# Lathe motor upgrade, is this overkill?



## 57buick (Dec 22, 2020)

So I have a 1954 model Rockwell 11" lathe that I have mostly restored. Nice setup with quick change and all that, I scrapped all the old crappy wiring and installed a VFD on the stock motor. The orignal cabinet is racked bad and I am going to be building a custom new frame bench for it.

I just happened to pick up two 7.5hp motors brand new never been wired for $75!!! score I know its overkill but Im thinking I can finally get rid of the crap Reeves drive which the bearings are squeaking in it anyway and replace motor with one of these 7.5hp ones I got for almost nothing.

Question...using the higher horsepower motor (same RPM rating as original motor) wont that just give me better torque when Im running it half speed like 30hz as long as the motor is getting sufficient cooling of course?


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## matthewsx (Dec 22, 2020)

Yes, overkill. Maybe you can program the VFD but probably better to find a 2hp.

John


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## 57buick (Dec 22, 2020)

What would be the disadvantage?


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## 57buick (Dec 22, 2020)

The VFD is already programmed and running great, I have an adjustable knob to vary speed and the RPM of the new motor is the same


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## ttabbal (Dec 22, 2020)

I imagine that the added torque could be more likely to damage something if bad things happen. It could also put more stress on the bearings etc.. It also means more expensive VFDs etc., but it sounds like you already have that handled. 

A bit like putting a 3x bigger engine in a car without improving everything else. 

Great deal on the motors.


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## 57buick (Dec 22, 2020)

My VFD is rated for 10hp just because it wasnt much difference in price and figured the extra rating would be good overhead for years to come especially if using the braking function which has to handle spiking


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## 57buick (Dec 22, 2020)

Here are some pics of my lathe, I got it for $500 and was working but really grimy so I disassembled everything and cleaned and repainted. The guy said it got dropped on the end moving it which is why  the cabinet is racked so bad. So Im gonna be building a new frame for it out of 3x3 1/4 wall. That will be the perfect time to scrap the reeves drive in cabinet and upgrade the motor and just use my VFD


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## Jim F (Dec 22, 2020)

Stubby like sucker, isn't it?


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## 57buick (Dec 22, 2020)

its a 11x24" model there was an extended 36" version but I think this is all I could ever need as a hobbyist lol


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## 57buick (Dec 22, 2020)

Im in the process of building the new control box for the variable speed and direction, ill post pics of that next week


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## Jim F (Dec 22, 2020)

Is the 24 bed length or between centers ?


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## 57buick (Dec 22, 2020)

Jim F said:


> Is the 24 bed length or between centers ?



between centers is 24"


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## Jim F (Dec 22, 2020)

SB used bed length, my 42" bed has 22" between centers.


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## westerner (Dec 23, 2020)

I put a 12 hp lawn tractor engine in place of the 8hp one that spit the rod out the side of the case.
So far, (15 years) all it has done is mow grass, and burn fuel


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## 57buick (Dec 23, 2020)

I do have a 2hp motor I just realised. I just thought if I remove the reeves drive and just use the vfd that means I will be running it at 30hz which is half speed almost all the time, is it gonna wear the motor out? would the 2hp or the 7.5hp last longer in this case? They are both inverter ready motors


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