Spindle speed slows down

[carlboe]

Hi

I have Tormach 1100 and it looses spindle speed. Here is the problem I have been running for about a hour and it will drop the spindle speed 200 rpm. the feed rate is 30 and the depth of cut .020 3/8 end mill spindle speed is 1200. I have not been running a hour strait 3or4 minutes between parts.

Thanks for the help
carlboe

[saabaero]

Is the spindle drive belt tight?

How do you know how many RPMs it is dropping? Have you put a tachometer on it?

[carlboe]

Yes I put a tachometer on it and belt is not that tight.

Thanks
Carlboe

[philbur]

Do you have the latest frequency converter (with LCD panel), if so have you looked to see if there is any corresponding change in frequency output. Apart for motor slippage due to load I thought that the motor speed should follow the frequency.

But what do I know.
Phil

Hi

I have Tormach 1100 and it looses spindle speed. Here is the problem I have been running for about a hour and it will drop the spindle speed 200 rpm. the feed rate is 30 and the depth of cut .020 3/8 end mill spindle speed is 1200. I have not been running a hour strait 3or4 minutes between parts.

Thanks for the help
carlboe

[TXFred]

I wonder if it's related to motor temperature.

Frederic

[bobeson]

I have also experienced a similar spindle speed problem, and in fact still do now and then. Tormach suggested that I wiggle all portions of the parallel port cable path going from the control computer all the way up to the machine control pcb. I found that wiggling just the parallel port ribbon cable connector at the machine control board seems to fix my issues, until they crop up again, days, weeks or months later. I need to get a replacement ribbon cable, as I'm fairly confident that is in fact the cause of my spindle-speed errors, which sound much like what you are experiencing.

[Wog]

+1
I had moved my Tormach about 1600 miles via the back of a Penske truck a couple of years ago. Ended up with several problems/glitches including speed control. Greg at Tormach suggested the same as Bobeson. I pulled and re-installed all the ribbon cables and haven't had a problem since. Hopefully, Carlboe, it's "just a loose wire".