Need some help from savvy machinist

poolcuemaster

poolcuemaster

AzB Silver Member
Silver Member
I have a very old atlas 10 by 54 inch gun barrel lathe from a US Naval ship made by Oldsmobile in the 40 or 50's. When the 88 year old navy machinist sold it to me 3 years ago he showed me that I would have to spin the belt pulley backwards with the switch in reverse to get it started. It has always started great in clockwise or forward direction in the three years till today, after I ran the lathe in reverse for a tip trimming. When I threw the switch in forward I had to spin the pulley every time the rest of the evening and can even spin the chuck to get it started. I think they call the switch a drum switch and it is mounted on a seperate flat metal rail above the middle of the lathe bed. I need to know if the switch needs replacing or rewiring possibly or if the old motor is just weak, it seems like the navy guy mentioned that rewiring the switch would help the reversing problem. Any help will be greatly appreciated he had every bearing and halfnut, handle wheel and gear to completely rebuild the lathe which he gave me but no drum switch to try.--Leonard
 
Capacitor or contacts in the drum switch. Also check all the connections on the motor.
 
Hi Leonard,
It sounds like the start capacitor is out.
There will be two screws on the bottom or top edge of the barrel switch, if you take them out, the front center cover will pull out and away. There will be 6 terminals, 3 per side in the switch. There should be a wire lead on each one. The clean the contacts, you need to take off the top switch handle. If it has a ball end and metal shaft, just unscrew it from the switch spindle cap a ways and the cap will pull straight up, then take the center contactor out of the switch and you can clean all the contacts. Make sure the lathe motor is unplugged. If it has an arrow type switch handle, it should have a screw on the back side that does the same thing.
You may be able to find a new start capacitor for the old atlas motor. If not, you will need a new motor most likely. If the lathe is an atlas 10 x 54, the new motors dont have the same foot print as the one that is on the lathe. You must also be careful that you get a motor with a start capacitor that is off to the side of the motor so that it will clear the counterbalance that sits above the motor. Been there done this before. If you get a new motor, I can give you the lead information to wire it up, but a motor rewind shop may be able to get a capacitor.

Kenny Murrell
 
poolcuemaster said:
Thanks Kenny the motor hums in both directions so does that mean the contacts are good ?--Leonard
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It usually means the start capacitor is bad. I just had to change out my motor on my 10 x 54 atlas lathe because the start capacitor died and I could not come up with one. You might want to check your switch contacts anyways, they will pit up pretty bad sometimes. A light sanding and you can bend the lead contactors so they mate up right when the barrel contact is turned.
You might have a good motor rewind shop around your area that can change the start capacitor or find one that is compatible. There is only one is my area he said he could not even look at the motor for about 4 weeks, I ordered a new motor.

Kenny Murrell
 
I had my old Atlas lathe do that several times through the years. Usually I was able to blow the motor out with my air hose and it would go back to working. My guess is that it had dust in the contacts.
 
I took the barrel switch completly apart today and filed all contacts to a fresh flat surface and filed the points style contacts with a round file and blew out all dust with a compressor. No luck so I blew out the dust from the motor and oil it up good and still no luck, and as far as I can tell there is no start capacitor on the motor. There is no hump or appendage on a perfectly round motor which would hold the capacitor and there is only a small oval cover for the brush contacts or wiring connections, so I'm lost again and spinning the chuck to make her run. If the start capacitor is mounted in the end plate somehow I don't see it so where do I look from here. This does not have to be the original motor for sure.--Leonard
 
Some fractional horsepower motors use a start coil which is engaged through a set of contacts built into the motor, they disengage though centrifugal force. Might have to take motor apart to get to them.
 
claymont said:
Some fractional horsepower motors use a start coil which is engaged through a set of contacts built into the motor, they disengage though centrifugal force. Might have to take motor apart to get to them.
Click to expand...
I believe they call it the centrifigal switch, and yes it would require dissassembling the motor, and trying to clean/file/adjust the contacts, if you can get to them. Some are totally closed up.If you can't get it going, you can check out Ebay, there maybe a used reversible motor for a good price.
Good luck.
Dave
 
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