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 Post subject: Re: Binding Router Bits
PostPosted: Thu Jan 05, 2012 10:33 am 
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Joined: Sat Feb 09, 2008 8:06 pm
Posts: 2990
Location: Visalia, CA
Darryl,
Your jig looks good. I think the area you are having trouble with has to do with the surface the edge is running on. It is too wide, and needs to be rounded so the contact area is minimalized. What happens as you go around the inside curves the "rest" is spanning the area to be cut and is probably lifting the bit a little. Give your rest a radius with a flat spot of about only 1/4 to 3/8" in front of the bit. I think you will find it works better. Also is this a router mounted jig, or is this used on a bench top and your are sliding the body into, like Ken Cierps jig? Looks like it could it be used in that way too. I like your sliding stop arrangement.

Kevin


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 Post subject: Re: Binding Router Bits
PostPosted: Thu Jan 05, 2012 2:20 pm 
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Joined: Fri Jul 30, 2010 6:44 pm
Posts: 1668
Location: Arkansas
I think you are probably right Kevin.

I started out using this jig horizontal like Ken describes his being used but I didn't like how it felt with the foam pushing the body up off the bit. It was awkward (for me) to push down into the bit and move the body around with a steady motion. So I mounted it vertically and let the side ride on the fence.

It cut perfectly......except in the waist the purfling cut wasn't deep enough. By this I mean it didn't cut deep enough toward the soundhole. Now that I'm thinking about this again, the fence that rides against the side is controlling this depth; however, if the body isn't maintained perfectly tangent to the bit, the bit can't cut to full depth (the radius at the end of the fence is larger than the bit radius so only at one angle is the entire bit exposed......if that makes sense). That's funny that I recalled (incorrectly) that the other dimension was the issue (the one you mentioned where the width of the saddle in contact with the top/back was causing inaccuracy).

So I didn't mess anything up using this jig to cut the channels, but I didn't get the full depth of cut.......and when I tried to clean up the cut with a chisel (maybe the wrong tool?), I accidentally went too far in the waist causing a small gap in the binding. I tried to make the sides flat before doing this operation and I thought they were, but while finish sanding I realized the sides weren't truly flat. So this may have contributed to my issue, not sure.

Thoughts?

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 Post subject: Re: Binding Router Bits
PostPosted: Thu Jan 05, 2012 3:01 pm 
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Joined: Fri Mar 03, 2006 7:09 pm
Posts: 5745
Location: Hegins, Pa
In order for any binding jig to work you have to be able to control all contact points without having variables to change the cutters position.
Controlling locations of the pilot is the key. On the top , the variables are less on the top than on the back. If you are loosing location at the waist you may have more area contacting the sides than you need. Now you also have to control the cutter position. I can't say what you need to do , but watch close how the pilots influence the cutter as you travel along the guitar. The other issue you may have is that the pilot allows a tangent change and your cutter width of cut can be changed by how you locate off that part of the rub pilot.

This is the advantage of a pilot bearing as that variable is removed. Holding the unit square and parallel can also be a challenge but I think the different diameters cause a chance of variability. This makes it more Hands On and you rely on skill.
With practice it can work but you need to learn to control those variables . I tried these designs early in my building and resorted to Tom Ribbeke's tower design and then the Fleishman / Williams. Having parallel and square control makes for more precise and controllable outcome.
Most times the issue presents itself at the back along the upper bouts is a parallel issues with the cutter in relation to the sides. At the waist with the channel width change is often pilot issues. If there is variable width all over the sides that is the tangent difference to the pilot and bit

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John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
Board of Directors of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com


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 Post subject: Re: Binding Router Bits
PostPosted: Thu Jan 05, 2012 5:21 pm 
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Joined: Sat Feb 09, 2008 8:06 pm
Posts: 2990
Location: Visalia, CA
Darryl,
The tower set up eliminates the worry of the contact fence on the edge of the guitar....there is none. Just use a bearing and bit and as you move the guitar body around the fixed router, it doesn't matter if the side is parallel to the bit, you will get a consistent depth of cut. This was one of the reasons I went to this set up as I had a little trouble with holding the router with the fence for the sides perfectly parallel all the way around the guitar, especially in the waist area.
I have to tell you when I used this on my last guitar, it was almost totally worry free. And I only spent about $30 to build it.
I'm sure the Fleishman set up accomplishes the same thing.

Kevin


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 Post subject: Re: Binding Router Bits
PostPosted: Thu Jan 05, 2012 6:17 pm 
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Joined: Fri Jul 30, 2010 6:44 pm
Posts: 1668
Location: Arkansas
Yeah, like John said, it's really not worth messing with just spend $100+ on bit and bearings and be done with it. I like the simplicity of the tower and it's quick and easy to build......but I like the thought of holding the router in my hand and moving it as opposed to holding the body and rotating like on the Fleishman system. Likely I will just break down and build a Fleishman system.

In the Trevor Gore book, he uses palstic hinges to connect plywood for the part that holds the router vertical. He said he tried hinges but they have a tiny bit of slop and the plastic hinges (thin plastic flexes for the hinge) removed the slop. So he uses this out of a tower to allow the router to raise up and down (as opposed to drawer slides) and still rotates the body around underneath the router. Sort of combines the Fleishman/Williams and tower (Ribbeke) systems.

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 Post subject: Re: Binding Router Bits
PostPosted: Fri Jan 06, 2012 6:17 pm 
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Joined: Mon Aug 02, 2010 9:43 pm
Posts: 18
Yeah, I think Darryl's jig is interesting and certainly solid, a really good effort... It couldn't do the same work as the KMG machine though. I get great results from Ken's machine. I bought it because I would rather spend time building guitars than inventing or reworking jig ideas, although I've done plenty of that too...


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 Post subject: Re: Binding Router Bits
PostPosted: Fri Jan 06, 2012 6:20 pm 
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Joined: Mon Aug 02, 2010 9:43 pm
Posts: 18
I've tried handhelds and even tried to invent my own. It worked but not nearly as well as the system I settled on.


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