Official Luthiers Forum!

Hello All,

I was curious how everyone goes about flush trimming a glued on redwood top. I've never had any problems in this area with spruce, but with redwood's propensity to split I was wondering if a router with flush trimming bit is the way to go.

Thanks,
Greg

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Gwaltney Guitars

Apply a coat of sealer before routing , though sealing may not help with splitting

You shouldn't have any problem since the top is glued. To be 100% secure you could rout in 4 passes, starting from the middle of the lower bout to the waist, then to the tail, and from the middle of the upper bout to the neck, and then from the waist to the middle. Make sure your pattern bit is sharp…

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

In the case of splitty woods, higher RPMs and smaller bits are better.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I do 4 climb cuts with a flush trim bit and then just take the rest in one pass with the router. Never had a problem.

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

Thanks guys, that's what I thought, just being cautious with the redwood.

Greg

I have had a chunk of sruce split off once. Can't remember how much overhang there was back then. I do the climb cut deal AND I creep up on the final cut. I use a taped bearing, then remove the tape from the bearing and do the final cut.

using appropreat climbing cuts in the transition areas will help, as will applying a sealer like shellac prior to the cut. Also small cuts and sharp bits. Treat Redwood pretty much the same as you would Red Cedar and add a bit extra care Most tear outs will accrue where the bit attack changes from with or perpendicular to the gran to against the grain That is why climbing cuts are important when removing the majority of the stock.

Oh yeah, climb cutting! I haven't used a 'conventional' cut in so long (since my 'router' is 11000lbs) that I forgot to mention that!

So now it's high speed, small sharp bit, climb cut. If you can spin a small sharp bit fast enough to stop it from breaking, you can cut -anything- without it chipping/breaking/etc etc on you.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I still laugh every time I trim a top or back with the roto zip bits. They're incredible... I don't even pre-trim my tops and backs anymore. Just glue them to the rim square, and trim the whole thing once glued up.

The one you want is the 1/8" Guidepoint. "GP10" is a 10 pack. Available everywhere....

http://www.rotozip.com/Shop/CategorySub ... HID=188064

Inexpensive, yet they cut incredibly clean. I tried their 1/4" bit, but the 1/8" is way better for this. The only trick" is that the bit needs to be buried in wood. In other words, don't trim off to less than 1/2" of your outline.

Mario,

How do you keep that bit from wandering into your sides?

Greg

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Gwaltney Guitars

It's a guide point....

I saw them at lunch, today. I was picking up a couple of Diablo blades, and the 1/8" guide points in a pack of 10 for $8.95, at the BORG.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

O.K. Mario, I went and checked out those bits tonight, I know you wouldn't use them if they did this, but I'm going to ask anyway.....don't they burn the tar out of the side of the guitar without a bearing. I mean that thing spinning at 20-30,000 rpms, bare metal tip on wood, seems like it would be a mess.

Greg

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Gwaltney Guitars

Only if you go too slow or stop.... Otherwise, barely a mark left.

Now THAT'S a useful tip, Mario. I'll definitely try it. Thanks!

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Wes McMillian
Santo, TX
http://www.wesmcmillian.com