Spindle Choice

Hi guys,

I have a question on spindle choice for a cnc Drilling machine. Will be used to drill holes of 10-12mm dia in mild steel plate up to 20mm thick

Machine design is to use a piece of structual steel C channel for the base. This is 380mm wide by 100mm deep "C" channel, 1700mm long The legs or "Flanges" are 17.5mm thick and the "web" is 12mm thick

It weighs 55kg / LM. I will have it milled square and slots cut out down each side to fit the 20mm THK linear guide rails. I will be running a double nut 20mm ballscrew up the middle. I am not worried to much about racking as the guide rail blocks will be 250mm apart O/A, which is the same as the "X" axis cutting width. Gantry wheight expected to be in the vicinity of 40kg

Any way to the question of the spindle, My idea to keep costs down was to use an ordinary 240V compressor style motor. About 1.5KW. I would replace both bearings on the motor with deep groove ball bearings which i have checked will fit fine. The motor comes in either 1400 or 2800 rpm. with a 19mm shaft. To this shaft I want to mount a ER20 straight collet holder also with a 19mm shaft via a sleeve.

Do you think this would be suitable for the job? also which RPM motor is suited better for drilling 10mm holes in mild steel ?

Thanks in advance for all replies

You should be able to pick up a drill spindle for cheap. Drive it by a belt drive.
Should be versatile and less work I would think. Is there any reason you don't want to do that?

Only reason I can think of is if I may want to do some light milling on very rare occasions.