Denford ZeroCentre Max rpm
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Denford ZeroCentre Max rpm
I have a Denford Zerocentre CNC Mill. At the moment if you program a speed of greater than 4000rpm the actual spindle speed drops as the machine assumes that a gear change has taken place.
The only way of changing the drive ratio is to change the position of the drive belt to a different set of pullies.
If I was to permanently change the drive ratio to allow the higher rpm which parameter would require to be altered to allow this change? such that if the machine was programmed at less than 4000 rpm it would run at the correct rpm. I guess that I need to set the speed that it assumes the gear change has taken place to be very low ie 10rpm.
I would also need to confirm that the ratio set in the parameters was correct - Where would this be specified?
Hugh Watson
Innova Design & Build Ltd
The only way of changing the drive ratio is to change the position of the drive belt to a different set of pullies.
If I was to permanently change the drive ratio to allow the higher rpm which parameter would require to be altered to allow this change? such that if the machine was programmed at less than 4000 rpm it would run at the correct rpm. I guess that I need to set the speed that it assumes the gear change has taken place to be very low ie 10rpm.
I would also need to confirm that the ratio set in the parameters was correct - Where would this be specified?
Hugh Watson
Innova Design & Build Ltd
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Hi,
I'm guessing this is a Fanuc OTA/B
I don't know the machine, but can help with the Fanuc parameters:
Parameters 540,541,542 and 543 correspond to the speeds in gears 1,2,3 and 4.
It depends on the PLC and machine as to how many are used.
If you only have one range then 540 would be set to 4000RPM for 10V analogue output.
If you had two ranges then you might have:
540: 2000
541: 4000
etc...
Hope this helps
I'm guessing this is a Fanuc OTA/B

I don't know the machine, but can help with the Fanuc parameters:
Parameters 540,541,542 and 543 correspond to the speeds in gears 1,2,3 and 4.
It depends on the PLC and machine as to how many are used.
If you only have one range then 540 would be set to 4000RPM for 10V analogue output.
If you had two ranges then you might have:
540: 2000
541: 4000
etc...
Hope this helps
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Not for these parameters.
My fault - I thought it was a lathe (OT)
If you look at those parameters and the values make sense, then they are the ones - give it a try - you can't do any harm (famous last words
)
If you change the 4000 to say 8000, then all your actual speeds will be halfed as the Fanuc is now outputting half the analogue voltage for the requested speed (eg, 4000 is now 5V 8000 is now 10V)
My fault - I thought it was a lathe (OT)

If you look at those parameters and the values make sense, then they are the ones - give it a try - you can't do any harm (famous last words

If you change the 4000 to say 8000, then all your actual speeds will be halfed as the Fanuc is now outputting half the analogue voltage for the requested speed (eg, 4000 is now 5V 8000 is now 10V)
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If I remember correctly, the Fanuc itself will choose the gear range according to the spindle speed programmed, by setting a gear change
request flag to the PLC logic.
It uses these parameters to decide which gear to pick. The logic will then confirm which gear it has changed to
Because the first three are set to 4000RPM (or thereabouts) I would guess its single speed - the 2nd and 3rd parameters look like they are set to 4000 just in case the PLC logic tells the Fanuc that it is actually in gear 2 or 3.
So, if you want to change the pulleys to get 6000rpm, I would change the parameters to:
540: 6000
541: 6000
542: 6095
543: 0035
request flag to the PLC logic.
It uses these parameters to decide which gear to pick. The logic will then confirm which gear it has changed to
Because the first three are set to 4000RPM (or thereabouts) I would guess its single speed - the 2nd and 3rd parameters look like they are set to 4000 just in case the PLC logic tells the Fanuc that it is actually in gear 2 or 3.
So, if you want to change the pulleys to get 6000rpm, I would change the parameters to:
540: 6000
541: 6000
542: 6095
543: 0035
Re: Denford ZeroCentre Max rpm
On the Zerocentre we never used\set the gear ratio on the spindle pulleys. ONLY PARAMETER 540 WAS SET. It may be that you need to set the speeds up as Andy is saying if you want to use the second ratio.
If you change to the other ratio then I guess you need to set Parameter 540 to the new speed.
If you change to the other ratio then I guess you need to set Parameter 540 to the new speed.
I have changed the belt position and change the parameters as you said and it does now appear to run to 6000rpm.
The only problem now is that I don't have any way of confirming the spindle speed as there is no encoder on the spindle. How do I know if Fanuc is using the correct ratios?
Any ideas on a way of checking this?
I did mark the spindle and run at 120 rpm and count the rotations. it did seem very slightly slow, 31-32 secs for 60 rotations. Not very scientific though!
The only problem now is that I don't have any way of confirming the spindle speed as there is no encoder on the spindle. How do I know if Fanuc is using the correct ratios?
Any ideas on a way of checking this?
I did mark the spindle and run at 120 rpm and count the rotations. it did seem very slightly slow, 31-32 secs for 60 rotations. Not very scientific though!
Zerocentre
The best way to tell the actual speed is to measure directly from the spindle using a tachometer.
It appears that E-Bay has lots of digital tachometers for around £20.
Good luck.
It appears that E-Bay has lots of digital tachometers for around £20.
Good luck.