shoptask turnado lathe to acorn

[martyscncgarage]

Try a G99 and then your G01 move

[tblough]

If you are setting G99 (inches per rev) and the spindle is not turning (no revs) then the Z axis will not move. The spindle must be running for the axis to move when commanded with G99.

[martyscncgarage]

If you are setting G99 (inches per rev) and the spindle is not turning (no revs) then the Z axis will not move. The spindle must be running for the axis to move when commanded with G99.

You're right. G98 should work for him....I must have fat fingered on my phone.

[KevinTaylor]

Ok, thank you guys for clearing up the g99/g98 for me. The g98 did work, thank you.

So now that I got that g98 working for me today I wanted to start to try to get the steps/rev dialed in.

I zero my z in cnc12. In mdi I enter g98. then I can enter g1 z1 f10. It does move a couple thou under an inch according to my 2" dti. HOWEVER, if I enter g1 z-1 f10 or again a g1 z1 f10 it always moves 2 inches after that first command. so Basically, the first command is always 1" but any command after that of 1 inch, moves it 2".

Becuase of that, I am unable to use marty's excel spreadsheet to dial in my steps.

I've looked through the wizard a couple times but nothing is popping out at me that needs changed. The only thing in the wizard that looks like I might need to check something is in ->Advanced axis configuration -> axis signal inversion?? Do I need to check either the step box, direction, or enable or combo of them?

[martyscncgarage]

Ok, thank you guys for clearing up the g99/g98 for me. The g98 did work, thank you.

So now that I got that g98 working for me today I wanted to start to try to get the steps/rev dialed in.

I zero my z in cnc12. In mdi I enter g98. then I can enter g1 z1 f10. It does move a couple thou under an inch according to my 2" dti. HOWEVER, if I enter g1 z-1 f10 or again a g1 z1 f10 it always moves 2 inches after that first command. so Basically, the first command is always 1" but any command after that of 1 inch, moves it 2".

Becuase of that, I am unable to use marty's excel spreadsheet to dial in my steps.

I've looked through the wizard a couple times but nothing is popping out at me that needs changed. The only thing in the wizard that looks like I might need to check something is in ->Advanced axis configuration -> axis signal inversion?? Do I need to check either the step box, direction, or enable or combo of them?

I would manually bring the axis back past Z0 in the Z+ direction(toward the tailstock, to take up backlash) and then enter G0Z0 to get it back to zero and repeat your 1" move. Don't try and keep moving in the negative direction. Then you read your indicator, let's say it says 1.005". You take the DRO value of 1"/1.005"=99502487 Then multiply that value by your the value in your overall turns ratio (Say it is 5) so 99502487*5=4.97512437.
4.97512437 would be the new value in your overall turns ratio box

Marty

[KevinTaylor]

I am having problems setting up my x axis. I have my z axis all set up and it works, so I am not sure whats going on with my x axis.

I set my steps per rev with a 2" DTI just like in Martys youtube video and use his excel spreadsheet.
I get the revs per inch set and test it out.. go x1...DTI says 1" DRO on my machine says 1"... looks good.

But the further out I go in the x+ direction the worse things become. So bad that by the time I get to x9.5 its off by 24thou.
I try to use the ballscrew comp table and the best I can do is get the entire x axis to 2thou off for every inch. I understand the ballscrew comp table isnt meant to deal with 24 thou.

I have adjusted my x axis gib many times, tightening until the axis wont move then backing off.

I have tightened the thrust bearing as well.

So I thought maybe it was my cheap limit switches, so I purchased and installed some nice metrol limit switches... no change.

I installed a new direct drive coupling... still no change.

I take the x axis apart and remove the ball screw to make sure everything looks good. Everything seems fine. I reinstall the ballscrew and make sure everything is bolted tight etc.

I have no clue as to what to do or what other adjustments can be made. Does anyone know what could be the problem for this?

[brittfussel]

October 25, 2019

Kevin

How are you measuring the 9.5 inches? Are you using the glass scales and the DRO that came with the machine? If so, is it possible the scales are off? As you know I have the mill/turn version of you machine and, quite frankly, I don't trust the glass scales.

Or are you using a gage block stack up? I would trust that more although I suspect there may be some cumulative error in stacking up the gage blocks. I know I have problems ringing them together. Do you have a large enough micrometer to check your gage block stack?

How does the Z direction look? I'm seeing similar discrepancies in the Z direction on my machine. But, I'm not sure if I should trust the ball screws or the glass scales.

Just today I was researching a third, reliable alternative to measuring axis movement to compare to the Acorn DRO and the glass scales DRO.

I spent some time this week using the mill and lathe with the Acorn hardware and the Centroid software. I'm very happy to date. I need to work out some issues with the Intercon threading routine but I have some ideas to try once I return to the machine.

I hope some of this helps.


Britt

[KevinTaylor]

Hey Britt,

Becuase of the way the machine's x axis is set up, Yes I am using the DRO the came with the machine. Although I did test the first inch with a DTI and it matched the machines DRO.

My z axis is great. off by only tenths/half a thou throughout the entire axis.

How would one use a gage block stack up? I think the biggest mic I have is only 4".

[brittfussel]

October 25, 2019

Kevin

What did you use that is exactly an inch? I used a one inch gage block and DTI to set my revs per inch. I'm probably within a couple tenths. I was finding some repeatability issues but I figured they were associated with my use of the gage block, the DTI and lack of patience. I have a Mitatoyo DTI and it is real finicky.

I have a set of gage blocks. The set I have came with a one, two, and four inch blocks (along with all the other blocks to do sub-inch measurements). With these three blocks I can get stackups to measure one, two, three (one plus two), four, five (four plus one), six (four plus two) and seven (one plus two plus four). I could probably get to eight but it would take at least three if not more of the shorter blocks. I've done this before (up to seven inches) with Mach 4 and did not like the results. Now that I'm running Centroid software on the Acorn board and know more about ball screw compensation table I may run through them again at half inch increments (using the 0.5 inch gage block). I don't want to under estimate your knowledge of gage blocks but if you are not familiar with them do a search on YouTube; you should find numerous videos on their use. The most difficult part I have is ringing them together. They are ground so flat that you can actually attach them together (ring) and they won't fall apart. This is how you make sure have no gaps between the blocks affecting their measured length.

According to the manual for the DRO, a compensation table can be developed for the glass scales. This tells me right off that the glass scales can be suspect.

Do you have any 1-2-3 blocks? If so, try using those to see what you get. With one you could get to three inches; with a pair you could get to six inches. You could confirm their dimensions with your calipers or micrometers. I'm real interested in what you find as I plan to head down this path soon.

Hope this helps.


Britt

[KevinTaylor]

Hey britt,

I think I confused you. I didnt use anything that was exactly an inch. I used a DTI to set my revs per inch. Once I got my revs per inch set correctly in the acorn wizard, I could go into MDI and use command g0x1 and my DTI would in fact say 1" exactly. Although it is a 1thou DTI, I am sure it could be better with a tenths indicator. So after i move the x axis using command g0x1 both my DTI and the DRO/glass scales are at 1". This worked out very well for my z axis.

I dont have any guage block sets but have been wanting to invest in a set anyway. Maybe now is the time. I do have a couple 123 blocks I have that I use with my tormach 770.

I am not sure I understand how to use 123 blocks or a guage block set to dial in my x axis however.