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Author Topic: Spindle  (Read 3476 times)

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Offline sml

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Spindle
« on: May 09, 2010, 06:23:52 AM »
Hi
Can anyone tell me , can i have a spindle pressure sensor for my milling machine by mach3 ?
What instrument i need for this ability on my spindle?
thank you

Offline Dan13

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Re: Spindle
« Reply #1 on: May 09, 2010, 08:53:48 AM »
Depending on your spindle motor, you could use an ammeter to reflect the load on the spindle. Pretty easy to add on a DC motor, not as so on other motor types though.

Daniel

Offline Hood

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Re: Spindle
« Reply #2 on: May 09, 2010, 11:58:27 AM »
Some VFDs and Servo drives support analogue outputs which you can configure for various things. The Servo drives I use have that function and on the lathe I have configured the analogue output to look at the amperage of the motor and scaled it so that 10v was 150% of the rated continuous current. I then set up to a voltmeter where 10v was full scale deflection and made a background for the meter to read 0 to 150% spindle load, works well :)
Hood

Offline sml

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Re: Spindle
« Reply #3 on: May 09, 2010, 12:08:01 PM »
Thank you

Offline RICH

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Re: Spindle
« Reply #4 on: May 09, 2010, 12:08:12 PM »
Not sure what you want to do. The amp measurement can be manipulated give you torque, but pressure is due to force and for that you would  want to measure strain which can be manipulated to force, which will vary in a non linear fashion above a certain point. But non of this is absolute due to the electronics. IE; measure pressure via strain gaging, null a bridge to zero, but that's only good to 1% of total. Accelerometers can be indicative of movement and related to pressure. Again not sure what you want to actualy measure and do with the info you aquire and i am not an instrument guy..... ???
RICH

Offline sml

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Re: Spindle
« Reply #5 on: May 09, 2010, 12:13:02 PM »
Hi Rich
I got it
Thank you for your reply

Offline simpson36

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Re: Spindle
« Reply #6 on: May 10, 2010, 05:01:07 PM »
The way I read this, the OP wants Mach3 to do something with the reading. I don't see a purpose for that other than for Mach to slow the feedrate or something. I've asked this question several times and the consensus is that feedback to Mach3 for the purpose of reacting with adjustments to a running program is not doable. However, it still seems to me that is would be if the right avenue could be found.

Speaking to this particular thread, 'Pressure' is undefined. methinks. If this means spindle load, that's one cat. If it means the downforce on the head, that's a differnent cat. There are lots of ways to skin them, but skining the wrong one is not particularly useful.

Offline BR549

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Re: Spindle
« Reply #7 on: May 10, 2010, 11:01:03 PM »
One method for spindle control we used a while back was to Monitor Spindle RPM and convert it to % based on" IndicatedRPM/programed RPM" then link the FRO to that % value.

We used a button to turn it on/off when needed.

Cruise controll (;-) IF the spindle slows below a deadband then mach adjusts(slows) the FRO to compensate allowing the spindle to catch up a bit then mach will readjust the FRO back up to what % represents the current Indicated RPM.

It worked better than the closed loop spindle control.

I think I can dig the code up again if interested.