[300sniper]

i was writing a program yesterday and heard a beep and noticed that the emergency mode was active. it said a limit switch had been hit. the machine was not even moving and was near the middle of it's travel. today the same thing happened a few times.

has any one had this happen or have any ideas as to what's going on?

[TT350]

I had a faults limit in the middle of a job one time.
Had made four or five parts and it decides to do this.

Posted the Q on a few boards and made a few calls
but no one had a real answer.

[300sniper]

i had it limit one time in the middle of a job and it turned out that chips had built up enough under that stainless cover over the x axis limit switch to trip it. i learned to keep an eye on that and keep it clean.

now it is tripping when the machine isn't even moving and i have no idea what axis it thinks it is.

[MichaelHenry]

I've also had false limit switch trips, but they only started after the main control board was replaced. Tormach suggested that I might have disturbed the wiring when replacing the board, causing some random noise pickup, and that re-arranging the wires might resolve the issue. It got a lot better after I did that but still false trips every few days, fortunately only when the mill is powered up but idle so no jobs have been affected.

Tormach also suggested that reversing the action of the limit switches might help and I'll probably try that if the problem continues or gets much worse.

Mike

On Edit - for some reason this message is being posted with all Caps changed to lower case. Wierd.

[Chincia]

I has something similar. Wound up having the VFD board replaced. One thing stood out when I was removing the board - Several of the terminal screws were not tight. I wound up tightening all terminal screws & about 1/4 of them were loose. If Tormach thinks it is a noise issue fixable by rerouting wires, loose screws could do the same thing.

[apeman88]

Heard on new (4 digit serial) machines... these problems are fixed by "better grounding". If noise is the issue... I would try looping the limit switch signal wire on a ferrite filter. They are the round black rings that most monitors and high end cables would put on to reduce interference. You can them cheap at surplus stores.

[steve127]

I too had this problem. I called Tormach and they had a me ground my mill. Plus they said that the serial port from the back of the mill (the multi pin (11?) pins) might be to close to the frame, causing an arch, so I took a file and moved about a 1/2 inch of material off the body of the mill.
Also I had a vacum hose attached to the head of the mill to suck all the chips off the table and I think it caused ALOT of static and caused the computer to freak out. So I removed the vacum. Any way I have not had the problem since. Except when I am drilling I will get just one limit swich call, I refernce everything and then I have no more trouble. But if that is the only time I get it I am happy
Steve

[300sniper]

I too had this problem. I called Tormach and they had a me ground my mill. Plus they said that the serial port from the back of the mill (the multi pin (11?) pins) might be to close to the frame, causing an arch, so I took a file and moved about a 1/2 inch of material off the body of the mill.
Also I had a vacum hose attached to the head of the mill to suck all the chips off the table and I think it caused ALOT of static and caused the computer to freak out. So I removed the vacum. Any way I have not had the problem since. Except when I am drilling I will get just one limit swich call, I refernce everything and then I have no more trouble. But if that is the only time I get it I am happy
Steve

thanks.

i have not had a chance to contact them about that yet but it sounds like you have the answer.

[Tormach]

There are conventional sources for false limit switch indications. This can be a loose wire or flakey switch. These are usually pretty easy to find.

We have also seen incidents where the PC has become overly sensitive. The shop vac example is a classic. I/O on electronics, such as the printer port, is normally protected by diodes. A severe stress, such as a static shock or nearby electrical strike, can leave the diodes blown and the computer very sensitive to spurious inputs. It works, but it's not reliable.

We have found that a EMI ferrite will often help. It should be snapped on at the computer end of the cable. If any Tormach owner has this problem, please contact Tormach and ask for PN 30749, EMI Suppressor. The ferrite is tuned to a 100-150 mhz range. Higher frequency (225 mhz) supressors are not effective, and lower frequency (75 mhz) work, but are not as effective. We have also found that adding a second IEEE 1284 cable in series has a very similar filtering function and works as well as the ferrite core.

G. Jackson