Thread: Lathe Issue Question

Originally Posted by azzrock

nice post malb. that would of taken me a long time to type

About 20mins and 5 more to proof read and fix. At my high school 45 years ago, boys got woodworking and metalworking, girls got home eco and typing. One boy managed to swap MW for typing, and to my shame was soundly stirred for the entire year. He went into the local bank at 16 and was a manager at 30.

Twenty years later, guess who was charged with introducing PC's into admin and student labs for a Faculty (4 departments, 32 different courses) in a Melbourne uni, but had to teach himself to type so he could learn about hardware and software and start writing training manuals. Have managed to get to 2 hands and 4 fingers, but slow as. Only good thing is that I can now type almost as fast as I can form sentences, (major brain fade due to the effects of successive illnesses over the last 10 years).

It sounds like the start capacitor has died. If it is a Cap start, Cap run motor(two capacitors) and the start cap had died(open circuit) the motor will still start with little or no load but may struggle to get away by itself if there is significant load. I'd have to think about it for a bit but I think you would see the same symptoms if the run cap was open circuit as well. Hmmm.. more likely to be the start cap as the run cap is a much lower value and the motor would struggle to start with it on its own. If the run cap is open circuit the motor would work like a cap start motor but the windings may be not optimised for that arrangement and poor performance would result.. sorry, lot of ifs and maybes in there but I was thinking out loud. Start Cap is my diagnosis.

Originally Posted by NCArcher

If it is a Cap start, Cap run motor(two capacitors) and the start cap had died(open circuit) the motor will still start with little or no load but may struggle to get away by itself

At least on the motor I removed the start cap from(cant get any more open circuit than that lol), it wouldnt start be itself and the only "load" was a disc rotor used as a lap........ Maybe the run cap is dead as well???

Stuart

Originally Posted by malb

About 20mins and 5 more to proof read and fix. At my high school 45 years ago, boys got woodworking and metalworking, girls got home eco and typing. One boy managed to swap MW for typing, and to my shame was soundly stirred for the entire year. He went into the local bank at 16 and was a manager at 30.

Twenty years later, guess who was charged with introducing PC's into admin and student labs for a Faculty (4 departments, 32 different courses) in a Melbourne uni, but had to teach himself to type so he could learn about hardware and software and start writing training manuals. Have managed to get to 2 hands and 4 fingers, but slow as. Only good thing is that I can now type almost as fast as I can form sentences, (major brain fade due to the effects of successive illnesses over the last 10 years).

ok well its one thing to type well but the post was informative and well written.

does the motor bearing have grease nipples.

Hi Guys, here are some pics, the "AC Contactors" look cooked, but seem functional. I think the "Heating Device Relay" might be the problem (JR16B-20/3 11A). I can get 1500 RPM which is top speed at all, even spinning the chuck by hand wont start it and it is this "Heating device relay" that is tripping. I suppose I'll just order another one and try to swap it over. Anyone know if you can just buy this stuff from JR Turk or some other electrical wholesaler?

Cheers

Aren't you talking about replacing the part that is working?

Stuart

What do you consider is not working?

Originally Posted by tbonesmith

What do you consider is not working?

Well your lathe. But (I guess) the overload is working.

Whats in the box on the top of the cabinet?

Something that I haven't seen anyone ask, is it still a 240V single phase motor? it looks at little "3 phase"y in the pictures but I'm far from sure in either direction.

Stuart

It's single phase. The box on top is a solenoid. It looks like it was in the (electrical) box on the right initially.

hmm I wonder whats its doing up there. There isn't a transformer in there as well?(although I do recall hearing that Hare and Forbes lathes use 240V on the controls???)


Did your sparky mate have a look at the caps yet? (can you see any caps?)

Stuart

Can't see the caps, where would they be? Sorry it's not a solenoid it's a transformer.

Yeah, my sparky neighbour had a brief look and was no help.."... I don't know much about machines.."

Would a regular electrician, be the person to sort this out?

Your sparky mate doesn't seem too interested! I thought single phase motor electrics were a pretty basic thing for a sparky to look at. He could at least have looked at your caps. They are usually attached to the motor, usually inside a metal or plastic case on the outside of the motor.


Simon

Your sparky mate doesn't seem too interested! I thought single phase motor electrics were a pretty basic thing for a sparky to look at. He could at least have looked at your caps. They are usually attached to the motor, usually inside a metal or plastic case on the outside of the motor.

Like the round thing hanging off this motor....


Simon

Originally Posted by tbonesmith

Hi Guys, here are some pics, the "AC Contactors" look cooked, but seem functional. I think the "Heating Device Relay" might be the problem (JR16B-20/3 11A). I can get 1500 RPM which is top speed at all, even spinning the chuck by hand wont start it and it is this "Heating device relay" that is tripping. I suppose I'll just order another one and try to swap it over. Anyone know if you can just buy this stuff from JR Turk or some other electrical wholesaler?

Cheers

Working from my small netbook at the moment so even if I download the pics to view, they are too small for me to pick out detail.

But from above, AC contactors are working but could have burnt contacts etc if they appear cooked, hard to tell. If they weren't working, there would not be power to the motor at any speed selection.

I assume the 'Heating Device Relay' is a thermal or overcurrent protection device. It's function is to monitor the motor current and isolate the motor if it is overloaded. If the motor can operate at some speeds, and the device trips at high speed setting, it appears to operate correctly though again calibration and/or contact condition may be questionable.

Faulty motor capacitors causing starting issues would cause the motor to draw excessive current as it is effectively stalled and this should trip the protection device.

From the pics, three multipole boxes there, one contactor, one thermal/overcurrent detector, whats the third one doing?. By any chance is the motor a two speed motor (switchable 1440/2850RPM) with seperate contactors for each speed range, i.e on the control panel is there provision for switching the motor to high and low speeds. If so, there is a possibility that the motor windings have a fault at the high speed setting only. Still possible that the issue is caps though.