Alternate title is "What to do when the tiny mini lathe motor burns out".
That is what happened while turning a rather large (2.5" diameter) part for my Grinding Fixture.
Selection of the motor and VFD was easy. Checked eBay but I found a very good pair at Amazon.
Shipping was free ( I have prime) so my total cost was about $300 for motor and VFD.
Price of the tiny replacement motor from LMS was $350.00....Really? for a 500 watt motor? Oh Well.
The controller was another $273.00 and that is just the circuit board without any controls.
I wanted to replace that motor last year but never got around to it. So I took some measurements,
pulled some bearings out of my stock (15mm inner diameter) and thought about it for a minute or two.
What I needed was a jack shaft. Used a piece of 3/4 inch drill rod. Turned both ends to fit the 15mm id
of the bearings. The main drive pulley for the mini lathe had a 15mm shaft so all that was necessary on that end
was a 15mm section with flats to match the pulley. (two types of pulleys are available from LMS for the Mini Lathe).
Other end has a 16mm section for the driven 48 tooth pulley and a 15mm section for the bearing. Flats as required for
the pulleys. The new motor pulley was to be 24 teeth but the hub was so small that it could not be bored to 5/8"
for the 1HP 3 Phase motor so I ordered another one with 28 teeth and bored it to fit the 5/8 motor shaft.
The jack shaft was mounted using the original motor mount and adding two 1/2" aluminum plates to house the bearings.
Bearings are a -.001 fit and pressed in easily after freezing the bearings in the fridge. New holes were drilled in the lathe bed
for the new bearing mount.
Found a $100.00 enclosure that was 6x6x8 inches on the bay for $30.00. Used a hole saw for the large fan hole and
greenlee chassis punches for the fuse,pushbutton, and lamp holes. After wiring it all up I went over the manual to pickout
the custom settings I wanted for my system and that was it. Used an old wall plug in power supply for DC power for the lamp power.
I removed the circuit board from the plastic enclosure with the dremel.
Motor current is easily read out while operating the lathe. All controls are external and just to my left side when running the lathe.
I prefer the new location for the controls as it frees up space on the headstock and keeps the controls from being bumped.
Total pulley reduction with the 3450 rpm motor gives just about the right amount of speed. I generally turn on the slower end and
the increase in torque is very welcome.
Prior to installing this new motor and VFD I had nothing but trouble with carbide insert tools. Now it is a breeze and I was cutting
twenty thousands deep (.040 off the part) on a 1.3" diameter part. Very smooth.
I should have done this mod last year when I could have kept the motor as a spare for my mini mill. The little motor is perfect for the mill
but I think it is a bit small for the lathe unless all you are turning is plastic and aluminum. Just sayin!