10ee VFD Conversion

Very informative. I have a 1975 10EE and am thinking on traveling the same path. The machine runs beautifully but sometimes just stops. The people at Monarch are great in helping me and they always get me up and running. But when I gaze into that electronic jungle I just know there will come a time that the old girl must be brought into the 21st century.

Yesterday I was drilling a 1/2" hole in a 1'' piece of 12/14. Everything was purring along at about 500rpm, I was bragging to my friend about what a beautiful machine and how much I loved it when, suddenly, it shut down. Probably not a big problem, I'll cal the factory and they will talk me through a fix.

Maybe the time has come....
 
Having read a ton of the commentary on the lathe, I'm not sure why anyone puts a 7 or 10 hp motor in this machine. Of course I'm just a hobbyist, so I'm not all that aggressive. However, I've yet to stall the lathe when machining something. It just keeps turning. 5 hp seems a good compromise especially with the back gear.

Best of luck with your lathe.
 
Deek did a wonderful job building a backgear into his upgrade. He does not need a monster drive motor.


Building a backgear assembly is too much for many. In that case, go huge with the drive motor and run without a backgear. Remember a 10 horse 1725 motor has 1 horse at 10%, 172 RPM speed, 1/2 horse at 86 RPM. You need this power and speed to thread.
 
Very nice install, top notch and a lot of thought went into your conversion. If you have any drawings for the adapter plate, shaft machining and or parts available, it may help others wanting to do a similar conversion.

One issue with going to something like a 10Hp motor is size and significantly more cost, also the ability to match a VFD to this size motor. If running off of single phase, you would need a 20Hp VFD to derate it for use in single phase. The input power side would need to be for 15kW. If you are generating 3 phase to run a 10Hp VFD you would need something like a 15-20Hp RPC.

Another single speed option is to use a 5Hp inverter/vector type motor (Baldor IDNM, Marathon BlackMax) which provides full Hp up to their top speed of 6000 RPM, and run a belt ratio of something like 2:1 or say 1.75:1 for a maximum speed of 3500 RPM. These motors offer massive torque almost down to 0 RPM and the VFD can provide 150% overload for up to 1 minute. A decent quality single phase 5Hp VFDs are available for around $500-600, the 5Hp inverter/vector motors come up on eBay for around $300.
 
I have learned you do not really need to oversize a VFD on single phase for a lathe. It will run just fine and not kick out. Yes, you will not get the full HP at top speed, but you WILL get 10%+ power at 10% speed. Oversizing by 200% is just way too conservative here. Now my 20HP three phase irrigation pump that hammers all day long at top power does need the 2X oversize VFD with the single phase input.

All this asiide, yes, its your money or your time. A back gear and smaller motor is the better more cost effective way to go. Just takes more time to build.
 
Hey Karl,
I had a similar discussion at the Practical Machinist forum, and there are a number of considerations that enter the equation. The main factor as explained to me has to do with the input diodes going south and long term affects on the DC supply capacitors because of the current spikes and also phase imbalance with increased harmonic distortion. There was also discussions as to RPC size and issues with phase imbalance/current draw of the wild leg if one were to run a 3 phase VFD off of an RPC. In an upcoming install, I am adding a DC bus choke for a 5Hp VFD running off of a 7.5Hp RPC and we will be closely monitoring each phase's voltage and current. As a minimum from what I have seen recommended you would need a 15Hp VFD derated for running on single phase to run a 10Hp motor and probably add a DC choke to tame the current pulses/harmonics. If using an input reactor, then there is the issue of overlap of diode conduction but at increased PF/less harmonics. All these add to the install costs. No doubt the quality of the VFD plays a big factor in their longevity. There are a number of different options, so one needs to pick what works best for their situation.
 
I've gotten a few pms asking for what I used in the way of major components, so here we go.

Motor - Leeson Electric, 171566.60, 5HP, 1760RPM, 3PH, 208V;230V;460V, 184TC Frame, C-Face Flange, Foot Mount, TEFC, General Purpose Motor from state motor and control
Vfd - Yaksawa CIMR-VUBA0018FAA, 5HP, 1-Phase, 200-240V (Input), NEMA 1 Enclosure, Variable Frequency Drive; Remote operator from state motor and control
Braking Resistor - GS-25P0-BR from automation direct
Lovejoy - 11093 Size L095; 11075 Size L-AL 090-095 from amazon
Bell Housing - 1-3249 from surplus center

The bell housing bolts right up to the motor as does the lovejoy so at least that part is easy.

I guess a disclaimer that I'm not promoting any particular site or brand or implying any sort of warranty might be required. In any event, your mileage may vary.

peace,
deek
 
I think I've watched YouTube's that take the reducer from the original motor and make new mounts for the new motor to match up. And the same potentiometer set up with the chain drive to keep the original look and use of the lathe . They are dream machines for most , it's nice to see them being used and not butchered up looking. Great job on this one l really do like it .
 
Today iI took the plunge. Pulled the motor and gearbox. I'm going to follow Deeks path.

The motor and all the electrics and electronics are for sale. The gearbox is not.

Now if I could talk The Wife into cleaning that cavity...
 
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Awesome. Best of luck Matt. If you're ever down this way (San Francisco Bay Area) you're welcome to drop in and see my lathe. I'm a sucker for talking about all things machinery. Please post pictures.

Incidentally, I found some of my notes on the conversion. Here's my step through order of the adapter plate:

1. Rough cut adapter plate
2. Locate and drill index pin locations.
3. Insert index pins and join adapter plate to housing.
4. Locate and drill and tap bolt holes
5. Bolt to back gear
6. Mark adapter plate for final milling; remove and mill.
7. Join back gear housing and adapter plate together on the mill; locate the center of the large bearing through-hole; and mark with center drill
8. Remove plate
9. Locate, drill, and counter-bore housing bolt holes based on marked center. I do have a DRO, so that was a pretty effortless task.
10. Bore bearing hole. I kind of recall I was .001 under. I didn't want to have to heat the plate and risk warpage because aluminum takes a lot of heat, so I went for a less tight fit and lock tite retaining compound.

The key assumption was that the large bearing hole on the back gear housing was concentric with the axle. This method preserves that center.
I used unsealed bearings because they are lubricated by splashing. I'm still wondering if I should have just gone with sealed bearings. I doubt there will be much dirt or shavings in there... I know this because when I opened the back gear housing up initially, there was very little in the way of shavings. I did, however, add a rare earth magnet to the drain plug so that any shavings should collect there.

The 2 bearings are stacked with an oil seal on the outside. I used 60355K211 bearings from McMaster. Can't remember where I got the seal from, but it

At this point I should say that I considered making the adapter plate 1 3/4" thick so that there would be about 3/4" space between the bearings. My thinking is that the added space would make the shaft more stable because there are no end bearings. In the end, I decided the shaft was supported enough by the motor and love joy connection and that the stacked bearings were sufficient. I have no engineering analysis to prove this, but it made sense at the time. I guess it was a gut call. Please feel free to chime in with actual facts here on whether this configuration will work as that will help advance the collective knowledge of this kind of conversion.

I used Gray Blended Fiber/Buna-N (Max. 350° F) 1/32" for gaskets with sealing (permatex permashield) compound. I have no leaks in the assembly.

peace,
deek
 
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