Clausing 5914 - VFD Direct Drive - Some Questions & Thoughts

[GrizzlyBagWorks]

I just finished restoring a 1966 Clausing 5914. I rebuilt the drivetrain and the rest of the machine but am not so thrilled with the amount of noise coming from the Reeves drive system. It works, and is very smooth, but above 1,000 RPM this machine is just too loud for my taste.....so, I'm looking at alternatives.

My first thought was to use the original Rueland 2hp motor with a Teco L510 VFD, keep the countershaft and use a 2-step pulley system w/ idler using micro-v belts. With this motor/vfd combination it seems like 30-90hz would be the range to avoid torque/hp loss and heat build up in the motor (at low RPM) so a two step pulley system seem necessary.

Recently I became aware of, and ended up purchasings a 3hp Marathon Black Max Inverter Duty Motor and a Hitachi WJ200 VFD. If you're not familiar with these motors they can be run down to almost 0 HZ while still maintaining 100% torque and run at 120hz while maintaining 100% HP. The motor is TENV (totally enclosed non-ventilated) so overheating while running at low Hz is a non issue. This style of motor seems perfect for the 5914 and would eliminate the need for a dual pulley system.

To further reduce the noise I'm also planning to do away with the cogged timing belt. It's just too loud. I replaced the stock belt with a new belt and that was even louder. I have already purchased a new spindle/countershaft pulley and will just turn down the cogs and machine in the grooves for the poly-v belt. Much quieter/smoother.

Initially I was thinking to keep the countershaft assembly but after looking at the pulley ratios from the counter shaft to spindle (3.625" Countershaft/6.125" Spindle) I'm realizing that with a 20hz to 115hz motor range my pulley ratio from motor to countershaft is basically 1:1 (~360rpm to 2000rpm @ spindle). Now I'm thinking of just going direct drive and bypassing the clutch/brake since the Hitachi WJ200 supports an external braking resistor (35ohm 400w = $35) If the VFD can stop/start the motor as fast as the clutch/brake why keep it?

Has anyone does this type of setup? Micro-V belt conversion with an Inverter duty motor 20-115hz running direct drive with a braking resistor hooked up to the VFD? This seems like the ultimate solution for the 5914. Dead silent drivetrain, full torque at low speeds, full torque HP at high speeds and a system that can stop on a dime without the rattling clutch discs.

Is there something I'm missing here? I would expect to see more people doing this but haven't run across much. Is it that the cost of the Black Max motors + WJ200 is so high? Any input appreciated.

 

[Rootpass]

I’m very interested in what you figure out. I love my 5900 but my goodness is it loud.

 

[Bob Korves]

You quoted ~360 spindle RPM at the low end with direct drive. For many operations on lathes of that size, a low speed spindle RPM of around 60 RPM, with full rated torque available, and without overheating, would be highly desirable.

 

[GrizzlyBagWorks]

You quoted ~360 spindle RPM at the low end with direct drive. For many operations on lathes of that size, a low speed spindle RPM of around 60 RPM, with full rated torque available, and without overheating, would be highly desirable.

360RPM at 20hz is direct drive. Back gear will bring the RPM down to ~50 RPM. I can go down to 15hz and bring direct drive/back gear even slower.

 

[mksj]

No limitations. BlackMax is rated to 6000 RPM. I ran a similar Baldor inverter/vector motor to 125Hz on my lathe and typically they easily run to 180Hz. The Torques falls off, but when you factor in the pulley ratios and load for high RPM work it is not a problem. I pretty much used my 1340GT with 2 speeds, Hi/Low when using the WJ200 VFD/Vector rated motor. You also have an up sized motor so even at 30 Hz you have 1.5Hp with gobs of torque, it will not slow down. Almost all factory manual lathes that come with a VFD are only 2 speed, typically speed ranges is 50-400 and 400-2000 RPM, so similar to what you have. The requirement is only that you need a second (low) speed, so back gear or similar. You are not missing anything, if you can pick up an inverter/vector motor at a reasonable price, and preferably upsize it slightly and change the drive ratios to run the motor at higher speeds relative to the spindle all is good.

The other factor is the you do not need a clutch or mechanical brake (for the most part) if you use the VFD electronic brake. I still incorporate lathes with a manual mechanical brake for safety and to hold the spindle locked for doing manual tapping via the tailstock. You must issue a free run command (or a baseblock which shuts down the VFD output) to the VFD when using a mechanical brake. This requires a dual pole foot switch, depending on how everything operates.

The Teco L510 would have been a bad choice for use with lathes, it does not support and external braking resistor that is required for this application along with a lot of other limitations. Just not worth saving $100 between it and the WJ200 (or the Teco E510) are better choices. Lots of possibilities, just need to know how to implement it all. The machine should run like a sewing machine after the conversion.

 

[machPete99]

See my VFD conversion, here:

Clausing 5914 VFD

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...

www.hobby-machinist.com

I used stock 2HP 3PH motor, eliminated countershaft, plenty of torque, especially in back gears.
Not much noise from the cogged belt, get some whine from the VFD and feed gears.

 

[GrizzlyBagWorks]

Thanks for all the feedback guys!

So I've given it some thought and I think I'm going to try and keep the countershaft. I'm sure the VFD brake would be as fast or faster and also quieter but there's just something appealing to me about the action of the clutch/brake arm on the apron. Going to try and keep it if I can.

My plan now is to convert the stock timing belt pulleys from the countershaft to the spindle to 8-groove K profile poly-v pulleys. I'm going to go with 8-groove k-profile poly-v pulleys for the mounter to countershaft as well.

For the motor/countershaft setup I was able to purchase some "Quick Disconnect" "SDS" size bushings. That was the only size I was able to find that will fit a 1.75" shaft that the countershaft requires. I can get 12" of 3.5" diameter 6061 for ~$42 locally or I can order some 3.5" x 12" Cast Iron from McMaster for $69 (https://www.mcmaster.com/8909k82) I'm still debating which route to go. I want to match the size of these pulleys to the countershaft timing pulley so that in the event I decide to eliminate the countershaft all together I can still use the motor pulley direct to the spindle since the size will be the same, or close to.

To fit the SDS bushing the bore needs a 3 degree taper. I'll need to drill/tap some holes as well. I'm going to grind an HSS form tool. The angles are 40 degree included and the spacing/depth information is available online (attached). I have a K-profile pulley that I can check my for tool with.

I'll let you guys know how it goes. Bushing are on their way and I just need to make a decision as to whether I want aluminum or cast iron for the pulley material.

Btw, I'm having a bit of a hard time finding a 35ohm 400w wirewound resistor. The one I was looking out is sold out and won't be restocked. If you guys have any other ideas let me know.

 

[mksj]

Braking resistor is a range of ohms, so for a 3Hp VFD 47 ohms is available and works well, it is what I typically use for the WJ200-022SF. Anything 400-500W is fine. Various vendors stock these. Might be easier to try a direct drive and then revert to a counter shaft if you aren't happy with it, but hard to say without seeing the lathe. In essence a VFD is a run-stop and the motor doesn't run continuously.

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[GrizzlyBagWorks]

*sorry about portrait mode, i made this video to send to someone via Instagram

I just want to give everyone an update on this project. It's been slow going but I've made some progress this week and thought I'd share the progress.

Yes, I realize this is an extremely Rube Goldberg setup. It's temporary and after finishing my pulleys last night I wanted to quickly test the poly-v belt to see if I was making the right decision moving forward with this upgrade. I can not believe how smooth and quiet this is and it's just bolted to a hydraulic lift cart and the belt aligned by eye.

Pulley Ratio is 1:1.75 (3.5" motor pulley to 6.125" spindle pulley. 60hz=1,000rpm

I installed a 47ohm, 500w braking resistor (thank you mksj!). After I installed it I realized how much better it was than the stock clutch/brake assembly so I don't think I'll be keep that.

To mount the motor I plan on raising the motor mount up to the clutch location (drilling/slotting as necessary into the pedestal). Then bolting a plate to motor mounting arms and bolt the motor to that. Depending on how much room is left I might relocate the entire VFD box below the motor in the pedestal.

Needless to say I'm beyond happy with this. The machine is so much smoother and quieter than the reeves drive. It's quieter and smoother than my Emco V10P. At 250rpm it's literally 15db quieter (45db vs 60db). At 2,000rpm the machine is 68db, which is the same as my Emco at 1,200rpm.

Machining stock timing pulley to poly-v pulley. BARELY fit. Wasn't able to use the compound to feed cutter in at 20*. I had to plunge straight in with compound and the surface finish suffered but the part came out nicely.

I used a depth mic and a pin to measure depth of each groove as it was cut:


Pulley Installed on Spindle:


Made the motor pulley from 3.5" 6061. Cut the grooves and then bored with a taper to fit on an SDS QD bushing. I could have bored to 7/8" and cut a keyway for the motor but I wasn't sure what motor I was going to use so I didn't want to remake or rebore it. I can also use it on the countershaft should I go that route in the end:

 

[Rootpass]

I’d really like to do this to my 5900. But I use my 4 jaw chuck almost exclusively. Can you spin the chuck by hand to dial in a part?