[chrisbee]

Hi All, Im new to cnc milling but have been using a Laser cnc for a while, I am looking to buy a cnc for cutting disks in 3-5mm perspex, I have been looking at the ebay cheap machines and would like to know which one is best for what i need. I do not need anything bigger than A4 cutting, but would go up to the 6040 machine, I see they vary in power and rpm the cheap ones are 230w and the more expensive are 800W water cooled, would 230W @8000RPM be suitable or would the 800W be better?

here are the specs for the more expensive one i was looking at. All help would be muchly appreciated!

6040 triaxial engraving machine part parameters: Effective working travel:400(X)mm*580(Y)mm*75(Z)mm Shape dimension:880*670*530mm Max.thickness of the materials:≤100mm(the distance between Z axis and the bottom of the working station) Max.workpiece dimension:750mm*450mm Work table dimension:750mm*480mm*20mm Frame materials:6061 aluminum alloy + 6063 Industrial aluminum Driving units X axis:NEW 1605 ball screws Driving units Y axis:NEW 1605 ball screws Driving units Z axis:NEW 1605 ball screws Sliding units X axisia.16mm chrome plate shafts Sliding units Y axisia.20mm chrome plate shafts Sliding units Z axisia.13mm chrome plate shafts Stepping motor type :57 two-phase 3A ,super-low noise ,NEW Spindle motor:0.8KW VFD spindle ,NEW Principal axis collet:ER11/3.175 collet Spindle speed:24000rpm/min (PWM stepless speed regulation) Empty line speed:0-4000mm/min Resetting accuracy:0.05mm Engraving accuracy:better than 0.04 mm (has been tested) Spindle precision:radial runout≤0.03mm Control unit:triaxial one-piece drive + ring variable power + PWM speed Carving Instructions:G code/TAB files/nc file/NCC files Communication interface:through parallel connection with computer Software environment:Windows 2000 / xp Carving speed:300-3500 mm/min (different materials differ) Machine weight:55 KG Control box parameters: Operating Voltage:110V or 220V 50/60Hz(we also stock USA.UK.EU.AU.plugs.) Work theory:3977 3-axis control box with the power supply + spindle speed regulator Control unit:3A stepping motor driver plus adjustable spindle speed controller Computer connectionn board parallel port Command code:G code Acceptable software:Mach3,EMC2 Protection:Emergency stop butto

[alan_3301]

If you plan on cutting at 8000rpm, you will only have 266W of power with the 800W spindle (800W / ( 24000 / 8000 ))
the 230W spindle is probably DC powered, with a 12000rpm max speed, so depending on speed control you will have 153W (230W / ( 12000 / 8000 ))

That is the max power you might have.It could be less in reality.

I would go with the vfd spindle. It has a higher max speed, and has real bearings.
The other one is just a collet holder pressed onto the motor shaft. The bearings on the motor are not meant for those kinds of loads.