Converting a Nova lathe to VFD.

[BobL]

In a previous thread (http://www.woodworkforums.com/f8/help-convert-nova-1624-lathe-206350#post1958888) I indicated that I was helping another member modify their Nova to run a on a VFD and outlined the problems.

After looking around for some time, said member has managed to purchase a near new 3P 2HP motor capable of easily being converted in the motor connect box to run on 240V 3P.

This post outlines the mechanical issues
This Nova uses a flange mount motor so it require the cutting out and fitting of a foot plate and providing some support for the plate.

Here is the 176 x 200 x 6 mm mm steel foot plate I made up.
I had a large piece (600 x 600) of 6mm steel plate which I didn't want to cut into so I welded the plate from a piece of 150 and 50 mm wide flat bar.
386032
The flange mount conveniently comes with 4 x 8mm threaded holes suitable for mounting a foot plate.
Given this is a bigger/heavier motor, and to reduce any possible flexing I added a small gusset to one side and trilled and tapped an 8mm thread into the side as shown.
A gusset could not be easily added to the other side as it would interfere with the main motor mounting bolt on the lathe itself.

386031

Now after a couple of coats of silver hammer tone paint
386033


386034
And here with motor mounted
I could have made the gusset a bit longer but this makes it easy to tighten the motor mounting bolts
386035

This shows the 2mm steel shim (green arrows) needed to centre the this motor's shaft in the middle of the flange.
386036

Next we will have to deal with the issue of the bigger (24mm) shaft on the motor and the 19 mm pulley on the Nova .
Solution 1 is to get/make a new pulley - the multi ribbed V pulleys are not cheap! ($100?)
Solution 2 is to bore out the old 19mm bore pulley - this is not really a good idea as it does not have enough metal to ensure a safe fixture to the shaft
Solution 3 is to bore out the old pulley and machine up a steel collar to fix around the the bored out shaft.
Solution 4 is to turn the motor shaft down and cut a keyway in the shaft.

I'm probably going to go with #3

[wheelinround]

Bob thanks for this any chance of a pdf drawing of the foot plate pls.

Getting a mounting motor to suit the flange mount has become harder although possible if you have the $$$$.

[BobL]

Sorry I didn't draw up anything.

I just measured up the plate that would suit the nova flange mount and this specific motor.
For this motor it came out to be 176 x 200 mm but the 200 mm might not be enough for some motors.
Then I placed the flange on top of the end of the plate and drew the 8mm holes on the plate and drilled these out to 8.5mm to allow for any alignment probs.
The guise was 40 mm at the high end and 150mm long. It could be longer - full length of the plat even.

A 6mm thickness of the plate is probably overkill, 5 or even 4 mm would probably be enough.

[hughie]

A 6mm thickness of the plate is probably overkill, 5 or even 4 mm would probably be enough.


Given the amount of vibration over time I would say 6mm is the better option as its a fairly good sized piece of plate.
Option 3 for me as well

[Paul39]

Given the amount of vibration over time I would say 6mm is the better option as its a fairly good sized piece of plate.
Option 3 for me as well

I have never heard anyone complain about a lathe or lathe bits being over built. Lots of bent sheet metal being sold to cry about.

My motto, learned from a couple of Swedish carpenters, long gone, "when in doubt, build hell for stout".

[BobL]

Just wanted to say this job has been completed simply by boring out the existing pulley and it has been working successfully for a month or so.