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View Full Version : Hafpos HM52 vertical motor problems



bob ward
16th Apr 2017, 09:34 PM
PART 1
I have a 10yo Hafpos 240V vertical/horizontal mill, the vertical 1.5kw cap start cap run motor is causing concern.

Recently the vertical spindle decided not to cooperate when I switched it on, it would turn maybe a quarter turn and that was it. The motor hummed as per usual, there was nothing loud or unusual about the hum. For the heck of it I tried to run it anti-clockwise and it worked, yay! Turned the switch to clockwise and it worked, double yay, I'm back in business. That start up system worked for a few days and then inevitably the vertical spindle decided not to work in either direction.

I replaced the 35uf start cap. I tested the new cap prior to fitting and it showed 35uf, the removed cap was down to 15uf. So now the mill starts but I'm thinking there is still a problem lurking. When it starts, the spindle makes a couple of slow turns and then goes to full speed, before these problems the spindle, like my similarly motored lathe, always went instantly to full speed.

Is there anything I can fiddle with or should I just bite the bullet and go buy a new motor.

PART 2
I have 3ph at the shed, the thought is that as a step towards putting a vfd speed control on the vertical spindle I should replace the single phase motor with a 3 phase motor. Redoing the wiring is beyond my skills, but so that I can talk intelligently to a sparky I'd like to know in general terms what is involved in hooking up the 3 phase motor but still have everything (vertical 3ph motor, horizontal 1ph motor, light, pump, E stop) work through the existing switches. I'll worry about the vfd later on, I just want to do a fairly seamless motor swap at the moment.

Michael G
16th Apr 2017, 09:38 PM
What are the bearings like on the motor and also the spindle (est with the belt slack)? Are one or more bearings stuffed and so causing the 'slow turns' thing?

Michael

bob ward
17th Apr 2017, 08:42 PM
Thanks for the thought, I've removed the belts and turned the motor shaft by hand, it feels just fine. Spindle and idler bearings are similarly good. When I turn on the unbelted motor it does a couple of slow turns before hitting top speed.

eskimo
7th May 2017, 09:43 PM
Sounds like you could have a "dry" joint. Ie a wiring connection not making good contact.

malb
8th May 2017, 08:53 PM
If the start cap has been replaced already, as indicated, I would suspect the the contacts on the centrifugal switch might be burned and adding a significant voltage drop in the start winding circuit. This would fit with Eskimo's thoughts about poor contact. I would also maybe check through the contacts of the FWD/REV switch for similar problems.

Re moving to 3 phase switchgear, there would be a bit involved, as you would need to add 3phase contactors for forward and reverse operation, although these items could be controlled by the original switchs. In terms of connections etc, you would need five wire cabling and connectors (L1, L2, L3, N, E) to give you 3ph for the new motor (L1, L2, L3, E), and single phase (any L, N, E) to the existing single phase and low voltage circuits.

jhovel
8th May 2017, 10:16 PM
My previous drill press motor behaved just as you describe. All electric contacts proved to be good, but the centrifugal mechanicals were dry and didn't flick in properly until they got the jolt from the armature vibrating on the run windings. The start windings would then be switched on and off it went. Check that your centrifugal mechanical all move smoothly while you check the contacts in there.

Re 3-phase conversion: make sure the sparky you talk to actually knows about motor connections, i.e. not a domestic wiring sparky. He would have learnt all about it at trade school and never given it another thought since. Then let him know about your future plans for VFD. The wiring for the switchgear then will be completely different. Might be a lot cheaper to go straight to VFD. Get a price for either wiring!