How do I troubleshoot bad threads? <Resolved>

[fusion]

I'm trying to thread 1/4-20 using Intercon.
The threads look bad. How do you test the encoder?
Pic of threads and report are attached.
Mike

[suntravel]

G-code file and picture of the tool pls.

Uwe

[lavrgs]

Do you have a thread gage? Are you cutting acme threads ? Intercon may require some tweaks to Minor Diameter depending on the type of tool you are using

[cncsnw]

That looks like unsynchronized starts, due to false index pulse signals. Likely VFD-generated noise on your spindle encoder cable.

On the PID Configuration screen, watch for the asterisk "*" next to the N on the 5th line (which represents your spindle encoder). The asterisk indicates when the index pulse is on.

If you turn the spindle by hand, the asterisk should flash just once per turn, always in the same location.

Assuming that checks out, then start the spindle running at about 60 RPM, and again watch for the asterisk. It should still flash, just briefly, just once per turn. If the asterisk is visible more often than that, it is is because Acorn is seeing false triggers due to noise.

[fusion]

cncsnw, that was my thought just without as much detail. It looked like bad threads Mach3 made when the index pulse wasn’t working properly. That’s why I asked for a way to troubleshoot the encoder. It is an eBay sourced encoder, so the quality it questionable.
I’ll do those checks and get back to you.
My VFD is located in the steel base of the lathe. The control enclosure is sitting next to that. I thought the steel base would be enough to shield the sensitive components from noise.
Also the VFD is 1 hp single phase in 3 out Automaion Direct GS2.
What steps should I take to eliminate the noise if that is what we determine is the issue?
I was hoping I miswired the encoder and was missing the index pulse.
Thanks for the help
Mike

[richardb15]

I mentioned on your comms issued thread that it looked like all the signal cable screens were not connected to anything, and you have mains and signal wires crossing and almost touching, plus your earthing is not best practice. I'd start there, the encoder might be okay, but unless you sort all the potential points of interference you'll be chasing interference issues forever.

[tblough]

Is the cable between your motor and VFD shielded and properly grounded? If you have an oscilloscope, you can look at the A, B, and Z differential pairs coming from your encoder to see if there is noise on those 6 signal lines.

Is this a stepper or servo driven lathe?

[fusion]

Hi!
Uwe, I have attached the files you requested.
tblough, I don't recall a shield in that wire. I will check. My electrical skills are very lacking. I remember 4 wires but not a shield. Where should the shield wire be attached? The ground pin on the DB9 BOB? What pin number is that? Its a stepper driven lathe. I have no oscilloscope.
richardb15, I do remember that. I moved the ethernet wire away from the power wires. I also moved the grounds to the common lug on the back panel. I will spend the weekend try to tidy up and move wires as you suggested.
The lathe is an old Atlas. It seems mechanically sound. My backlash is about .0015 on both axis.

Thanks for all your help!
Mike

[tblough]

If your lathe is stepper driven, then one other possibility is that your Z stepper cannot handle the acceleration on the thread return and is loosing steps. Turn your feedrate and rapid rates down to 10% and try again.

Your VFD manual will show the proper way to ground the motor cable shield.

[fusion]

I think I have a bad encoder or bought the wrong kind.
I think I have it wired correctly, but see what you think. When the orange lead is connected to pin 6 my asterisk "*" next to the N on the 5th line is always ON.
If I move that lead to pin 3, the asterisk "*" next to the N on the 5th line is ON all the time except for one spot where it will turn OFF.
It seems like if I could invert the Z signal with it wire on pin 3 it would work. Is that possible?
If I need a different encoder, could you make a recommendation that isn't too expensive? This one is a Chinese eBay special. I thought I ordered the same one I used on my mill project, and it seems to work just fine.

Thanks for your help!
Mike