ESSTLCAM with G92 and boundary limits

Software / Firmware EstlCAM
#1

Ok maybe someone can chime in and help me understand this.

So I don’t use end stops at the moment. Build is a low rider.

At start of gcode I issue G92 based on where the bit is on the cutting piece. So absolute is set at start.

Now I’ve noticed something strange and I am wondering if this is the problem.

So normally I set zero position in estlcam slightly before the boundary of my work sketch so let’s say bottom left corner. Sketch is to the right and above slightly.

In two recent cuts I let the zero be default which was let’s say at bottom left corner again but this time slightly inside the square in sketch.

Now the machine has cut all inside profiles where they should be but on 2 axes the outer square seem to be clipped.

Is it possible that the machine isn’t going left of the start zero position so clipping it? Possibly g92 at very beginning related? It only is in pieces where zero is slightly inside the sketch.

@jeffeb3 any ideas mate?

#2

So been doing a bit of reading and seems like that is the culprit. I will just have to cut a few pieces out to understand it but was trying to not waste wood ha! Oh well time to put some pen and paper on it.

So seems like once an absolute 0,0 is set in XY via G92 at same place your estlcam Zero origin is, anything before it in X or Y is out of bounds.

#3

Yes. This is called “soft stops” and it is enabled in the dual endstop firmware, even if you don’t attach endstops.

You can test it just by jogging. If you can’t jog below 0, then the min softstops are on.

You can disable it with a gcode M command. I always forget which one. M121, M112, M211. One of those :slight_smile:

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#4

Thanks bud, ruined two pieces :slight_smile: live and learn.

#5

You could also make sure your sketch inset from 0,0 is greater or equal to the tool radius I suppose.

#6

Just to be clear, this is with dual endstop firmware or serial firmware? The version number should have a D if it is dual, like 508D. M119 also will show more endstops with the dual version.

#7

it was the mini rambo already flashed from Ryan. So it might be the serial one.

However I still think it has to do with start Zero origin in Estlcam being slightly inside the sketch. I am going really slow and everything is tight so I doubt its missing steps, I dont even see it vibrate when cutting through so there should not be stress causing some misteps in a cut - I thought first it could be that then I noticed other piece came out fine earlier and this clipping is only happening where the ESTCAM Zero origin is inside the sketch.

What I do is set G92 once the program starts, which means thats the new 0,0 ofc.

It is still drawing though the outline of the square but it just seems either clipped or skewed more to right to fit within the absolute boundary if that makes sense. Like machine starts to draw the square outline and it does but the square is drawn slightly more to right maybe, maybe to compensate for the fact that Zero origin in Estlcam is slightly inside the square and that is translating to somehow actual machine drawing it further outwards? because the absolute 0,0 is there now so it has to somehow fit it?

Come to think of it after writing above, I think it is clipping the part on the left of Zero origin and that is making me think it has drawn more to right because dimensions are clipped once it tries to fit the tool on the line, that would take some mm’s as well.

Basically am I correct in thinking that the tool will not draw to the left of 0,0 as that’s where the outline should have been, instead it starts from 0,0 + tool width and hence ends up changing the square outline dimensions in reference to the pockets inside? Because pockets were to the right of Zero origin, just the square outline was more to the left of Zero origin.

It is weird.

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#8

Min software endstops shouldn’t be enabled on the mini rambo firmware. That is odd.

#9

Yep just realised mini Rambo won’t even do dual end stops so prob not the firmware limit.

I guess I’ll have to see if it can indeed go left of 0,0 if it needs to. Maybe even in estlcam if things left of zero origin are drawing left or being pushed to right of zero origin in estlcam. In preview seems the outline to left is drawn though.

The only other change was using a finishing pass with 1/8 mill, full depth at 0.60mm offset for roughing ones.

Perhaps it is missing steps. Grub screws on pulleys were tight.

#10

I have centered the origin in estlcam before and didn’t have any trouble. You could also check the gcode.

#11

Yep I will give it a crack when back home :slight_smile: ! It is loosing steps someplace before it starts the square piece part cut. That was the next thing to work on once I worked out its not the Start origin etc. related.

I am going to reduce the DOC, current was 4.0mm on 1/8th 2 flute straight. Also will check how gantry is behaving around x movement. Fun times!

Thanks for chiming in as always.

#12

I am not using Marlin for my CNC, so the following could be wrong…

The G92 command does set an offset and afaik no new zero? Could this be the problem?

#13

You could be on to something mate. https://marlinfw.org/docs/gcode/G092.html it does say that it sets sort of soft limits or software end-stops. But it does say that you could set 0,0 middle of bed and start printing, what it doesn’t cover is if the print will go behind this x,y etc. Firmware limits in CNC system might further be doing something interesting. ESTLCAM in preview shows going there behind its Zero origin, but the way this Zero origin behaves when it also becomes the g92 cords is where I want to test this more. Since I have only seen this once the recent two pieces had Zero origin slightly inside the sketch, the other change was finishing pass changes but they seem alright on paper.

I will have to try some samples putting the origin out of shapes like 5-10mm out to cater for bit diameter as I used to, to confirm if that was it.

#14

I use GRBL, and when I have to cut a pocket in a piece of wood, I mark the center on the piece of wood and set the 0,0 in ESTLCam on the center of the pocket. When setting the machine I move the point of the tool to the centermark and I press set-zero in my g-codesender.

I don’t know if this is posible in with Marlin (it should, because this is the way my Deltaprinter works)…

#15

Ok so in my Gcode start one, right after G92 0,0,0 I have G90 which says use absolute coordinate system. Not sure if this is causing issues when ESTLCAM start origin is inside the sketch. Shouldn’t though.

Ill try this with putting Start on centre and do a dry run see if goes left of it, it should.

#16

For others facing similar issues with scaling out etc. on cut outs. Issue my end again was the loose pulleys. Consistently an issue for me so I am now looking at some good long term solution for these. I think the small grub screws just aren’t machined that well and I have seen pulleys with same dimensions but larger screws so will be moving to those.

No issues with estlcam Start origin being inside shapes even with G92 command.

#17

You can use tiny m3 screws, I believe. You should also use some blue locktite. That should fix it.