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So here's the first piece of inlay I cut on my CNC. It's the first fret of a pinstripe look that's going on a guitar I'm making for my son. The lines are .015" wide, and I used .06" shell material. I cut it with a .033" bit. I tried cutting the points with a .010" bit, but it broke immediately. I think the .033" looks just fine, so I'll make that work. The left triangle section broke off as I tried to remove it from the Masonite, but it'll be fine.





I'm going to cut the pocket with a 1/64" (.0157") bit. I figure that it will need a couple thousandths of clearance on each side, which means the pocket should be .019", right? That should be just fine for a .0157" bit, shouldn't it?

I'm still learning, but it's coming along!

One more question: I superglued this to a piece or Masonite to route it, but I couldn't get the CA loose. I soaked it in acetone; no luck. I had to sand the Masonite off in my belt sander. Is there a better trick? I may try hide glue nest time.

You can't be certain the bit is perfectly .0157"....unless you have the means to measure it. That takes more than a set of calipers to do accurately.

So...if you don't TRULY know the bit diameter, and you can't ascertain that it is perfectly concentric in the holder...then you can't really be certain what kind of fit you will achieve merely by adding a little to the groove cut. A non-concentric cutter will undersize the plug and oversize the grove and you'll have a looser fit than expected. A cutter smaller in diameter than the planned program calls out will do the opposite and the pieces might not fit at all.

The best thing to do is to sneak up on the fit by running consecutive, slightly expanding recuts.

Get some two sided tape. Obviously, CA was overkill. The tape should work well if you aren't too aggressive with the cutter.

Another trick is to cut the inlay wrong reading (or opposite) and leave on a base. You can glue the inlay into the groove and then face off the base later. I use this method exclusively for inlays. It allows VERY delicate inlays to be made without risking breakage.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Acetone doesn't do a good job as a debonder. Fast cap sells a debonder as part of their CA glue line that is NitroMethane, funny car fuel I think, and it works great. Otherwise I'd trust Stewart with his ideas.

I haven't tried hide glue yet but for delicate MOP inlay, I just use regular old titebond and release in hot / boiling water.

I use CA a lot as well but the latest bottle I bought holds really tightly even in boiling water. I'll probably be sticking to titebond in the future.

A word of caution though - for Abalam, always use titebond or something else that will release at a low-ish temperature. Abalam will delaminate in boiling water but it stays together just fine in anything short of boiling.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Thanks, everyone! This is very helpful advice. I'm well on my way!

My next step is to cut a pocket in some scrap material to see how things work with the .0157" bit and some very hard wood. UPS can't deliver the Precise Bits package soon enough!

Hide glue works best. I always used hide glue to glue the shell to pieces of masonite, then turned them upside down in a clear bowl of water and turned on the microwave until they started falling off. I could cut parts with 0.014" lines and get them off without damage.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Kelby I am in the same boat with you man! my first mop inlays I used 1/4 mdf scraps and when finished with the cuts I would slice it thin close to the mop blank then dunk in acetone for a couple mins and that seems to work for me. I Sold My Old CNC Router Romaxx hd1 And Ordered My New One wd1 A Couple Weeks ago So I'll Take All This Advice And Apply It On The Next run. Thanks