need help with fan on hs4 hp spindle.

[knight_toolworks]

this is on a prt alpha and the cooling fan used to go a couple years then they started dying way too often. then I noticed as my machine came to rest home after jogging the fan would slow down and then start up again or completely stop then start. I have wiggled and jiggled the power cord to it and nothing. last week the fan died again after only two months maybe.
I have never been able to find anything that caused it to stop. though finally this last time I found frayed wires on the female part of the plug attached to the black cap the fan sits in. I cleaned them up and was hoping it solved it. well so far it seems it does not slow or power down while moving but just today it stopped while idle then started again.
when I called shopbot they said the whole system uses the same power supply so if it was that I would see the effects in movement.

[ssflyer]

Hmm - I might be mistaken, but I'm pretty sure the fan is powered from 24V DC from the VFD. Some, if not most use the same power supply for the relay board - if any...

[knight_toolworks]

Your right. been so long since I looked at the wiring. but it is weird it is in the same place the fan slows or stops. it would be easy to add an external 24v power supply if that will take care of it.

[ssflyer]

Can you check the 24VDV output? Might be a bad regulator...

[knight_toolworks]

I checked voltage and it was 24v at least while the machine was sitting still.

[Brady Watson]

Check for loose wires. The HSDs pretty much came wired for an external power supply in the control box (24v) - although there is a slim chance it is powered through the VFD depending on what year you got it. The 24v PS will be at the top of your control box about mid-way over. It is probably blue.

On the spindle the fan wires are housed in gray conduit going to the black rectangular connector held in by a single screw. There is a chance it is fatigued or stretched at that connector if adequate strain relief was not added. If zip tied to the orange spindle wire, it gets worked back and forth as the Z goes up & down - so there is a chance it could be getting worked loose.

-B

[jTr]

Steve,
How uncanny - when my machine was new 2 yrs ago, my HSD 2hp fan motor would stop almost exactly every time a part file was complete and it parked home. I really thought it was supposed to do that, until the intermittent switching became more random. Oddly, it still was prone to shut off upon completion of a file. Pretty funny.

Called tech - they enlightened me - checked the wires where connected to the circuit board inside the control box, re-tightened those tiny cable clamps and it's been 100% reliable ever since. I'd look inside the control box at the connection there.

jeff

[ssflyer]

Thanks Brady - Just checked mine - sure enough, separate 24v supply from the control box!

[knight_toolworks]

will check the control box. I took apart the pug attached the spindle housing and fixed the frayed wires and was hoping that was all it was but nope. my machine was the latest prt before they changed to the prs 2009 I think. I know the gray wire I have zip tied to the orange from the spindle control so I guess the power is coming from that?

[knight_toolworks]

so much for my memory opened the control box and the wires were not loose and I am not sure how to even remove them. but I yanked and pushed on them and they seem solid.

[srwtlc]

Steve, when it in a position that the fan is not working, use a voltmeter to see if there is power at the plug on the spindle.

When the fan isn't running, if you give it a spin with something you can stick through the grill, does it start spinning again? I've had several of the PABST brand fans stop working. The small wires inside the fan motor don't handle the vibration well and break and they don't seem to start spinning without a kick start if at all. I finally stopped getting that OEM brand and just order a handful of 24 volt 80mm fans that were close to or above the CFM rating of the PABST fans. I did have to make a 0.25" spacer because the new fans were taller. I got 3 fans for the price of one of the PABST ones and I'm still on the first one. I got one that has a much higher CFM, but it's a screamer, so I haven't used it yet.

I have a switch that allows me to turn off the fan when not in use (can't start the spindle if it's not on) and I've still gone through four of the PABST fans.

By the way, HAPPY BDAY ;)

[knight_toolworks]

ya been using the same brand but they are having these issues right away.

[coryatjohn]

I have a 4hp spindle too and the fan has just started making odd sounds. Sometimes it's constant and then it starts talking to me in Latin. I thought I was going crazy but now I think it's either the devil or the fan is going to fail.

[Brady Watson]

For all who own spindles: Preemptively buy a replacement electric spindle cooling fan. They don't last forever on any spindle. (and depending on your shop voltage and brand of spindle, not all are 24vdc)

If PS shows 24v, do a continuity test on the grey wire to the spindle - both wires. Make sure it isn't internally broken some where down the line. Usually if the 24v power supply fails on an Alpha, you'll get all kinds of COM problems or disconnects - so if your machine is running good and not dropping out, chances are the PS is fine.

The other thing may be the wiring from the 3-prong spade connector (black one) that runs inside the spindle to the fan itself. That's a bit hairier to mess with, but a possibility if replacing the fan is not curing the problem.

Check your grey wire first...

-B

[knight_toolworks]

checked and the ps is only to the fan and the connections seem good. I have checked and fixed the bad wire in the plug that was frayed been debating on replacing it with direct wire. but the whole time I have wiggled and jiggled the plug and never had a slow down.
this fan stopped once while the machine was idle then started back up using air to get it going or flipping it did not work. thats usually the method when the fan is getting worn out. but the fan was only a week old.