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Hey guys:
I need to cut some 0.070" ebony inlay for my next build. Does anyone have a good fixturing method for this short of double sided tape? I use HHG on a sacrificial substrate for all of my shell inlay, but don't see that as an option for thin wood inlay. And I hate using double sided tape as it gums up my bits and its difficult to get the inlay off without destroying it.

Any good ideas out there that you're willing to share?

Thanks,
Dean

-double back tape (what i use)
-wax (jewelers dopping wax)
-ceramic vacuum chuck ($$$$)

db tape is available in different tacks. i use a low tack version. comes off easy but still holds. 3m makes it and i buy it at Target for $2.

Thanks Arie:
I'll give that a try. I think the stuff I've been using (for larger pieces) is the permanent stuff and is a bear to get off. I've seen the removable type, but haven't tried because I was afraid of seeing my parts fly across the room.

If it were me I would use double sided tape (mcmastercar has a great industrial strength tape) and leave a thin layer of the stock so you don't touch the tape and sand the layer off with a sanding block. Hope that made sense. Good luck

Oh wow I just read the thickness! That might not work

My 2nd, 3rd, and 4th best tricks for cutting wood inlays- enjoy

1-Cut the inlay in reverse as a boss on a thicker piece of wood, then glue it into the pocket face-down and mill off the extra.

2-If milling after install is an issue, you can also cut it just a little tall on the base piece (0.100" total) and then cut it off with a razor saw and sand level when installed.

3-CA will release from metal with heat. It's quite a bit of heat, and you probably shouldn't check how it smells, but it'll do the trick. Cut it in reverse so you're leveling off the side with the CA on it on installation.

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

It's a headstock inlay so I guess I can go as thick as I need and milling it flat after the inlay won't be a problem. I guess since most of the shell inlay I do is around 0.060", I was stuck in that mindset and there's really no reason to with wood inlay. Thanks for the wake-up call Bob!

I suppose I'll share a secret....Here's a flow through vacuum fixture I use to hold down head plates and also the inlay that I put in there. Key points to remember:

1 - seal the edges of the MDF and then surface it on both sides.

2 - The head plate or inlay material must be very flat. In fact I've added some wide hold downs on both ends for pieces with a little cup/twist/warp to them

3 - For the inlay itself, use a small bit and don't try and blow away the dust - let it build up in there. It will hold the piece down.

4 - climb cut all the way around.

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

Andy:
Not sure I'm following. Are you pulling the vacuum through the MDF? If so, that could be the perfect thin veneer/inlay solution.

Also, what material did you use for your vacuum fixture? It looks too dull for aluminum.

Vacuum flows through MDF fairly well. Large router setups use this to advantage in cutting 5x9 and 4x8 panels into cabinet parts.
Hold down pressure is based on surface area so it can be tricky given that the maximum a vacuum can achieve is around 14lbs per square inch.
If your inlay is only a square inch finished, there isn't much holding it down, whereas a body at around 2 sq ft would have around 4,000 lbs of force on it.
Even a head stock comes in around 200 lbs.
My problem with cutting small parts with vacuum has been that they are pushed sideways ever so slightly even when using low feed rates.

Cutting inlay as a boss on a larger piece using vacuum to hold it down is probably the best way to go. I imagine the base could be left paper thin under the tool for easier removal. I'm going to try it in the future in place of tape.

Bob, another great suggestion!

That is indeed an issue but the solution has already been provided. Cut in passes with a very small bit and do not blow away the dust. While there's a skin at the bottom, the part won't move. When you do your final pass, all the dust in the slot (which is compacted down at the bottom by vacuum) holds the piece in place.

I just contacted a client to see if I can share some work I've done for him and if I get the green light, I'll post a pic of what can be done this way.

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

Got the ok. This is just a crappy iPhone pic but you get the idea. Jason said he'd send me some pics with the inlay under nitro as well.

The material in this case is 3 layers of maple veneer laminated together with titebond in cross grain fashion. The plywood lamination makes the inlay stronger across the grain.

Enough secrets for today!!! I highly recommend that people not attempt something this difficult and outsource all of their inlay needs to me

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

Don't forget the humble sticky tape over the top method for holding parts before they are cut free.Works quite well for manual inlay to hold pieces inn place as you knife around.Possibly pause the cutting, put tape over the already cut free areas and then finish it off.

Very nice, Andy! I really appreciate you sharing your secrets.

You know, if we let you have all of the fun, where would we get our daily dose of aggravation?

Thanks again,
Dean

Andy, is that bottom fixture cut from aluminum?

No, that's something called tooling board from General Plastics. It's the absolute bomb for fixtures. Cuts like butter but is still plenty strong. Doesn't warp after cutting either. Amazing stuff. Very expensive to have shipped but if you can find a local supplier you're hooked.

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

Dean, It seems you may have already found a satisfactory solution, but what I've always done with thin woods (all of my inlays are cut at .05-.06) is glue them to a backer with regular Titebond. I just boil/steam the wood loose after. No prying whatsoever and absolutely no slippage during the cut. The only setback is about an hour of glue setting.

Nathan:
I ended up using a thicker veneer (0.100") and double-sided tape and that worked out OK. I tried out Andy's method but I got some slippage. I think the reason for that was my vacuum pump. I'm using a small diaphragm pump on my CNC. It has the ability to draw a 28" vacuum, but it can't move much volume. I think you need to be able to pull a decent volume through the porous MDF to make this work (maintain a high vacuum).

You might want to give hide glue a shot if you're looking for a quicker turn around. I use that for all of the shell inlay I do and can usually cut it in 15 minutes or less.


Do you ever have condition problems with the wood inlay after you've boiled/steamed it?


Thanks,
Dean

If you use double back tape, you can weep in a little acetone to separate the pieces like magic when you are done. Works really well, especially for the fragile parts,
Mike

Naptha also works to release double-stick tape.

_________________
Steve Smith
"Music is what feelings sound like"