50,000 RPM Mill Spindle

[JimDawson]

I have been wanting a high speed spindle for my mill for light routing and engraving. I did a project a while back that required that I use my friends router to get the spindle speed that I needed to run the really tiny end mills I was using.

So with a Micro Air Die Grinder from HF, I made it happen. The HF grinder is about 5/8 diameter, so it fit nicely in an end mill holder, after a bit of lathe work on the end.

A little modification to a #30 taper tool holder. I had to drill it 5/8 all the way through, and trim the end a bit. I don't need the drawbar threads on my mill. It got a little warm on the end while drilling, these tool holders are made of some pretty tough stuff. I was only turning at 115 RPM.




The air grinder inserted in the tool holder.



Connecting the air line.

The grinder has a M6 threaded air fitting on the back. This was supposed to provide the grip on the air line in the original configuration. The air line blew off the first time I tried to run the thing, the collar had split so it was loose. So much for Chinese engineering. It worked out well for me, the M6 thread screwed nicely into polypropylene fitting I wanted to use. I didn't even have to make an adapter, it just screws right on. The polypropylene is soft enough that it formed the threads very nicely.



The air line goes down through the drawbar hole. Note: Don't turn the spindle on!! There is an in-line oiler to the right of the regulator.

I need to install a 1/4 turn valve on the regulator as an On/Off switch.





A carbide V-cutter engraving bit installed.




The first test run in a scrap piece of acrylic. Everything worked great!! This is engraved from the back side, so you are looking through the acrylic. To get the contrast in the picture, I'm holding a piece of paper behind it.

~50,000 RPM, 10 IPM, 0.006 deep, with soy based cutting fluid.

This is part of the labeling on my new mill control panel. It will be side lit with LEDs. I'll post that project when I get to it.

 

[dave2176]

That's pretty sweet. I'll stick that in my box of future projects.

Dave

 

[Dave Smith]

Jim---I have about 10 of the HF small grinders for the high speeds of small cutters and drills---one question--did you turn the small drill speed adjuster to wide open when you mounted it inside the holder?--if so then do you have an external speed switch or do you just run it always at full speed?----I guess I never thought about mounting the unit inside of a collet or tool holder-----good idea-----Dave

 

[JimDawson]

Jim---I have about 10 of the HF small grinders for the high speeds of small cutters and drills---one question--did you turn the small drill speed adjuster to wide open when you mounted it inside the holder?--if so then do you have an external speed switch or do you just run it always at full speed?----I guess I never thought about mounting the unit inside of a collet or tool holder-----good idea-----Dave

I turn the internal valve wide open and adjust the regulator to adjust the speed for now. I may play with putting a flow control valve down stream of the regulator. I need to also put a shut off valve before the regulator.

 

[DMS]

I have a setup with the same little pencil grinder, except I mad a clamp that goes around the spindle collar, rather than through the spindle. I made mine for cutting PCBs (worked great). Haven't tried engraving anything yet though. That panel looks really clean.

 

[JimDawson]

I have a setup with the same little pencil grinder, except I mad a clamp that goes around the spindle collar, rather than through the spindle. I made mine for cutting PCBs (worked great). Haven't tried engraving anything yet though. That panel looks really clean.

Please post a picture or 2 of your setup.

I am going to make a mount that clamps onto the spindle also. That one will be for a larger drive motor, probably a small router, or something similar. I thought about building a system that would have the motor on top of the spindle and drive it with a shaft down through the drawbar hole. Then I realized that it would have so much shaft whip that it would tear it's self apart.

 

[george wilson]

I have planned some day to make a clamp that goes around the spindle housing and holds my 10,000 RPM Dumore die grinder(electric) on the other end. Since we have a home business of jewelry making,and I sometimes make brass master models using small end mills,such a rig would be helpful. And,you do not run the risk of automatically turning the milling spindle on!! I'm going to make it out of 1" thick aluminum plate. Or,I could use my sweet little polished aluminum Stanley 1/4 HP router,which goes twice as fast. And can also be regulated with a router speed control.(As can the Dumore).

I saw a little rig made out of a Dremel tool,connected to a small ball bearing spindle by a little belt,at a Cabin Fever show. I don't have that much faith in Dremels,though. Their puny plastic coupler breaks so very easily,I have quit using mine. I have never used it hard,and the silly plastic coupler breaks anyway. Plus,lack of much power at all. Must be a regular problem,because Lowe's sells the couplings.

 

[JimDawson]

I have planned some day to make a clamp that goes around the spindle housing and holds my 10,000 RPM Dumore die grinder(electric) on the other end. Since we have a home business of jewelry making,and I sometimes make brass master models using small end mills,such a rig would be helpful. And,you do not run the risk of automatically turning the milling spindle on!! I'm going to make it out of 1" thick aluminum plate. Or,I could use my sweet little polished aluminum Stanley 1/4 HP router,which goes twice as fast. And can also be regulated with a router speed control.(As can the Dumore).

I saw a little rig made out of a Dremel tool,connected to a small ball bearing spindle by a little belt,at a Cabin Fever show. I don't have that much faith in Dremels,though. Their puny plastic coupler breaks so very easily,I have quit using mine. I have never used it hard,and the silly plastic coupler breaks anyway. Plus,lack of much power at all. Must be a regular problem,because Lowe's sells the couplings.

I agree about turning on the spindle accidentally, in my case I can pop the control console off of my VFD and put it in my tool box. Just squeeze and pull, as long as I remember to do that!

I may build 2 brackets, one for my router so I can use 1/4 and 1/2 bits, and then another for a RotoZip so I can use 1/8 and 1/4 bits in it. I think the router has enough power that I might have to use 2 inch thick aluminum for that bracket.

I think your Dumore would make a great tool to use that way. A Dremel is just about useless for metalworking with the exception of light deburing and chewing out broken taps and ez-outs. I have a little cordless that is kind of handy, but I don't use it that much.

Be sure and post pictures of your project when you get to it.

 

[Dave Smith]

I turn the internal valve wide open and adjust the regulator to adjust the speed for now. I may play with putting a flow control valve down stream of the regulator. I need to also put a shut off valve before the regulator.

Jim--it is best to put the speed control on the exhaust side of air motors so you still have full power at lower speeds--but I don't think there is any exhaust port that you could put a control on the tiny grinders--probably full speed is all a person needs to use on those and a shutoff ball valve---very cleaver idea of mounting in a holder--:thinking:---Dave

 

[JimDawson]

Jim--it is best to put the speed control on the exhaust side of air motors so you still have full power at lower speeds--but I don't think there is any exhaust port that you could put a control on the tiny grinders--probably full speed is all a person needs to use on those and a shutoff ball valve---very cleaver idea of mounting in a holder--:thinking:---Dave

Dave I agree 100%, unfortunately this has a rear exhaust and without coming up with a coaxial air hose system, that will fit down the drawbar hole it would be impossible. It may be possible to fabricate a coaxial airline that will fit. I have only made one test cut with it so far, haven't really had time to play with it. Later this week I'll have a bit more time to play.