cutting mother of pearl inlays

[rlf]

This is my first posting but while surfing the internet i found shopbot owners with frustrations cutting inlays. My hobby has been building acoustic instruments using my my prs shopbot and have been able to inlay both mop and abalone on about ten instruments. Being new to the forum I would be glad to pass on my learning as i have done this for at least three years now. I retired eight weeks ago and intend to live in my woodshop for the next year. I would appreciate any information on use of a cnc laser with the cnc shopbot on projects.

[stumpgrinder]

Congratulations on retirement Ray! Just got in the shop after making this. We've been using our bot (desktop) to do most of our inlays. Our client sent us the turning blank to be used for the headstock overlay. I glued up 4 pieces, then had the bot cut the pockets for the inlay, then the profile cuts to cut it out. The shell was blue abalone which costs about $75 an oz.! Our desktop has the pc router and we have been using bits from precise bits. All vectors were designed in Rhino then imported into Partworks. How do you go about doing yours?

[nailzscott]

I successfully cut some pearl for my first bass guitar, but it was with some trial and error. I would be interested in the size but you used and some cut speed information - if you don't mind sharing.

Thanks

[stumpgrinder]

I've been using both the 0.0200 and 0.0156 bits. I use the larger one for the script inlay and the smaller one for areas that have sharp corners. I've used the same 0.0200 bit for the last 25 inlays and it is still cutting great. Speed is set for 0.1 inches a second with the router set at 20,000. On a typical piece of shell that is 0.060 it is done in about 6-9 passes. The only issue I have is that the dust sometimes gets packed onto the sides of the inlay and I have to do a little scrapping to get it off, but it shure beats the heck out of hand cuttign the script which used to take about 45 minutes, then another hour to file, and I almost always broke it.

[paul_z]

Lauri,

Are you using a router or a spindle? I've used 0.030" bits on a router but I was reluctant to try smaller.

Paul Z

[stumpgrinder]

Hi Paul,

Yes we have the Porter Cable router on the desktop. We commonly use 0.023 bits for fret slotting, and 0.020 and 0.0156 for pearl. No problems at all and all cuts are extremely accurate. I slot about 15 boards with one bit, and we cut about 25 script inlays with one 0.020 bit and it is still cutting nice. It will be interesting to see how much longer that bit will last! You'll have to come up and visit the shop one day when we are cutting some pearl.

[paul_z]

Lauri,

Thanks for the info. I'd like to drive up some day and see you cut MOP. I've never done that.

Paul Z

[stumpgrinder]

Cut our new prototype inlay out of mother of pearl today on the desktop. Those tendrils on the G are only 0.015 thick!

[gerryv]

Wow, that's quite incredible! Never seen such wonderful stump grinding.;) Koodos to both you and Shopbot.

[jim_ludi]

Lauri, how are you holding the MOP down when you cut it?

BTW, l like your creative use of the musical note in your new logo - looks cool.

[stumpgrinder]

Super glue the shell onto a scrap piece of wood, then double stick the scrap to the spoil board. I also use a couple of drops of glue and accelerator to quick cure the drops as security. We had a few pieces come unstuck during the machining. Once the pearl is cut, I just pry it off the spoil board then soak in acetone to release the pearl from the scrap.

[tomwillis]

Ray,

I have twin Z's on my SB - one for router and the other for laser. It's a 40watt Universal. I do some cutting, engraving and etching with the laser. Recently made a Cribb board. Playing around with inlays for a briefcase that I'm making. Used the router to pocket the basic shape and then came back with the laser to cut sharp angles so the inlays fit nice and tight. However, when I met Paul Z over at the Maine Camp - he showed us his technique of cutting inlays - which was very intriguing. I use Rhino and RhinoCAM and not Aspire - so not sure yet, how to use his method. I'll have to talk to Paul soon and see if I can figure that out. Attached a pic of the cribbage board.
Tom

[richard_saylor]

Could you post the Precisebits product numbers for the bits that you use for MOP and fret slotting?

[stumpgrinder]

Hi Richard,

For the fret slots we mainly use MM3I8-0230-009F

For the inlay we use several sizes but most commonly MS3I8-0200-008F

It really depends on the job, and that will determine which size bit we use.

[dougk]

A couple tips:

I use the cutters from precise bits for cutting mop too. Their suggested feed rates work fine for us. I use the 1/16 for fretboard inlays and the .4mm(!) for my headstock.

Smear some vasoline over the pearl before machining. The dust is very toxic and murder on the equipment. The vasoline will help keep most of the dust from going airborne.

The other tip, use the odorless thick hobby ca glue to glue the pieces to a board of melamine (I use the ca glue from grizzly but most rc/hobby stores carry the same stuff). I find the odorless releases the easiest when hit with acetone and the texture on melamine is enough to let the acetone run in under the mop.

[stumpgrinder]

That is a really good tip on the vaseline, think I'll give it a try. Just a quick note about shell, it is not toxic as there are no poisons or chemically harmful substances in the shell. It is however hazardous to breath as is any dust. Here is a good article explaining it all:

http://www.luthiersupply.com/files/Articles/CutShellAndDie.html

[dougk]

That is a really good tip on the vaseline, think I'll give it a try. Just a quick note about shell, it is not toxic as there are no poisons or chemically harmful substances in the shell. It is however hazardous to breath as is any dust. Here is a good article explaining it all:

http://www.luthiersupply.com/files/Articles/CutShellAndDie.html

Sorry should have been more clear. The dust is really bad for you, not toxic as poison but really harmful to your lungs (and its almost like pouring glass bead in to any bearings ect)

[Max Girouard]

Just posted this on the desktop forum, but figured we'd add to this already existing thread in the general message board section..........

Mother of pearl Fleur de lis that we wanted to be able to offer as an inlay on our headstock overlays for our mandolins and mandolin family instruments.........

[scottp55]

Beautiful Max, as usual.:)

[Hoytbasses]

Hi Max:

still trying to find time to come by your shop when I'm up in Washington next: I'm thinking we'll be up there around Feb school vacation, maybe I'll PM you when it gets close and sneak over if you're open to that.

I cut my first inlays on the desktop last week. I shocked myself at how well it went. Nothing as fancy as your stuff right now. I did learn the hard way that 'a little dab'll do ya' when it comes to gluing down the pearl/abalone. I really flooded the pearl and ultimately had a wrestling match getting off the backer board. I like the melamine idea.

I have yet to cut pockets in the headstock or fingerboard, so I'm wondering: do you use separate bits for cutting the inlay pocket, or do you just use the inlay cutting bit to do it? Those precise bits are great and the company is wonderful to work with.

Thanks in advance.

Karl

p.s...... beautiful inlays!

[bleeth]

Really beautiful work and a fine demonstration of the resolution and smoothness of the desktop. Most would be satisfied with a filled in one piece fleur. Doing it as such fine line work is amazing, like your Logo.

[Max Girouard]

Thanks Scott and Dave!

Karl, I use separate bits. For the pocket I used a 0.023 fret slot cutter as I've got a bunch of them. For the shell it was their specific 0.020 cutter designed for shell. I'm sure I could have used the shell, but each bit is optimized for certain materials.