[ranchak]

I have an 1986 Acromax MX-16 Mill with a 11M control, NO gearbox. Recently I have had a problem where the spindle is "stalling" intermittently in a cut. I use the word "stalling", but what is happening is the 0-10VDC signal is dropping out at the spindle amplifier. This is being measured between 0 VDC and pin 13 on the spindle amplifier. I can see the voltage drop while the machine is running, but ONLY while the tool is engaged in the workpiece. It happens with a shallow cut or a heavier cut. Sometimes running 15 IPM, sometimes at 7 IPM. The material I am cutting is .500 6061, 1/2 Niagara 37 degree end mill designed for aluminum. DOC varies from .085" to .270". The tool could be fully engaged or removing .050 on a finishing pass, doesn't matter it still will have the voltage drop out. If I cut air using the same program the machine runs flawlessly. Also I can jog the table violently while the spindle is running and I have no issues. One thing that I did try is I cut a different part and I had no issues. Might have been luck, I don't know. The only difference is the Z axis is cutting at about three inches higher than the part that I am experiencing problems with. This was a slot cut in 6061, .270 DOC, 3600RPM, 30 IPM, 2.5" total depth. Cut two slots like this experienced no problem. This is using the same G54 offset for the part, so I don't think it is related to table travel, although the cutter is not in the exact same tool path as when I experience the voltage drop. I had a service tech out and this is what we did:

Swapped out the spindle amplifier

Swapped out the feedback sensor cable

Checked both channels of the feedback sensor using an oscilloscope

Swapped out the I/O board

Swapped out the Main Board

Swapped out the PC cassette


None of these fixed the problem. One thing that I haven't done is changed out the power supply or the feedback sensor. Does anyone know what the gap setting is for the feedback sensor?


In the diagnostics we can see address Y0000.5 (this is the spindle run address) turn on and off. This coincides with the 0-10 VDC voltage dropping off. Looking at my ladder diagram we can not find address Y0000.5. Also my machine does not display the ladder at the monitor.I am hoping if someone can tell me what address Y000.5 relates to I might be able to find a faulty component that is cause the 0-10 VDC to drop out.

Sorry for the long post, but I wanted to give as much details as possible. My service tech pretty much has given up on my machine, I don't blame him, but I'm not quite ready to give up the fight. I've googled and can't find any post where someone has had the same or similar problem. Anybody have any ideas?

[tc429]

I dont have a book handy, but signal *sstp (will be a 'G' address) has to be a 1 to get analog out. Theres a block instruction in the ladder called 'spcnt' for spindle speed control- it may be outputting your 'Y' address directly. there is a parameter to turn off the ladder display on most controls...sorry dont have a book handy to look it up, but bet the *sstp is whats shutting it off...

[ranchak]

Thanks for the reply tc429, I found *sstp. It is address G011.5. I have a copy of my ladder that I can send to you by email. I can not find spcnt. Thanks, Ron

[ranchak]

I think I might have found the problem. There are two limit switches that are on the spindle lock cylinder. It looks like one of them may be faulty. I have two new ones on order and will replace them and see if that solves the problem.