Hello Guest it is August 23, 2019, 05:33:58 AM

Author Topic: strange behaviour / offset  (Read 6753 times)

0 Members and 1 Guest are viewing this topic.

strange behaviour / offset
« on: September 16, 2012, 01:56:47 PM »
I have a JCUT CNC with the USB interface.

from time to time, I get the machine not going to the requested coordinates input in g code. for example if I do z50, it may go z51. this happens very little but in the middle of long machining this is a big pb (see pics).

mach 3 shows the right coordinates. If I pause the machine and start again then if catches back the right coordinates.

any idea?

Offline Hood

*
  •  25,849 25,849
  • Carnoustie, Scotland
    • View Profile
Re: strange behaviour / offset
« Reply #1 on: September 16, 2012, 05:01:01 PM »
If Mach is showing the correct position then it is likely an issue with the JCut plugin or hardware.
Hood
Re: strange behaviour / offset
« Reply #2 on: September 16, 2012, 11:52:41 PM »
hep...I am thinking of that UAB being the pb... I got few times USB link crash.

also crash are random. was using mach 3 with parallel interface on a previous machine and never got such pb...

which breakout board would you guys recommend to me?

I have 3 axis to drive, 3 home switches, one vfd spindle.

Offline Hood

*
  •  25,849 25,849
  • Carnoustie, Scotland
    • View Profile
Re: strange behaviour / offset
« Reply #3 on: September 17, 2012, 02:49:56 AM »
I would say either look at the CSMIO-IPM or a Ethernet SmoothStepper.
The SmoothStepper would also require at least one breakout board and I think the PMDX ones are hard to beat, you would also need a spindle controller.
The CSMIO would just require the extra connection kit they sell as it already has analogue outputs to control a spindle..
Hood
Re: strange behaviour / offset
« Reply #4 on: September 17, 2012, 03:13:39 AM »
I have this driver.

http://www.leadshine.com/ProductList.aspx?Type=9

the CSMIO-IPM looks good to me. I guess it would just work fine with the driver. correct?

Offline Hood

*
  •  25,849 25,849
  • Carnoustie, Scotland
    • View Profile
Re: strange behaviour / offset
« Reply #5 on: September 17, 2012, 03:38:50 AM »
That page covers quite a few drives but as long as they are Step/Dir capable then they will work fine with either CSMIO or ESS.
Hood
Re: strange behaviour / offset
« Reply #6 on: September 25, 2012, 05:03:11 PM »
hi,

just received the Ethernet card as recommended.

my dirvers are leadshine:
http://www.leadshine.com/UploadFile/Down/MA860Hm.pdf

on the USB card I used to have, puls+ and dir+ connected together to Vcc.

on the new CSMIO I have output pin for Dir+/Dir- and Pulse+/Pulse- this is why I do not see how it can be...

The overall machine stability is ok and repositionning sound ok.

when running 10hrs project, I found out that Z would go up sd machine (very slighty but after 10hrs I have about a Cm difference)

How shall I perform the connection? shall I insert the recommneded resistors?
« Last Edit: September 25, 2012, 05:10:28 PM by Overloaded »

Offline Hood

*
  •  25,849 25,849
  • Carnoustie, Scotland
    • View Profile
Re: strange behaviour / offset
« Reply #7 on: September 25, 2012, 05:42:07 PM »
You have differential outputs on the CSMIO/IP-M and your drives can accept differential Inputs have a look at this document and connect as per the differential input diagram.

You could if you wanted connect single ended, if you did then you would not need resistors as your signals are 5v, the drive manual states you only need a resistor for voltages higher than 5v.

However as you have differential signal output from CSMIO and Differential inputs on your drive you would be much better to use them as they are much more noise immune and will give you less problems than connecting single ended.


http://www.cs-lab.eu/en/upload/pdf/CSMIO_IP%20EN%20differential%20outputs_rev2.pdf

Hood
Re: strange behaviour / offset
« Reply #8 on: September 26, 2012, 04:42:55 AM »
I actually did connected the inputs in differential mode and for some reason that I can not understand, I am getting some issue with the Z axis that loose it's position toward the +.

I did a test as follows: up and down at 4000mm/min for 15 min and it comes back perfectly. however when I launch my milling code for the part, after few minutes it is already offset by few mm.

on x and y, there is no position loss, only on Z.

the stepper in x and y are setup a 10000 steps per rev and the z to 5000 steps per rev which bring all of them at 1000 value in motor setup. I put acceleration to 350mm/s2 which seems fine.

kernel speed (not sure that it affect anything with the RJ45) is set at 100khz.

any clue on what is going on?

hope we can solve this crazy situation...

Offline Hood

*
  •  25,849 25,849
  • Carnoustie, Scotland
    • View Profile
Re: strange behaviour / offset
« Reply #9 on: September 26, 2012, 07:03:14 AM »
What is in your code, is it faster than the previous 4000mm/min commande speed you did?
Hood