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Author Topic: Another dumb question  (Read 8773 times)

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Offline dresda

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Re: Another dumb question
« Reply #10 on: January 29, 2011, 06:54:37 PM »
If I am running my spindle externally with the VFD using for/rev buttons but then want to control the spindle through Mach, where is the mach3 output for the m03/04.
Do I have to use a separate pot to control the spindle when using it externally or can i use the mach3 spindle override?
Does it operate like other CNC's where it uses the last MDI commanded speed when operating the spindle externally.
Ray.

Offline Hood

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Re: Another dumb question
« Reply #11 on: January 29, 2011, 07:05:11 PM »
To actually control the speed from Mach you would need a board such as the DigiSpeed from Peter Homann or PMDX do one and also CNC4PC.

To just switch on/off/reverse you wouldnt need that, you would just use relays connected to the VFD's Fwd/Rev/Stop inputs.
Hood

Offline dresda

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Re: Another dumb question
« Reply #12 on: January 29, 2011, 07:39:08 PM »
Sorry, I should have said I am using DSPMC with analog +- 10v.
I have found the the screen now showing the outputs to use for m03/4.
Still need to know if I can control the speed from mach if I turn on the spindle externally.
On Fanuc If you just press spindle start, It will will not run unless a command had been put in through MDI then he start push button will run the spindle from the last commanded speed.
Ray.

Offline Hood

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Re: Another dumb question
« Reply #13 on: January 29, 2011, 07:42:25 PM »
If controlling the speed from Mach then M3/M4 would start it and it would start at the speed that is set in the Spindle Speed DRO. You could quite easily edit your M5 macro to set that DRO to zero if that is what you are wanting.
Hood

Offline dresda

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Re: Another dumb question
« Reply #14 on: January 29, 2011, 08:06:01 PM »
Now I see I can put the value in the speed DRO. If I use output 5 for m03 and output 6 for m04, what about m05? is that internal and allready to go?
Another topic: whats with the feed hold. Why have feed hold and stop? the stop works like a feed hold should, the feed hold is a bit wishy washy, don't see the point of it.

Offline Hood

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Re: Another dumb question
« Reply #15 on: January 29, 2011, 08:25:31 PM »
Yes M5 will deactivate whatever output (M3 or M4) is currently active so no need to do anything.

Stop should only ever be used when all axis are stationary as it will not decelerate your axis and you may well lose position. If an axis is in motion you should feehold then if you require Stop then you can press it. I think pressing Stop clears the buffers.

Hood

Offline dresda

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Re: Another dumb question
« Reply #16 on: January 29, 2011, 08:59:39 PM »
On all the CNC's I have worked on, the feed hold is instant, I have never seen a feed hold where the axis just slows down and stops when you press it, you shouldn't loose postion if using Dc servo's with pulse coders right..
Is this that way because of the stepper motors loosing step or something even though mine does it and I'm using DC servo's.
I wonder if there is a parameter to change it.
I must admit, I do like this mach3. I went to Camsoft last year, but $5000...for the CD

Offline Hood

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Re: Another dumb question
« Reply #17 on: January 30, 2011, 11:52:58 AM »
These other controllers are closed loop to the control and cost probably 100x more than Mach ;) Having said that Feedhold should stop quickly, if its not it may be due to the DSPMC being in the mix.

Hood

Offline dresda

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Re: Another dumb question
« Reply #18 on: January 30, 2011, 03:53:53 PM »
DSPMC is closed loop, I will ask Rufi.
Thanks.

Offline Hood

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Re: Another dumb question
« Reply #19 on: January 30, 2011, 05:17:00 PM »
Yes DSPMC is closed loop just like my servo drives close the loop to my AC motors but if the pulse is stopped immediately without the deceleration then the motors may end up out of position from where Mach thinks they are.
Hood