Installing the Acorn with Adtech CNC drives

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cncsnw
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Re: Installing the Acorn with Adtech CNC drives

Post by cncsnw »

If your spindle encoder is counting the wrong direction (or rather, the number you put in Parameter 35 has the wrong sign), then a feed-per-revolution move will go backwards. That could explain its ending up at X+16mm on a move that was supposed to go from +12.45 to +0.05.
dmbgo
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Re: Installing the Acorn with Adtech CNC drives

Post by dmbgo »

tblough wrote: Sat Oct 24, 2020 7:10 am If the commanded feedrate exceeds the capacity of the motors you will loose steps on an open-loop controller like the Acorn and the axis will end up in an incorrect position. Once this happens, you need to re-home the machine before proceeding.

In Intercon, when you enter a feedrate, you can toggle it between F/R and F/M. I'm curious why you have your DRO's set up to display X in radius mode instead of diameter.
Thanks Tom, I'll look at the way that I have it set up in Intercon.
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Re: Installing the Acorn with Adtech CNC drives

Post by dmbgo »

Radius mode Vs Diameter mode:
When I first set up M3 in 2002, I read the current thinking on the M3 forum about Radius and diameter. Radius was suggested as harder to get your head around, but better in other ways (I don't remember the reasons) so I decided to use Radius mode and because I always used M3 in Radius mode, I set up my Acorn to use Radius as well.
I can easily change it back to diameter though, and I'm happy enough to do so, since every now andf again I'd catch myself enering the diameter instead of the radius in M3 as well.
dmbgo
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Re: Installing the Acorn with Adtech CNC drives

Post by dmbgo »

cncsnw wrote: Sat Oct 24, 2020 12:08 pm If your spindle encoder is counting the wrong direction (or rather, the number you put in Parameter 35 has the wrong sign), then a feed-per-revolution move will go backwards. That could explain its ending up at X+16mm on a move that was supposed to go from +12.45 to +0.05.
I'll check parameter 35, but whatever parameter it has is what the wizard has put in the there. That's not to say it's right though....
dmbgo
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Re: Installing the Acorn with Adtech CNC drives

Post by dmbgo »

tblough wrote: Sat Oct 24, 2020 7:10 am If the commanded feedrate exceeds the capacity of the motors you will loose steps on an open-loop controller like the Acorn and the axis will end up in an incorrect position. Once this happens, you need to re-home the machine before proceeding.

In Intercon, when you enter a feedrate, you can toggle it between F/R and F/M. I'm curious why you have your DRO's set up to display X in radius mode instead of diameter.
You were right Tom, the feedrate in intercon was set to feed fer rev, rather than feed per minute. I toggled it to feed per min using the F1 key, and voila!
Thank you.
dmbgo
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Re: Installing the Acorn with Adtech CNC drives

Post by dmbgo »

Feed rate per rev seems to me me to be more practical than feed per minute though. I am guessing this is the reason that per rev is the default in intercon. Is feed per rev something that you just play with to find the right feed rate, or are there guidelines as to what feedrate to use for a designated material and cutting tip type somewhere?
dmbgo
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Re: Installing the Acorn with Adtech CNC drives

Post by dmbgo »

dmbgo wrote: Sat Oct 24, 2020 5:43 pm
cncsnw wrote: Sat Oct 24, 2020 12:08 pm If your spindle encoder is counting the wrong direction (or rather, the number you put in Parameter 35 has the wrong sign), then a feed-per-revolution move will go backwards. That could explain its ending up at X+16mm on a move that was supposed to go from +12.45 to +0.05.
I'll check parameter 35, but whatever parameter it has is what the wizard has put in the there. That's not to say it's right though....
Here is a screen shot of my parameters cncsnw (what is your name btw), as you can see parameter 35 is set to 5000. I have noticed that although my spindle max speed is set to 1500rpm in high, it actually spins at 1700rpm according to the encoder. Intercon doesn't have an error about exceeding maximum spindle speed however. The spindle is capable of spinning far faster than the maximum speed according to the lathe's speed chart, since I have changed the motor from a one HP single phase (1440rpm) to a 3 phase 3.5hp motor which is rated at over 2000rpm. I don't spin it that fast though, there doesn't seem to be a need to, and I don't know what will happen to the lathe's gearbox in the long term
Cheers
Dave
Acorn lathe parameters-25-10-20.jpg
if I do that :).
cncsnw
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Re: Installing the Acorn with Adtech CNC drives

Post by cncsnw »

I mis-spoke (mis-typed). Parameter 34 is the one which specifies spindle encoder counts per turn.

Parameter 34 is a signed value. If your spindle encoder counts up with M3 (CW, forward) rotation, then P34 is positive. If your spindle encoder counts down with M3 rotation, then P34 is negative. Since you have -4096 in P34, your control expects the spindle encoder to count in the negative direction when the spindle rotates forward. You can verify that simply by turning the spindle forward by hand, and watching whether the RPM display in the status window shows "+" or "-" speed.

A typical per-revolution feedrate, in metric, might be between 0.10 and 0.30. It is simply the chip load: how thick a chip do you want to cut?

You could try your facing program again with feed-per-revolution, but with suitable values, and see if it feeds the correct direction.
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Re: Installing the Acorn with Adtech CNC drives

Post by dmbgo »

Thanks CNSNW, I was able to resole my facing issues using the info you provided. The feed rate was the cause, since I was still thinking in terms of feedrate per Metre rather than per revolution.
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Re: Installing the Acorn with Adtech CNC drives

Post by tblough »

Just to be pedantic, it's not "feedrate per Metre", it's mm per minute.
Cheers,

Tom
Confidence is the feeling you have before you fully understand the situation.
I have CDO. It's like OCD, but the letters are where they should be.
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