Emco PC turn 55 upgrade..

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19 Feb 2014 09:57 #43964 by jmelson

james-mech wrote: Hi Jon,
you are right - thanks. Quite a few possibles there on that search.

Am I right in thinking I can plug one of the vexta drivers into a mesa card combo and go from there?


thanks, J

Maybe. Some Super Vexta drives have a 1P/2P switch. One of those positions selects
the two inputs as a move reverse and move forward pulse, the other selects step
and direction. If they don't have a switch or jumper for that, then you need a little
gate circuit to convert step/dir to the 2P mode.

Jon
The following user(s) said Thank You: james-mech
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24 Feb 2014 20:03 #44121 by andypugh

jmelson wrote: Some Super Vexta drives have a 1P/2P switch. One of those positions selects
the two inputs as a move reverse and move forward pulse, the other selects step
and direction. If they don't have a switch or jumper for that, then you need a little
gate circuit to convert step/dir to the 2P mode.


The LinuxCNC software stepgen can do up/down pulse generation (also quadrature and user table). See the step_type modparam)
www.linuxcnc.org/docs/html/man/man9/stepgen.9.html
The Mesa card stepgens also support the three 2-pin modes and also (in master) user table-based patterns (see the step_type HAL parameter)
www.linuxcnc.org/docs/html/man/man9/hostmot2.9.html#stepgen
I had thought that the Pico cards could do the other step types too.

This seller in China seems to have "More than 10" Vexat drives:
www.ebay.co.uk/itm/321302774338
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15 Feb 2015 07:19 #55979 by james-mech
Did some tests with a logic analyser to check what was going on. Mesa card combo should work fine. No need to change drives or driver cards. I will update with details when done...

Cheers,
James
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15 Feb 2015 09:51 #55980 by jmelson

andypugh wrote: I had thought that the Pico cards could do the other step types too.

Nope, the choices are step/direction and quadrature (wave drive) output.
There is also a "Mariss mode" which causes direction to only change immediately before
a step pulse, to accomodate old Gecko pulse multiplier drives such as the
G210.

So, our Universal Stepper Controller does not have the CW/CCW pulse
option.

Jon
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16 Apr 2015 23:20 #57843 by james-mech
After a very long wait the mesa cards finally are delivered. Now to actually do something! More to follow.

Cheers,
James
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20 Apr 2015 10:12 #57921 by james-mech
Working! Two days chasing a non related hardware fault, one evening getting linuxcnc setup and my lathe running. Still got work to do tidying it all up and getting the tool changer/estop/spindle encoder properly integrated but basically its all there. Very happy!

Cheers, james
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20 Apr 2015 16:22 #57928 by andypugh

james-mech wrote: After a very long wait the mesa cards finally are delivereds


Hang on, surely Mesa didn't take a whole year to deliver the cards? (I just noticed the message dates)
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20 Apr 2015 16:53 #57929 by james-mech
Hi Andy
one year no, about 3 months yes... No idea why it took so long.

The easiest part of the machine conversion was actually doing it. Deciding what to do and gettting the parts took an age...

Just have to learn how to use linuxcnc properly now but I have a machine to play with so that should be fine.
Need to finish all the litttle bits off - tool changer, spindle encoder (i want to do threading) and keep playing with it.
For a desktop machine it seems quite capable.

Cheers,
James
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24 Mar 2016 00:43 #72075 by jcposada
I know this thread is almost a year old, but I was wondering if you would be willing to hold my hand through this conversion. I have the same machine in working condition, making chips using WinNC under Win98 and would love to move to PP.

I don't want to do a full electronics overhaul, but would gladly invest in a mesa card to make this work.

Any tips you can share?
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24 Mar 2016 11:04 #72085 by james-mech
Tips! Sure, the most important tip if its working, leave it alone and make parts.

If you want to learn something new, are into this sort of thing i.e. have no friends and like spending lots of time alone in your cellar get started :-)

I had some help from friends. It was moderately straight forward if you already have test equipment and time.
We almost completely rebuilt the machine. The only bits we did not touch really now need to be touched.

The mesa card will control the existing driver cards, just unplug the main controller.

Post pictures of your machine and give it a go. I will add info where I can and where necessary.

Cheers!
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