Re: [CAD_CAM_EDM_DRO] Aluminum cutting,,,,,,,

One way to get a bit more speed is to install a variable frequency
drive, which synthesizes 3 phase AC changing the voltage and frequency
as necessary to make the motor run at different speeds. Usually you
can run them substantially above the nameplate speed of the motor. A
side benefit is that if you get a unit rated about twice your motor
horsepower, you can use it is a solid-state phase converter and plug
it into single phase.

However you might need a better quality motor (rated for inverter
duty) if you want to run faster than 60hz a lot. You also may need
better spindle bearings.

A simpler method would be to double the speed of your mill by
substituting a 3450 RPM motor for the likely 1725 RPM one on there.
Concern about spindle bearing life remains, and you may miss the low
speeds...

Chris

> And how do I go about doing that...without rebuilding the entire drive
> head...and would the cost be worth it?
>
> This machine is a 3HP vary-speed (speed adjusted thru a crannk) 9 x 49 mill.
> A Chinese "knock off" of a Bridgeport.
>
> Smoke
>
>
>
> >Smoke wrote:
> >
> >> Max speed on my mill is only about 3200 RPM and I think I'll pass on
> using
> >> an 1/8" end mill when surface finishing a 5"+ wide piece or cutting 1"
> plus
> >> groove widths.
> >
> >Well, up to the max RPM on your spindle, the interesting thing is that a
> large
> >end mill doesn't actually allow higher feed rates, at least for finishing.
> >I used to think that you needed really big end mills to remove a lot of
> >metal quickly, but finally figured out that a small end mill, turning fast,
> can
> >remove metal FASTER, given that fairly small depth of cut and chip load
> >will be used. Yes, when carving out big cavities or grooves, then the
> >larger tools do better, but when finishing on the side of the cutter, the
> >smaller tools can spin faster, therefore more teeth per minute, so you
> >can feed faster. The limit, of course, is the length of cut. The small
> >end mills will deflect or chatter on the longer cuts, while the larger
> tools
> >will stay rigid.
> >
> >Jon
> >
> >
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--
Christopher C. Stratton, stratton@...
Instrument Maker, Horn Player & Engineer
22 Adrian Street, Somerville, MA 02143
http://www.mdc.net/~stratton
NEW PHONE NUMBER: (617) 628-1062 home, 253-2606 MIT