repair or replacing motor on old Rockwell Delta lathe

[mark ahlenius]

A few questions about my old lathe for the experts here: I have a vintage Rockwell Delta lathe which I believe was made back in the 1950 era - I do not know the model number but have attached pictures of the lathe and the motor. I have not used the lathe for about 6-8 months. Today when I tried to use it there was a loud screeching noise which I isolated to motor. I took off the motor and ran it separately and that is for sure where the noise is from. It sounds like bad bearings to me. The shaft spins ok but after running for 20+ seconds it starts to make this screeching sound. Nothing seems loose on the motor chasis. The motor is an original Rockwell motor (see pix). Its a 1/2 HP, 120VAC, 1725 RPM single phase motor, with a 5-step pulley. Is what is best to try to find a replacement or to have it rebuilt? There is a Dresilker Motor repair facility in the next town over where I could take it later next week. Question 1). Wondering what the wood turner's wisdom is for this older unit. It seems like a good lathe, and I am a very basic amatuer turner. Would you recommend getting the old motor repaired or just buying a new one. Question 2). If I should purchase a new motor, recommendations on where to get one and what kind so it would not be effected from all the dust and shavings? Question 3). There was no real way to tension the belt on this when I got the unit. So to change the belt to another pulley pair, I had to loosen the motor from the bottom plank enough to lift the motor up and release tension on the belt and then move it to another pair of pulleys. There must be a better way. Is it recommended to put the motor on a hinge-plate with some sort of spring tensioner to make speed adjustments easier? thanks very much for your assistance. Looking forward to learning more on this forum. best, 'mark

[Bill Dufour]

Probably just need to replace bearings. Is it ball bearing or sleeve bearings? Lokks easy to repalce those bearings. Get sealed not shielded bearings from the bay. I would use a TEFC motor. I would get one that is same rpm, double the horsepower, but three phase. You can buy a VFD that can take single phase 120 (rare) or 240 and make three phase. Turn the knob and the motor speed will change. Also gives you reverse which is probably not a good thing on a woodlathe. I recommend the extra HP because at lower speeds it will lose HP.
make sure to get the same size output shaft as the pulley and not too hard a change. A lot of older machines have a hinged motor plate and let gravity tension the belt.
Bill D.

[Carroll Courtney]

Welcome Mark,good questions.If your handy you can make those repairs for about 10-12.00,bearing can me had fairly cheap unless you go with one of the top of the line bearing names.But for us guys that play around the cheap ones are good enough.I would think if you had the repairs done,the cost would be just about around the cost of a new motor from Tractor Supply.Going with a new motor gives you more choices such as getting your self TEFC motor which is Totally Enclosed Fan Cool motor which means no more dust to deal with and you could increase the hp if needed.Your right about the belt,I had that lathe at one time had those same issues.If you can do some research looking at Delta band saw manuals of that same vintage as your lathe you will find how belt tension was handle in a band saw which could be done the same on your lathe.If you could find yourself a butt hinge thats kinda on the heavy duty side,half hinge bolted down and the other half with a 1/8 plate bolted or weld to the other half of the hinge that would have the motor mounted on it.Look at some manuals would give better ideals than what I am trying to explain.Those cast iron legs adds alot of value to that lathe.Good luck and lets us know about your repairs-----Carroll

[Jim Barkelew]

+1 on what Bill said if you want to keep the lathe. I looked at the cost of doing it right for my newer version and I was getting up to the cost of a new midi lathe. My tail stock is junk so replacing that and a motor/VFD was not worth it. I just bought a 1HP motor and suffer with the tail stock.

Replacing the bearings is relatively easy but opening up the motor can ruin it if the nuts are frozen and the bolts break.

[mark ahlenius]

Hi

first - thank you for everyone who responded to my questions. All very educational and helpful for me.

Nevermind my pre-edited post, I was able to get the pulley off by heating it with a heat gun and rubber mallet.

Now I just need to try to find a 1 to 1.5 HP motor with a shaft which is at least 2.5" long and 3/4" in diameter.

best

'mark

[Ed Aumiller]

I have an old Powermatic, very similiar to that.. I did what Bill said and it is GREAT..

Highly recommend putting a used 3 phase motor on it with a vfd.. cost should be less than 150-200.

You will then have a true variable speed on a rock solid lathe frame...

The ability to adjust speed so easily makes it equal to or better than some of the newer lathes..
It will make your turning much more enjoyable...

[mark ahlenius]

I have an old Powermatic, very similiar to that.. I did what Bill said and it is GREAT..

Highly recommend putting a used 3 phase motor on it with a vfd.. cost should be less than 150-200.

You will then have a true variable speed on a rock solid lathe frame...

The ability to adjust speed so easily makes it equal to or better than some of the newer lathes..
It will make your turning much more enjoyable...

Hi

where did you find the motor and VFD? The shaft of the current motor with its 5-step pulley is 3/4". That's not something very common from looking at the Tractor sales store nor Grainger.

thanks!

'mark

[Olaf Vogel]

First, try soaking your bearings with WD40 or silicone. Chances are, the lubircant just dried out.

Small motors like this are typically not worth rebuilding, but as others have said, swapping bearings is easy - with a bearing puller.
This is a very standard motor.

If you want speed control:
Look on Craigslist or other used suppliers.
3 PH motors are really cheap, like ~$50. 1 hp should be enough for that lathe.

A new pulley is also easily available so don't bother looking for a 3/4" shaft.
And McMaMaster has EVERYTHING https://www.mcmaster.com/#step-pulleys/=1axs7ve

Delta VFDs are available on eBay, used, very cheap. I recently priced a 1 hp at $75, incl shipping, from China.
I personally really like the Delta ones because they have a READABLE manual.

[Jim Barkelew]

I have a single pulley on my motor a built a sliding motor mount to align it with the step pulley on the spindle. Not great but usable for a 40 year old lathe I bought new.

[mark ahlenius]

Thanks Olaf,

I was able to pull off the old pulley by soaking it with white lithium grease and I also soaked the 4 long bolts which hold the motor frame together with the same. I then heated up each of them with a heat gun and they each came off without damage. I'll see what the bearings look like when I pull the chasis apart today. If I can get/replace the bearings for cheap, then its a no brainer, otherwise I'll try to find the 3 phase 1 HP (or 1.5 HP) TEFC motor with a VFD.

Appreciate all the help everyone!

Happy New Year to you all.

'mark

[Dennis Ford]

Check the fan, sometimes they get damaged or loose on the shaft and make loud noises.

[mark ahlenius]

Thanks Dennis,
opened up this little puppy and I think its just time to say goodbye to this Delta Milwaukee motor. Inside the frame housing the wiring appears to be shot, a number of bare spots in the insulation of the wires coming from the connection block. They have the insides packed with fiberglass insulation - most likely to keep the dust out of the rest of the frame.
best
'mark

[mark ahlenius]

<p>
Bill and rest, since I am new to VFD&#39;s - should I only be looking for &quot;inverter-rated&quot; 3-phase motors? Searching around eBay this afternoon, but don&#39;t want to order something which is not going to work. Also been reading up a little on the kinds of VFD units. If any of you have done this (Bill, Jim or others) could you share a little more detail on the kind of motor and VFD model you used? Anything to be aware of as far as brands or specifics? I can easily add a new 220 volt outlet for a VFD unit, if I cannot find 120 VAC unit. thanks again everyone, this help has been great! &#39;mark</p>
<p>
&nbsp;</p>
<p>
p.s. &nbsp;- I attached a pix of my motor&#39;s internal wiring to its terminal block, as can be see the wiring is a bit toasted.</p>

[Olaf Vogel]

I have no idea why insulation would be inside.

eBay is not a good source for motors, typically. Their value is too low to be worth shipping.
And you should be able to source them locally.
3 ph, 208v are typically industrial cast offs - hence cheap.

https://www.ebay.com/itm/ORIGINAL-De...oAAOSwv0tVWs3d
is an example of a VFD that will work, but almost all will need 220v input.

Look here for the model you want: https://www.deltaacdrives.com/delta-vfd004s21a/
Then search for that model.

I have 5 of these VFDs up to 7.5 kw, none have let me down.

[Bill Dufour]

I would say any fairly modern 3 phase motor can handle a VFD drive. If it is painted any color other then factory black it is probably new enough to have good insulation.
3 phase motors tend to be made to industrial standards so they are not cheapy home owner adequate insides. Plus a three phase motor has no starter switch or capacitors to go bad.
If you are buying a used motor check all three power leads to ground for infinite resistance. then check each pair. Each pair should have the same low resistance. Probably less the 5 ohms.
On my drill press I installed a VFD and have not moved the belts in ten years. If you want you can use the factory switches as low voltage control switches or install new switches where you like.
Bill D

On Ebay many sellers do not list the shaft diameter or key slot size. Most will respond to questions so you have to ask. I like to ask with suggested sizes but a spread like is this 1/2, 5/8 or 3/4 diameter. If I just ask is it 5/8 I figure they may be lazy and just say yes without measuring.