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Author Topic: How to resume after G code is stopped safely - problem  (Read 4878 times)

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Re: How to resume after G code is stopped safely - problem
« Reply #10 on: January 19, 2018, 01:38:03 PM »
A few things you could try to eliminate the problem and negate the work-around.

Adjust the speed/feed rates  (power permitting)
Generate chips instead of a bird nest.
More appropriate tooling (2 flute ?)
Pilot hole ?
Change drilling strategy (peck)

Similarly: If turning the OD and stalling the spindle, I'd adjust the doc, feed and speed appropriately to match the machines capabilities instead of the approach you are taking.

Kind regards,
Russ
Re: How to resume after G code is stopped safely - problem
« Reply #11 on: January 19, 2018, 04:06:16 PM »
A few things you could try to eliminate the problem and negate the work-around.

Adjust the speed/feed rates  (power permitting)
Generate chips instead of a bird nest.
More appropriate tooling (2 flute ?)
Pilot hole ?
Change drilling strategy (peck)

Similarly: If turning the OD and stalling the spindle, I'd adjust the doc, feed and speed appropriately to match the machines capabilities instead of the approach you are taking.

Kind regards,
Russ

Hi Russ, yes this is work around what you suggest, even how I bore holes like this is work around how I initially started, I bore 8.5 mm pilot hole and used carbide boring bar to increase inside bore, and I was stalling spindle because of chips built inside of hole which is deep. So I changed strategy, made spindle overload protection about I talked in topic to protect tools.  So in video that is possible to see I already bore 8.5 mm pilot hole, then bored 12 mm hole with 4 flute endmill and after that bore with 4 flute 14 mm end mill. I am using peck drilling, I even made pauses where after few peck I  clean end mill. So machining process is not problem for me, problems is that I ran complicated programs then this from example and saw that weird things are going on when I pause feed or stop program and I want to continue where I stopped. As it all develops pretty fast in front of screen you are not sure did you think that something is going on strange or you just think that you made it up and probably everything is Ok. So just to be on safe side I rewind program in most cases and start from zero and that means spending lot of time cutting air. So now when I finally mange to see on simple example what is going on I am trying to figure out is it possible to make something in mach 3 in order to solve that problem or I will edit post processor to generate feed value for every G01 command (which I still did not mange to do).

My machine have 1.5 kW motor , originally it was around 4 Kw motor  but when I bough machine it came with 1.5 kw so I left it , so motor could be stronger but that is not what interests me, I am asking about software solution of problem if it exist. Anyway thank you for help, and yes I have also bird nest and they prevent coolant to get inside deep in hole,so this is why I made also spindle protection system. When I turn OD I can use higher RPM and motor then have more torque so there I do not have problems.
Re: How to resume after G code is stopped safely - problem
« Reply #12 on: January 19, 2018, 04:24:13 PM »
FYI Nobody watches a 36 minute video.
« Last Edit: January 19, 2018, 04:25:56 PM by wmgeorge »
Retired Master Electrician, Commercial HVAC/R Service and lots of Hobbys.
Re: How to resume after G code is stopped safely - problem
« Reply #13 on: January 19, 2018, 04:31:27 PM »
Hi zmajmr.
I hope you find the solution that works for you. Mach3 "is what it is" and will never be troubleshot or developed further.
I'm sorry I can't help you with that part.

I did not notice the peck in your video.
Maybe you could try a peck with full retract cycle in order to keep the tool and the bore clean ?
All I can offer is various machining strategies.
Regards,
Russ
Re: How to resume after G code is stopped safely - problem
« Reply #14 on: January 19, 2018, 04:45:19 PM »
FYI Nobody watches a 36 minute video.
I assume that majority will not watch 36 min video, I posted 4 minute video before that 36 min and i conclude even 4 minute is to long concluding from what I can read in topic, but if somebody will have or will be aware of problems like I do maybe it will watch 36 min video, 4 min video is part from 36 min video where I basically talk about all what is written here. I also do not watch videos about thing that do not interests me but if video is about that will solve my problems I will watch it FYI.
Re: How to resume after G code is stopped safely - problem
« Reply #15 on: January 19, 2018, 05:02:12 PM »
Hi zmajmr.
I hope you find the solution that works for you. Mach3 "is what it is" and will never be troubleshot or developed further.
I'm sorry I can't help you with that part.

I did not notice the peck in your video.
Maybe you could try a peck with full retract cycle in order to keep the tool and the bore clean ?
All I can offer is various machining strategies.
Regards,
Russ

Hi Russ one more time, I know that Mach 3 will not be developed further because Mach 4 exist, I was trying to find out do I wrote something in wrong format (I am talking about Gcode) so that is maybe  reason why is this happening or is it possible to edit something in Mach 3, some function by me, something I do not know, that is it, mainly I was expecting to hear what I could do software wise.  You are right you probably did not see end mill how it goes in and out because I remove it out of tool changer for testing purposes but If you read G code from example you will see that starting point is Z = 1 mm and endmil enters 3 time out of part untill it rich full depth.
Will try to edit postprocesor from CAM that I am using to generate  G01 together with Feed value and will use Mach 3 like that, main thing that everything work as I expect, more letters on screen will not hurt me or my computer :) Will make short video about drilling hole.
Re: How to resume after G code is stopped safely - problem
« Reply #16 on: January 19, 2018, 06:18:35 PM »
If you are fixed on a sw solution so be it ... I wish you all the best.
 
IMO, your 25mm (+/-) peck depth is a bit excessive considering the results you are experiencing.
That's producing a BIG birdnest between each retract.
Drilling 75mm (+/-) deep might perform better with more frequent pecks.

Just something I would experiment with.
Good luck to you, my friend,
Russ

Re: How to resume after G code is stopped safely - problem
« Reply #17 on: January 19, 2018, 06:58:04 PM »
If you are fixed on a sw solution so be it ... I wish you all the best.
 
IMO, your 25mm (+/-) peck depth is a bit excessive considering the results you are experiencing.
That's producing a BIG birdnest between each retract.
Drilling 75mm (+/-) deep might perform better with more frequent pecks.

Just something I would experiment with.
Good luck to you, my friend,
Russ



Hi, here is video , just to get idea how I drilled until I figured out how many pecks is needed and until I decide to add 15 seconds pauses after every peck with 14 mm (there is no pauses shown in video) end mill so I can clean long chips from end mill and also , I show "system" and example where it is possible to see how it stopped boring operation safely.

https://youtu.be/b6eO-k6hoyw

After every attempt I improved something until I got G code where nothing will be stalled, I only need to clean chips from end mill and like I said I add feed information with every G01 but manually (so just in case "system" is triggered I can contine from where I stopped) , so will try to make to postprocessor do that instead of me. When you make holes wit endmill, endmill need to be aligned pretty good with axis of spindle otherwise is chatters , so when you remove it in and out until it gets in contact with material it makes nasty sound so less pecks better for my ears , this is why I only have 3 pecks, for pilot hole with 8.5 mm drill which is not shown in video I have 26 pecks, but I was not concentrating on machining process so this is why there is no all that in video, I also cut of out of video those noises to save your ears :)
Anyway thx to all you guys for help, if I manage to make post processor to "spit" code as I want that will be next video.
Re: How to resume after G code is stopped safely - problem
« Reply #18 on: January 19, 2018, 07:36:16 PM »
Zmajmr,
What you want is to do something wrong and the machine will gracefully stop and let you try again?  Hitting the Stop button, not E-stop while any axis is moving looses position. It may be a small amount if your machine is slow and you don’t notice it. My machine travels quite fast and no way I can recover from a Stop push, but no problem with feed hold. So lets work on your skills.

When drilling a hole almost any depth always use a peck until you know how the material reacts. The CNC can’t that you can drill 3 holes and will suddenly wrap the chip. A peck is a chip breaking technique that is why it is there.  

When opening up a hole you drilled using a boring bar try pecking that too. Going from a 1/2” drilled hole to a 1” hole x 2” deep, do it in 1/4” pecks leaving a little for a full depth finish pass.  This will keep the chips from packing.  The part will be stiffer for each cut and may reduce chatter.

When you program a part set your feeds higher than you think you need. Mach 3 feed overide goes up only 250% but it can go down 20 to 1 to 5% with no problem. Then always start with the overide way down and increase it until it is cutting properly.

The faster you can feed the better. Not only do you get done faster but tool life goes up to. That happens because the cutting edges pass through the material less time. A heavier cut also helps to break the chip. If you haven’t broken any cutters by feeding too fast you should. You will likely be shocked how far from too fast you really are. I had a slotting job in steel that was 1/3 done and had worn out 3 end mills. Pushing the feed way up finished the job in half the time using one endmill.
Re: How to resume after G code is stopped safely - problem
« Reply #19 on: January 20, 2018, 05:42:04 AM »
Zmajmr,
What you want is to do something wrong and the machine will gracefully stop and let you try again?  Hitting the Stop button, not E-stop while any axis is moving looses position. It may be a small amount if your machine is slow and you don’t notice it. My machine travels quite fast and no way I can recover from a Stop push, but no problem with feed hold. So lets work on your skills.

When drilling a hole almost any depth always use a peck until you know how the material reacts. The CNC can’t that you can drill 3 holes and will suddenly wrap the chip. A peck is a chip breaking technique that is why it is there.  

When opening up a hole you drilled using a boring bar try pecking that too. Going from a 1/2” drilled hole to a 1” hole x 2” deep, do it in 1/4” pecks leaving a little for a full depth finish pass.  This will keep the chips from packing.  The part will be stiffer for each cut and may reduce chatter.

When you program a part set your feeds higher than you think you need. Mach 3 feed overide goes up only 250% but it can go down 20 to 1 to 5% with no problem. Then always start with the overide way down and increase it until it is cutting properly.

The faster you can feed the better. Not only do you get done faster but tool life goes up to. That happens because the cutting edges pass through the material less time. A heavier cut also helps to break the chip. If you haven’t broken any cutters by feeding too fast you should. You will likely be shocked how far from too fast you really are. I had a slotting job in steel that was 1/3 done and had worn out 3 end mills. Pushing the feed way up finished the job in half the time using one endmill.

Hi , thx for post, I do not claim that I do know everything about machining but I understand lot of things that you wrote but as I wrote my machine (cnc lathe have 1.5 Kw motor for spindle motor instead original 4 Kw motor, so even with this what I am doing I am pushing my machine).

So just to try to explain what is the problem for me, lets ask our self first one things , is this what will follow next legit G code that Mach 3 can "understand" , maybe somebody see something that I do not see:

N20 G21 G18 G64 G80 G90 M48 G90.1 G40 G49
N30 M08
; TOOL definition
N50 T0909
N60 G00 X0.0 Z10.0
N70 G49
N80 ( End Mill  12mm Dia )
N90 T0202
N100 G00 X0.0 Z5.0
N110 G97 S1000
N120 M04 G94 F40.0
N130 G00 Z1.0
N140 G01 Z-24.633
N150 G00 Z1.0
N160 Z-23.633
N170 G01 Z-49.267
N180 G00 Z1.0
N190 Z-48.267
N200 G01 Z-73.9
N205 S300 F300
N210 G01 Z1.0
N220 M05 M09
N230 M30

I will try to explain it by words, select tool number 2, position that toll in Z axis with coordinate Z=5 mm , set Spindle RPM to 1000, set spindle direction to M4, set Feed to 40 mm/ min, from there go with rapid feedrate to Z = 1 mm. From point Z= 1 mm start to drill hole with feed 40 mm/ min , go till coordinate Z =Z-24.633 mm, after that retract with rapid feed rate to Z = 1 mm and so on...

So in my opinion it is legit G code that Mach  3 can understand (I believe).

Now lets focus (I mean really hard :)) "go till coordinate Z = Z-24.633"  or originally written N140 G01 Z-24.633 and let imagine that I pressed Feed hold button in Mach3 (I could pressed E stop or Stop file but I decided on purpose to press Feed hold check 4 min video if you do not believe me https://youtu.be/VSHC9O4CVrA).

Now, let ask our self what we expect with which feed will machine continue to move after we press Cycle start button?

Options available : a) F =40 mm/min
                         b) rapid feed rate
                         c) F = 300 mm/min
                         d) something else

Anwser is......................





b) + c)  (rapid feedrate , and then F = 300mm/min)



And my question is why?

Please look where is F = 300mm/min written in G code, and try to count how many times there is G01 command before you get to command
N205 S300 F300


To be honest I never experienced that machine lose position after I press Stop file, I have toolchanger as Y axis so I would notice that something is strange, tools would be unlocked, x axis needs to be on x=0 when I drill, so I would notice there also that something is strange, and when I am drilling I use Feed 40mm/min so there no reason in my mind to lose anything.

Thing is if you watch my 4 min video that I would lose my tool ,I would jam it with 300 mm/min inside part that I am trying to drill  or in better case I would just push part inside of chuck and score surface of part, .

I appreciate all comments but I have feeling like I asked question on Practical Machinist forum and not on Mach 3 forum , just little joke :)

« Last Edit: January 20, 2018, 05:53:44 AM by zmajmr »