What's new
What's new

Milling mother of pearl

wmprice

Aluminum
Joined
May 29, 2007
Location
SE Pa.
My friend wants me to enlarge the holes in his peg tuners thumb grip on his banjo to a flat bottomed 1/4''.They are solid mother of perl and he had no extras. I am thinking of using a solid 4 flute carbide end mill with very slow downfeed and coolant. Does anyone has experiance with this or an idea of the rpm? Thanks in advance, bill
 
X axis powerfeed that doesnot lesson travel?

My buddy says there used to be an X axis poerfeed that did not reduce the amount of travel on a vertical milling machine like a bridgeport or Lagun. Can anyone point me to a source for these? Thanks in advance, Bill
 
Just use a 2 flute HSS cutter,run it fast to make the hole in the peg. Buy pearl dots cheaply from Grizzly,or stewmac.com. They are too cheap to make.
 
Don't use coolant. Mother of pearl is shell and is layered. Coolant may seep between the layers. It is calcite and not hard and can be cut with ordinary carbon steel.
Ted
 
Concur with not using coolant....and do rig a low/medium pressure air line to surely blow the dust away as you mill, as.....from folklore at least.....MOP dust is very bad for you should you inadvertantly inhale the dust.

Be warned.....this is not easy material to machine, as it may contain hidden flaws in layers, which will have the part shattering when the tool first touches it. Be very certain the owner understands this, and is comfortable with taking that risk.

cheers

Carla
 
I've been cutting pearl since the 50's. Yes,it isn't good to breathe,but I think you'd have to cut a large quantity to be dangerous. it makes a poison gas. Never ever got sick from sawing out pearl shaped with a jeweler's saw. I advise keeping a vacuum nozzle near it so as to not get the pearl dust on the machine. Just last night I was using a circle cutter to skirt the edges of a pearl soundhole inlay,to inlay banding next to it. the cutter was a lathe tool ground down to make a .020" wide groove. The bit actually cut a little of the pearl just to insure the circularity of the pearl inlay. I was running the circle cutter at slowest drill press speed. It cut the pearl perfectly without chipping it.
 
Look around Frank Ford's website at frets.com. Lots of neat stuf about machining and fixing string instruments. there's got to be something there about working with mother of pearl...
 
wmprice,

I machine a lot of pearl. Take note of the advise in to other replies with regard to the dust. Your initial sense of the correct method is sound. Use a 4 flute new carbide end mill. High rpm's and a very slow downfeed untill you are under the surface is advisable. It is a somewhat chippy material and this will give you the best chance of enlargement without chipping at the entrance to the hole. Since these appear to be blind holes your major concern is the entrance. Make sure that the flutes do not clog with pearl powder. Feed out as slowly as you feed especially as the tips of he cutter clear the work. Ensure that the work pieces are firmly held with no possible movement or you will most certainly cause chipping.

In patograph profiling pearl I run a 3/32" cutter at 19000 rpm. Whist you can cut it with HS it is Pearl rather abrasive and HS will dull quickly. In order to machine a near perfect hole carbide is yr best bet.

Owen
 








 
Back
Top