Fadal Spindle speed (Odd) isssue

[Togeneral99]

Machine is a 1997 Fadal 15xt with the 88HS control and 7500 rpm spindle (Gentek inverter drive)

Machine has been running good and suddenly during a tool change the spindle speed (commanded 6100 rpm) was turning ~3700 rpm.

Multiple parts had been run prior to this happening so it’s not a programming issue.

Started to troubleshoot and put the machine in MDI and entered M3 S2400 (low speed range) and proceeded to use the spindle override knob to spin up above 4300 rpm. Then I type in M3 S3000 (high speed range) and I can run it up to ~3700 with the override knob but it won’t spin any faster. The display will show faster but the spindle stops accelerating (audibly noticeable).

The contactors seem to be moving correctly when changing speed ranges (one contactor - top one, looks to be newer as well). I’ve also pulled the motor cover and inspected the encoder (rigid tapping machine) and it had been replaced at some point and was very clean.

I’m at a loss and not sure what to look at next.

I’m leaning toward the spindle card (1010 card) being the issue but I’d like to make sure first before I drop several hundred bucks on a guess.

 

[Bobw]

That is a weird one.

Have you tried running the spindle from the spindle drive?
What is the spindle drive telling you?

If you don't get an answer here, I would definitely call ITS
tech support and ask what they think before you spend a bunch
of money.

Sitting here thinking.. You command a speed, the spindle control
card tells the spindle drive to spin that speed.. But then what?
You've got an encoder up top, I'm not sure what that talks to, and
you have the little magnet on top of the spindle, and that should talk
to the spindle control card...

Seems that something somewhere wouldn't be adding up, and it should throw
an error.

 

[Togeneral99]

Not 100% sure on what you mean by “running the spindle from the spindle drive”.

When I force it into low range and turn the override up the commanded spindle speed matched the rpm readout on the spindle drive. When I do the same thing in high range the rpm’s on the spindle drive don’t advance past 3700.

I’m thinking the encoder is only really used during rigid tapping but not 100% sure on that. I’m wanting to rule out the encoder because the machine operates correctly in the low speed range. If the encoder were the issue I’m thinking it would be across both speed ranges.

The contactors seem to be pulling in correctly and running a multimeter across the contacts when engaged shows low resistance across the contacts.

If it’s a “dumb” system and the encoder is only used for rigid tapping and the magnet is only used for spindle orientation then I don’t expect it would throw a fault. I’m leaning toward the issue being the spindle control card.

Really wish I could find a schematic for the board itself

 

[ZfMax]

I had similar issues on my 4020. Turned out to be the encoder. I disassembled it, cleaned it carefully, reassembled it, and it worked for awhile. But then it started acting up again, and I just replaced it. No more issues.

A couple of tips on replacing it. First, there's an upgrade encoder available that's sealed, so that presumably it won't get contaminated. ITS sells it under part number ENC-0004, you can see it here: Buy Fadal Resolvers and Encoders Online | ITSCNC.com . Although I could see how it physically mounts, the connector had no relationship to the connector on the machine, and no wiring information came with it at all, and ITS couldn't tell me the wire functions or how to wire it. So that was pretty annoying, and I just sent it back to them and got the ENC-0007 instead. The ENC-0007 is identical to the original and just plugs right in. It's also about a third the price. My first encoder worked fine for almost 20 years, so upgrading to a sealed unit doesn't seem like a big deal to me.

Second tip, the height of the little disc is incredibly critical. A nanoinch too high or too low results in erratic spindle operation. Fortunately, the ENC-0007 comes with the special tool needed to set the height.

Finally, if you haven't already, get a filter kit for your spindle fan. It'll make the encoder last longer because your fan won't be spraying so much coolant mist and crud into the encoder's environment.

Caveat on all this: I have the 10K spindle with high/low. I wasn't even aware there was a high/low on the 7500 spindle. Are you sure about that? You can hear it switching when you do an S.1, S.2, S.1, etc?

 

[Togeneral99]

The hi-low is the WYE/Delta, or star delta, waiting configuration.
You can hear the contactors switching when you switch speed ranges >2500 to <2501.

Surprisingly my encoder was spotless looking. Of course that doesn’t mean it couldn’t be bad. It’s just odd that the spindle works as expected in the low range (WYE or star configuration)

 

[Bobw]

Not 100% sure on what you mean by “running the spindle from the spindle drive”.

If you have the keypad to the spindle drive, you can run the spindle directly from
the back cabinet. Basically eliminating the spindle control card. I had an old
Mits that I could do it with, I have a Baldor I can do it with, and you can
do it with the Yaskawas.. Of course you have the Glentek, so...?

This is probably not your issue, but many moons ago I was playing with a new
to me yaskawa, and one of the functions on the spindle drive was to set whatever
parameters to the motor automatically.. That sounds like a good idea, so I did it,
and then my spindle speed was limited.

This was on a 10k 2speed. It wouldn't go over about 1200 in low, and 4k or so in high.
What happened was the spindle drive, doing its automatic thing had re-set the max frequency
it would run at to 60hz. Did the math, reset the max to whatever HZ, 140 or something
(it was a long time ago, I don't remember), and its been fine since.

 

[Togeneral99]

The Glentek has no punch button pad on the back like the Baldors so not sure about that one.

The machine was running good on the part just before and then had this issue on the next part (believe me it shook the hell out of the machine by running 2500 rpm slower than commanded and at full feed rate - so I can say with certainty when it started lol). This leads me to believe something failed and it doesnt seem to be heat related either as the machine still has the same issue after sitting overnight.