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10 EE Gearbox and New Motor Adapter Plate

pecosbill

Plastic
Joined
Jan 1, 2016
I was going to rebuild my motor/generator set, but the motor shop I took them to said they were too far gone and did not recommend rebuilding them. So I will use a new AC motor and VFD. I have read some threads already existing in this forum, but I have not seen exactly what I plan to do. So I would like to get feedback from the experts here, as to whether my plan is ok or if I failed to consider something.

It appears that most people are using a new motor larger than 3 hp. My motor shop said with a VFD and the gearbox, 3 hp should be plenty. This lathe will be for occasional hobby use. If 3 hp is slightly underpowered but I can still get any job completed just maybe at a slower pace, that is ok. If it will be underpowered and cause limitations to what I can do (aside from speed of the job) then I may have to reconsider the size.

My new motor has a shaft diameter of 1-1/8, and the gearbox needs a 1-1/4 shaft. So I would like use a shaft adapter like shown in the pics. It is probably not a precision piece, but for this purpose I am thinking it does not need to be.

I will need to have an adapter plate made. If anyone has a dimensioned print of the gearbox interface I certainly could use it. I will plan to seal the motor shaft to the adapter plate, and then seal/plug up the bottom "recirculating" hole in the gearbox.

Does this seem like a reasonable plan? Any input or advice?
Thanks.
 

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Reason to use a more powerful motor is that's a real lathe, not a toy. That you envision hobby use today means nothing about the future. My advice, and only because you asked, is follow the crowd and install a more powerful motor from the get go. As for the shaft sleeve, turn one, instead.
 
Others here are made adapter plates but I agree on the motor. A 5 hp will usually have the same frame size as a 3 and you will be running at lower speeds so the torque of a larger motor is your friend. The weakness of a vfd conversion can be low end hp so a larger motor compensates. When I want a wide speed range which is what you want even with the back gear, I use a vector duty motor like Baldor IDNM, Marathon Black or Blue Max, Allen Bradley cm202, etc. I watch for them on CL or ebay and if you have time you can find one NOS in the 200-400 range plus shipping. I've bought several 5 hp in that price range and even a 10 hp Black Max. The third picture is a Baldor ECP which isn't vector duty but a good inverter duty motor I found for $100.

Dave
 

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There's a conversion on another website that uses a casting of a pump housing and a lovejoy coupling to connect the the AC motor to the backgear unit. I'll send you a link.
 
If that mickey mouse sleeve gives you any runout at all you will have endless vibration issues. I'd get another opinion on the motor generator before you muck up yet another 10EE. If you are dead set on an AC motor VFD conversion go with 5 or more hp as you need the power at low RPM with a wimpy AC motor. you can probably find the correct size motor shaft in a bigger motor.
 
I was going to rebuild my motor/generator set, but the motor shop I took them to said they were too far gone and did not recommend rebuilding them. So I will use a new AC motor and VFD. I have read some threads already existing in this forum, but I have not seen exactly what I plan to do. So I would like to get feedback from the experts here, as to whether my plan is ok or if I failed to consider something.

It appears that most people are using a new motor larger than 3 hp. My motor shop said with a VFD and the gearbox, 3 hp should be plenty. This lathe will be for occasional hobby use. If 3 hp is slightly underpowered but I can still get any job completed just maybe at a slower pace, that is ok. If it will be underpowered and cause limitations to what I can do (aside from speed of the job) then I may have to reconsider the size.

My new motor has a shaft diameter of 1-1/8, and the gearbox needs a 1-1/4 shaft. So I would like use a shaft adapter like shown in the pics. It is probably not a precision piece, but for this purpose I am thinking it does not need to be.

I will need to have an adapter plate made. If anyone has a dimensioned print of the gearbox interface I certainly could use it. I will plan to seal the motor shaft to the adapter plate, and then seal/plug up the bottom "recirculating" hole in the gearbox.

Does this seem like a reasonable plan? Any input or advice?
Thanks.
In my opinion the best way to start a VFD conversion on a 10EE is to be very clear about what your goals are for the machine and its performance. I think you are a little low on the horse power. At a minimum I would go with 5 hp with back gear but 7.5 hp with the back gear and vector motor is a better choice in my opinion. There is more to consider than what you might be turning.

Things to think about are acceleration and deceleration rates and how this relates to motor size and braking. You’ll also need to consider pulley size as it relates to direct drive top end speed. VFD’s perform better in this application at a 1-to-1 ratio and not overdriven. You also need to consider what was the original rpm of your machine and what rpm are you going to try to achieve. For example, driving the original gearbox in direct drive at a 1-to-1 and achieving 4,000 rpm can result in a few vibration issues. These can be dealt with but you need to be prepared for this.

VFD conversions are sometimes considered downgrades and all too often this is true. If thought out and executed carefully, you can equal the original performance or even improve in a couple of areas - but it is a high mark. I say this because I believe there is an old unwritten rule in machine design that goes something like: If you think you are going to need 3 hp, you’ll probably need 6. If you think you need a machine that is 2,000 lbs., you probably need 4,000. If you think you are going to use 1,500 rpm, you are probably going to need 3,000. It’s with this larger reserve that Monarch and many of these old machine tool manufactures designed their machines, and it is often the missing piece of the puzzle with newly designed machines and VFD conversions.
 
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I was going to rebuild my motor/generator set, but the motor shop I took them to said they were too far gone and did not recommend rebuilding them. ...
What year is your round dial? If the original 3 HP DC spindle motor is functional why not just replace the motor/generator unit?
 
Others here are made adapter plates but I agree on the motor. A 5 hp will usually have the same frame size as a 3 and you will be running at lower speeds so the torque of a larger motor is your friend. The weakness of a vfd conversion can be low end hp so a larger motor compensates. When I want a wide speed range which is what you want even with the back gear, I use a vector duty motor like Baldor IDNM, Marathon Black or Blue Max, Allen Bradley cm202, etc. I watch for them on CL or ebay and if you have time you can find one NOS in the 200-400 range plus shipping. I've bought several 5 hp in that price range and even a 10 hp Black Max. The third picture is a Baldor ECP which isn't vector duty but a good inverter duty motor I found for $100.

Dave
Thanks. I will look around. I should have asked here before I bought the one I have. :(
 
You will find some great conversion info here. As a point of reference, my Smart Brown 1024 has a 4-1 ratio two speed clutch and an 8-1 back gear. I don't need or use the back gear much so the clutch equates somewhat to your back gear range. I could not easily swap pulleys so I was limited to about 1-1 on the high range. The vector duty motor operates the spindle at about 1600 rpm at 60 hz and about 2800 at 120 hz which is the highest i run a vector motor. Torque and hp hold pretty well up to 90 hz and then both drop off. The 1024 is slightly smaller at 11" swing but the spindle and bed are a little heavier than the 10ee although the drive train and apron seem a little lighter. My feeling is the 10ee is capable of more stock removal than the 1024. I don't use the full 5 hp and set the flat belts so they will slip under heavy load as my toolpost is a Multifix A which is really rated for more like 3 hp. A 10ee will run a size E which is a much stouter post and capable of 6-7 hp.

I find i seldom run much over 2200 rpm although in a pinch I can go higher. I have some HSS CCMT type inserts which reduce the need for higher speed on AL. I'd target 2500-3000 as an rpm top end so as to keep as much low end hp as possible. I can't argue with a 7.5 hp choice although a deal on a 5 hp vector 1800 rpm motor would tip the scales. Trying for higher rpm with only the back gear Monarch used and with the oil bath bearings in the round dial machine doesn't gain much bang for the low end cost.

As said above, research the entire system. Match the correct type motor with the speed range you can achieve, and match the vfd with the type of controls you want to incorporate as well as the braking desired and external resistor needed. Doing it right costs more than I anticipated but spending less and turning a 10ee into something less than it can be is frustrating too.

Dave
 
If you read through the past posts about doing this conversion, you will find several that used the DC motor end bell (since it is already machined for the 2-speed gearbox), and adapted it to work with a new motor. If that approach is of interest to you, I have an end bell with a 2-speed gearbox mounted on it I would like to sell... Contact me off-line.
 
Fortunately, I called Monarch for advise and they had a AC motor and gearbox they pulled from a rebuild donor. This one is using the end bell of the DC motor. There's also a good write up of a conversion on the Facebook 10EE group.

IMG_3349.JPEG
 
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Here's a GREAT build thread using a gear pump bell housing from Surplus center.

I used the DC motor bell housing on one of my two 10EE builds. LOT of work this way. Doing either this or the above thread, you must work carefully or there will be vibration issues in the finished job.

I did a second 10EE a couple years ago and went with a 10hp VFD rated motor and no back gear. GREATLY simplified the job and made for a super sweet machine.
 
That's a nice looking conversion, thanks for sharing the photo. I would like to know what's inside the access cover, i.e. how the motor is coupled to the 2-speed gearbox.
Here's a dark picture of the coupling. Gearbox is on the right side . I haven't removed it, so I'm not sure if there are different shaft sizes within.

cheers,

Jim
IMG_3351.JPEG
 
As Tailstock mentioned “ At a minimum I would go with 5 hp with back gear but 7.5 hp with the back gear and vector motor is a better choice in my opinion”.

I concur also. My 30 inch 10EE has the 7.5 with a back gear and a VFD. It works great BECAUSE it has the additional power. Anything less and I’d feel underpowered when using it.
 
Rigid shaft rigidly connected to rigid shaft will be a source of trouble unless the work is done to tenth accuracy ......and generally a single sided keyway will upset alignment ......far better to use a flexible coupling between the two shafts,such as a rubber cross or a toothed plastic coupling .....these need take up no more space than a rigid coupling.
 
I had to take a break from this project for awhile, but hoping to make some progress now. My motor-generator and DC motor were no good. The machine sat for a very long time, and when the motor shop checked them with a megger, they were not good enough to use. The DC motor was most critical to try and salvage - as somebody suggested above, but it was the worst one. So my plan is to use an AC motor and VFD. My original question here pertained to adapter plates and shaft couplings. But then people stated I will be underpowered with the 3 HP motor I bought and provided some recommendations. So getting back into this now I have a couple of questions and clarifications regarding the recommendations.

1) Would I be better off going with a 10 hp motor and not use the original back gear? Or should I look for a 7.5 hp and still use the back gear. Would a motor rpm of 1725 or 3450 be a better starting point for each case? My lathe has a 4000 RPM gauge, and I believe the back gear is 6:1.

2) If the motor I find has a larger shaft than the back gear 1.25 diameter, is it possible to turn down the motor shaft without compromising the integrity and without breaking the bank?

3) How important is "inverter" or "vector" specified motors for VFD use? And if people don't specify what they are selling, should it be obvious whether it is or is not by looking at the plate on the motor?

Thank you for the help.
 
For what it's worth, here's what mine looks like. It has plenty of torque. When I got it it had a three phase speed controller but I changed to a VFD so I could run on single phase power. I don't know what's in that adapter between the motor and the gearbox, but someone did a nice job on my conversion.
 

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No idea if it's worth a look to you. In the Home Shop Machinist magazine Jan-Feb & Mar-Apr 2022 issues is an article series on a conversion.

The author elected to re-use the gearbox and make the adapter plate the front plate of his motor. If you choose to subscribe to the magazine or sister publication Machinist's Workshop they are digitalizing back issues and to date have posted back to early 2018.

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