Soft Start for Lathe?

All discussion about lathes including but not limited to: South Bend, Hardinge, Logan, Monarch, Clausing and other HSM lathes, including imports

Moderators: Harold_V, GlennW

User avatar
liveaboard
Posts: 888
Joined: Sun Dec 08, 2013 1:40 pm
Location: southern Portugal
Contact:

Re: Soft Start for Lathe?

Post by liveaboard » Thu Apr 25, 2019 5:10 pm

whateg0 wrote:
Thu Apr 25, 2019 12:45 pm
Is a GFCI breaker? I have a buddy who has GFCI on one wall and he can't start his mill without it tripping.

Dave
A friend of mine had a drill press; gfi would trip if you touched it while it was running.
So he put a thick rubber mat on the floor in front of it to stand on while using it.
Problem solved.

User avatar
BadDog
Posts: 4802
Joined: Wed May 17, 2006 8:21 pm
Location: Phoenix, AZ

Re: Soft Start for Lathe?

Post by BadDog » Thu Apr 25, 2019 5:51 pm

I just checked mine, and with the main drive disengaged (gear head H/N/L in N), grabbing one jaw of an 8" chuck and giving it a firm (not hard) throw, I get more than 1.5 turns without trying hard.

But I don't believe your's is a clutch, nor is mine. You can't really compare a direct drive with a clutched spindle lathe in this respect, at least not as apples to apples (depending on clutch integration).
Russ
Master Floor Sweeper

User avatar
WesHowe
Posts: 175
Joined: Sat Sep 19, 2015 9:52 am
Location: Huntsville, Texas

Re: Soft Start for Lathe?

Post by WesHowe » Thu Apr 25, 2019 6:44 pm

On a 4th of July weekend a few years ago, my house A/C quit cooling. A quick analysis showed it was because the outside unit (compressor) was not powered because the breaker popped. Reset the breaker, unit started and cool air returned. But after the unit stopped and tried to restart later, the breaker popped. After several rounds of this I called a repair company, and paid dearly for the holiday service.

Turns out the starter capacitor had burnt out. Due to it's functional absence, when the unit tried to start it drew a very high current very briefly. While an A/C is not a mill, they both have motors. The symptoms sound alike, may be worth checking into.

- Wes

David2011
Posts: 26
Joined: Wed Apr 24, 2019 3:18 pm

Re: Soft Start for Lathe?

Post by David2011 » Thu Apr 25, 2019 9:27 pm

BadDog wrote:
Thu Apr 25, 2019 5:51 pm
I just checked mine, and with the main drive disengaged (gear head H/N/L in N), grabbing one jaw of an 8" chuck and giving it a firm (not hard) throw, I get more than 1.5 turns without trying hard.

But I don't believe your's is a clutch, nor is mine. You can't really compare a direct drive with a clutched spindle lathe in this respect, at least not as apples to apples (depending on clutch integration).
I get a half turn with the tumbler disengaged and the belt off of the spindle pulley so will pursue that. I think with everything disconnected it should be pretty comparable.

David2011
Posts: 26
Joined: Wed Apr 24, 2019 3:18 pm

Re: Soft Start for Lathe?

Post by David2011 » Thu Apr 25, 2019 9:30 pm

WesHowe wrote:
Thu Apr 25, 2019 6:44 pm
On a 4th of July weekend a few years ago, my house A/C quit cooling. A quick analysis showed it was because the outside unit (compressor) was not powered because the breaker popped. Reset the breaker, unit started and cool air returned. But after the unit stopped and tried to restart later, the breaker popped. After several rounds of this I called a repair company, and paid dearly for the holiday service.

Turns out the starter capacitor had burnt out. Due to it's functional absence, when the unit tried to start it drew a very high current very briefly. While an A/C is not a mill, they both have motors. The symptoms sound alike, may be worth checking into.

- Wes
We had that happen as well, middle of the Summer on 105 degree day. It was the cap but nowhere to buy one. It was well worth the AC service man's after hours charge. An aging/failing capacitor did cross my mind and they aren't expensive. I should probably replace it just as a PM. It's 41 years old.

RSG
Posts: 1089
Joined: Fri Feb 04, 2011 9:59 am
Location: Ontario, Canada

Re: Soft Start for Lathe?

Post by RSG » Fri Apr 26, 2019 6:49 am

For what it's worth, my new mill was giving me a problem on start up and doing the same thing, blowing the breaker. We (Electrician and I) eventually identified the issue to be a faulty cap start switch arcing. Once I replaced it and set it up properly I haven't had an issue again.
Vision is not seeing things as they are, but as they will be.

John Hasler
Posts: 1275
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Soft Start for Lathe?

Post by John Hasler » Fri Apr 26, 2019 8:03 am

David2011 wrote:
Thu Apr 25, 2019 9:27 pm
BadDog wrote:
Thu Apr 25, 2019 5:51 pm
I just checked mine, and with the main drive disengaged (gear head H/N/L in N), grabbing one jaw of an 8" chuck and giving it a firm (not hard) throw, I get more than 1.5 turns without trying hard.

But I don't believe your's is a clutch, nor is mine. You can't really compare a direct drive with a clutched spindle lathe in this respect, at least not as apples to apples (depending on clutch integration).
I get a half turn with the tumbler disengaged and the belt off of the spindle pulley so will pursue that. I think with everything disconnected it should be pretty comparable.
That doesn't sound good. I think you should still check the starting capacitor, though. More than one thing can be wrong.

User avatar
SteveHGraham
Posts: 7787
Joined: Sat Jan 17, 2009 7:55 pm
Location: Florida

Re: Soft Start for Lathe?

Post by SteveHGraham » Fri Apr 26, 2019 9:36 am

I don't suppose you have the wrong start cap? A capacitor sucks a lot of juice when you hit the switch.
Every hard-fried egg began life sunny-side up.

John Hasler
Posts: 1275
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Soft Start for Lathe?

Post by John Hasler » Fri Apr 26, 2019 10:27 am

Yes. An oversized starting cap would increase starting current.

Glenn Brooks
Posts: 1794
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Soft Start for Lathe?

Post by Glenn Brooks » Fri Apr 26, 2019 12:51 pm

Generally the lathes I’ve worked on have a fairly free spinning chuck. Some of my old time lathes, with split bearings, sometimes actually stall the motor if I tighten the bearing caps down to much. Puts excessive pressure on the head stock shaft, and it binds up. Even then, I can’t recall a time when this popped the breaker.

You could try to pull the bearings, and check lubrication and wear. but if this is a gear head lathe, you will be probably looking at a major tear down and lots of trouble pressing the existing bearings out of the headstock casting. I went through this on my old, 1950 12” Standard Modern lathe years ago - a big heavy, old school industrial machine, with a 5 hp motor. Massive job, and at the end, found nothing at all wrong with the bearings. They were actually lubricated from the oil bath in the headstock.

The only other question to ask is: is this the original motor? If not, maybe some prior owner put an improperly sized replacement in the lathe - to small for the machine. 1 hp seems light if the gear train is as heavy as you describe.

Another idea, might be to just call Jet service center and see what they know them about this model lathe.

All in all, I think the easiest test to run would be if you replaced the breaker with a 30 amp breaker and made a bucket of chips at all speeds- see what happens. If you’ve got some kind of short going on, this likely would trip a 30 amp breaker as well. If all is well, maybe your initial thought that the existing 20a circuit is just to light for the motor, is the correct one.

Good luck. Let us know what happens.
Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

David2011
Posts: 26
Joined: Wed Apr 24, 2019 3:18 pm

Re: Soft Start for Lathe?

Post by David2011 » Fri Apr 26, 2019 1:00 pm

SteveHGraham wrote:
Fri Apr 26, 2019 9:36 am
I don't suppose you have the wrong start cap? A capacitor sucks a lot of juice when you hit the switch.
I know the history of this lathe since it was 4 years old and it's 41 years old now. I'm pretty sure the cap is original. Good because it would be the right size. Bad because it's 41 years old. I'm pretty sure capacitors dump electricity on starting; not draw it. (They can be used as batteries in some conditions.)

David2011
Posts: 26
Joined: Wed Apr 24, 2019 3:18 pm

Re: Soft Start for Lathe?

Post by David2011 » Fri Apr 26, 2019 1:46 pm

Glenn Brooks wrote:
Fri Apr 26, 2019 12:51 pm
Generally the lathes I’ve worked on have a fairly free spinning chuck. Some of my old time lathes, with split bearings, sometimes actually stall the motor if I tighten the bearing caps down to much. Puts excessive pressure on the head stock shaft, and it binds up. Even then, I can’t recall a time when this popped the breaker.

You could try to pull the bearings, and check lubrication and wear. but if this is a gear head lathe, you will be probably looking at a major tear down and lots of trouble pressing the existing bearings out of the headstock casting. I went through this on my old, 1950 12” Standard Modern lathe years ago - a big heavy, old school industrial machine, with a 5 hp motor. Massive job, and at the end, found nothing at all wrong with the bearings. They were actually lubricated from the oil bath in the headstock.

The only other question to ask is: is this the original motor? If not, maybe some prior owner put an improperly sized replacement in the lathe - to small for the machine. 1 hp seems light if the gear train is as heavy as you describe.

Another idea, might be to just call Jet service center and see what they know them about this model lathe.

All in all, I think the easiest test to run would be if you replaced the breaker with a 30 amp breaker and made a bucket of chips at all speeds- see what happens. If you’ve got some kind of short going on, this likely would trip a 30 amp breaker as well. If all is well, maybe your initial thought that the existing 20a circuit is just to light for the motor, is the correct one.

Good luck. Let us know what happens.
Glenn
I like your plan. Yes, it's a gearhead lathe. In spite of the small size in many ways it's built like much larger lathes. The spindle bearings are held in place with external caps so I don't think they would be pressed onto the spindle. I don't see how it could be installed with the bearings already on the spindle. Pretty sure the lathe has never been disassembled. The year on the motor is the same as the year of manufacture of the lathe and both are made in Taiwan. The original spec is for a 1 HP motor and I believe the belt was original when I got the machine. I can't guarantee it's the original motor but it has all the indicators of being original. The gearbox is run dry with grease applied to the gears. The bearings are lubed through fill caps on the front of the headstock and they have sight glasses for the oil level.

After looking at the bearing installation from the outside it appears that I could remove the caps and flush them out with a brake cleaner type aerosol without removing them. I have PDFs of the instructions and assembly along with parts lists.

I bought a 30A breaker some time ago but was reluctant to install it on a 12Ga circuit. Other comments indicate that it's not unsafe for a dedicated circuit so I'll find the breaker and install it.

Thanks!
David

Post Reply