Converting Nova 1624 to variable speed drive.

My goal was to do the upgrade for under $500.  And I wanted the upgrade to be a two-way street, I wanted to be able to reinstall original motor if necessary.  I wanted to use the original motor sheave so I’d have 8 speed ranges to choose from.  I had 230V single phase in my shop and couldn’t upgrade to 3phase so wanted a VFD with single phase input.

The tech support at automationdirect.com was very helpful.  They answered a number of ‘amateur’ questions and helped me select the equipment.  The total price on motor, motor mount, and variable frequency drive was $379 delivered.  I spent another $50 for accessory items and the homebuilt small remote box.

I started my conversion planning by choosing the motor.
Specs:
2hp (A 1.5hp motor was almost the same price – and VFDs don’t usually come sized for 1.5hp so I’d be buying the 2hp VFD anyway).
1800 rpm
3phase – 230V  (VFD operation requires 3ph)
Mount with a CFace (to match up with the existing Nova motor mount).
Shaft diameter of .875inch (7/8 inch) to fit Nova motor sheave.  (I considered this very important as I really wanted use the original motor belt sheave combo.)
Physical size and weight approximating Nova original motor.  (Same diameter motor case  so motor would fit beside the T-handle belt adjustment slider.)


AutomationDirect.com
MTC-002-3BD18 AC MOTOR 2HP 1800RPM 208-230/460VAC 3PH IRONHORSE, CAST IRON 145T 1 $137.00 68.0
  MTA-CFACE-140TC C-FACE KIT FOR 143T AND 145T MOTORS REPLACES DRIVE END BELL, FIELD INSTALL 1 $11.00 6.0
(You can also purchase motor with Cface mount preinstalled.  They were out of stock when I ordered  MTC-002-3BD18CK  $158).
Online Manual for motor Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to or

I did not purchase a more expensive “inverter duty rated” motor.  Tech support told me I just didn’t need it for the light duty usage I would be putting this motor to on a wood lathe. 

Then I speced the VFD – based on the hp rating of the new motor.

AutomationDirect.com
  GS2-22P0 GS2 2.0 HP AC DRIVE 230V 1/3 PH IN 3 PH OUT 1 $241.00 3.68
Online manual for VFD
Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to or
This unit is the bottom end of prices for a 2hp drive that can use single-phase input.


I didn’t purchase a more expensive “vector sensorless” VFD because I would also need the “inverter rated” motor.  The small variable loads we put on these motors doesn’t require a sophisticated speed control system.  Leave the expensive stuff for the factory floor.

First uninstall the old motor mount from lathe.  Put the belt at a middle position on the sheaves and it will help hold the motor while uninstalling.  First remove the visible small screws holding the red endplate on.  Then move motor to full up position and remove small screw revealed at bottom of endplate.  Then set motor back on belt and remove the back large nut and the slider plate with T handle.  This will reveal the final small screw, in the slot of the motor mount at the back.  Take off the red endplate, then remove other large nut and slide motor off.  It’s heavy so handle with care.

Important – measure the distance between the large end of the sheave and the motor mount plate.  Mine measured .36 inch (got good use out of $10 ebay digital caliper on this project).   Loosen set screw on sheave and use small wood wedges to lightly pry sheave away from motor.  Pry equally on all sides.  My sheave freed up easily.

Remove 8 flat head cap screws which hold motor to mount.

To install new CFace motor you will be using the 4 larger holes in the motor mount.  You will need to purchase four 3/8x16 x 1/14” flat head cap screws.  I mounted my motor upside down, with the mounting feet (which are not used in this application) on the top side to use as mounting point for the VFD.  (I did give the motor a coat of Rustoleum grey metallic spray – it really spruced it up.)

The only spec I couldn’t match was the size of the shaft key, the square piece which fits into a slot on the motor shaft and also in a slot in the sheave.  The Nova motor key was .245” and the Ironhorse was .188” – so with a file and dremel I cut a “T” shape into a new ¼” key, the lower leg of the T was .188” width and matched the motor shaft and the wider top of the T was .245” to fit in the sheave.   (I forgot to take a picture of this.)

Also, the new motor shaft was a real .875inch and the original Nova sheave was slightly undersize.  So I used a round sanding cylinder mounted in a drill press to ease the inside of the sheave.  Work carefully so you keep it in round.  The difference was so slight that I was afraid that having the sheave bored out to 7/8inch would oversize the hole.  This was the only fussy part of the project. Everything else just fit together.  Be sure to match the distance between sheave and motor mount that you measured earlier (.36").

Part 2 in next message

Looks like a great upgrade, Steve.    Well done.

For your remote control box, I'd highly recommend using a box with magnets on it so you can place it in a variety of locations. I just have a magnetic remote on-off switch for my Powermatic, and I use it much more than I use the main power switch on the front panel of the lathe. I often have the remote stuck on the bed of the lathe right by the banjo. I can just drop my right hand and hit the switch.

Looks like you got it goin there,but now you got me thinkin,I have the 1624 and was givin that some thought.let me know how it works when all is done.
PS where you from?ain't near NC are ya 

Thanks Steve,I may give that a try when I get back to NC.i live in Tampa during the winter then back to NC in April,thats where I have the Nova.Oh and thanks for taking all that time to put that on the forum here.

Well done Steve.  I have a 1624 as well and I would love to know how this does over time.  Keep us posted!
Jeff

Bob - I'll bet your DVR does a better job of smoothly controlling speed at low rpm while taking heavy cuts.  But I will be using a low belt setting on the 1624 - if I'm turning with lathe rpm of 100 the motor will be turning at 400 rpm so it won't bog down as much.  Not an apples to apples comparison.  And I'm still trying to tweak the "over-torque" and "over current" parameters to see if they can provide some of the same 'friendliness' that the DVR does if you have a major catch.  I'd be interested in your comments on the DVR and how it handles a major catch.

Excellent writeup -- with a little formatting this would be a classic addition to the "library" as a tech paper.   You have a good style of writing for this kind of material.   I do not have that brand, but loved the story!!!!

Ken Vaughan wrote on 03/11/10 at 19:45:17:


I appreciate everyones' comments, it makes my effort seem very appreciated. 

When the dust settles in a couple of weeks I'll take my articles, further thoughts and any replies that add content and put it all into a pdf that can go into the forum tips section.