling the wood apart. I was using an Actionwood riser with 2 -parallels, 1 - taper, 2 - lams in the Green Mountain Camo, and 2 - clear glass. Can anybody give me any input on what happened? Here's some pics.

kennym · « **Reply #1 on:** May 02, 2015, 02:16:00 PM »

DA , from here it looks like the fades needed to be thinner. Can't tell for sure, but I make mine .065" thick at 1 inch from tip of riser and about .140" at 2", then a nice sweep on up.

Troy D. Breeding · « **Reply #2 on:** May 02, 2015, 02:25:00 PM »

What Kenny said was my first thought, then I noticed that it looks like you didn't roll the edges of the glass enough as well.

Combine those two things together and disaster is headed your way.

D.A. Davis · « **Reply #3 on:** May 02, 2015, 02:26:00 PM »

I was afraid that might be it, Kenny. Well, I've got the materials for one more bow, so I guess I'll start over. Here's a pic of how I have things on the wall. This picture was taken yesterday when I exercised the limbs, and identified the lower limb.

Al Dean · « **Reply #4 on:** May 02, 2015, 02:34:00 PM »

Looks like a flawed design to me from the draw picture. All the stress or bend is at the fades. Outer 3/4 of limb has very little flex.

kennym · « **Reply #5 on:** May 02, 2015, 02:39:00 PM »

Like Al says, the fades are working real hard in that drawn pic. More taper per inch would help there. What taper are you running?

D.A. Davis · « **Reply #6 on:** May 02, 2015, 02:43:00 PM »

Al, this was done before I began shaping the riser, and limbs. The limbs had been been narrowed to approximately 3/8" at the tips running in from the fades. I had more flex in the limbs on the outer 3/4 when the bow let loose. I'm sure that what you're saying is a valid point that I need to address. I appreciate your input. I'll go back and try it again.

D.A. Davis · « **Reply #7 on:** May 02, 2015, 02:46:00 PM »

Kenny, the taper was .002. I'll just try it again, and pay more attention to the fades and limb taper.

Robertfishes · « **Reply #8 on:** May 02, 2015, 02:48:00 PM »

Looking at your pictures on small screen cell phone. I am no expert but It looks like your putting a lot of stress on the fade area..You could add a power lam that extends 3 inch's past each fade along with a longer thinner riser fade. Not really a powerlam but I use a 040 parallel and make it 6" longer than my riser, then taper the last inch of each end.. What is your total taper?

Robertfishes · « **Reply #9 on:** May 02, 2015, 02:58:00 PM »

Wow..I'm a slow Typer..and I had a phone call before I hit send..

Robertfishes · « **Reply #10 on:** May 02, 2015, 03:00:00 PM »

Wow..I'm a slow Typer..

D.A. Davis · « **Reply #11 on:** May 02, 2015, 03:54:00 PM »

Robertfishes, my total taper was .088; .352 at the tip of the fade and .264 at the string grooves.

Robertfishes · « **Reply #12 on:** May 02, 2015, 04:15:00 PM »

Im sure the next one will go better. I now see your taper is 002/inch. Kenny has done alot of proto typing.. He is "the man"

D.A. Davis · « **Reply #13 on:** May 02, 2015, 04:58:00 PM »

Can someone point me the right direction to view some posts on power lams? I might have to give it a try with the next one.

kennym · « **Reply #14 on:** May 02, 2015, 05:21:00 PM »

Here ya go buddy!

http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=011391#000000

http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=007528#000000

http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=002968#000000

http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=008109#000000

Bowjunkie · « **Reply #15 on:** May 02, 2015, 06:47:00 PM »

You dont need a power lam. Create a more gradual fadeout with the riser and put more taper in your limbs and you'll be ok. Oh, and I shape the bow and riser almost completely before I draw it.

D.A. Davis · « **Reply #16 on:** May 02, 2015, 07:13:00 PM »

Thanks, Bowjunkie. That's what I need to do.

Robertfishes · « **Reply #17 on:** May 02, 2015, 09:29:00 PM »

I agree with Bowjunkie, you dont need a powerlam if you make long thin fades..

jsweka · « **Reply #18 on:** May 03, 2015, 12:16:00 AM »

All good advice here.

Another tip - change your riser design to have some deflex in it as well since this is a deflex/reflex bow.

There's simply way too much bend right at then ends of the fades.

D.A. Davis · « **Reply #19 on:** May 03, 2015, 01:25:00 PM »

So, you guys are saying that I need to lengthen the thin part of my fades. Looking at the picture below, I need to extend the end of my fade about 2", or so, and maintain a gradual increase, not to exceed .060, or so, for that 2". Then, ramping up to the riser handle as gradual as possible.

And, adding more deflex to the riser design would require building a new bow form, correct? Here's a picture of my current bow form setup.

Thanks for the help guys.

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Author Topic: What Happened? (Read 1054 times)

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