Electrical problem bad vibration

[Duneracer]

New to the home machinist good day everybody. My problem I bought a Logan 12 inch to replace my Logan 9 inch I think . I have not been able to use the Logan 12 inch due to an electrical problem I first cleaned up thr bearings and drives new belts replace a 1 hp Dayton 5k921 with a North American electric f56ch2s4c same rpm and shaft size 2hp the Dayton motor was struggling to start I cleaned up the starter change the capacitor still problems new motor has a bad vibration took to an electrical shop to check out the motor and wiring all check out good no vibration back home hooked backup it ran for a few minutes made a couple cuts stopped the motor set up for another cut and had a bad vibration took off the belt the same vibration took the motor out same vibration so I checked out the switch cutler hammer 0 cleaned all contacts same problem I also checked all wiring and connections all are good also checked out the plug is new and good checked power at the wall good power to the motor is 250 volts . Any suggestions ? Thanks steve also cold or warm does not make a difference

[John Evans]

If the motor is out and it vibrates is that with the pulley removed??? If so it has to be the motor. Put the 1HP motor back in if everything worked OK with it as a test to confirm that cures the vib problem . A vibration is a mechanical issue NOT electric ! If motor on bench runs with pulley removed and no vibration either the pulley or motor mounting is suspect.

[Steggy]

As John noted, vibration is a mechanical issue, not an electrical one. Due to the way in which squirrel cage motor armatures are made, the likely culprits are: 1) centrifugal switch; 2) loose "winding" in the armature; 3) delamination of the armature. Problem 1 may be repairable, problems 2 and 3 would require the services of a motor shop. Replacement in the latter case would be less costly than repair.

[Duneracer]

I took the motor and wiring had the motor check out the shop is a motor electrical shop why because the noise and vibration I thought I hurt the new motor it all checked out ok no noise no vibrationwhen benched checked checked out ok . the pulley was one of the first thing I did remove i thought it may be out of balance the Dayton motor that I replaced made noise when it ran I also was able to stop the rotation of the spindle with my hand so I don’t think is dependable. Is it possible that the cutler hammer 0 is to small for a two hp motor wired 220 single phase

[John Evans]

One more time ,the vibration is not caused by the electric supply ,switch-cord size etc. You have confirmed the motor is receiving 220 volts AT the motor ? Stopping the spindle by hand makes me think you are only getting 110-120 volts to the motor. Wiring a drum/reversing switch for single phase is a bit tricky ,beyond my pay grade,I call on my pro electrician friend for that work.

[GlennW]

Dunno nuthin' about Logans, but if it has rolling element bearings it sounds like the pre-load on the spindle bearings is too tight and the start circuit on the motor is kicking in and out.

[John Hasler]

I took the motor and wiring had the motor check out the shop is a motor electrical shop why because the noise and vibration I thought I hurt the new motor it all checked out ok no noise no vibrationwhen benched checked checked out ok . the pulley was one of the first thing I did remove i thought it may be out of balance the Dayton motor that I replaced made noise when it ran I also was able to stop the rotation of the spindle with my hand so I don’t think is dependable. Is it possible that the cutler hammer 0 is to small for a two hp motor wired 220 single phase

The switch is not the problem. I strongly suspect that your vibration comes from an entirely mechanical problem unrelated to the motor. Can you rotate the spindle easily by hand with the belt off the motor and the back gear disengaged?

[Duneracer]

Please let’s don’t debate electrical or mechanical it’s a description of my problem. John I rebuilt the spindle new belts rebuilt the variable drive shafts and bearings it is a-line perfect and when testing all was lose so there was no load on the motor final adjustment on the belts where not done . with the noise and vibration took off the belts and pulley the problem is the same . Thank for your time John

[spro]

It would be normal to say that you didn't bring the drum switch, when you had the motor tested. The 2hp ran okay at their bench- right ?
There are case grounds and there are neutrals (which are not neutral, for they carry current). If case ground maybe got mixed up at the machine, it would pull current through the machine chassis. I would take some voltage checks before and during a run.
This would account for one coil being shorted/low power/ humming and why the switch was mentioned earlier. With 110 v the neutral carries current back from the supply and it is all ground, at That point. With 220 v the power is between the two phases and there is still an insulated "neutral" which is used to convey power from and back to the supply, for one coil or both. This isn't case ground.

[Duneracer]

Yes I did i took the cord that plugs in the wall, junction box cutler hammer 0 drum switch, wire and motor without the pulley I wanted a reputable electric motor company to check all , each wire is numbered at the drum switch and at the motor . I have 250 volts at the plug I have 250 volts to the junction box , 250 volts at the switch forward and reverse , and 250 at the motor , each wire has been checked from the junction box to the switch and to the motor with continuity test also I have used the wall socket to run a saw and a welder no problems . The drum switch is old I did rebuild it by cleaning each contact the motor is new in the box but it was built in China

[spro]

Well, Duneracer ...First thanks for understanding what I was trying to say. I was about to edit or delete the whole thing when my cp went black and shut down. That was it. I expected to have been dismembered on return but that didn't happen yet.
Cutler Hammer is a really fine drum switch. Somewhere you said that you were able to grab the pulley and slow it down. I haven't tried that lately with 2 hp+ motors ( I think once was enough). It looks like you have double checked everything and it may be bad motor. Drum switches can be rather tight in the wiring department. Take a voltage reading across the unmounted drum switch case to the lathe chassis when it is live and when the motor is running. Be careful, it is an important check.

[ChipMaker4130]

It amuses me that so many of you have adamantly stated that motor vibration is always mechanical, never electrical. That, my friends, is simply not true. Single phase and three phase units each have a number of potential electrical problems which can cause rather high-intensity vibs.