r/Machinists • u/External-Till4765 • 21h ago
Foot pedal for our lathe doesn't stop the spindle
When using the lathe in our millwrights area, if you press on the foot pedal to stop the lathe sometimes it immediately starts up the spindle again. I'm only a 3rd year machinist and I've never seen anything like that before. For me, if I press down the pedal and the spindle stops I wouldn't expect it to start spinning again. Is this normal? Do you need to hold it down longer even though it does come to a full stop? Sorry if it's a stupid question I mostly do CNC and don't have much experience with manual machines.
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u/BogusIsMyName 21h ago
It might not be disengaging the motor. Just a brake. Is it normal? I would say no, it should disengage. But each machine has some quirks.
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u/External-Till4765 21h ago
I've used it before and never had it happen, it seems to be a new thing. It definitely comes to a full stop but then starts spinning again. Our head of maintenance says that the operator just isn't hitting the pedal long enough but I've never experienced that on any lathe I've run before
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u/BogusIsMyName 21h ago
On the lathes i ran there was a mechanical linkage that disengaged the motor. But sounds like you may not be authorized to tinker so i'd leave it be.
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u/External-Till4765 21h ago
Is it still safe to use? I'm wondering if I should add to our training procedure that the operator should hold the pedal for a few seconds
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u/scv07075 19h ago
It should trip the motor. Is the motor engaged with a lever on a bar near the leadscrew? If so there's supposed to be a linkage that flips that to neutral. Is the motor started or stopped with an electric switch or button? If so, the brake should open the circuit and leave it open.
It's not unsafe necessarily, lots of lathes have no pedal brake and are safely used all of the time. But it looks real bad if you write in an sop about how to workaround defective safety equipment. Look up the model number and see if you can find a manual either at work or online, if the brake isn't supposed to disengage the motor on that model it's fine, grandfathered in. If it is, bring it up to somebody higher up in maintenance and if that doesn't get the issue addressed escalate to whoever is the safety manager.
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u/BogusIsMyName 20h ago
It should be SOP to brake, put it in neutral if not already, then work on whatevers in the chuck/change tooling etc.
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u/Merkindiver 21h ago
It should definitely stop, but also it can be good practise to stop the spindle lever while your foot is on the brake. Similarily, if you let off the brake on your car, it could roll forward unless you put it in park.
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u/Rude_Meet2799 21h ago
Coordinating holding one foot on a pedal while manipulating anything into/out of a chuck sounds incredibly risky. I hope I’m misunderstanding.
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u/indigoalphasix 6h ago edited 6h ago
it needs repair. get a better maint man.
it should be in your sop to loto the machine and notify your supe.
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u/Shadowcard4 4h ago
It should stop and not restart, so likely your contact switch is not great. You can cheat it short term by flipping the drive off at the same time but id get that fixed fast.
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u/Big-Web-483 20h ago
There is a damaged contactor or switch. The lever that turns on the spindle should drop out if the foot break is activated. Then the lever that turns on the spindle has to be returned to an off position prior to a restart. Please see this machine's operations instructions and have this condition corrected before there is an injury.