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Author Topic: Feed hold, am i using it correctly?  (Read 4227 times)

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Offline Davek0974

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Feed hold, am i using it correctly?
« on: February 10, 2014, 10:10:59 AM »
I'm trying to figure out how to temporarily stop a program running on my plasma table.

I know all about the big red button but that's not ideal if i just need to pull a tip-up out the way etc.

I have tried the Feed-Hold (space bar) feature and it does stop it running but as soon as i hit cycle start to get going again, it just raises the Z-axis into the soft-limit and all action stops.

Am i thinking of the correct method or can you not simply hold a program.

I have my z-limit at the top and I'm using soft-limits as well and G31 for the height probe on my floating head.

Thanks
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Hood

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Re: Feed hold, am i using it correctly?
« Reply #1 on: February 10, 2014, 10:54:59 AM »
You seem to have a safe Z set up and have it incorrectly set by the sounds of it.
Do you home the Z axis?
Hood

Offline Davek0974

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Re: Feed hold, am i using it correctly?
« Reply #2 on: February 10, 2014, 01:51:37 PM »
Yes I home all three axes, unless it's a default, I can't remember setting a safe z axis??

Dave
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Hood

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Re: Feed hold, am i using it correctly?
« Reply #3 on: February 10, 2014, 02:26:03 PM »
Config menu then Safe Z Setup,  see if you have it enabled.
Hood
Re: Feed hold, am i using it correctly?
« Reply #4 on: February 10, 2014, 04:58:28 PM »
Feed hold doesn't work right in most versions of Mach. Ver .066 is the worst release ever and should be avoided. Hopefully Mach 4 will fix the many long standing problems with Mach 3. Then again.... it's questionable at this point if Mach 4 will ever be released. 

Offline Hood

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Re: Feed hold, am i using it correctly?
« Reply #5 on: February 10, 2014, 05:06:38 PM »
Never had an issue with feedhold myself, then again if I use it and move away I tend to restart with a RFH at a suitable point. If I just feedhold and dont move then I just resume with Start.
066 however does have issues although I have never heard FeedHold being one.
Hood
Re: Feed hold, am i using it correctly?
« Reply #6 on: February 10, 2014, 05:24:48 PM »
Well... Feed hold is just that, "Feed Hole" I assumed. I found out the hard way it doesn't really work the way it's suppose to work. In my experience issuing a "Cycle Start" after a "Feed Hold" command caused the Z to move to home then X & Y would get out of sync. Result= a junk part and broken tool bit for the recycle bin.  I fooled around with most versions of Mach... all the same results. Now I use a "Stop" then "Start" which works as designed. The program continues from where the "Stop" was issues. 

Offline Hood

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Re: Feed hold, am i using it correctly?
« Reply #7 on: February 10, 2014, 05:27:53 PM »
If you press Stop when you have axes in motion then you risk losing position, unless of course you are using a controllers such as the CSMIO/IP-A as the positioon is updated from the encoders.
But if it works for you then fine :)
Hood

Offline Davek0974

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Re: Feed hold, am i using it correctly?
« Reply #8 on: February 11, 2014, 03:46:58 AM »
Config menu then Safe Z Setup,  see if you have it enabled.
Hood

Well it was set to zero in m/c co-ords which should have been ok but i set it to -25 just to be sure.

Makes no difference, it pauses ok but when restarted it just lifts the Z into the upper soft-llimit and sits there, pressing start again simply starts the cut with the Z at top-zero position!

When the pause is pressed, why can't it..
1 - Store the current parameters - X, Y, Z, Torch status etc
2 - Stop at the end of the current line
3 - turn the torch off
4 - Lift the head
5 - wait

When resume is pressed...
1 - Return to the last X, Y position
2 - Lower the torch and detect z position again,
3 - Turn the torch on
4 - Resume cutting at the last coordinates

Obviously there will be a bit of plasma muck where the torch was turned off / on but seems a reasonable tradeoff for stopping mid-cut????
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Davek0974

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Re: Feed hold, am i using it correctly?
« Reply #9 on: February 11, 2014, 03:48:32 AM »
Ver .066 is the worst release ever and should be avoided.

That's the one I'm running ??????
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives