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SBL9 GE Motor and Reverse Drum wiring issues.

Kevin5150

Plastic
Joined
Jun 12, 2024
Location
Winters Ca
Hi Guy's I'm new to the site and have only had my SB9 for about 2yrs now. When I first got the lathe I tore it down, cleaned and went through everything, painted, polished and replaced the wicks and felts as well as I did thrush bearings on the main shaft and swapped the old dry leather belt for a serpentine as well as built a decent table for it all to mount to. The lath works great and came with tons of equipment but in order to get it going I need to pull the belt as I flip the forward/reverse switch and I read somewhere on here that it is a wiring issue.

So after a lot of searching and hours of going down some great rabbit holes the big issue I have is the (4) leads that come out of my motor. All (4) are labeled but not 1,2,3,4. Mine have the alum tag on each wire but are labeled 1,4,5,8. Has anyone else come across this or can someone explain how to check for pairs or what ever? Your experience and guidance is greatly appreciated. Also the drum switch is the 789 model.

Thank you in advance for any help or direction that you can provide.

Kevin
Winters Ca.
 

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Sounds as though the start winding in the motor is not being connected through the drum switch. The numbers on the leads don't have any real significance in a general sense. It's what they hook to in the motor that matters. The little tag inside the terminal space of the motor will usually say which two leads have to be reversed to change direction. Those are the leads to the start winding. The get reversed by the drum switch to change rotation direction.
 
Unfortunately it does not give the reversing wires and if it did they don’t have colors that are traceable. I need to try and figure out how to ohm test them.
 

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So I found the pairs and ended up swapping the #8 and #5 and it started up great, forward and reverse but only about 5-8 times. Then it was back to me needing to hand start the belt before hitting the switch. Guess it is time to start looking for a new motor set up.
 
I thought about that but was under the impression that the capacitor was for reverse breaking or something, is this not correct? That would be great if it is that simple. If not I may go with a new set up with VFD.
Thank you
 
In general for most typical single phase motors used on shop equipment, the capacitor is used during the starting of the motor. It helps increase starting torque and reduce the starting current.

It's possible you have a bad capacitor. It's also possible that you've got some corroded contacts in the starting switch itself. Unfortunately, to get to those contacts most of the time you have to pull the end bell off the motor at the terminal end. Once you get in to them, they can be cleaned with a bit of fine sandpaper just like most other contact points.
 
Well when I got home last night my SB9 started up just fine several times, I then used the lathe for a few minutes and it would no longer self start. So I pulled the start cap and will pick up a new one today. The current one is a Vanguard BC-340 M-165, I'll see what's available at a local motor repair shop here in S.F. and go from there. I'll report back after I get the new one installed.
Thanks guys.
 

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Ya may be able to find a cap at a Air Conditioning repair place or even a Well driller . Gotta be a couple of them @ WInters
animal
 
Well I work in SF :( so I looked up an old motor repair shop and told the guy what I was looking for and he said swing on by. So I stopped in yesterday afternoon and let me tell you, an old shop it was! The shop has been in the same location since 1932 and Mike the owner started working their around 75 and purchased the shop in 95.They are still using their 1921 lathe that was bought used in 1932 for turning their armature's (not a south bend but looked very similar). Any ways I told him my issues and he said it's not the start cap but lets check it anyways. He did 3 different checks, he had a set up built into his wooden work bench with a light bulb, a 50 amp resister that looked more like a heating coil shaped like an ice-cream cone and lastly he did a continuity test and all passed. He then said it is an issue with the internal centrifugal start switch. He pulled a motor off the shelf and removed the start cap and explained how to check the leads for continuity while slowly turning the motor to see is there was any dead spots in the internal switch (contacts, springs, stuck centrifugal thingy). So when I got home I checked the leads as instructed and everything was good. So I put the start cap back on and it fired right up several times so I let it run for a few minutes. I shut it off and turned it back on and just a hum, so I shut it back off and after sitting for a few minutes and then heard a mechanical "pop" and when I hit the switch it fired right up. I shut it off and again nothing but a hum, shut it back off and shorted out the start cap thinking that maybe it was holding something open but that was not it and about a minute later I heard the same "pop" and she fired back up with no issues. So I'll call Mike back today and let him know but I suspect the internal start switch is sticky and once it runs for a bit and is fully open that it is getting stuck but the spring is still pushing it closed but takes a minute or 2 to happen and probably just needs to be pulled apart and cleaned. Mike went over this whole process and gave some pointers in doing it yesterday but figured I'd give him my new info before cracking that sucker apart.

One tip that he gave me was when after pulling the trough bolts holding the ends on the motor to remove everything through the front like I have read on this site. Bu the added part he mentioned since this is an old GE fully enclosed motor that he suspects it will have the old cloth wrapped wires connected to the parts on the back cap that are very brittle and tend to break when bent. So the tip was to take a heat gun and just crack the back of the motor off enough to expose these wires and then heat them up before pulling the cap further and they will bend just fine. He also said to block the motor on the bench so that the end cap kind of "hinges" open and rests on the bench.

Well that's it for now and I'll let you all know what comes next. But I have to say I loved checking out his 115 year old shop, wooden floors and most of the equipment that's older then my Dad (1945) and still being used on a daily bases. It's a2 story building with his shop on the ground floor and residential space above right in the heart of down town San Fran.
 
Kevin, can you post a photo of the motor plate, it's just for my files to determine if a newer cover has been put on the wiring access box, that shows a dual voltage motor. Does the motor plate show a single voltage of 115V ?
Steve
 
Well I had some time on Saturday afternoon when I got home from my centerfire match and took the motor apart. It was dirty and dusty but nothing really stood out as being the 1 issue. So I cleaned everything using a brush, steel wool, scotch bright pad and 400grt sandpaper. I made sure the start switch had free movement, the contacts were clean and free and then I put it back together and everything worked great. I ran the lathe for about 10 minutes, loading and unloading the motor and all is good. Sorry I can't tell you just what the issue was but probably a little bit of everything and a good cleaning just did the job.
 

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