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alanb
20-11-2010, 04:39 PM
Hi,
I have finished the CNC part of my computerised rose engine (see http://blog.alanbattersby.co.uk/ for picture) but need to drive my cutting frame. For this I require around a 1/2 hp motor that will run continuously for 4+ hours at around 1500-2000+ rpm preferably with speed control. Can anyone suggest a suitable motor/controller combination. Don't know if dc or ac single or 3 phase is best so any advice appreciated.

Thanks Alan

M250cnc
21-11-2010, 12:11 PM
but need to drive my cutting frame. For this I require around a 1/2 hp motor that will run continuously for 4+ hours at around 1500-2000+ rpm preferably with speed control.Thanks Alan

I am puzzled by your description "Cutting Frame" as what you are implying is the headstock/workpiece. If that's the case you should be very aware of the correct speed when using large workpieces.

Phil

alanb
21-11-2010, 02:32 PM
See attached image the cutting frame normally holds a small extremely sharp cutter which rotates at high speed say 3000+ rpm and depths of cut are very slight, less than 1mm. The work held on the headstock moves very slowly say rotation speed 2 rpm and the cutting head can move slowly backwards and forwards across the face of the work.

In my design the horizontal headstock movement is achieved by running the headstock along linear rails with the headstock is attached to ball nut, through which runs a ball screw connected to a stepper motor. You can of course achieve the same effect by fixing steppers onto the cross-slide etc of a metal lathe. I just wanted to make one that did not tie up my metal lathe and that would handle work with larger diameters (18 inch capacity same as my wood lathe) than can be held in my small metal lathe which has only 8 inch capacity

Let me point out that the cutter in the attached image is not yet shaped or sharpened it is just for illustrative purposes. It is a piece of gauge plate 10mm wide which needs to be finished. Also the paths I intend to cut my extend over many rotations of the headstock before they repeat thus the need to run the motor for long periods. At present I am using a proxxon BFW40 head but this tends to get very hot after half an hours continuous running so I have to keep pausing to let it cool down.

Thanks
Alan

ptjw7uk
21-11-2010, 03:03 PM
If you want to run for long periods then go for an induction motor, only down side is tehy tend to be on the large side for the same power as DC.

peter

M250cnc
21-11-2010, 03:33 PM
So you want a cutting spindle basically.

Have you thought about a round belt drive as used on the old engravers

Tony at lathes.co.uk supplies the belts made to measure

Something like this in the attached poor quality picture
3388

Very quiet and can run all day this is from a Taylor Hobson i was going to mount it on my mill for engraving, but i might get a water cooled spindle instead, it will be clamped in the middle part


Criticism i looked at your machine build and you really should protect the ballscrews from dust ingress.

Phil

alanb
22-11-2010, 02:43 PM
I have already built the spindle, its the motor that I need. Yes I could cover the ball screws but with what? It would require some expandable material where do I get that from?
Alan

M250cnc
22-11-2010, 02:54 PM
Alan AC motor will run all day

As for screw covers the company i got my telescopic ball screw covers sell them

For wood dust you need bellows type http://www.dqr.co.uk/bellow_covers.html

Phil