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Hello all. I have read some stuff in the archives but would like to know what
the general consensus is now. I am thinking of making a set of bridge
making jigs based on John Hows that are in the Jig,Tools, and Techniques
section of the forum. I think I read in the archives that John no longer uses
these. John? Do any of you who use these or similar jigs have any opinions
or suggestions for using them properly? Do any of you use them with a
pattern sander (Robo) as opposed to pattern bits? Climb cuts? Starting in
the middle of the bridge and working outwards? Some woods better than
others? For my first 5 guitars I used a 1/4" pattern screwed to my bridge
blank and blew up one ebony but all the others (another ebony included)
went ok but it was a little nerve wracking because I had no lead-in for the
bit to ride against and no good handholds. Thanks as usual.

I've used the John How pattern bit method with great success. Thanks John!

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JJ
Napa, CA
http://www.DonohueGuitars.com

Yep. I made a variation of the original John How jig too. It's nice. I haven't gotten around to doing the little door insert with the drill guide bushings, but I created my saddle slotting jig with the door in mind. In the meantime, I'm still using a plexiglass template for drilling the string holes.

To answer your questions: I haven't experienced any blowout at all so far, but I've only used one ebony blank, and the others have been either EIR or Brazilian. I do tend to start in the middle, climbing into the bit and then back up gently "whittle" the blank down to near final shape. The pattern bit I use is a 3/4" so it's fairly beefy. But little bites and all seems to work fine.

Bill

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Eagles may soar, but weasels don't get sucked into jet engines.

For a simple curve like the one in the above picture, you should have no problems using a pattern bit.
If your bridge has "points" a la Somogyi & others, the router bit will tend to knock off the points. (no matter how careful you are.)
I assume Bill is not trimming the ends of his bridges on the router table. It's all too easy to chip off a corner on the ends of the bridge with a router bit.

Yes, that's right Daniel, and I do have points on my bridges, hence
some of the concern. I will make my bridges this way just because I think
it's a great, repeatable method but appreciate all of the tips and tricks I can
get regarding the use of this technique. Thanks for the info guys and
looking forward to what others have to say.

I have a similar jig that I use for making my bridges.  It is a two sided unit so I can cut one side first then move it to the other side and do it.  Since my bridges have basically no straight edges, a two sided jig is needed.  As for profiling I do that by hand with rasps, files and sanding blocks.



It ain't fancy but it works.  I have done ebony and rosewood with no tearout problems. A good sharp bit is a must.

I just read the concern about points.  I have some points and so far have had no problems with rounding.

Here are a couple of my bridges.

Nice bridges David.  Thanks for the info.  Here is my bridge.  I would like to come up with a more unique shape but for now...Anyway, here is an example of the "tips".          ;           ;           ;           ;           ;           ;