X-2 Mill Question

[75Plus]

My X-2 mill has developed a hum while in the idle state. It does not always do this but it has gotten to the point that it occurs more than 50% of the time. There is definitely a voltage going to the motor as turning the spindle by hand changes the level of hum. There is also slightly more resistance when turning the spindle anti clockwise. When the stop button is latched the spindle drag, from the magnets in the motor, is about the same in both directions.

I have checked the board for obvious problems, i.e. bad soldering or loose connections, and found nothing. I just thought that I would ask the group if anyone had had this problem and how was it resolved?

The hum is not very loud and as far as I can tell not detrimental to the machine but it is an irritant that I would like to eliminate.

Joe

[Bluechip]

Joe

Not sure what you mean by 'idle state'. On my mill. if I turn the speed control back to zero, the spindle rotates very slowly but with pretty much zero torque. So, it should be off, 'cos it ain't any use at that speed.

It may be normal for a PWM motor drive. The pulses going to the motor are not long enough to move the motor, but you can hear it trying to respond.

Dave BC

[raynerd]

Joe

My X2 has always hummed when off. It goes a little quiter when I hit the cut off switch but it is definately still there even then. Like you, the hum level changes if I rotate the spindle by hand when off.

You have concerned me thinking that your hasn`t always hummed - should mine not be?!?!    
Chris

EDIT: I presume "idle state" you mean when the motor speed controller is turned around to off.

[Stilldrillin]

Joe,

My Chester Conquest lathe does the same thing, and the chuck creeps, occasionally.....

My Chester Conquest mill doesn`t, yet.......

The lathe is some 4yrs older than the mill. I put it down to wear in the speed controller knob thingie..... 

David D

[Darren]

My 7x12 lathe does it, but it didn't used to 

[John Rudd]

Chances are that the 'zero' setting pot needs a tweak....

If its the KBIC controller board then adjusting R3 marked MIN is the minimum speed setting pot

Can you post up a piccy of the board and I'll try and identify which controller you have......

[75Plus]

Thanks for the replies. It seems that this is a common occurrence. I do not believe, however that the motor should creep when the pot is in the OFF (idle) position. I can see safety problems arising from this.

JR the board is a Sieg 350BJ, third (latest) edition. I have only had the mill a couple of months and I had to wait for the boat load to come in before I got it so it is a recently made unit I would think.

My purpose in posting the question was to prevent me from re-inventing the wheel so to speak should someone have a solution. Since this seems to be a fairly common problem I will pull out the test equipment and track down the problem for myself and others that might be interested. I have the tools and a bit of experience in electronics. Worked on two-way radios for years.

Stay tuned.

Joe

[John Rudd]

Joe,

I've added a picture of what I think is your board......



The speed control adjustment pot is second from the top cirlced in red....Adjust it slightly one way or the other to eliminate the buzz...

[75Plus]

John R, That is my board. The speed pot changes the max voltage thus the max speed but it has little or no effect on the hum.

I have been putting together some voltage and current readings while the hum is not present. I will retest when the hum comes back to see if I can narrow this down. BTW, I am using a Fluke 75 DVM which was recently inspected for calibration.

Joe

[John Rudd]

Joe,

I've emailed you a pdf of the board...

Hope it helps 

[75Plus]

Joe,

I've emailed you a pdf of the board...

Hope it helps 

Got it! Thanks John, It should be very helpful.

Joe