3 Piece Longbow/Accents In

Mad Max · March 14, 2016, 03:14:00 PM

SORRY
Your CNC guy know's what he is doing, but he does not know how to build a riser.

You need to do it like this.

http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=012495;p=1
Then
I sand my limb pad angles and top curve of the riser (this riser has cracks in it so not the best to make my point) then I get my limbs bolted on and the bow tillered.
Then I can put it back on and finish sanding the profile.

bowhntineverythingnh03743 · March 14, 2016, 06:16:00 PM

Mark I am not sure if my last post was clear enough for what we are doing. I needed help to make some templates like the ones that your link made. The different pieces are to help make jigs so that I can get the three pieces to match for accent strips and not spend hours sanding by hand.

The riser design is my own. I have attempted to make some templates on my own but having them tight and accurate was hard for me. So he took my design and helped with the curves and will make some templates so that I can glue all the pieces up perfectly.

Hope that makes more sense...

Mad Max · March 14, 2016, 07:43:00 PM

I PM you

bowhntineverythingnh03743 · March 30, 2016, 12:08:00 AM

Well I finally received the templates and tomorrow I start my jigs for the riser. Can't wait to get started on this bow again and hope to have everything set for turkey season starting in May.

Pheonixarcher · March 30, 2016, 01:15:00 AM

Justin, that is a very cool riser design! But if you don't accommodate for the width of your accent lines in the templates, you will have gaps at glue up. The reason being you will be changing the size of the radius of a particular curve.

As an example; say you have template "A" for the back of the riser, and template "B" for the belly of the riser. A and B are made so they fit perfectly together with say a 1" radius. Now you add material to B (an accent line) thus changing the radius to 1.125". Now template A has too tight of a curve to fit the larger radius that is now template B. Add compound curves like the ones in your design, and it becomes even more critical for the templates to include the width of any additional material.

If you already planned for that, great! I hope this will help others that come across this thread looking to up their game in riser design.

bowhntineverythingnh03743 · March 30, 2016, 02:49:00 PM

Yeah I think I may have to change them slightly. I was only looking to add at the most .100 of an accent strips but I see what you mean. Think I'm just getting impatient now and just want to build... Been a lot of designing and little to show for it this far.

monterey · March 30, 2016, 04:22:00 PM

The design in your car program needs to have an "offset" feature. Put the offset onto the two outside pieces of the template to the exact measurements of your accent material. I'd do it before you start milling, otherwise you are going to be doing the work by eyeball.

That is going to be a sweet riser!

bowhntineverythingnh03743 · March 30, 2016, 05:47:00 PM

Yes I am going to fix the offset of the templates. I did not take that into consideration. I will make that happen though.

monterey · March 30, 2016, 09:45:00 PM

Wish I could figure out how to do those compound curve designs in my car program. :(

passion for knowledge · March 30, 2016, 10:49:00 PM

You have to be really careful when it comes to using CAD for things.
The devil is always in the details.
I set up a lot of files for router cutting on a CNC machine. there's a lot to be aware of. Sometimes it's important to take into account the diameter of the cutter bit when fitting things together.
A good way to avoid expensive mistakes is to print out your pieces on paper and check them for fit.
Paper is way cheaper than wood and router time.

bowhntineverythingnh03743 · March 31, 2016, 12:15:00 AM

I think that I am going to keep the center section the same because I like the set up of that section. I will take the offset into account on the front and back piece.

Does that fix my problem guys?

These pieces were made on a 3D printer. This is some pretty tough plastic so it's not as expensive but still has cost to it.

monterey · March 31, 2016, 01:18:00 AM

How are you going to fix it?

I agree about leaving the center as is.

Pheonixarcher · March 31, 2016, 05:07:00 AM

Leaving the center section as is makes the most sense. The compound radii of the other two sections should be adjusted for the width of your accent lines.

If these templates were created with a CAD type software, it should be relatively easy to make the adjustments. If they were scanned in, then it may prove a bit more difficult, but still doable.

The most important thing to consider, is what exactly are you going to use for the accents? If you have access to a thickness sander, then that problem is reduced. If not, then you have to decide what is the most commonly available thickness material you can use. You can get wood lams and phenolic in 1/16"-1/4" from Binghams and others. And there is also Core-Tuff glass strips in .030". I'm sure there are more options that I'm forgetting right now. The point is that you have to decide which is the most practical method for you to use, and take advantage of it. You might still be able to achieve good glue lines with +/- .015" or so, but I'm not sure exactly where that limit is. With compound curves like yours, it's best to be as exact as possible.

bowhntineverythingnh03743 · March 31, 2016, 12:45:00 PM

I'm getting there with the fit.... Just a little more adjustment

bowhntineverythingnh03743 · April 01, 2016, 08:45:00 AM

Got home last night at midnight and immediately started working again on fitting these pieces... Anyhow at around 0230 I got them fitting and light tight with no gaps

monterey · April 01, 2016, 06:33:00 PM

That's looking very clean.

mikkekeswick · April 02, 2016, 03:11:00 AM

Nothing like throwing a late nighter!

BrushWolf · April 03, 2016, 11:26:00 PM

Looking good. The templates that I use fit together tight. I have always done them that way from the get go. I guess when I started doing footed risers I didn't think of the need for gapping them. The stripes in them usually are no more than 1/8 thick. I am a stickler for good glue ups can't stand gaps. I do like the cad idea something I might have to check into in the future. Keep up the good work can't wait to see more.

bowhntineverythingnh03743 · April 04, 2016, 01:19:00 PM

Well after a long process I think I am ready to start building. Got all my jigs built except for the back support on one because I need to see where I end up with for the first curve pice and will fit it together accordingly.

Also made a sturdy gluing jig so I don't add any twist into the riser during glue up as well... It's made out of 1x1 tube and 1/4 thick angle iron

Let the build begin later in the week!

bowhntineverythingnh03743 · April 06, 2016, 06:41:00 PM

Worked on squaring up the riser materials with my 1920-1930 Stanley hand plans and used my templates to cut out my first pieces... With minimal work they are fitting perfectly. Now if I just remembered to cut the Koa to proper thickness... Oh well... Just a little more sanding after glue up... My metal frame works great as well