shoptask turnado lathe to acorn

[martyscncgarage]

First check all couplers to make sure they are tight.
Since you have a DRO on the axis use it and command a longer move. As long as you have travel.. And recalculate the revs per inch.

Just remember if you call 4", calculate based on half or in this example 2"
Try and report back

[KevinTaylor]

Ok did some quick testing.

I reset my revs per inch again
1" =5.093088039
this made it so a 1" move moves the x axis 1" exactly
bring the x axis out to far limit of travel at x9.5 and it is at 9.52461 24 and a half thou to much. This is consistent with all other times I have done this. Its always around 24thou off at the far limit of + travel.

I rest the revs per inch again, this time to 9.5"
now 9.5" is at 9.53169 31 and a half thou off
1" is at 1.00059
2" is at 2.00394
3" is at 3.00728
etc.

So my problem is every time I set my revs per inch, a 1" move is always spot on at 1" but then I keep gaining the further out in x+ travel I get. And by the time I get to x+ travel limit of x+9.5 its always 24thou off.

It will always go back to zero though. so if its at 9.52461 and I do a g0 x0 it will go to zero or at most +/- 2 tenths

My z axis is perfect. I set the revs per inch, did a ballscrew map table and its perfect. I am having lots of trouble with this x axis though.

[martyscncgarage]

Can you post a fresh report?

[KevinTaylor]

Here is a report file.

[martyscncgarage]

Your numbers look much better.
You aren't trying to use leadscrew compensation are you? I'd leave all that off until the machine is running properly. (even then, give your machine I wouldn't waste my time with it really)

You used your DRO and went much longer distance to calculate your revs per inch?
I would use a nice round number like 8"
Obviously you call 8" its only going to move 4 inches so that number is your basis for setting up the revs per inch.
Also, head in the X- direction to take up backlash, say .200" and then set part Zero there and move the 8"
If you set it up properly it should dead nuts travel 4" consistently IF you did the calculations correctly.

Also, again, check all mechanical issues. The G540 is pretty reliable.
Please post pictures of your control cabinet, overall shot, shot showing Acorn and surrounding wiring as well as G540 and surrounding wiring.
You are using a good quality shielded DB25 straight through wired cable?
All grounds and cable shields are taken back to ONE point where the power ground enters the cabinet and is terminated?
Marty

[brittfussel]

October 29, 2019

Kevin

I spent some time in the shop yesterday setting up to calibrate the revs/inch for both the X and Z-axis. The tools that I used include: the Noga MG6161 articulated holder with fine adjustment at both the top and bottom; Starrett No. 708A tenths dial test indicator; Fowler 81 Piece Rectangular Steel Gage Block Set 53-672-081-0; a six inch by 1/8 inch steel parallel; and two toe clamps. I removed the tailstock and the right way cover so I could get to the steel ways to mount the Noga holder. With this setup I was able to measure nine inches along the X-axis and eight inches along the Z-axis. I calibrated my revs/inch at one inch and took measurements at one, two, three, four, five, six, seven, eight and nine inches along the X-axis and at one through eight inches along the Z-axis. I'll report these measurements in another post as I have not had the time to analyze the information.

Here are some pictures of my setup.


Positioned at one inch off the parallel along the X-axis.


Positioned at nine inches off the parallel along the X-axis


Positioned at one inch off the parallel along the Z-axis


Positioned at eight inches off the parallel along the Z-axis.

I found this setup to be very effective and efficient as I could use the top and bottom fine adjust on the Noga to set the DTI at zero rather than trying to adjust the bezel. I always approached my target point in the same direction to remove any backlash in the system. I would then read the actual distance traveled from the DTI. For example, I would set the DTI to zero on the one inch gage block and the CNC axis DRO I was measuring to zero, removed the gage block and commanded the table to move one inch towards the parallel. If the DTI read 0.0003 short of reaching the one inch of travel, I'd record the movement at 0.9997 inches. If the DTI measured 0.0004 past the zero setting I'd record the distance as 1.0004 inches. I'd make adjustments to the revs/inch and test again. I'd move back 1.25 inches and then move back to zero (this removed any backlash in the system by always approaching in the same direction) and reset the DTI to zero if necessary, and repeated the test until I was happy with the results. For the X-axis I set the software to radius mode so that when I would command one inch it would move one inch.

Let me know if you have any questions.


Britt

[KevinTaylor]

Britt,
Thank you so much for doing that.
I am going to give it a try.
I'll post back with results.