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Main Boards => The Bowyer's Bench => Topic started by: buckeyebowhunter on April 10, 2019, 09:16:57 AM

Title: Flat spots on limbs
Post by: buckeyebowhunter on April 10, 2019, 09:16:57 AM
Guys, after glueing up my limbs for my take down i noticed flat spots which i realize are imperfections in my form.  They're not real noticeable with the naked eye but i can feel them when i run my hand across the limbs. I'm still learning a lot since this is my first attempt but are these flat areas harmful to the integrity of the bow? And how do you get rid of the flat spots in the form when you've cut it with a band saw or is it possible to get rid of them?  Thanks for all the help!
Title: Re: Flat spots on limbs
Post by: Shredd on April 10, 2019, 10:21:12 AM
How are you sanding the form??

  The flat spots should not be a problem unless they were extreme... If extreme then you might have a problem with a difference of stresses in a small area which could possibly lead to failure...
Title: Re: Flat spots on limbs
Post by: JamesV on April 10, 2019, 10:28:24 AM
The flat spots should not hurt the integrity but maybe the performance will suffer.  With a little work you can eliminate the flat spots in your form. I used a 12-14" 1x2 with 80 grit paper attached and sprayed a guide coat (flat black) to the face of the form.  Light sanding will show you the flat spots and where to sand with long strokes, or you can fill the flat spots with bondo and sand until the form is uniform.

Hope this helps

James
Title: Re: Flat spots on limbs
Post by: buckeyebowhunter on April 10, 2019, 01:33:05 PM
Shredd, i sanded first with a spindle sander then finished with a sanding block and then glued a strip of formica to the form. I honestly thought i had taken care of the flat spots but after gluing they showed up. They're not awful. But they are noticeable. I guess I'll shoot it an see what happens. Thanks for the replies.
Title: Re: Flat spots on limbs
Post by: Bvas on April 10, 2019, 03:33:05 PM
How did you hold/clamp the formica in place?

I bend a piece of glass over the form to reveal  flat spots.  I would assume a piece of formica would do the same. 
I'm thinking you may have created the flat spots with uneven pressure while putting the formica on.
Title: Re: Flat spots on limbs
Post by: Crooked Stic on April 10, 2019, 04:04:02 PM
Bondo it and block sand until flat. I use about a .060 A-boo lam on the form face. I use a router table and a pattern bit. I still bondo and sand for any uneveness.
Title: Re: Flat spots on limbs
Post by: buckeyebowhunter on April 10, 2019, 09:24:38 PM
Bvas. You are probably correct. I used the top half of the form as the pressure for gluing the formica. And it was not a good cut by any means. This probably did not help with the flat spots. Never even thought of that being harmful at the time.
Title: Re: Flat spots on limbs
Post by: buckeyebowhunter on April 13, 2019, 05:47:11 PM
Here is a pic of the limbs strung. You can see the bad spots. Also a lot of hand shock/ kick when shooting the bow. Limb form obviously needs some work.  [ You are not allowed to view attachments ]  [ You are not allowed to view attachments ]
Title: Re: Flat spots on limbs
Post by: Wolftrail on April 13, 2019, 09:26:15 PM
I know some guys build bulkier heavier risers (handles) to absorb the vibes.
Title: Re: Flat spots on limbs
Post by: Bvas on April 13, 2019, 10:01:54 PM
How bout a pic of the limb unstrung
Title: Re: Flat spots on limbs
Post by: buckeyebowhunter on April 13, 2019, 10:52:45 PM
The bow looks nice. But the limbs are definitely not the most graceful things in the world.
 [ You are not allowed to view attachments ]  [ You are not allowed to view attachments ]
Title: Re: Flat spots on limbs
Post by: buckeyebowhunter on April 13, 2019, 10:57:26 PM
Another question for you guys. When i string her up it makes a ton of awful noise. I do have finish on the riser but haven't finished the limbs yet. It sounds like popping/ cracking from the riser also hear it some when shooting. But when i take it apart i see no damage on the riser or limb butts. Is it rubbing on the finish or is it getting ready to fail/blow up?   :help:
Title: Re: Flat spots on limbs
Post by: Crooked Stic on April 14, 2019, 08:48:41 AM
Limb pads and pins need lube. After you finish them. string wax or petroleum jelly.
Title: Re: Flat spots on limbs
Post by: Roy from Pa on April 14, 2019, 09:32:15 AM
Riser looks very nice.
Title: Re: Flat spots on limbs
Post by: buckeyebowhunter on April 14, 2019, 10:50:44 AM
Thanks for the replies!  And thanks Roy I'm pretty happy with how the riser came out. 
Title: Re: Flat spots on limbs
Post by: Crooked Stic on April 14, 2019, 12:57:00 PM
How does it look at full draw ? your noise and shock could be a limb timing issue.
Title: Re: Flat spots on limbs
Post by: buckeyebowhunter on April 14, 2019, 09:15:33 PM
Stic, ill try to get a pic tomorrow.

Also put wax on limb pads. No more creeking. Thanks for the tip!
Title: Re: Flat spots on limbs
Post by: Flem on April 14, 2019, 09:25:58 PM
Looks like you got a nice riser for the next set of limbs  :)
Title: Re: Flat spots on limbs
Post by: buckeyebowhunter on April 16, 2019, 07:59:48 PM
Here is a pic of the bow drawn. The limbs are surprisingly smooth drawing. This is not a great pic as it was taken at the school. I apologize.  [ You are not allowed to view attachments ]
Title: Re: Flat spots on limbs
Post by: Bvas on April 16, 2019, 08:22:50 PM
Hard to tell much on the bow with it canted in the pic. But the bandsaw behind you looks sweet :biglaugh:
Title: Re: Flat spots on limbs
Post by: buckeyebowhunter on April 16, 2019, 08:38:02 PM
Thanks Brad haha didn't even realize the band saw was in the background. I'll try to get a better pic tomorrow
Title: Re: Flat spots on limbs
Post by: buckeyebowhunter on April 18, 2019, 09:05:53 AM
 [ You are not allowed to view attachments ]
Here's the finished product.Shot her a few times. Not a bad shooter. Pretty happy with it considering its my first attempt. Appreciate the help from all you guys. Can't wait to build the next.