Myford VM-B CNC Conversion.

[John S]

Next instalment, as I said this is only being done on Tuesdays and Fridays as it's the only time my Grandson can get down.

Still awaiting balls crews etc so got the motor today.



Bog standard 1.1kw, 1.5 HP motor and stripped it down, nothing to these, cover off, fan off and an end shield then pop the rotor out.



Original bearing on left, similar but double row angular contact on right.
One thing to note with these new inverter metric framed motors is the absence of slots in the rotor. These are now coming out with the allow 'winding' pressure die cast into internal slots so the outside of the laminations is uninterrupted, less chance of flying out at high speed.



Shaft pressed out the rotor, keyway broached in and set around the rotor are the existing bearings, two different sized angular contact bearings, existing 20mm and the one I'm going to use at 25mm bore plus a collet and nut for ER25.

I was going to use ER20's but on checking I don't have collets for ER20's so it was a choice of 16's, 25's or 32's so 20's won out.


Next step is to make drawings up of the existing motor so the details can be transposed without cutting metal. This is the existing motor as an accurate drawing.



Drive shaft is on the right.

Same drawing with the modified nose superimposed on it.



Because the bearing can't go on over the collet nose it's designed to assemble the opposite way and the bearing is held into the front cover by a keep plate so it's held firm with no end float.

This means the rotor will have to assemble onto the shaft after hence the keyway for a sliding fit as opposed to a press fit and a nut on the fan end to secure it all.



Next job is to copy the spindle, spacer, nut and end cover from the second drawing and dimension up [ only part done so as not to crowd the drawing ] We now have all the details we need to start making the spindle on Tuesday.