Clausing 5914 VFD

That one didn't work either, but I did manage to locate the photos that you made of the left end of the machine. Take a look at the photos that Pete posted above of his modification. You might want to do that eventually. It's a very neat mod, and about what Clausing might have done had VFD's been common when your and his machines were new. Now back to your thread.
 
machPete99 said:
I did this a while back, but figured I'd post the info for others that might be interested.

This setup completely replaces the original Reeves drive and countershaft arrangement. The motor is the original Doerr 2HP 3PH unit. I am using the stock cogged belt size/length, but have fitted the motor with a slightly smaller drive pulley (22T). I redrilled the motor support brackets so they could use the slots previously used for the countershaft support. A piece of 1/2" steel plate is used to get the motor in the correct location, in line with the spindle pulley.

Mechanical parts, from McMaster-Carr:
6495K615 - H Series Quick Disconnect Timing Pulley (1-1/2" wide H series Quick Disconnect 22T)
6086K34 - Quick Disconnect SD 7/8" ID 3/16" keyway
6484K284 - H Series 63" x 1-1/2" Belt (630H150)
99020A420 - 3/16" key stock

VFD is Hitachi WJ200-022SF, from Drive Warehouse. I am using 4 x 50 ohm 100 watt resistors (in series/parallel pairs for 100 ohm total) for braking. Most of the control items are from Automation Direct. The enclosure is good sized (14 x 12 x 8), from factorymation, so does not need a separate fan. I am using a (2) pole motor switch as a disconnect, relatively simple control wiring. The original motor flexible conduit has been rerouted to enter the enclosure, near the top. Everything is mounted to a an aluminum plate which can be removed for service.

The speed control is pricey but industrial quality (Allied: Honeywell 53C11K + Schneider Electric ZB4BD922). The control panel is located where you stand so you can change speed etc. while machining.

Pete
Click to expand...

Looking at that setup and reading what you wrote makes me think that machine came with one belt only. Mine has two belts and I'm wondering if it would even be possible to change mine over to what you did to that one. I'd look at the downloads and diagrams but I'm on my phone and it would take hours to check. Any thoughts?
 
DH,

His machine originally looked exactly like yours does now. What he did was remove the mechanical variable speed pulley from the motor and remove the entire countershaft assembly above the motor. Then he mounted the motor where the countershaft was, and he said that he also used a slightly smaller toothed pulley on the motor and a slightly longer belt. He didn't say why, but possibly to get the required belt length to be an available belt length/ and/or get the desired motor RPM range with the desired spindle RPM range. Go and read the PM I just sent you.
 
Robert described it pretty much exactly, but the belt I am using is the exact same as the upper belt used on the original configuration. There is some tradeoff on the motor pulley sizing between lowest speed, highest speed, and the "hole" in the middle. I leaned towards better low end speed and torque, as I never run much up in the 2000 RPM range.

You can think of the "fixed" cogged pulleys as being near the middle of the Reeves speed range, but with the VFD you can safely double the motor speed, since stock is around 1800 (1740 nameplate) and most bearings/armatures are rated to 3600. I also figured on being able to run at 40% of nominal speed for the low end. You can go even lower but lose a lot of torque.

Top speed calculations for direct drive pulley ratios (keeping spindle pulley at stock 40T) running 120 Hz, various drive pulleys:
(back gear supplies 7:1 step down)
1740 * 2 * 24/40 = Spindle 2088 RPM <--Stock countershaft pulley size
1740 * 2 * 22/40 = 1940 <--What I used for VFD conversion
1740 * 2 * 20/40 = 1740
1740 * 2 * 18/40 = 1566
1740 * 2 * 16/40 = 1392

NOTE: Above calculations are for 5900 family (59214 12x36) lathes, which use 40T spindle pulley. You may need to adjust these for other size lathes that might use different spindle pulley sizing.
 
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For clarification, please confirm that for example 24/40 means 24T 40DP.

I remember now that you commented that you used a spacer plate to get the motor in the proper vertical location for proper belt tension.
 
"T" is for Tooth, so 24/40 is referencing the motor pulley (24T, or 24 Teeth) to the spindle pulley (40T or 40 Teeth) ratios.
1740 is the motor normal RPM (not sure why its not 1800...).
The *2 is the doubling of the motor speed by running at 120Hz.

The steel plate under the motor is needed to support it as it needs to hang out of the cabinet a bit so that its pulley is directly below the spindle pulley.
The motor bolts to the plate (from above), the plate sits on the brackets, and there are bolts that hold the plate to the brackets (from below).
The bolts need to be trimmed so they don't protrude through the plate, at least in the rear.

Once I figured out how everything was going to line up I drilled new holes in the motor brackets to match the center of the mounting slots originally used for the countershaft brackets, So I have some adjustability in the motor up and down, to set the belt tension.
 
hey pete you mentioned that you get motor whine.
if you significantly increase the carrier frequency the whine will go away.
 
Thanks for the tip, Mike. I increased the carrier frequency from the default of 2KHz to 15KHz and it is much quieter now.

I still do get some gear whine, and may try going to a thicker oil in the headstock at some point.
I am currently using Mobil DTE24, but some folks think DTE25 is better:

1st post: New to me Clausing 6913 lathe. Basic Maint. Questions....

Hey team, I'm a 4 year school trained, 20 year career machinist....FINALLY have a lathe in my garage at home now! I found the manual for the lathe online... I want to change all the fluids. The manual calls for all these Texaco Blah blah models of oils that I can't find listings for. Don't...
www.practicalmachinist.com
 
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