Circle cutting jig for trim router

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Talladam
Posts: 123
Joined: Mon Sep 21, 2015 9:43 pm

Circle cutting jig for trim router

Post by Talladam »

So I got a bit of time to build a circle cutting jig for my Bosch Colt trim router. The next operation to do on my guitar build is the rosette and soundhole and to be honest, it kind of makes me nervous. Every time I touch a router to wood it makes some kind of unexpected groove or chipout where I don't want it. It also absolutely screams while messing up my stuff. I just hate routers! So I want to try to make the circle cutting easier. I also am cheap and enjoy messing around building jigs ect. So I bought a cheap plastic cutting board (3/8" thick) and a bunch of parts from Home Depot. I got a few 1/4" carriage bolts, some acorn nuts, wingnuts and regular nuts. From work I got a scrap piece of 1/4" aluminum bent into 90 degrees which I cut up into L-brackets. I started by drawing out a template to see if I could fit all the parts together. Then I routed a 3/4" slot halfway into the bottom of the cutting board, followed by a 1/4" slot all the way through for the small carriage bolt to go through. I cut out the shape of the jig on my bandsaw and smoothed the cuts with my block plane (actually cuts wonderfully!) I then tapped a 1/4-20 hole into the rear bracket, and epoxied a short piece of drill rod into the front bracket. I used thread-lock to keep the threaded parts together that I didn't want moving. After putting everything together I was pretty happy, but the minimum cut diameter was about 4", which is about the largest soundhole size from what I gather. So after some going back and forth, I notched out the base of my router, so that the diameter gets down to around 3 1/2". I considered whether this might compromise the router, but after doing it, it seems like there is still plenty of meat there. Anyway, let me know what you think. You could build it just as easy from plywood, but I figured the cutting board would slide easier. Plexiglass would be best, but I couldn't get any thick stuff for less than a fortune. I haven't actually used it yet either... It remains to be seen if this works, but it seems pretty tight.
routing cutting board.jpg
planing plastic.jpg
notched base.jpg
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Talladam
Posts: 123
Joined: Mon Sep 21, 2015 9:43 pm

Re: Circle cutting jig for trim router

Post by Talladam »

Here's a picture of the bottom of the jig.
jig bottom.jpg
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ruby@magpage.com
Posts: 1564
Joined: Thu May 24, 2012 8:03 am
Location: Chestertown Maryland

Re: Circle cutting jig for trim router

Post by ruby@magpage.com »

If the router scares you, these are nice and controllable:

http://www.lmii.com/products/tools-serv ... cle-cutter

Nice job -

Ed
Ed M
Talladam
Posts: 123
Joined: Mon Sep 21, 2015 9:43 pm

Re: Circle cutting jig for trim router

Post by Talladam »

After I already built the jig?!? Perish the thought! I did try to do binding by hand (on the cribbage board I built for my father in law) and it wasn't the best. I've just got to get used to the router. Most of it is fear of it ruining my project in an instant rather than fear of the machine (though I am a bit nervous of the thing, honestly). I occasionally read about someone decapitating their guitar when routing binding channels, and that sounds like about par for the course for me with routers. If the thing screws me over during the rosette I'll just make my guitar a Clarence White model ;)
Diane Kauffmds
Posts: 3246
Joined: Sun Mar 09, 2014 8:13 pm

Re: Circle cutting jig for trim router

Post by Diane Kauffmds »

We're all nervous about using the router the first few times. It's completely normal. The jig looks great.
Diane Kauffmann
Country Roads Guitars
countryroadsguitars@gmail.com
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