Asymmetric lost steps on X axis.

[breezy]

I have a strange problem, the X axis is losing steps when travelling in the X+ direction and only after conducting a particular G2 command. Here is the first portion of the G-code.

(DUST EXTRACTION SUPPORT)
(DRILL HOLES SHAPE)
(MACHINE)
( VENDOR 3D TEK)
( MODEL HEAVY MILL)
( DESCRIPTION 3D TEK HEAVY MILL)
(T13 D=12.7 CR=0. - ZMIN=-16. - FLAT END MILL)
(T14 D=12.7 CR=0. - ZMIN=-16. - FLAT END MILL)
N10 G90 G94 G91.1 G40 G49 G17
N15 G21
N20 G28 G91 Z0.
N25 G90

(HOLE)
N30 M5
N35 T14 M6
N40 T13
N45 S20000 M3
N50 G55
N55 G0 X98.573 Y308.158
N60 G43 Z15. H0
N65 Z5.
N70 G1 Z3. F5000.
N75 Z-2.
N80 G2 X128.35 Y275. I-3.573 J-33.158 F10000.
N85 G1 Y185.
N90 G3 X145. Y168.35 I16.65 J0.
N95 G1 X275.
N100 G2 X308.35 Y135. I0. J-33.35
N105 G1 Y25.
N110 G2 X275. Y-8.35 I-33.35 J0.
N115 G1 X160.355
N120 G2 X136.774 Y1.418 I0.001 J33.35
N125 G1 X1.418 Y136.774
N130 G2 X-8.35 Y160.355 I23.582 J23.582
N135 G1 Y275.
N140 G2 X25. Y308.35 I33.35 J0.
N145 G1 X95.
N150 G2 X98.573 Y308.158 I0. J-33.35
N155 G1 Z-4. F5000.
N160 G2 X128.35 Y275. I-3.573 J-33.158 F10000.

When line N150 is processed the spindle doesn't move and plunges down and repeats the loop from line N80. But now the whole loop is moved over about 2mm (in the X- direction) from the previous cut.

I reduced the speed & acceleration settings in MASSO, which is the usual procedure to fix missed steps to about third of their previous settings.

Only after I changed the plunge to a 3 deg ramp, it reduced the missed steps to about .5mm, allowing me to finish and clean up the part.

There is about a .5mm backlash in the X axis. Would this accumulate in one direction (eg X-)?

At one stage during this testing and adjusting, when MASSO went to zero the tool after the tool change, because of all the missed steps the machine was about 30mm out in the X- direction from the center of the tool touch plate. Had to abort and re-home the machine.

Still not satisfied that the missed step has been fixed.

Has anyone had a similar problem? Any suggestions?

Have included files. In the ramp file the stock is mounted at a 45deg angle because of the piece of MDF was narrower than the part when mounted square to the machine.

Regards,

Arie.

For the Bicton Men's Shed.

 

[tayloredtech]

Quote from Breezy on May 13, 2019, 1:32 pm

I have a strange problem, the X axis is losing steps when travelling in the X+ direction and only after conducting a particular G2 command. Here is the first portion of the G-code.

(DUST EXTRACTION SUPPORT)
(DRILL HOLES SHAPE)
(MACHINE)
( VENDOR 3D TEK)
( MODEL HEAVY MILL)
( DESCRIPTION 3D TEK HEAVY MILL)
(T13 D=12.7 CR=0. - ZMIN=-16. - FLAT END MILL)
(T14 D=12.7 CR=0. - ZMIN=-16. - FLAT END MILL)
N10 G90 G94 G91.1 G40 G49 G17
N15 G21
N20 G28 G91 Z0.
N25 G90

(HOLE)
N30 M5
N35 T14 M6
N40 T13
N45 S20000 M3
N50 G55
N55 G0 X98.573 Y308.158
N60 G43 Z15. H0
N65 Z5.
N70 G1 Z3. F5000.
N75 Z-2.
N80 G2 X128.35 Y275. I-3.573 J-33.158 F10000.
N85 G1 Y185.
N90 G3 X145. Y168.35 I16.65 J0.
N95 G1 X275.
N100 G2 X308.35 Y135. I0. J-33.35
N105 G1 Y25.
N110 G2 X275. Y-8.35 I-33.35 J0.
N115 G1 X160.355
N120 G2 X136.774 Y1.418 I0.001 J33.35
N125 G1 X1.418 Y136.774
N130 G2 X-8.35 Y160.355 I23.582 J23.582
N135 G1 Y275.
N140 G2 X25. Y308.35 I33.35 J0.
N145 G1 X95.
N150 G2 X98.573 Y308.158 I0. J-33.35
N155 G1 Z-4. F5000.
N160 G2 X128.35 Y275. I-3.573 J-33.158 F10000.

When line N150 is processed the spindle doesn't move and plunges down and repeats the loop from line N80. But now the whole loop is moved over about 2mm (in the X- direction) from the previous cut.

I reduced the speed & acceleration settings in MASSO, which is the usual procedure to fix missed steps to about third of their previous settings.

Only after I changed the plunge to a 3 deg ramp, it reduced the missed steps to about .5mm, allowing me to finish and clean up the part.

There is about a .5mm backlash in the X axis. Would this accumulate in one direction (eg X-)?

At one stage during this testing and adjusting, when MASSO went to zero the tool after the tool change, because of all the missed steps the machine was about 30mm out in the X- direction from the center of the tool touch plate. Had to abort and re-home the machine.

Still not satisfied that the missed step has been fixed.

Has anyone had a similar problem? Any suggestions?

Have included files. In the ramp file the stock is mounted at a 45deg angle because of the piece of MDF was narrower than the part when mounted square to the machine.

Regards,

Arie.

For the Bicton Men's Shed.

That is some trippy confusing stuff, I can see how frustrating that would be!

I have no clue if it's the Masso. But is it possible to test it with X and Y reversed so to see if You does the same thing. Just thinking it would be good to rule out the axis drives from the issue maybe?

Mitch

 

[breezy]

UPDATE.

Did more testing today and found that the X axis could be moved when it should have been held in place by the stepper motor and also a small amount of resistance could stop the carriage.

Everything looked to be a faulty stepper motor. Checked the grub screws in the pinion, they were tight. So as last resort removed stepper to have a closer look at the pinion and found that the grub screw had come loose and the pinion had rotated slightly. So when I had tried to re-tightening the screw I was no longer tightening against the flat on the drive shaft, so under load the pinion was slipping. Repositioned the pinion and tightened the screws, replaced the stepper and tested again. Now everything was as it should be, locked when it should and strong resistance was required to stall the stepper.

Hopefully all is fixed and that I can again crank up the speed of the axis.

Regards,

Arie.