New Build: Another Techno Lathe

[dustboy]

Thanks all for the help! Worked perfectly the first try. Verified RPM with tachometer and it is dead on at 4000 counts.

Input DB9 Pin vs. wire color from original encoder:

2 = Black
3 = White
4 = White/Black
5 = Red/Black
6 = Blue
7 = Orange
8 = Green
9 = Red

[dustboy]

I'm testing the machine with air cuts on some of the sample programs included with CNC12 Lathe. Both PAWN.cnc and Sample_Part_1.cnc start with the Z axis on a rapid straight toward the chuck. I stopped it before it crashed. I think I've setup the tool offsets and G54 correctly per the Youtube videos.

What's going on here?

[cncsnw]

You seem to be homing both Z and X in the minus direction (towards the chuck and towards spindle centerline). Those are unusual choices on a lathe.

A typical CNC program includes G28 to move the axes to a safe position at the start and end of a job, and for tool changes.

G28 moves to the coordinates you specify for return point #1 (on the F1/Setup -> F1/Part -> F9/WCS -> F1/Return table). By default this is Z0 X0, measured from Machine home. On a lathe that homes Z and X both in the plus direction, that default is naturally safe, and rarely needs to be changed.

If you have a compelling need to home your axes in the minus direction, then you should enter appropriate numbers for the G28 return point, so that it takes the tool to a safe clearance position (e.g. near the plus limits for both axes).

[dustboy]

Got it..thanks! I'm new to the lathe world.

The max Z travel changes with the location of the tailstock. This means that sometimes the software travel limits could be more than the actual Z travel available. Is there a way to address this, or do we just depend on the limit switch to stop the axis?

[tblough]

On my lathe I attached the home switch to the bed where the carriage would contact it with the tailstock at the far end of the bed. When I start the machine and home it, I have to ensure the tailstock is moved to that position before homing. Soft limits are set to this max travel.

I have attached my z+ limit switch to the carriage so that it contacts the tailstock. If the tailstock is moved forward to use it and I forget to move t out of the way, the carriage will trip the limit switch when it contacts the tailstock stopping further movement. As soon as the tailstock is moved clear, you're free to continue on.

As Marc states, a return position for Z0 X0 is "safe". That's should be the farthest point away from the headstock and work. However, while he mentions that it rarely "needs" to be changed, my work style has me changing it for every job.

Since my lathe has a QCTP versus a tool changer or gang tooling, I set my G28 return position for every job. Sometimes I have a chuck mounted necessitating a Z position far from the headstock. Other times, I'm working with collets much closer to the headstock so I don't want to waste al the time having the carriage move way out of the way for tool changes. Many times I set my X home position just larger than my stock diameter and my Z home position at Z0. I can then use the tool as a gauge to extend my stock for the next piece.

Everybody's workflow is different, but it but you should take the time to locate where the G28 return position is set and know how to adjust it if necessary. I believe with the latest version of CNC12, Keith had the team add a teach function to the return position screen so you can move the tool to the location you want and instead of having to copy the DRO values into the table, you can just push a button to do it for you.

[dustboy]

I am playing with intercon, and tried to turn a simple punch from a piece of brass pipe.

The program will run the carriage back to home, then as the tool moves in for the first cut, the spindle runs up from the programmed 500 RPM up to 800 or so, then I get a "438 Spindle slave position error". Report and code attached.

I have run the PAWN demo file without this error.

[cnckeith]

post the intercon file you are working on.

[dustboy]

punch.lth

(1.15 KiB) Downloaded 2 times

Here's the Intercon file

[dustboy]

I tried to run another Intercon program. This time the tool moved into position but stopped at Z0.000 and it gave me a 327 Fault: Job canceled.

I reset the control (big red reset button) and the Z DRO went to 100.xxx (no carriage movement), my lathe has a Z travel of 13" as configured. And like a dummy, I hit cycle start anyway and it crashed the tool into the stock with no spindle RPMs.

I've successfully run programs from Fusion and sample files. What have I done wrong with Intercon?

Intercon file attached.

[suntravel]

with 13" Z how do you get the DRO to +98.8845" ?

Uwe