Hello Guest it is May 08, 2021, 10:31:09 PM

Author Topic: Getting small movements which not supposet to..  (Read 21331 times)

0 Members and 1 Guest are viewing this topic.

Re: Getting small movements which not supposet to..
« Reply #20 on: May 31, 2013, 07:24:14 PM »
How do I tell if G95 has been output? will it show in the first line of the Gcode?

"What you have above is for every revolution of the spindle the axis will travel 800mm.
 When doing feed per rev it will be a fraction of a mm you want your feed set too,  as I mentioned in my previous post."


so are you suggesting to change all 800mm/rev to 0.35mm/rev?, like this:



Offline Hood

*
  •  25,838 25,838
  • Carnoustie, Scotland
    • View Profile
Re: Getting small movements which not supposet to..
« Reply #21 on: June 01, 2013, 02:44:54 AM »
That programme has a very unusual strategy for calling feeds. Normally you would just have a feed to call and the programme would do all non-cutting and non-approach moves automatically as rapids. You don not seem to have that choice as such, you have the choice of rapids for Tf but not the others. You can obviously put a high value in them and Mach will treat them as rapids though.

Anyway I would suggest you try 0.3 Af, Ef, Cf, and Rf and possibly have large numbers entered for Pf and Df and leave Tf as Rapid.
Make sure you cut air for the first time to make sure it is working as expected.

Also the code needs to have a G95 near the beginning and it will also be a good idea to change Mach to default to G95, that is done by adding G95 to the Initialisation string on the General Config page of Mach. If your post processor does not put out G95 then it would be a good idea to get it to do so, that could possibly be done by you or if you dont know how to edit the post processor in your CAM then ask the vendors to do it for you.

Hood
Re: Getting small movements which not supposet to..
« Reply #22 on: June 03, 2013, 05:54:51 PM »
Sorry for the late reply.
As I was testing the code, the Z axis belt came off, still fixing it, will probably re-design the Z a xis motor mount.
I tried 0.35 mm/rev, but it was a bt too slow, then changed it to 100mm/rev which seemed to be ok.

Offline Hood

*
  •  25,838 25,838
  • Carnoustie, Scotland
    • View Profile
Re: Getting small movements which not supposet to..
« Reply #23 on: June 03, 2013, 06:00:24 PM »
You were obviously not in Feed per Rev mode (G95) or 100mm/rev would not be slow ;)
If that was the case then the axis would travel 100mm for each revolution of the spindle.

One thing I should ask, do you have an index pulse set in Mach so you can read the spndle speed?
Hood
Re: Getting small movements which not supposet to..
« Reply #24 on: June 03, 2013, 10:04:09 PM »
One thing I should ask, do you have an index pulse set in Mach so you can read the spndle speed?
Hood

I don't think so, is the Index Pulse set in General config?

Another thing, when you said : If that was the case then the axis would travel 100mm for each revolution of the spindle.

100mm for each revolution of the spindle, it sounds like the spindle is synchronise with the X and Z axis, is it?, cos currently the AC servo spindle is in speed mode. I'm thinking to add it to A axis for threading when all systen is stable.

Offline Hood

*
  •  25,838 25,838
  • Carnoustie, Scotland
    • View Profile
Re: Getting small movements which not supposet to..
« Reply #25 on: June 04, 2013, 02:55:33 AM »
The index pulse would be input to Mach on an input pin then you would tell Mach which pin by setting that up in Ports and Pins, Inputs.
If you do not have an index connected then that may well be your issue with the very slow feedrate, if you have "Use Spindle Feedback in Sync mode " chosen then Mach will not see the index so will not feed very fast. If you go to Config menu, Ports and Pins, then Spindle Setup you will see that option top right.

If you do have an Index input and you tell Mach to use it in sync mode then the axis will not be truely synchronised with Spindle. What will happen is each time a feedrate is called Mach will look at the true RPM and feed accordingly. If however the spindle speed drops/increases (spindle override or due to load) then the axis will not change its rate until a new feed is called, only then will it look again at the true spindle speed and adjust the feed accordingly.
Hood

Hood
Re: Getting small movements which not supposet to..
« Reply #26 on: June 04, 2013, 12:41:53 PM »
Ah! I get it. So this is what Index about:
http://tetralite.com/lathe/spinsensor.html
Basically add an encoder to the spindle, but since my spindle is driven by an AC Servo Motor can't I use the signal from the AC servo encoder as feedback or do I still need to add those sensors at the back of the spindle?

Offline Hood

*
  •  25,838 25,838
  • Carnoustie, Scotland
    • View Profile
Re: Getting small movements which not supposet to..
« Reply #27 on: June 04, 2013, 01:22:38 PM »
If you are using the parallel port then the encoders index will be too short, you would either have to electronically stretch it or use similar to your link. If you are using an external controller then likely it will be fine with the Index from the encoder.
Hood
Re: Getting small movements which not supposet to..
« Reply #28 on: June 05, 2013, 10:53:40 PM »
I decided to use an encoder for Index pulse and input to MAch3.
I have some spare Rotary encoders dunno if this is suitable for this application, encoder brand = Omron E6B2-CWZ6C




http://www.ia.omron.com/data_pdf/data_sheet/e6b2-c_ds_csm491.pdf

Other Rotary Encoder brands like US digital single ended have 5 pins, A,B, +V, -V and 1 index pin. For Omron I'm not quite sure if "out Z" is the same as Index in US Digital's encoder, any idea?



Re: Getting small movements which not supposet to..
« Reply #29 on: June 06, 2013, 01:27:15 AM »
Ok I think I found the answer for Z in cnczone. It is index pulse.