|Stephen Ward 6||21/12/2014 15:36:25|
|7 forum posts|
I had thought that the capacitor could be the problem as it is quite an old
|Neil Wyatt||21/12/2014 15:43:20|
19076 forum posts
My 1/3 Hp Hoover motor has a centrifugal switch that connect the starting winding (and the capacitor). Those symptoms sound like the switch sticking open.
|john fletcher 1||21/12/2014 16:59:28|
|805 forum posts|
The start circuit is open circuit an Neil says, and the weak point is the centrifugal switch. Capacitors are pretty reliable, never the less the do fail. If you have an old fluorescent light capacitor you could try a substitution initially. You could get your friendly electrician with his 500 DC insulation tester to care out a rudimentary test on your capacitor before removing the motor from the lathe.If you do have to take the motor to pieces you will find the switch is at the no drive end, so its a complete strip down. Mark both end of the motor using a scriber and steel rule two lines one end and one the other. These lines are to help with alignment when you re assemble the motor. with a bit of care you might be able to take out the through bolts and just ease out the drive end shield and rotor. The centrifugal switch actuating bits are attached to the rotor, they fly out due to centrifugal force against spring tension as the rotor speeds up. The assembly should be free to move, don't oil them. You will see the actual switch which is attached to the end shield, it might not be obvious how the thing works, the contacts might need a clean up with a bit of fine wet & dry,not too vigorous. As your motor is quite old so be careful with the wire insulation. It might be a good idea to get an electrician to give the motor an insulation test. When replacing the motor ensure you a have good sound earth, to the lathe and motor.Ted
|Speedy Builder5||21/12/2014 18:32:25|
|2644 forum posts|
I have a similar problem with 3/4 Hp on my home made circular saw. Its laziness to the extreme. To get it to start, I 'tap' it with a hammer, then switch it on - works most times. As John says. I expect it is the centrifugal start switch. Mine is probably clogged with sawdust - waiting for a nice hot spark to set it alight!! This Christmas week I must strip it down and clean it, its probable that the contacts need cleaning at the same time.
|Tony Simons||21/12/2014 18:54:48|
|37 forum posts|
You can normally hear the centrifugal switch click as the motor slows down. I have cured them temporally by squirting WD40 in there, either through the vents if its a vented motor or by gently separating the cover from the body to insert the WD40 straw. No substitute for stripping and cleaning though.
Edited By Tony Simons on 21/12/2014 18:55:36
|Stephen Ward 6||22/12/2014 12:34:57|
|7 forum posts|
Guys thanks for your comments looks like I will be stripping it down over the Christmas break. The capacitor shows no obvious sign of damage so looks like it the switch.
Thanks again and have a great Christmas. Regards Stephen
|304 forum posts|
|I seem to remember there was a previous post regarding a Hoover motor with perished rubber interior wiring so a rewire job may be on the cards as well to keep it safe !|
|3089 forum posts|
I had the same problem with my belt and disc sander, I had to give it a shove or even a few revolutions to start it. In the end it wouldn't start at all. A replacement Capacitor sorted the problem, the "ectoplasm" had leaked out of the old one by the look of it. Maplins had a suitable replacement.
|Speedy Builder5||23/12/2014 14:26:07|
|2644 forum posts|
All good advice above. Seems stupid, but do disconnect from the power supply (Don't just trust to it being switched off).
Now mark the position of the end covers in relation to the frame.Unscrew the long bolts that hold the covers on - in this photo there are 4 of them. Remove the end cover at the junction box end - it may be stiff as you are pulling the bearing out of its housing. Be careful of the wires which will be attached to the switch plate attached to the cover which go to the field coils and capacitor.
Unscrew the switch plate from the cover. In this photo, the switch contacts are just by my left finger. Clean these contacts with a bit of fine wet and dry. You may be able to 'spring' the contacts apart to make life easier.
Edited By Speedy Builder5 on 23/12/2014 14:28:50
|Stephen Ward 6||26/12/2014 21:34:27|
|7 forum posts|
Thanks for those pics, always helpful.
Please login to post a reply.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
Sign up to our newsletter and get a free digital issue.
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.