Denford Software & Machines

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 Post subject: Triac spindle stalled, now won't start!
PostPosted: Thu 05 Oct , 2017 21:51 pm 
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Posts: 35 Hardware/Software: Denford Orac
Hello all,

My triac spindle stalled today while plunging too aggressively into steel. I was hovering over the pause button so stopped the machine straight away, within a fraction of a second. Went and re cam-ed the operation, came back to run it again and and the spindle wouldn't start. It's a Triac PC from about 97 I think, although Denford told me it might have upgraded electronics as it has a USB interface. I checked all the fuses I can see, but they're all fine. I've taken some pictures of the electronics cabinet: https://photos.app.goo.gl/UN3B3gT7J1ticShr1

Any suggestions?

Thanks,

Luke


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 Post subject: Re: Triac spindle stalled, now won't start!
PostPosted: Thu 05 Oct , 2017 22:46 pm 
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Posts: 66 Hardware/Software: Cyclone TU150E (Running KMotionCNC with Servos)
Novamill running V5
Triac VMC
Have you tested the fuses with a multimeter, or just visually?

Have you tested the fuse on the spindle drive?

Do you hear a click when you try turning the spindle on?


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 Post subject: Re: Triac spindle stalled, now won't start!
PostPosted: Thu 05 Oct , 2017 23:07 pm 
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Hi Moray,

I tested all the fuses I could see my multimeter, including the one on the motor drive. Yes, a relay clicks when I turn on the drive. The two LEDs on the drive don't light up at all.

Cheers,

Luke


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 Post subject: Re: Triac spindle stalled, now won't start!
PostPosted: Thu 05 Oct , 2017 23:27 pm 
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Posts: 66 Hardware/Software: Cyclone TU150E (Running KMotionCNC with Servos)
Novamill running V5
Triac VMC
Next step would be to do some testing for power with everything powered up.

Start with the basics. With the cabinet open, turn the power on, then activate the spindle.
Check that there is power on both sides of the main fuses, just to rule out any faulty fuse holders.
Next check for power at the spindle drive (wire 2 and N). Wire 2 comes from the E-stop relay, and IIRC Wire 1 is the input to the E-stop relay contact for spindle power. (If you need to check, power everything down, find what terminal number wire 2 connects to on the base, pull the E-Stop relay out and there will be a contact diagram on it, so you can see where power should come in).

Obviously, be careful when testing with the cabinet powered up.


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 Post subject: Re: Triac spindle stalled, now won't start!
PostPosted: Fri 06 Oct , 2017 9:21 am 
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Thanks Moray. I won't have a chance to do this till next week now, but I'll report back what I find.

Luke


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 Post subject: Re: Triac spindle stalled, now won't start!
PostPosted: Fri 06 Oct , 2017 22:22 pm 
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Check fuse F1. Its in the top left hand corner. You need to unscrew the black cap.


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 Post subject: Re: Triac spindle stalled, now won't start!
PostPosted: Tue 10 Oct , 2017 20:45 pm 
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Yeah it was fuse F1. Don't know how I missed that, must have been rushing!

It's only 3.15A though - is that right? One of the electrical diagrams has it at 6.3A. That said I don't know if it's the correct version of the drawing for my machine though.

Thanks,

Luke


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 Post subject: Re: Triac spindle stalled, now won't start!
PostPosted: Tue 10 Oct , 2017 22:32 pm 
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I would have said it should be a 10 Amp fast blow fuse.


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 Post subject: Triac spindle stalling!
PostPosted: Thu 26 Oct , 2017 23:10 pm 
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I phoned Denford and they recommended a 6.3A slow blow fuse, which is what I've replaced it with. I was able to complete my drilling operation without any difficulty, but I'm now finding that the spindle stalls when I attempt to pocket in mild steel (the fuse isn't blowing though).

I'm pocketing a 19mm diameter hole in mild steel with a 12mm HSS slot cutter, and I've already drilled the centre of the pocket to 6mm diameter. This mill is new to me, so I started off with (what I thought was) a pretty conservative feed/speed of 750rpm, 0.5mm step down, 250mm/min. In fact when I run the operation I've been reducing the feed to about 20% (left the spindle at 750rpm tho). As soon as the cutter hits the material it grinds to a halt, at which point I hit the e stop. I tried jogging it manually slowly in the material (just plunging straight down) in very small increments, and when it makes contact the cutter significantly reduces speed before picking up again.

This really doesn't seem right to me - there are plenty of videos of Triacs chewing through steel on youtube. Could it be a servo drive problem, or perhaps mechanical? I'd be grateful for any suggestions!

Thanks,

Luke


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 Post subject: Re: Triac spindle stalled, now won't start!
PostPosted: Fri 27 Oct , 2017 9:04 am 
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Have you tried increasing the spindle speed? At 750 rpm you won't have much power.


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 Post subject: Re: Triac spindle stalled, now won't start!
PostPosted: Fri 27 Oct , 2017 10:39 am 
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Up to about 1000rpm. Could you recommend a feed / speed for this? I tried the same operation on my manual machine (1kW @ 1400rpm) and it didn't flinch when I plunged.

I was under the impression the Triac had a closed loop controller for the spindle drive, so it would just increase motor torque if the speed dropped - is this not correct?

Thanks


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 Post subject: Re: Triac spindle stalled, now won't start!
PostPosted: Fri 27 Oct , 2017 11:16 am 
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It's classed as open loop although the spindle motor will have a Tachometer on it so it should pick up to a point.

You could try adjusting the pots on the spindle drive. A small turn on the IR COMP pot may help on the Sprint 1200 drive.


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 Post subject: Re: Triac spindle stalled, now won't start!
PostPosted: Tue 31 Oct , 2017 13:53 pm 
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I would agree with Martin the spindle fuse should be a 10A F rated fuse. If you don't have this you could cause damage if you stall the spindle motor the slow blow will not act fast enough to prevent this.

There is also a thyristor fuse on the spindle drive itself that will blow if you really crash it.


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 Post subject: Re: Triac spindle stalled, now won't start!
PostPosted: Mon 06 Nov , 2017 10:46 am 
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Hi,

Steve - Ok, I'll swap for a 10A fast blow fuse.

Re the spindle stalling in steel... I checked the motor brushes, although there was a little dust inside (don't know if this is a problem, wiped up what I could), it otherwise didn't look as if there was much brush wear. Also spoke to Sprint Electric (unbelievably helpful), who basically said it seemed everything was set up correctly. What I'd really like a pointer on is whether the spindle stalling at ~800rpm while making light cuts in mild steel is suspect, and ideally a 'recipe' that I can try out for DOC, feed, RPM etc which should produce good results with a 12mm slot cutter in mild steel.

Thanks again,

Luke


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 Post subject: Re: Triac spindle stalled, now won't start!
PostPosted: Mon 06 Nov , 2017 11:14 am 
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I would doubt there is an issue with the motor. At lower RPM you have lower torque which could cause a stall. does the stall occur when plunging or cutting? feeding in at an angle may help.

I would select Manual Mode set your spindle to 800 rpm and then set the feed to around 100mm/min turn down the over ride then take a cut starting outside the block as 1mm deep. Just adjust the feed override as you cut to a point where the tool is cutting ok and it sounds right. With the Override you will get from 10mm /Min to 150mm/min. Record the feed you get and then use that in program.

By default we would set the feed to 75mm/min for steel but it all depends on the grade. Also check the cutter type is suitable for plunge cuts.


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 Post subject: Re: Triac spindle stalled, now won't start!
PostPosted: Mon 06 Nov , 2017 11:38 am 
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Posts: 66 Hardware/Software: Cyclone TU150E (Running KMotionCNC with Servos)
Novamill running V5
Triac VMC
I've not currently got a feeds and speeds calc installed to calculate the required spindle torque, however I suspect that size cutter will be pushing the limits of the spindle.

You have to remember, if the spindle is rated at 1kw at 3000RPM, then at 800RPM, you've only got around 260w of power at 800RPM.
Electric motors produce relatively constant torque, so only produce they're rated horsepower at their full rated speed.


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