Feed rate on mach3

Mach3 and Mach4 questions, tips and topics can be posted here
Post Reply
D3workz
1.5 Star Member
1.5 Star Member
Posts: 37
Joined: Wed Jul 29, 2020 10:42 am

Feed rate on mach3

Post by D3workz »

Hi,

I need a clarification on something. Is it normal that on Mach 3 feed rate display, when a cut is running, the actual speed reads as if its struggling to keep an average of what I initially set it to be. Example lets say I set the speed 1000mm/min, when the cut initiates the feed rate would rapidly oscillate between let say 950 to 1050mm/min.

Is this normal?

Thanks

Dim
adbuch
6 Star Elite Contributing Member
6 Star Elite Contributing Member
Posts: 8598
Joined: Thu Sep 21, 2017 5:22 pm
Location: Tucson, Arizona
Contact:

Re: Feed rate on mach3

Post by adbuch »

This does not sound normal to me.
David
User avatar
djreiswig
4.5 Star Elite Contributing Member
4.5 Star Elite Contributing Member
Posts: 1929
Joined: Thu Nov 19, 2015 10:02 pm
Location: SE Nebraska

Re: Feed rate on mach3

Post by djreiswig »

Is this on a straight line cut or a cut with a lot of turns? If it's not on a straight path then it is probably trying to maintain speed, but can't due to the geometry.
2014 Bulltear (StarLab) 4x8
C&CNC EtherCut
Mach3, SheetCam, Draftsight
Hypertherm PM65
Oxy/Acetylene Flame Torch
Pneumatic Plate Marker, Ohmic, 10 inch Rotary Chuck (in progress)
D3workz
1.5 Star Member
1.5 Star Member
Posts: 37
Joined: Wed Jul 29, 2020 10:42 am

Re: Feed rate on mach3

Post by D3workz »

djreiswig wrote: Wed Mar 10, 2021 9:45 pm Is this on a straight line cut or a cut with a lot of turns? If it's not on a straight path then it is probably trying to maintain speed, but can't due to the geometry.
Hi.

I will triple check, but I am sure its un stable in very situation, even on straight cuts.

I wish to know, as in rare situations I get piercings that start not where they should, but the cut ends up being where it should! Its like having a weird 'lead in' cut until it arrives to its destination of the proper cutting path and executes the proper cutting of the part.(hope I explained well).

Can anyone figure out what can cause this?

Could this be from the fact that I am running 15us step pulse? (Shooting in the sky here)

Thanks

Dim
D3workz
1.5 Star Member
1.5 Star Member
Posts: 37
Joined: Wed Jul 29, 2020 10:42 am

Re: Feed rate on mach3

Post by D3workz »

One other information I should share after reading this yesterday https://www.machsupport.com/forum/index ... c=19117.10
Is that I am running G31 probing, piering height, pierce delay, torch on, and cutting height from the M3 macro. I even have script in the M5 macro. I cannot say I did not have issues, especially during probing, but lately I noticed that if I slow the Z axis movement, the problems I had became rare... As in I get a failed pierce after 250 or 300 pierces...

I thought I'd share this aswell, as maybe this could be part of the issue.

Thanks Dim
D3workz
1.5 Star Member
1.5 Star Member
Posts: 37
Joined: Wed Jul 29, 2020 10:42 am

Re: Feed rate on mach3

Post by D3workz »

HI again,

I took a short video, but I just realized that I cannot upload video clips :(...anyways I took some images from the video just so you can assess the feed rates. So here I was cutting one straight line and this keeps on thought out all the cuttings... there is no stabilization.

Is this normal?

Thanks

Dim
Attachments
6.jpg
5.jpg
4.jpg
3.jpg
2.jpg
1.jpg
adbuch
6 Star Elite Contributing Member
6 Star Elite Contributing Member
Posts: 8598
Joined: Thu Sep 21, 2017 5:22 pm
Location: Tucson, Arizona
Contact:

Re: Feed rate on mach3

Post by adbuch »

D3workz wrote: Thu Mar 11, 2021 1:22 am
I wish to know, as in rare situations I get piercings that start not where they should, but the cut ends up being where it should! Its like having a weird 'lead in' cut until it arrives to its destination of the proper cutting path and executes the proper cutting of the part.(hope I explained well).

Can anyone figure out what can cause this?
This can be caused by your torch starting to move before it fires. With the Plasmacam machines, there is a box to check for "Wait for signal before moving". Perhaps your software has something similar. Also make sure you have entered a "Pierce delay time" sufficient for the material you are cutting and your plasma cutter. For Hypertherm, the mechanized cut charts list the pierce delay time for different materials and thicknesses.
David
D3workz
1.5 Star Member
1.5 Star Member
Posts: 37
Joined: Wed Jul 29, 2020 10:42 am

Re: Feed rate on mach3

Post by D3workz »

Hi David,

I think its not the case, as it actually stops in the wrong position, runs the whole probing/ piercing procedure but then completes the correct cut....
D3workz
1.5 Star Member
1.5 Star Member
Posts: 37
Joined: Wed Jul 29, 2020 10:42 am

Re: Feed rate on mach3

Post by D3workz »

I found a photo of one instance... lucky I was running a marker! You see, the table stopped in the wrong place, probed the marker in the wrong place, but then it marked the correct line in the correct place.

Dim
Attachments
20210311_213549.jpg
D3workz
1.5 Star Member
1.5 Star Member
Posts: 37
Joined: Wed Jul 29, 2020 10:42 am

Re: Feed rate on mach3

Post by D3workz »

D3workz wrote: Thu Mar 11, 2021 3:39 pm I found a photo of one instance... lucky I was running a marker! You see, the table stopped in the wrong place, probed the marker in the wrong place, but then it marked the correct line in the correct place.

Dim
Regarding the image that I posted (where I circled the problem). After reading tons of forums threads about Gcode and scripting in macros, I think I can make one plus one and derive to a possible solution of why I getting these random piercing in the wrong place. I think its because, since I run a G31 from the M3 macro, and since I have learnt that Mach3 runs Gcode and M-codes as multi-threads, I am guessing that randomly there be instances where the G31 get executed before the torch is actually in its right position.... Well I may be wrong but theoretically sounds correct.

Before I edit my post processor to make the G31 probing function and all the other coding I currently have in the M3 macro to run from the main G code, I think I ll try a test in hope to prove that lines of code can get scattered during execution (since these are coming from a multi threading process ), by forcing a delay just before the M3 as I currently have it (i.e with the G31 in it). My aim is to delay the M3 function to allow the full gcode execution from the main g-code... In any case I might learn something, or make a chicken out of myself haha :HaHa

Regarding the oscillating speed rate on my mach3 screen, I got no feed back :Sad . Even though I think this has nothing to do with my initial problem.

Thanks guys

Dim
Post Reply

Return to “Mach3 & Mach4 CNC”