My lathe is aknockin

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Jim Burr said:
Hmmmm...piece of debris stuck in the motor housing? That tick would be more random...but maybe?
Found this on SMC...might help?

Troubleshooting a lathe noise - Jet 1642
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Good info but he had the problem with the belts on.

Your suggestion (debris in the motor housing) is a possibility but I agree it would probably be more random. This is a constant ticking sound which occurs more frequently as speed is increased.
 
Rotate the motor by hand and see if there is any roughness or slight catches in the rotation. It may be a bearing in the motor, which might not be that hard to replace depending on the design.
 
larryc said:
Gary Beasley said:
Rotate the motor by hand and see if there is any roughness or slight catches in the rotation. It may be a bearing in the motor, which might not be that hard to replace depending on the design.
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Good idea.

Took the belt off and just tried that and couldn't feel or hear anything.
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Next thing is do the same with the headstock then do a thorough inspection of the belt looking for imbedded debris or shredded edges.
 
you can run the motor without the belt on.. and if the bearing is REALLY bad you might hear it, but without the side load of the belt I doubt it would show up. I would be inclined to think it was in the headstock instead as the motor is probably running at 1725 or 3450 rpm and you say you can hear it in conjuction to the turning of the lathe itself. If it is in the motor, I would try blowing it out with DRY air first, then if that does not work, pull the end bell off on the shaft end. Depending on the motor type sometimes there is a lot of things attached at the opposite end. There may be a start switch on the end opposite the shaft that is bad, or a bearing itself. While the motor is together.. and turned off.. try putting pressure side to side on the shaft end. You should not feel much movement. end play is typical.. but side play is bad. If you have never taken a motor apart I am sure there are You Tubes on how to do it, or if you need help PM me. I have been an electrician for 40 years and have no idea how many I have taken apart. One hint if you are going to take it apart yourself is to take a sharpie and make a series of marks on the motor extending across the end bell, like when you are making sure you reference the two halves of a blank together, but do it more than one place around the outside of the motor. It makes reassembly MUCH MUCH easier.
 
sorry I got confused there for a minute. Knocking noise in the motor without any belts attached I would guess would probably be either something inside it, but normally if it is wood it will soon be demolished inside a motor. Can you take a picture of the motor and post it? I am just curious about what type of motor it is. If it is a capacitor start motor on the end opposite the pulley there will be a starting switch. That is what caused the capacitor to be in the circuit or not. I have seen the contacts go bad, as there are typically a set of two and if one is not working correctly it can cause noise. I have also seen something as simple as a wire inside touching the the shaft of the motor and making noise. You would think that it would wear in two, but the insulation is pretty tough.

I would check for side play before you disassemble it though. It can be tough to feel if it is just starting to go bad, but what I do is get the motor free where I can place it on the floor and put a knee on it and try lifting the shaft up and down. it should have no slop. If the bearing are really bad sometimes you can actually hear the slop in them. If that is the case you can change the bearings yourself, but it can be involved. It is not difficult, but I know some times people are weary about doing that kind of work. I found this you tube on changing bearings which is OK, but not perfect. But it will give you an idea if you want to tackle it or not. replaced bearing for electrical motor.wmv - YouTube Bearings have a number on them. It is typically very small around the seal of the bearing. You can buy most bearings online using those numbers.
 
wyone said:
I am just curious about what type of motor it is.
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The Jet 1642 1-12 HP lathe uses a 230 volt 3 phase motor that is powered by an inverter that runs on 110VAC single phase.

I would probably not tackle any repairs on this motor myself since my bum shoulder would not tolerate the strength it would take to horse this thing around.
 
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Hey: Wyone.

You may be a newbie... but your comments and suggestions are a hint of your knowledge and skills!!! You go guy! I'll be reading as I have the same lathe!
 
Awww see that brings a whole other set of things. a three phase motor is simple inside. It only has the windings and the stator. Typically not a lot of other parts like start windings. But the inverter can have issues. I am not familiar with the particular inverter that is used, but I can tell you that a lot of the inverters read the amperage all the time and if the sense a change in amperage can adjust the speed to keep it consistant. If that is the case, I am thinking you could have a wiring connection issue, such as a loose wirenut, terminal or whatever method they use for connections and the electronics are trying to adjust for that.

I have to say, what I would most likely do as you seem to have done so much troubleshooting already, is to check all connections, and if they are good, make a call to Jet Tech Support.

Knowing you have a 3 phase motor, it is not nearly as likely that you have a bearing issue. Three phase motors are just built better typically.

Sorry I was not more help. if you were lived in the area I would offer to stop over and help you troubleshoot some more, but thinking, GA to CO is a bit far. LOL
 
OK so I did a bit of research on your particular lathe and found this forum. I am not sure how old your lathe is, but it appears that the motor has a 5 year warranty and that model has had issues with the motors. My first thought regarding the motor after seeing it is something really simple like something in the end bell of the motor. The way it hangs off the headstock makes me suspect on that. Looking at the picture of the lathe, my guess is that there are three, maybe 4 screws that will remove just the outer shield that covers the fan blade on the end opposite the shaft of the motor. I would probably pull that apart, but thinking, if your motor is less than 5 years old I would make the call to jet before I did anything else. I would hate to have you mess up a warranty trying to solve the problem.

Oh.. and by the way... I am jealous.. I want that lathe!! :)
 
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