Soundboard and Back Overhang

[turnertj]

Hey all...

How much overhang do you allow before closing the box? I don't want to leave too much so I don't get any tearout, but it makes me nervous to put my soundboard and back in the bandsaw too!

Thanks,

Tj

[tippie53]

You want to work close but don't cut yourself too close. Try to keep under a 1/4 and more than 1/8 inch. That gives you a little wiggle room

[Jim_H]

You want to get it close to minimize other issues when removing the excess. It's a lot easier to remove it before you put it on the guitar than it is once it's on there.

It's very important to be absolutely sure of your fit (brace notches, etc...) before you commit.

[Tom West]

Tj: When I put the body outline on tops and backs I put them on both sides. If you do that you can score the plate about 1/8" plus from your outline with a sharp knife. Put that side down on your bandsaw table and cut slightly bigger then your score mark. OR you can cut the plates a fair amount bigger then needed and on a drum sander trim to where you want. No need to fear the bandsaw.
Tom

[Herman]

Up till now I did about 1/4" and got away with it. So I guess that would be a safe spare space.

good luck
Herman

[Darryl Young]

I found that leaving excess around the perimeter changes the tuning of your plates. So if you are tap tuning or using Chladni patterns etc., the more extra you leave the more it changes things when you trim to final shape.

On my last top, I did as described above.......used bandsaw and tried to leave 1/8" or slightly more around the perimeter.......except in the waist. I left excess in the waist area and sanded on a drum sander down near the waist line.

[turnertj]

Hey guys...now that I have my soundboard attached, how do you trim the excess? With a flush cut bit, or a down-cut bit? I have the stewmac router bit for cutting my channels. Should I use that with the flush cut bearing on it?

[johnnparchem]

I have had very good luck with a 1/4 spiral down cut bit from Whiteside. Seven tops with no issues even with nearly an inch of overhang. The flush cut bearing on the stew-mac should work. Make sure you are always cutting from the widest part of the bout down. That way if the bit rips the wood it will be off the guitar instead of into it.

[watergunn]

Just be sure that you follow the recomended routing path and what part of the overhang to cut first so you do not get any chip out.

I just did this on my first build and I used a flush trim bit that came with my router. I was a perfectly smooth edge and no chip outs.

I was scared to death while doing it though!

[tippie53]

The cutter needs to be sharp. Also as some woods tend to tear out more than others , You can tape the bout areas for some support. Also learning how you work the router and listening to the feedback from the wood. I do a combination of climb cutting and routing.
As John P points out be aware of the waste and also direction of attack of the cutter
Climb cutting is working the router in the same direction of the spin , rout cutting is pulling into the cutter. Small nibbles in the critical areas can help a lot in the tear out areas . You will be doing this again when you rout for the binding.
You will soon learn how this works . If you smell smoke you are going too slow , you need to match the feed rate to the cutter for best results.