Z Axis issues on larger/longer carves?

Mostly Printed CNC - MPCNC Troubleshooting
#1

Hello All,

I have been working on making some signs and plaques while learning and fine tuning my new MPCNC.

Smaller jobs are working fairly well. The problem that I am having appears to manifest at the latter part of longer running jobs.

I don’t know if it is relative to the actual duration or due to the location of the gantry. On larger jobs I am working further along the X axis than I am on shorter jobs. I have trouble seeing gantry location affecting Z axis though…

The jobs start well an I sit an watch closely as everything behaves well. Then my attention begins to wander. I look away and I hear that “off” sound of a stepper skipping or binding. I look and everything looks fine except, maybe, the letters are now carving a bit deeper. Then it happens again and the failure is obvious as the clearance move (z axis) and the cutter does not come up above the surface of the workpiece and then moves to its next location while cutting a swath across the face of my project.

In short, it is failing to make positive Z axis moves after about 30 minutes of carving and when the toolpath has reached a point that is about midway on the X axis.

The Z axis has no trouble on smaller/shorter jobs. The difference that I can see are limited to duration of job and working distance down the X axis.

What do you all think? Suggestions?

Thanks.

S.

#2

Try fusion, we ironed out some z axis speed issues so it should perform correctly. Estlcam doesn’t always have the correct z speed in the gcode it turns out.

#3

A few more details:

All parts & RAMPS controller purchased here within the last couple of weeks.

Router is a DW660.

Running the latest Repetier Host on an i5 Windows 10 laptop.

#4

Your timing is priceless…

I just paid for Estlcam about an hour ago…

I have Fusion360 and can give it a try.

I do wonder though, if I am not having Z axis issues on smaller jobs with Estlcam, why am I having trouble with longer jobs?

Thanks

S.

#5

It isn’t the length of job it is the amount of incorrect speed commands and how far apart they are.

#6

I know it is very subtle we didn’t know about it until RC8. This whole time with all the z axis issue I redesigned the machine three times. I thought I was doing something wrong. It wasn’t until RC8 did I check through the gcode line by line. Estlcam was made for different controllers in mind that handle rapid movements. Marlin leaves out rapids and achieves them in a different way. Because of this the Estlcam code is “missing” commands. I asked Christian from estlcam about this, he doesn’t seem to have any plans on changing it. His software is correct it is Marlin’s fault but I have no plans of switching firmware.

So we then we dug into the Fusion 360 post processor and it had the same issues. A few of us got into it and fixed them all. That post processor seems to be perfect right now.

Sorry about the timing. If you stay with estlcam keep the speeds and rapids low, and stay on the RC7 firmware. It does work pretty well, just not perfect.

#7

Thank you.

If I am understanding correctly, it is a somewhat random and additive issue. I could occur a few times on a smaller job and I may not notice. A longer job offers more opportunities for failure and a more substantial accumulation of error.

I have been reading on the Fusion360 thread about the post processor. A good bit of the discussion is beyond my full understanding. Is there any kind of “idiots guide” that offers a bit of guidance for the challenged?

Thanks again.

S.

#8

Not exactly, The estlcam thing is a bit different than that. The marlin firmware should limit the max speed but it does not do it all the time for some reason. So if you continuously ask it to go to fast it seems to have a buffer of some sort that just kinda starts skipping commands to keep up, or the stepper itself can;t move that fast. The reason behind it is over my head as well.

Fusion has an amazing amount of great informative videos to make it all very easy.

I will be adding a fusion tutorial to all the ones I currently have for estlcam but it might take a few days to get situated after the holiday madness and family being in town.

The basics after you open you part up, make your setup (meaning pick you origin and stock size if you want). Then pick a tool, and the rest is similar to estlcam use 2d pocket or 2D cut 3d adaptive, ect… After that you use the post processor. I will try and get up some of the basic speeds you should be using ASAP.

#9

I have been using Fusion360 a bit for creating projects for the laser cutter/engraver but we are not using Fusion360’s CAM functionality. We “print” the project to a print driver that launches a 3rd party app and runs the laser.

Any tips for setting up the post processor and using Fusions CAM features would be most appreciated.

Thank you very much for your help. It is MUCH appreciated.

S.

#10

Just search in YouTube “fusion 360 cam tutorial” and watch some videos.
Then with your toolpath created fire the posts processor and you will have the .gcode file.

Search in the forum to download posts processor script.

#11

Martin,

Thank you for your reply. I have already downloaded the post processor. I started to dive in and figure out how to make it play. Then after considering how much time and effort I have wasted so far trying to get Estlcam to work I am reluctant to waste even more on another app that may or may not work.

I am not a “CNC Hobbyist”. I am not doing this for the joy of tinkering. I need a machine that works and I am concerned that I made the wrong purchase decision.

Very frustrated…

#12

It will take some learning. There are a lot of full time cnc jobs, cnc programmers and CAM specialists out there. This is not an easy topic to master. Every single cut brings something new to the table.

If you have some more specific questions we all might be able to help a little more. The part or gcode in question. The size and shape of your machine, what tool you have on it, the bit you are using and how old it is, the material you are using , ect. Your issue could be as easy as one checkbox not being checked. Or you could be doing it all wrong. Most of us here love to help but poking in the dark doesn’t get us anywhere quickly.

#13

Well… Is it more likely flaws in Estlcam as you indicated in your earlier post or could it be a setting?

I have one very specific question: WHAT APPLICATION & CONFIGURATION WILL WORK TO PROVIDE REASONABLE FUNCTIONALITY?

I have no problem researching, studying and learning. Where I get frustrated is when I spend many hours learning the “recommended” application only to be told that it has flaws and I have wasted my time.

What I have:

MPCNC parts kit, power supply and controller purchased here about three weeks ago.

Dewalt DW660 Router.

Lenovo t520 laptop (i5 processor & 8gb RAM) with a recent fresh install of Windows 10.

My machine bed is 48"x 36".

The problem that has turned this machine into a “doorstop” for me is the Z axis issue.

Question: What application & configuration is known to work with this machine?

If I am not providing enough detail, please let me know what additional information I can provide to help find a solution?

Thank you.

S.

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#14

Looking back over your responses I see one item that I have question on. You suggested staying with RC7 firmware. Is that the version that the controller shipped with? How can I check the firmware version?

Thanks.

S.

#15

I understand you are frustrated. So am I. I redesigned my entire machine 3 times trying to figure out why everyone was having Z axis issues.

I am trying to be upfront and honest about all this, I am not hiding anything. I did screw up by recommending estlcam…but it was by far the best piece of software at the time. The consumer cnc routing market is in it’s infancy.

So every single z plunge move on your tool list is too fast. Those are not the settings I use in the tutorials. Our max Z move is 510mm/m…but you should not be cutting at that speed.

In the tutorials I plunge at 3mm/s (180mm/m) and cut at 15mm/s in wood with a short axis and I would presume one of the best tuned machines. You should use my numbers if not slower until you get perfect cuts and then try faster.

#16

I have only shipped 8 boards with RC8 last week so if you did not flash it or buy it last week you are on RC7 or older.

#17

What appears to be the best recommendation today may not be the best in two weeks or two months down the road. I understand that. If I had never made a tech purchase recommendation that wound up biting me in the ass I would count myself very lucky. I am not that lucky.

I did tinker with Z rates in the tool list but I based my expectations on the first screen shot of the tool list in the tutorial. I somehow missed the later, and easier to read, screen shot that shows a MUCH slower Z feed rate.

I will try again with a 3mm/sec Z feed rate. Hopefully this will get me productive.

I do intend to pursue Fusion 360 as well. I have been using it for projects on the laser engraver/cutter and it is a great application. I have spent many hours on Youtube videos learning Fusion 360 and (unfortunately) Inkscape. Along with the power and flexibility that Fusion 360 enjoys comes a level of complexity that makes the learning curve a bit steeper.

I appreciate your patience and assistance.

S.