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Author Topic: Softlimits  (Read 43774 times)

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Softlimits
« on: July 29, 2006, 12:45:56 PM »
Hi

I've noticed that the soft limits work brilliantly when jogging the machine around, I've got them set so they slow the axis right down before stopping just before the limit switch but when I ran a program the soft limit still work but no longer slow the axis down before it reaches the soft limit allowing it to carry on far enough to trip the machine out on the limit switch. Am I doing something wrong or do they all do that?

I'm very new to Mach 3 and have only just set my machine up to work with Mach 3 so please excuse me if my question is a bit silly.

Cheers

Chris

Hood

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Re: Softlimits
« Reply #1 on: July 29, 2006, 02:55:45 PM »
Hi Chris, great to see you here. Not sure if I can help you with your question as I cant remember whether the slow down happens when running code and my mill is not handy to test it out. One thing you could do however is make your soft limits a few mm in from the physical limits, obviously its not ideal but it may help for the time being.
Hood
Re: Softlimits
« Reply #2 on: July 29, 2006, 04:51:01 PM »
Hi Hood

I tried putting the softlimits a little away from the limit switches and while it does stop it going into overtravel the motors don't seam to like it, it sounds like they hit the end of the ball screw (a real loud thud), I would much prefer them to deaccelerate as they do when jogging, thought there would just be a tick box somewhere that I had missed.

Cheers

Chris

Hood

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Re: Softlimits
« Reply #3 on: July 29, 2006, 05:04:53 PM »
Now you come to mention it I seem to recall the "thud" sound , so maybe the slow zone is only active in jog. Dont really think it will harm the motors just it doesnt sound too good and the same would happen if it hit the physical limits anyway. Best thing to do is once you have your zero position set and your code loaded change the display mode to table view and you should see whether you will be near any of your limits.
Hood
Re: Softlimits
« Reply #4 on: July 29, 2006, 06:18:51 PM »
Yeah, I've got my display mode on table view but you can't see the Z axis which is the one that is most likely to go past the limits.

Like you say I don't think it will do the motors any harm but I guess it will lose steps when this occurs which I thought was the reason for having softlimits.

Cheers

Chris

Hood

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Re: Softlimits
« Reply #5 on: July 29, 2006, 06:22:37 PM »
table view should show the Z as well, you just need to use your mouse to skew the toolpath window. Dont think the motors will loose steps as the thud is surely them stopping abruptly and Mach will be at the same position. If I remember I will test this out tomorrow as I have glass scales fitted to my mill and I will be able to see if there is any discrepancy between them and mach.
Hood
Re: Softlimits
« Reply #6 on: July 29, 2006, 06:46:43 PM »
"table view should show the Z as well, you just need to use your mouse to skew the toolpath window" Oh I, didn't know that, thanks

Just had another idea is it possible to slow the feed down when a switch is triggered as there is already a switch mounted and wired up for this very purpose that the original control used when homing the z axis (Bridgeport Boss). It used to rapid travel up to this switch then slowly feed up onto the home\limit switch.

Cheers

Chris

Hood

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Re: Softlimits
« Reply #7 on: July 29, 2006, 06:51:52 PM »
Dont think so, but I am fairly new to mach so there might be, maybe Brian or someone else will know for sure.
Hood
Re: Softlimits
« Reply #8 on: July 29, 2006, 07:12:02 PM »
Alright thanks again.

Just been looking at what you said about it showing the z axis, I notice it doesn't take into account of the the tool length offsets so it doesn't really help but thanks for trying.

Cheers

Chris
Re: Softlimits
« Reply #9 on: July 29, 2006, 08:10:38 PM »
I think we should add in code to look and see if the machine can run the program :) We Know if it is not going to fit..

That would take care of the thud  ;D
Fixing problems one post at a time ;)

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