H.E.S. 24NCS Lathe (24 X 60) conversion

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24 Apr 2015 17:56 #58078 by andypugh

It worked, what great news. I feel comfortable saying something is wrong with the original encoder, I just don't know what.


It was quite an expensive one, is it worth returning it?

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05 May 2015 12:21 #58395 by canner

It was quite an expensive one, is it worth returning it?


I purchased this encoder several years ago, it is possible that in that time it was dropped or something happened to it. There are enough things that go on around here without anyone claiming knowledge that I don't feel comfortable trying to return it. I might call in on the service line to see if they have any suggestions. I think for this application the smaller encoders will work just fine.

Well in the time since I last wrote this lathe has been used to turn a thread, thank you so much for the help. I was struggling to hit a consistent od and id of parts and started looking at the cross slide. There is an extra 5 thou. of slop in the x axis then several years ago when I first set up the machine and so I will be pulling the cross slide of to see what is happening. I really don't think this is in the ball screw but we'll see.

I will post a few pics as I go along here to document what is inside this machine.


canner

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05 May 2015 16:46 #58397 by andypugh

Well in the time since I last wrote this lathe has been used to turn a thread, thank you so much for the help. I was struggling to hit a consistent od and id of parts and started looking at the cross slide. There is an extra 5 thou. of slop in the x axis then several years ago when I first set up the machine and so I will be pulling the cross slide of to see what is happening. I really don't think this is in the ball screw but we'll see.


The thrust bearings for the screw are the other likely place to look, but perhaps it is just a general "lathe thing"? Boring bars do tend to deflect on manual lathes, and there is no reason to expect a CNC lathe to be different.
If the same size final cut gives a different finished size on one component than another, though, it might be a sign of something slipping. Backlash or slop would be expected to be consistent, you can make consistent parts with a sloppy leadscrew on a manual lathe, after all.

Given that the machine is running with stepper motors I would be considering the possibility that the motors might be losing steps, perhaps due to over-aggressive acceleration numbers. This better fits the randomness you are hinting at. One way to check might be to home the machine and MDI a move to a particular diameter then measure a convenient distance between parts on the cross slide. Then run some parts, repeat the MDI move (in the same direction, ie manual lathe practice) and see if the distance measures the same. If it doesn't then I would very much suspect loss of steps or a slipping pulley rather than a backlash problem.

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05 May 2015 23:45 #58408 by canner
Andy,

Thanks for the suggestion of items to check, I also had some concern about missing steps and it still could be this. I did make some efforts to check for missed steps by homing the machine, setting a dial indicator and running a part then rehoming. X and Z came back within 5/10ths and read the same location in linuxcnc. I believe that initially this indicates that I am not missing steps but I need to look at this a lot more to be sure.

I am busy with other work here for a few days but will be able to get back to the lathe later in the week. Thanks

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05 May 2015 23:53 #58411 by andypugh

I did make some efforts to check for missed steps by homing the machine, setting a dial indicator and running a part then rehoming.


That sounds like a test equivalent to what I suggested, so it sounds like lost steps isn't the problem.

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01 May 2023 16:39 - 01 May 2023 16:39 #270412 by The Feral Engineer
did you ever get this machine to work with the DR8010 drives? What motion card did you use? Do you have any wiring information for step/dir?
Last edit: 01 May 2023 16:39 by The Feral Engineer. Reason: subscribe

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