The Shop > Tools
Myford VM-B CNC Conversion.
John Stevenson:
So got most of the big bits of a VM-B from the Myford sale for £100.
Brand new but well shop soiled and robbed.
No motor, spindle, pulleys, covers etc
Main bits are base, saddle, bed, screws and head.
problem is this is a right backwards arsed design as where the spindle locates.
Rough assembled with a lump of tube to represent the missing spindle.
Right at front of travel with a plate on bed that it will need to machine, plate is 150mm or 6"
Full back and it overhanging the bed.
Shot inside the head showing how cored it is, no spare metal anywhere.
I can squeeze another 15mm to give me 165mm but the problem is the spindle hole is in the wrong position, plus I don't have a spindle anyway or any of the drive mechanism.
So this is the bit that poses the problem.
So a bit of hacksawing, not shown, a bit of angle grinding, definitely not shown due to artisic license and a bit of surface grinding.
Only shown because they show it on tele and it's only microns being killed <g>
And we get this:-
The motor in the picture is only a slave for pics, new motor ordered.
After searching all the motor specs we can get a 1.1Kw [ 1.5HP ] motor in a reduced 80 frame size at 2800 rpm [ remember we are on 50 Hz ]
80 Frame means 80mm from feet to centreline, that one in the pic is a 63 frame.
So if we run a 2 pole motor at 120 hz which they will stand, they are good for 6,720 which is about the right speed for a 3mm drill.
At low speed usuable torque on a 1.1Kw motor is about 20 Hz giving a low speed of 1,120 rpm.
Not much use for a manual machine but for a CNC only using small cutters this spread is ideal.
So plan B is to strip the new motor when it comes, make a new end up out of solid alloy as most motor ends now and very skimpy, fit a double row angular contact bearing that held in place by a keep plate.
Press the shaft out and make a complete new shaft to take ER 20 collets, because the bearing won't be able to go over the collet chuck bit the rotor will have to be modified to be a push fit, not press fit and have a keyway and retaining nut to hold it in position.
Many grinder rotors are built this way.
Get the rotor re-balanced and rebuild the motor.
motor then bolts to a conversion plate between the cut down head and the motor.
Ballscrews are on order from China, motor should be here later this week or early next week.
John S.
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Swarfing:
John if you ask nicely the Chinese collet chucks can be had with different dimensions than the standard ones they sell. I did inquire and they said they could do that for me for an extra £15...bargain. In the end i found one already with a 10mm shaft so changed my design a little to suit. Forgot his name but the one that sells all the ballscrews and kits is the man. I think you should know the one i mean.
John Stevenson:
Yes got a few of them kicking about but I need a collet chuck that has the same bearing diameters on it as the motor, plus the rotor bore with keyway and a thread for a lock nut to hold the rotor on.
Long short it will be quicker to make a complete new shaft to suit.
John s.
Swarfing:
See what your saying now you put it like that.
Rob.Wilson:
Cool project John :thumbup:
Is that a swing grinder your using there ?,,,,,must have missed that at your shop
How many division plates are you planning to make ::)
Rob
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