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Author Topic: run amuck on STOP  (Read 5239 times)

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run amuck on STOP
« on: October 21, 2006, 12:11:31 AM »
On several occasions, I have noticed that the CNC will move to some random position when I push the stop button.  A few of the times it did not lift the bit to the safe travel height and broke the bit. I have not seen the "Feed Hold" do this, and whenever I do a feed hold first, the stop acts correctly. I feel that this only happens while cutting an arc or circle. Today, it lifted the bit and moved the Z-axis to the positive limit, and Y-axis went to zero. I don't know to reliably repeat this effect. It is not unique to the current version.

Any ideas?

Re: run amuck on STOP
« Reply #1 on: October 21, 2006, 05:10:32 PM »
That is new.. i never hit stop because you will loose steps... could you post a file is giving you trouble and tell me where you hit stop?

Thanks
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Re: run amuck on STOP
« Reply #2 on: October 21, 2006, 09:41:39 PM »
This is a play/learning file, and I was engraving (v-bit) in scrap material. This is approximately the same file except that the DOC was 0.075. It was cutting the last inside letter loops when I aborted the cut by pressing stop. The bit took off for about X6 and Y0.  I couldn't tell if Z moved first to the fast plane or moved with X and Y. I just noticed that there are almost no curves in it, just lots of quick vector changes. I wonder if one interrupt is interferring with another.
Good luck.
Bill
Re: run amuck on STOP
« Reply #3 on: October 24, 2006, 11:11:42 PM »
You need to press "FeedHold" and Mach3 will not miss steps when it stops :)

Thanks
Brian
Fixing problems one post at a time ;)

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Re: run amuck on STOP
« Reply #4 on: October 25, 2006, 12:08:15 AM »
My primary concern is not losing steps, it is moving the bit to a safe height and stopping the motor (I can always back up to a predictable starting point). Problem is that the motor does not always go to a safe height and regularly moves to an unpredictable(??) x and y position, which I consider very dangerous (not to mention it breaks tools). I have a second file that while drilling the first hole will gump to X0.3635 Y0.2500 and Z0.000 on about every 4th stop. This position is not a safe directly above the hole (safe is set to 0.25 inch). Interestingly enough, the bad position is always the same for this file. And it looks like Y got the safe height value instead of Z, and It looks as though X got Y's value.

Thanks.
Bill

Re: run amuck on STOP
« Reply #5 on: October 25, 2006, 11:36:52 PM »
Okay...
What are you doing STEP BY STEP....

1. Start load the file
2. move the machine to the start position
3. Press Cyclestart
4.??????????????? I have no idea what you are at this point. Are you pressing the Esc key? Are you pressing Stop? Are you pressing FeedHold?


Thank you, this will help :)

Brian
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com
Re: run amuck on STOP
« Reply #6 on: October 26, 2006, 11:15:46 AM »
Brian,
The problem is fairly easy to reproduce with the file. Since, during a test, I am not cutting any real material and the movement is not large, it is pretty safe to do live, and I watch the motion of the head. The pattern cuts several shallow holes using multiple passes for each hole. I don't press ESCAPE or FEED-HOLD in this procedure. I am currently using a touch screen to press the buttons, but have observed this problem using a PS2 mouse. I do not have a hardware START and STOP.

1) I load the G-Code, zero X, Y, & Z near the center of the table, touch REWIND, touch GOTO-Z, and touch START
2) I then wait until cutting a circle and touch STOP (on the screen)
3) if the error is not observed, I press START (I don't bother restarting the motor or repositioning anything) and then repeat step 2. 

I was able to get it to fail about one of every four tries, and never had to let it go on to the second hole.
The PC is a 500MHz 1999 vintage machine running XP-home. My 1.8GHz laptop was able to do the same thing.
I am running Mach3 2.0.1i on both.
Thanks.
Bill

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Re: run amuck on STOP
« Reply #7 on: October 27, 2006, 11:12:28 AM »
Bill:

 Hadnt heard of that one. Sounds related to Safe_Z settings. Ill run some tests..
Art

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Re: run amuck on STOP
« Reply #8 on: October 27, 2006, 11:18:00 AM »
Bill:

 Does this ever happen the first time you hit stop? You are not permitted to hit start again after hitting stop, you can do that if in a linear move, but hitting start after hitting stop can terrible screw up and arc, because the current position is not appropriate for the arc your about to command when you hit start again. For example, if you have an arc startiing at 0,0 and the arc command is
G2X10Y10R5 , then if you hit stop halfway through, then pressign start again will recall the command G2X10Y10R5, but your not at the correct start position for that move. Hitting stop is a termination of the program..period. You canot restart unless you KNOW your in a position that is legal for the Gcode to do so. Feedhold will remeber where it is IN the arc, so you can restart, but Stop means Stop..no restarting allowwed unless you KNOW the current position is OK for the next Gcode line..

Art
Re: run amuck on STOP
« Reply #9 on: October 27, 2006, 11:18:24 AM »
Bill,
Stop is not what you should be doing.... Use Feedhold and tell me  if you have trouble. Feed hold is a Pause and Stop is if you are going restart the file from the start... I think that the stop button shoulf rewind the file :) ( that is what I have on my system) Stop should only be used IF you are in a feed hold OR at a tool change to kill the running of the file

Thanks
Brian


Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com