In the meantime, you can keep the thread from rolling if you raise the Z height and the clearance amount about .250" above the actual hole. You will have to make the hole depth deeper by the same amount in Fusion. This does two things. It lets the spindle get to speed and stabilize before entering the hole and it lets the compression tap release its length after coming out of the hole.
It is just a work around!
Dave C.
Rigid tapping skips holes randomly
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Re: Rigid tapping skips holes randomly
Grizzly G0678 Mill ,CNC conversion with Acorn. G4004G Lathe, Mach 3 conversion to Acorn.
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Re: Rigid tapping skips holes randomly
OP isn't really doing rigid tapping since the spindle speed and feedrate are not synchronized. My advice is instead of wasting time trying to adjust the spindle speed in Fusion, or adjusting the retract height, or fudging the thread lead, or any other work-around, is to fix the spindle encoder. Then, you can do away with the tension/compression holder and not worry about speed adjustments.
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.
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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Re: Rigid tapping skips holes randomly
Yep, tune the hardware....
My servos with cheap SFencoder on the spindle are less than 5 rpm off over the whole range
Uwe
My servos with cheap SFencoder on the spindle are less than 5 rpm off over the whole range
Uwe
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Re: Rigid tapping skips holes randomly
I have decided after banging my head against the wall for hundreds of hours and many forum posts wasting all yall's time thattblough wrote: ↑Mon Jul 11, 2022 5:53 pm OP isn't really doing rigid tapping since the spindle speed and feedrate are not synchronized. My advice is instead of wasting time trying to adjust the spindle speed in Fusion, or adjusting the retract height, or fudging the thread lead, or any other work-around, is to fix the spindle encoder. Then, you can do away with the tension/compression holder and not worry about speed adjustments.
yeah, you guys are absolutely correct
basically i tried to do a clever, non standard solution, and it ended up taking way more time and way more farting around than if i just did as yall recommended.
How we got here:
I have a PM-30 and replaced the standard brushless motor with a 6 pole brushless servo. I happened to have one from the early 2000's that fit the exact same bolt pattern and shaft size as the stock one, except with way more torque and speed.
What is neat about the servo driver, is that it has a virtual encoder output. Basically it is supposed to output a quadrature signal matching the motor's encoder.
The idea was this was going to be real slick, drop in the motor, run an encoder cable from the servo drive to acorn to not have to mount an encoder, real plug and play upgrade.
Then the problems started:
1: it is an early 2000's driver. ALL tuning is done with potentiometers and jumpers. no fancy vfd controls (think Giddings & Lewis)
2: the encoder output of the drive was a different pinout than acorn. I had to make my own encoder cables
3: the encoder cables used differing wire color codes, and DB9 pinouts are hard depending on if plug or pin side
4: the spindle driver is in a separate enclosure from everything else because it was an after thought, meaning running lots of cables
5: with all this cable running i have been fighting tons of EMI/EMF interference in the encoder cable
6: the motor encoder isnt 1:1 with the spindle, so had to figure out the ratio off of pulley size, which were all weird numbers
Basically the motor runs fine. the acorn to driver to motor works great. i set it to 3000 rpm, it goes 3000 rpm, verified with a tachometer.
Only problem is from the motor to acorn, it thinks the motor is turning faster than it actually is by about 120 rpm (divisible by 60hz, hmmm).
Ive just got to ditch the idea of using the servo driver for an encoder, and figure out how the heck i am going to mount an encoder to my mill, which is why i have been trying to avoid it.
Here is pictures of my mill, and my idea of how im thinking of mounting an encoder. Feedback would be appreciated.
I am thinking of 3D printing the pulley for the encoder to perfectly match the 6 groove micro V belt pulley on the spindle. I cant find a matching pulley anywhere so ill just 3d print one. I can get belts though and would just use the low range pulley on the spindle for the encoder, since i never switch out of high range
Would this encoder work?
https://www.automationdirect.com/adc/sh ... 0r1n1024vd
auto direct doesnt have many medium duty ones in stock that go 5k rpm. Want a medium duty one so can use encoder shaft to mount pulley too (can take radial loads)
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Re: Rigid tapping skips holes randomly
You can mount a thin timing belt pulley on top of the pulley for the spindle drive.
The encoder from your link should work.
Uwe
The encoder from your link should work.
Uwe