Trimming the soundboard and the back without a router

[Doug Shaker]

Maybe it's just me, but I hate using a router on the soundbox of my guitars. Just too much noise, too much at stake. I can do it, but I hate it.

Does anyone have a good way of trimming a newly glued-on back or soundboard to the profile of the sides? Chisel? Knife? Spokeshave? Tiny plane? It can't take that long with sharp hand tools.

Suggestions appreciated.

[Steven Smith]

I started out with edged tools but it was real slow. Ended up using a robo-sander for a while. Now I use a 1/4" flush trim bit in a laminate trimmer.

Edit: I suppose if I where going to use edged tools again I would clamp the body in a troji and use a 1" chisel and mallet to get close then finish up with a small plane.

[Dan Pennington]

I use a good 'Scary Sharp' chisel.
But always going downhill around the curves.

[Doug Shaker]

Yeah, I'm a big fan of scary sharp chisels.

I have a friend who did a short apprenticeship with a Japanese mask maker. The mask maker said that he always devoted at least a half-day to sharpening. If he tried to sharpen just the tool he needed then, he was always in such a rush to get back to the mask-making that he did a half-hearted job of sharpening. However, if he devoted a full half-day to sharpening, he did it right and with the attention and thoroughness it deserved.

I think I am due for a half-day of sharpening soon.

[Mario Proulx]

A utility knife and a fresh blade is all I needed for my first few dozen instruments. Put some good music on, sit down in a comfy chair, and in about 10-15 minutes you're done. No sawdust, no noise, no tear-outs...

[Doug Shaker]

Mario-

Sounds kind of relaxing...

[Clay Schaeffer]

Like Mario, I've used a utility (razor) knife also, and as Dan mentioned, cutting out of the grain. For soundboards it goes pretty quick, for the harder hardwoods slower. I would cut it close and follow it up with sandpaper on a hard block. There is still some risk involved. If you loose your concentration and allow the knife to slip off the edge you can cut into the top or back with the blade.
Having used routers for many years I am comfortable using them for this task. Double checking everything (cutter, bearing, setup, cord and tool path, etc.) before putting the tool to the wood is always a good idea

[Mario Proulx]

Also, there's no need to trim completely flush and smooth, because routing for the bindings will remove the rest; just get the top/back within 1/16" or so of the sides, and go right to the binding cuts...

Yes, I used to do a neat job of "flushing" the top and back to the sides, until one day I realized the above.

[Jeff Highland]

A couple of things I have found useful
-cover the rim side of the plane chisel or knife with a piece of binding tape to make it relatively safe from gouging the rim
- a few razor saw cuts to depth in the waist area make it much easier

[Joel Nowland]

Doug

I could not find it but there is a video of a Mexican builder in Paracho who uses a Mexican luthiers knife called a (Cuchillo Knife) used for a large portion of the building process.

I was amazed at how quickly he moved through the process with this knife including trimming the top and back.

It looks something like the attached drawing.

Joel

[Doug Shaker]

Hmmm. Interesting. It doesn't look like it would be hard to make, though I am not sure how I would sharpen it. Which edge is the sharp edge?

[Charlie Schultz]

Joel, this may be the one you're thinking of... Ron Fernandez has a DVD on Paracho builder Benito Huipe and he uses that kind of knife. It was pretty amazing to watch him use it. You surely do not want to get your finger in the way though!

[Simon Magennis]

When I made my first steps in making, the people I met just used a violin makers knife. Now I usually just go around it with a japanese saw and slice little bits off until it is all gone. Maybe a slight tidy up with a chisel too. Same for both top and back. I saw with the material to be removed supported on a flat surface. As Mario points out, 100% precision isn't needed as you will be removing the evidence when you cut the binding channels.

[Doug Shaker]

Joel, this may be the one you're thinking of... Ron Fernandez has a DVD on Paracho builder Benito Huipe and he uses that kind of knife. It was pretty amazing to watch him use it. You surely do not want to get your finger in the way though!

Charlie -
Did you mean to include a photo or URL in your message? It reads like you did, but I don't see it.

[Doug Shaker]

Joel, this may be the one you're thinking of... Ron Fernandez has a DVD on Paracho builder Benito Huipe and he uses that kind of knife. It was pretty amazing to watch him use it. You surely do not want to get your finger in the way though!

Perhaps this is the URL you meant to reference:
http://www.fernandezmusic.com/MexicanGu ... Knife.html

[Jim McConkey]

That video is pretty amazing, especially because the knife is just about the only tool he uses on the entire instrument! LMII and Amazon both carry the DVD, if anyone is interested.

[Doug Shaker]

Progress report on actually doing the trimming without a router:

Trimming the back with a box cutter was OK, but I ended up scratching the back a few times. Nothing terrible, everything sanded out in about five minutes, but not what I want in standard method of work. And definitely not what I want if I am working on the soundboard where the scratches would be way deeper.

For the top, I did most of the trimming with a block plane, slightly tilted so that the blade wouldn't hit the sides, even when I was close to my final trim line. That worked fine, especially since my block planes had been newly sharpened and I like using a plane. I couldn't do most of the waist with a block plane. For that, I used a Japanese saw, sawing the overhang down close to the side, but not TO the side. Then I just broke off most of the overhang and went back with a sharp 8mm chisel and carved the overhang down to the sides. Quiet and relatively efficient.

A router would have been MUCH faster, but also much louder.

[Craig Bumgarner]

An alternative to a big noisy router is a little noisy router. I use a 3/32" down cutting bit (sold as an inlay bit), a Dremel tool with a router base and a guide. I use Stewmac's Precision Router Base and Precision Router Edge guide:

http://www.stewmac.com/shop/Tools/Speci ... e_Set.html

Works dandy and feel very much in control and really not all that noisy. Takes a minute to trim a back or a top. Never had the slightest scratch. I do run my hand over the router base regularly checking for a sharp edge that might have slipped in.

[Trevor Gore]

As no one seems to have mentioned this method yet, I will. It involves a router, so pass on if you wish...

Flush trim bit in router table. Always rout into the "dips", so a combination of standard and climb cuts, or climb cut all the way around, but don't let it get away from you. A sand bag or shot bag on the guitar to add a bit of mass may help until you get the feel. I do everything that way now, but used a spoke shave when I started out.

A word of warning: if you need to push the body through your mould to get to the other edge, you definitely need to trim flush or even under cut a little. Even slightly proud and the edge that sticks can split pieces out.

[Chuck Tweedy]

+1 on Mr. Gore's suggestion. That's what I do as well. I use the smallest size flush trim bit I have - minimizes tearout.