Options For High Speed Milling

I think I have a workable plan. I'm going to buy a 2 HP router motor that has a speed range of 8,000 to 23,000 RPM and a router speed controller. The largest end mill I'll run with this setup is 3/16" and small DOC in aluminum so I don't think I'll have a problem with reduced torque with RPM's below 8,000. Mostly I'm looking at end mills in the 1/64" to 1/8" size range cutting aluminum and some plastics. For larger end mills (up to 1/2") I'll be able to run them at the speed appropriate for the material I'm cutting. We'll see how this works out.

Thanks to all for your input.

Tom S
 
TomS said:
I think I have a workable plan. I'm going to buy a 2 HP router motor that has a speed range of 8,000 to 23,000 RPM and a router speed controller. The largest end mill I'll run with this setup is 3/16" and small DOC in aluminum so I don't think I'll have a problem with reduced torque with RPM's below 8,000. Mostly I'm looking at end mills in the 1/64" to 1/8" size range cutting aluminum and some plastics. For larger end mills (up to 1/2") I'll be able to run them at the speed appropriate for the material I'm cutting. We'll see how this works out.

Thanks to all for your input.

Tom S
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Slight change in plans. I bought the router as planned and currently working on the mount to adapt it to my mill. Pictures to follow once the machining is done. As some of you said the motor torque is significantly reduced at lower speeds. I wasn't too worried about the reduced power as my plan is to run small end mills (1/64" - 3/16") most of the time. But you never know. Reading through some of the woodworker forums I ran across this website - http://www.vhipe.com/product-private/SuperPID-Home.htm. The woodworkers rate it very high, RPM can be reduced and controlled to 5000, and it's compatible with Mach 3. Price isn't too bad either. Anyone have experience with this board?

Tom S
 
That's what I'd get if I wanted a simple solution for router control. If I use an existing Porter Cable 3 HP router for a future CNC router table, I am going to get the SuperPID. I haven't had first-hand experience, but I would trust the satisfied users on the woodworking forums. At the cost after router motor and the SuperPID, you should compare one of the generic Chinese 2.2kW spindle motors from eBay with VFD.
 
compsurge said:
That's what I'd get if I wanted a simple solution for router control. If I use an existing Porter Cable 3 HP router for a future CNC router table, I am going to get the SuperPID. I haven't had first-hand experience, but I would trust the satisfied users on the woodworking forums. At the cost after router motor and the SuperPID, you should compare one of the generic Chinese 2.2kW spindle motors from eBay with VFD.
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The lowest cost I've found for a 2.2kw air cooled spindle and VFD is about $360 delivered. Water cooled spindles are a bit more because they require a water pump. My router cost $150 (Porter Cable 1-3/4 HP) and the Super PID is $155 plus shipping. Adding in the miscellaneous hardware to make the Super PID run puts the price about the same as the Chinese air spindle setup. I have Chinese motors and electronics on my mill and they work just fine so quality doesn't appear to be an issue. I've already bought my router so the Super PID is the direction I'm headed.

Thanks for your input.

Tom S
 
I know you guys have this conversation going into motors and bearings but I would like to point out that High Speed Machining isnt exactly the spindle, Ive always understood it to be a tool path technique that removes the metal faster than standard tool paths. Advanced Pocket is a type of HSM. All that being said, I too would like to have some more speed out of my spindle, 4200rpm max right now, I do have a Mitsubishi VFD but ive read that its hard on the motor to run em up much more than the plate rating.... not sure if its really fact to a point or what but I don't really turn mine up that much, anyone can chime in on that.

edit: LOL I just reread your title, MILLING, key word eh. Dummy haha
 
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chevydyl said:
I know you guys have this conversation going into motors and bearings but I would like to point out that High Speed Machining isnt exactly the spindle, Ive always understood it to be a tool path technique that removes the metal faster than standard tool paths. Advanced Pocket is a type of HSM. All that being said, I too would like to have some more speed out of my spindle, 4200rpm max right now, I do have a Mitsubishi VFD but ive read that its hard on the motor to run em up much more than the plate rating.... not sure if its really fact to a point or what but I don't really turn mine up that much, anyone can chime in on that.

edit: LOL I just reread your title, MILLING, key word eh. Dummy haha
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FWIW I asked Matt if running a 3450 RPM motor on my PM-932 would have a negative affect on the spindle bearings and headstock gears. His advise was the higher speed would not be good for the gears and bearings. So if you increase spindle speed the existing bearings may be a limiting factor. Upgraded bearings would solve this problem, to a point, but then the gears become the limiting factor. I guess that's why most gear head VFD conversions are belt drive. As I remember your mill is variable speed so gears may not be part of your equation but bearings may be depending on how fast you want to go.

Tom S
 
I agree on the bearings, and yes Im vari-speed, Bridgeport clone. I would be especially hesitant of the bearings because of the cost of the machine, everything is purpose built, and not much room for more out of it. The max freq I run is around/under 75, 5200 rpm max, and not for very long durations.
 
chevydyl said:
I agree on the bearings, and yes Im vari-speed, Bridgeport clone. I would be especially hesitant of the bearings because of the cost of the machine, everything is purpose built, and not much room for more out of it. The max freq I run is around/under 75, 5200 rpm max, and not for very long durations.
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I'm limited to 1970 RPM so running an end mill smaller than 1/8" is virtually out of the question unless I crank the IPM way down and wait hours for the program to run. I want to do engraving. That's what's driving me to an auxiliary spindle.

Tom S
 
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