Sudden stop

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zerotact

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I have a H.F. 7 X 10--it`s in good condition and works well, however im doing some pretty tough stuff with it because I have to. I have no other way to do what I need to. I am building a Front loader for a Cub Cadet garden tractor and im making all the bushings and pins on this little lathe. I know--get a bigger lathe--I am looking for one I can afford. I am retired and have to be careful about how much I can spend on what. I probably have 30 thousand worth of tools, but they were accumulated over 40 years in the trades. Random tool buying kind of stops when you cant work anymore. So im making a die holder to thread a 5/8-11 taper bolt and the machine starts --like -whining --not bad, but I never heard this before, so I stop the lathe to check the gears. There was no visible damage, and very little chip fragments in the gear area. i cleaned out the area and started the lathe, and ran at low--RPM while watching the gears--also, no signs of problems, so I sprayed a little lubricant on the gears to see if the sound abated--No--I stopped the lathe to reverse the motor to listen to it in reverse--I switched the lever in the back down to the reverse position and pushed the start switch---and--Nothing--I thought--what-?--so I put it back in Forward and pushed to start it again--and--Nothing again--now im getting worried. What could have happened between stopping and restarting the lathe and how could it have anything to do with switching to reverse. I then checked the fuse to see if it blew. It checked good with a DVOM, but I checked further with meter to follow the AC path. I had ac voltage from L1 in From power cord to L1 terminal --through power on switch--to-Fuse--through to other side of fuse, and had ac voltage all through to- PCB- terminal. Tried lathe again--Nothing-. Detached -DC-outs to motor--from terminal block switch and fed-12 v dc from a car battery directly to motor and it fired right up and ran fine--slow--but fine. So now im Lost. Sorry about the Long dissertation but ive always thought in life--More information is better. Any Help would be greatly appreciated . Greg---aka--zerotact
 
You have isolated your problem to the circuit board. Without a schematic, it is hard to say definitively what failed but usual suspects are in the power circuit rather than the control circuit. Check the rectifiers and output transistors. Wth a little detective work, you should be able to narrow the problem.

If you have a schematic, it would help us help you.
 
yes , figured I would have to trouble shoot the PC board--now--but that was not the original problem--I stopped to check a noise on the machine, and the lathe was running ok, but when I switched the Drive from forward to reverse and then restarted-- the lathe would not start--what could changing the drive direction have to do with the Lathe now not working at all-?
 
There's a guy who specializes in repairing those boards- www.olduhfguy.com
I think his name is Pete and it's a flat rate of 50$ (or used to be)
Mark
 
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Starting and stopping create some of the greatest stresses for electrical circuits. Particularly, if you reversed the motor while it was still running, a large back emf would be created. Mosfet transistors are particularly susceptible to transients. There is snubbing circuitry to absorb the transients but it can only do so much.

Since you were able to run the motor on a battery, the problem with no run is the control board. You will have to sort that out before moving on to the noise problem.
 
zerotact said:
yes , figured I would have to trouble shoot the PC board--now--but that was not the original problem--I stopped to check a noise on the machine, and the lathe was running ok, but when I switched the Drive from forward to reverse and then restarted-- the lathe would not start--what could changing the drive direction have to do with the Lathe now not working at all-?
Click to expand...

It doesn't have to be related, but running any circuit at maximum output can fry it. Especially if it was built marginal in the first place. Old UHF Guy has troubleshooting on his website and seems to have quick turn around at a good price.

John
 
Used KB controllers on ebay are far superior to the oem units. Just buy the appropriate resistor.

www.ebay.com

KB Electric KBLC-240DS (3375D) 87VDC DC Motor Speed Control Controller 115VAC | eBay

<p>KB Electric KBLC-240DS (3375D) 87VDC DC Motor Speed Control Controller 115VAC. </p><br><p>More information</p><br><p>-Input voltage: 115VAC / 230VAC</p><p>-Output Voltage: 0-87VDC</p><p>-Output Amperage: 6amps</p><br><p>Good working drive. Includes speed pot and 3/4HP resistor.</p>
www.ebay.com
 
Firstram said:
Used KB controllers on ebay are far superior to the oem units. Just buy the appropriate resistor.

www.ebay.com

KB Electric KBLC-240DS (3375D) 87VDC DC Motor Speed Control Controller 115VAC | eBay

<p>KB Electric KBLC-240DS (3375D) 87VDC DC Motor Speed Control Controller 115VAC. </p><br><p>More information</p><br><p>-Input voltage: 115VAC / 230VAC</p><p>-Output Voltage: 0-87VDC</p><p>-Output Amperage: 6amps</p><br><p>Good working drive. Includes speed pot and 3/4HP resistor.</p>
www.ebay.com
Click to expand...

Yeah, why just repair a tool when you can upgrade....

Next step CNC conversion;)
 
The noise problem is more than likely the plastic gears in the headstock. If you need to replace them replace the gear on the spindle with a steel one. When they break again you can replace the plastic one on the jackshaft without removing the spindle. They sell steel gears for both but they are noisy. It's also a good idea to leave one plastic gear in place to act a weak point to protect the rest of the drivetrain.
 
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