spindle speeders and engraving.

I have a 3500 rpm Tree 325. it has a cat 40 quill style z axis.

I just bought an nice sign engraving program (vcarve) I'd really like to speed up my spindle alot to turn little < 1/4" bits in brass, aluminum, plastic, wood and maybe some steel.

can I run a planetary type -yuasa etc. speeder for hours on end?

is an electric "grinding head" better suited? Or air powered? Or shall i try to mount a small palm router?

also, since it's a quill... if i run a router etc... i will be vibrating and loading my spindle bearings while they are stationary.. unless i make up a z axis way system and use the spindle only to drive it to the height position and it take the vibration and most of the load.

anyone gone down this road?

Thanks, Dan

I have used a air powered spindle attachment to get up to the speeds necessary. One of the Vulcanaire units. Only bad thing about this is the amound to air it uses. A 5HP cfm compressor runs almost all the time.

My next spindle is one of the Precise brand spindles. They pop on on ebay all the time available from 35000 to over 50000 rpm. ABEC 7 or 9 bearings inside. Make a mount and attach it to the size of your head.

I use NSK 50,000 rpm air jig grinding spindles in my VMCs to engrave. They appear on Ebay for around $350, and are available in several rpm ranges. I can't say that they will or won't have the power to run a small endmill. Similar units are made by Yuasa.

I have one of these:

http://www.macrotechnologies.com/spec_high_speed_air_spindle.htm

I researched the options and selected this one because it has lower air consumption than the turbine types. Mine is a positive displacement air motor rather than a turbine. The advantage, as mentioned, is lower air consumption. Though mine is still intact after a fair amount of use, I am told that the advantage of the turbine type is longer life. I bought the unit new for about $600. It works well for engraving and drilling printed circuit boards.

Dan, these Fimec spindle/motor assys seem pretty neat though I doubt that making an auxiliary head with one of them is going to be inexpensive. John Stevenson seems to have some positive things to say about them.

My compressor runs enough with just the MicroDrop bleeding off air through two nozzles. Running a pneumatic spindle speeder sounds like it would be really noisy as the compressor would probably be running all the time.

I do like the idea of a separate power source for the high-speed spindle instead of having to run your Tree flat out all the time so a mechanical speeder can step that up. Also, aren't a lot of those mechanical speeders limited to 3-4X? That's not going to get your cutters moving very fast.

cheers,
Michael