Bore not centering on X0Y0

[Delco]

I have a wierd issue and thought someone may be able to shed some light on it. Using V1.2115 and using the built in circle probe routine.
I am 99.9999% sure it is not my touch probe .
In fusion 360 I setup to do a bore - say 22 mm and a contour finishing path with a 6mm endmill . I use this to reference for a tooling plate and my WCS is the centre of the bore .
So I move to WCS G54 X0Y0 and it does the bore and contour.
Now I load the touchprobe ensuring the runout is as good as I can achieve.
In theory when I probe that bore the centre should be at G54 X0Y0
but what I probe I get the following values when the connection cord aligned such that it is
Pointing to X+
X0.0375
Y-0.1275
Pointing to X-
X0.0475
Y-0.1300
Pointing to Y-
X0.0350
Y-0.1350
Pointing to Y+
X0.0400
Y-0.1250
And moving the lead each time to point to direction of probe
X0.0375
X-0.1250
Now I understand there will be some errors due to pretravel and concentricity but the consistant -0.1mm error on the X is a issue for repeatability.
I believe if there was a setup error or probe error it would move as the probe is rotated .
Below is a snippit of the start of the gcode
G3 X0. Y8. I-0.6 J0.
X-8. Y0. Z-0.192 I0. J-8.
X0. Y-8. Z-0.384 I8. J0.
X8. Y0. Z-0.576 I0. J8.
X0. Y8. Z-0.768 I-8. J0.
X-8. Y0. Z-0.96 I0. J-8.
X0. Y-8. Z-1.152 I8. J0.
X8. Y0. Z-1.344 I0.
To me that shows the circle cut on X0Y0


Backlash and settings have all been checked
I also did a manual check with a indicator and the actual bore centre is off X0.026 and Y-0.132

is this a Constant velocity issue or a error in the software or some sort of rounding issue.

[dezsoe]

Can you just drill a hole and find its center? With this test you could find the failing operation: the boring or the center finding. Also, if your spindle is not trammed then you'll get this result, because I'm sure that the length of the tool and the probe is different.

[Delco]

Get same result when boring a hole , I did a bore and contour operation to get a bigger dia hole to see if the edge contact of the ball is a issue. Have done it with a square cutout as well same issue.

To see if its a machine issue or a probe issue I have just repeated the test on another completely different machine with a different touch probe but V2.115 installed - different gcode and a 40mm hole

Same result -0.15mm out on the Y

Going to roll back from V2.115 on the machines and repeat test and also change probing order to see if the problem flips.

[Delco]

Well I rolled back to v2.113 on the second machine , re zerod and redid the gcode cut from a new X0Y0 , after cut completed reprobed the hole and it is still out consistantly in Y by -0.145 mm .

I loaded up probelt to recheck and do a tip calibration
re-probed with probelt . and the same error is shown.

Swapped probing setting from X first to Y first - no change in error.

Gcode shows a cut occurring centred at X0Y0

Size of bore in all directions probes to 39.994 - 39.998 so consistant enough - measures same.

I am now waiting for a tenths indicator so I can check mechanically with more accuracy than the mechanical indicator I have .

Totally stumped any more tests I should run ?

Anyone with a good quality touchprobe able to do the test and see what their results are ?

Been struggling trying to get consistant chamfers when repositioning a job and its always off in Y

[dezsoe]

I don't beleive it's version dependent.

(I had the same problem on the weekend and I'm sure that I have tramming problems. On this experimental machine I've never tried to set the spindle to perfect perpendicular, but now I had to drill 4 precise holes. The difference between the length of my probing tool and the real tool was about 30 mm and the result was terrible. Y was about .2-.3 away, X was "just" .1. I had to make corrections by eye. The workpiece was only 2 mm thin, so the result was just acceptable.)

[eabrust]

Delco,

Thought for a test for you. Do you have a laser pointer you could grab in your spindle collet? Aim a dot w/ Z at a certain height, then as you retract up or move down, if the dot moves on you it shows you're out of tram as Dezsoe suggests.

I have the same issue trying to use a microscope camera with UCCamCopy to set locations, because the location you 'center on' w/ cross hairs via the camera is dependant on z height and how well the camera is perfectly trammed, you can only use it if you know the camera is an exact repeatable height from where it is 'calibrated' for spindle offset.


regards
Eric

[Delco]

Delco,

Thought for a test for you. Do you have a laser pointer you could grab in your spindle collet? Aim a dot w/ Z at a certain height, then as you retract up or move down, if the dot moves on you it shows you're out of tram as Dezsoe suggests.

I have the same issue trying to use a microscope camera with UCCamCopy to set locations, because the location you 'center on' w/ cross hairs via the camera is dependant on z height and how well the camera is perfectly trammed, you can only use it if you know the camera is an exact repeatable height from where it is 'calibrated' for spindle offset.


regards
Eric

Eric both my machines are in near perfect tram , I use a tramming tool with dual 0.002mm digital guages and regularly surface large areas with a 400x300mm plates with a 50mm bit with no tramming marks in aluminium . the second machine has a diode laser on it so I did the test you recommended and can se no visual movement over the 150mm of Z travel , I have also checked via indicator on the spindle body as it runs through its travel and on the Z linear just in case a error had creaped in that was negated by the tram.

Also the bit I use to bore the hole I selected one that winds up being in the same position roughly as the touchprobe so that error would be negated if it was a issue - but valid point , I have gone and recheched tram to ensure it is correct.

[Delco]

Well after lots of testing I have found the root cause of my issue , my spindle was trammed within 0.01mm over 400mm in the X and Y BUT it turns out my spindle is not parallel to my Z Axis travel in the Y direction.

I had to spend a lot of time tramming my Z axis first then tramming my spindle in the Y direction as it was not in the same plane as the Z .

After much trial and error I got my spindle mount machined so the spindle is in the same ZY plane as the column and now when I do a bore then probe straight after the results are a acceptable X0.005 Y-0.01 error - now given that there is more than 0.005mm flex in the Z assembly I cant expect any better than that at this stage

[dezsoe]

Thanks for the feed back. Now you have a much better machine!