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Anyone ever replace the motor on a K&T with a modern motor?

saryon7

Plastic
Joined
Oct 1, 2017
So, my motor has some problems and I am contemplating what I want to do to solve the problem. The motor drive shaft is really buggered up and someone sleeved it as a repair. The only problem is the the pulley wobbles. Something isn't straight. I think it is either the shaft is bent, or the sleeve isn't quite right. Anyways, I wanted to see if a modern 2hp motor could replace the old one. The old 2hp motor is HUGE! Wasn't sure if a new one could handle the machine. Didn't look like too hard of a job for the motor, but wanted to check what the experts thought. Thanks in advance :))
 
Replacing a generations-old motor with a newer one is a perfectly reasonable thing to do.

Electric motors are highly optimized designs these days. About 2/3 of the size difference between old (1950's and earlier) and new motors of the same rating is due to improvements in design. The remainder is due to reduced margins (basically designing down to the spec).

If you select a new motor of the appropriate service factor (SF) and application type, you should have no issues. Do not select an intermittent duty cycle motor or one with minimal (1.0) SF for a milling machine. If the old motor frame is an obsolete frame, you may have to fabricate an adaptor motor mount.
 
So, my motor has some problems and I am contemplating what I want to do to solve the problem. The motor drive shaft is really buggered up and someone sleeved it as a repair. The only problem is the the pulley wobbles. Something isn't straight. I think it is either the shaft is bent, or the sleeve isn't quite right. Anyways, I wanted to see if a modern 2hp motor could replace the old one. The old 2hp motor is HUGE! Wasn't sure if a new one could handle the machine. Didn't look like too hard of a job for the motor, but wanted to check what the experts thought. Thanks in advance :))

"HUGE" means probably "TENV". Totally Enclosed Non Ventilated.

The hosing has to hold and move enough air to transfer heat out to the shell by convection, and the shell in turn has to have enough surface-area to in turn hand the heat off to ambient air. These are GRAND for keeping conductive or corrosive coolants OUT and conductive or abrasive metal chips OUT.

They are still made, and for the same reasons. See also "washdown" rated motors, foodstuffs industry, et al.

Most now have smaller cases and lots of fins on the case. Marathon Black Max and Blue Max are well-regarded as value for money, and common enough to find NOS or used-but-good.
 
The motor drive shaft is really buggered up and someone sleeved it as a repair.
Depending on the equipment you have and the time available for repair, it may be a good option to replace the shaft. Adam Booth (abom79) just posted a video on YouTube this past weekend showing how he removed the shaft from the rotor in the motor of his K&T. He's going to turn a new one from 4140 and press it back into the rotor laminations.
 
Depending on the equipment you have and the time available for repair, it may be a good option to replace the shaft. Adam Booth (abom79) just posted a video on YouTube this past weekend showing how he removed the shaft from the rotor in the motor of his K&T. He's going to turn a new one from 4140 and press it back into the rotor laminations.

Galis "normally" bought from the motor OEM for the 100 HP DC motors, Joy 1CM Continuous Mining machine.

Now and then there'd be a long lead-time, so we also made them. About half a shift, ancient lathes, taper, threads, blind-ended captive keyway endmilled on a Toolmaster vertical.

A mere 2 to 5 HP one should be cake. More of the time spent establishing dimensions than actual turning to them, I'd guess. We at least had the prints.
 
Simple,look in the free ads,and get a likely replacement with a taperlock pulley for a few pesos........Take your megger with you ,and test before buying,or offer what the scrap price is ,and save the taperlock.........nextdoor neighbour bought a new taperlock for one of his shoemaking machines....cost $100.....I got drum full of them...he never asked.
 
I put a 5HP single phase motor in my K&T 2H when I had it in my garage. The new motor was smaller than the 1941 vintage motor. No issues with the installation, I did have to turn the armature on the motor to size. I still have the motor in the machine here in a shop with 480 three phase. I don't do much heavy work on the lil 2H but it was nice to have in my garage, it and my lathe were both single phase. Today with cheap inverters I would do a three phase motor and inverter as phase converter.

Steve
 
Replacing a generations-old motor with a newer one is a perfectly reasonable thing to do.

Electric motors are highly optimized designs these days. About 2/3 of the size difference between old (1950's and earlier) and new motors of the same rating is due to improvements in design. The remainder is due to reduced margins (basically designing down to the spec).

If you select a new motor of the appropriate service factor (SF) and application type, you should have no issues. Do not select an intermittent duty cycle motor or one with minimal (1.0) SF for a milling machine. If the old motor frame is an obsolete frame, you may have to fabricate an adaptor motor mount.

Thanks for responding. I was kinda figuring that the improvements in technology made a huge difference because I never see those type of huge motors anymore. I am not sure if the old motor frame is obsolete, but it wouldn't surprise me. I will try to figure out what it is and see if I can find a direct replacement at somewhere like grainger. I am sure it will be too expensive for me, but it wouldn't hurt to look, and then I can post the info in case it helps someone else.
 
"HUGE" means probably "TENV". Totally Enclosed Non Ventilated.

The hosing has to hold and move enough air to transfer heat out to the shell by convection, and the shell in turn has to have enough surface-area to in turn hand the heat off to ambient air. These are GRAND for keeping conductive or corrosive coolants OUT and conductive or abrasive metal chips OUT.

They are still made, and for the same reasons. See also "washdown" rated motors, foodstuffs industry, et al.

Most now have smaller cases and lots of fins on the case. Marathon Black Max and Blue Max are well-regarded as value for money, and common enough to find NOS or used-but-good.

Thank you for the thoughtful reply. Yeah, that motor is huge. It fills up the entire cavity in the column and the cavity is pretty huge. (also a giant mess in there :crazy:)
I am going to look for a suitable motor, but my guess is I am going to have to end up modifying one. The only difficult part is that the old motor has a really long spindle that will likely be hard to replace. I will post some of my ideas when I figure them out over the next couple of days and if you don't mind, you could let me know what you think.
thanks,
 
I have been watching that eagerly. Unfortunately, Adam is far more skilled than I am, and has a much better shop. I don't have a big press like he has. I am going to keep watching though, because maybe I could do it. I must say though, the whole time I have been watching, I have been thinking....damn that is a LOT of time and effort. I am not sure if it is worth it. I am sure it is for him, but it would be much more difficult for me, with a MUCH lower chance of actually succeeding:D.
 
Well... for me, I don't think it would be cake. I MIGHT be able to do it.

A mere 2 to 5 HP one should be cake. More of the time spent establishing dimensions than actual turning to them, I'd guess. We at least had the prints.[/QUOTE]
 
Thank you for the thoughtful reply. Yeah, that motor is huge. It fills up the entire cavity in the column and the cavity is pretty huge. (also a giant mess in there :crazy:)
I am going to look for a suitable motor, but my guess is I am going to have to end up modifying one. The only difficult part is that the old motor has a really long spindle that will likely be hard to replace. I will post some of my ideas when I figure them out over the next couple of days and if you don't mind, you could let me know what you think.
thanks,

"What I think", is that with it being all about shaft FUBAR'ed AND NOT burnt-up windings, and a LONG shaft as well, the EASY way forward - having made dozens of motor armatures, is that you JF make a new one.

Might be different if you were a baker's boy trying to get a Hobart bread mixer back online, but yer a Machinist, yah?

AFTER finding what you HOPE is a suitable alternative motor, the work in making a shaft extender and mounting adapters will be simple, each individual step, but there will be far more steps, more frustration, and ultimately more time and more MONEY leaving the room than if you simply duplicate what the factory shipped.

Just price about 24" of 4XXX pre-hard in an appropriate diameter plus a skosh and a set of modern "sealed" bearings. There's your total out-of-pocket cash.

No mystery left but your skill-level at nailing the several feature OD's and a few shoulder positions. Scares yah, turn it over to a more seasoned hand. Shafts of this sort are very ordinary "white bread" to a lathe hand. Pressing them out and in without bending actually calls for the greater ration of care, but its still just common sensical.

Try that first. Destroy the old armature right up front? THEN you go seek a new motor.
 
I put a 5HP single phase motor in my K&T 2H when I had it in my garage. The new motor was smaller than the 1941 vintage motor. No issues with the installation, I did have to turn the armature on the motor to size. I still have the motor in the machine here in a shop with 480 three phase. I don't do much heavy work on the lil 2H but it was nice to have in my garage, it and my lathe were both single phase. Today with cheap inverters I would do a three phase motor and inverter as phase converter.

Steve

Well, I just looked through my surplus motors- I have (2) 1/3HP motors which will obviously be too small, (1) 1-1/2HP motor, that might work and is the right rpm, and a 3HP motor that spins 2x as fast as the old one and would require a different sized pulley. What do you think about the 1-1/2HP motor? Too small? I doubt I will ever push my machine to what it is capable of, but I don't want to have to change the motor again after only a short time. I am leaning towards a new 3 phase motor. Plus I can keep using my same phase converter that way.
 
This has me curious, what is a QD hub?

Quick Detach. A bulkier "Taperlock" competitor that needs more space, but is superior for repair work or any other time the pulley has to come off for other work more than once in a great while. Had nicer tits, I'd probably have married 'em some tight-spaces jobs. Straight-bore and silly-setscrews simply suck slime up their sorry sphincters by comparison.

The common ones are all on one page, here:

Bushings | Drive Components | Browning

MMC and MSC also stock them.

CAVEAT: They need large-bore sheaves and pulleys made to fit or DIY to fit, usually in steel or CI. ZAMAK or shiney-wood ones just don't handle the taper's stresses for long!
 
This has me curious, what is a QD hub?

QD, taper-lock, etc are all two piece pulleys with a split center like a collet.

Regarding a new motor, look on ebay 2-5HP motors are plentiful and sell for way less than retail. If you go with a VFD think about 3HP to maintain power at low motor speeds. I bought a motor with a shaft that was a bit larger than the original, so I took the armature out and turned it to size. Even a used 3 phase motor is likely to serve your needs with no issue.

Steve
 
I scrapped a 2HL a while back. If you were closer, I’d give you the exact replacement motor for your machine. It’s going to the scrap man in a week or so.
 








 
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