New guy jumping into the deep end: favorite G-code resources?  

RE: New guy jumping into the deep end: favorite G-code resources?

This is the reference I use:

https://marlinfw.org/meta/gcode/

RE: New guy jumping into the deep end: favorite G-code resources?

Posted by: @james-watriss

I bought my MK3s and assembled it in mid July. Doesn't feel like it's been that long, but there you go. Time flies.

I've been through about two spools of PLA. I'm now experimenting with PETG, and I'm trying to calibrate for stringing issues. I've been through temperature changes, and now I'm dialing in retraction distance and speed. I was playing with the 9-point retraction towers for a while, but printing for 30 minutes on each variable was taking a LONG time. Methodical can be like that, but enough is enough.

So I went for one of the big segmented towers, and set pauses at each notch for me to adjust the temperature settings. And I figured I'd run a different tower for each retraction setting.

But ultimately, the prints that I've done with PETG have turned out best around 240-245, and so what I really want to do is print a tower at that temp, but vary the retraction speed, or retraction distance. But that's not change-able on the fly on the lcd panel, I don't think, so I need to start playing with G-code.

Are there any favorite resources that people have for writing custom g-code? I know there's a list of commands on the knowledge base, but I want to make sure I'm actually doing it right. I don't *think* I'm going to crash firmware in a major way by messing with retraction in g-code. But I'd also like to know that I'm doing what I think I'm doing, so I can gauge the results appropriately.

 

I would first dedicate myself to the PrusaSlicer settings and then the gcode. Most of the Marlin commands can be used on the MK3, but you should be sure to use them correctly, otherwise you might cause damage to man and machine.
The special Prusa commands can be found here: https://help.prusa3d.com/en/article/prusa-specific-g-codes_112173

RE: New guy jumping into the deep end: favorite G-code resources?

Posted by: @james-watriss

[...] what I really want to do is print a tower at that temp, but vary the retraction speed, or retraction distance. But that's not change-able on the fly on the lcd panel, I don't think, so I need to start playing with G-code.

Unfortunately, "retraction settings" are slicer settings and not a separate class of gcode commands, so the slicer computes everything before generating code. You can't easily go back and edit each retraction by hand. What I found works is simply creating multiple "virtual extruders". Create a printer profile with an extruder defined for however many different profiles you'd like to try (9 works for small prints), then configure each extruder with separate retraction settings. I've got some summary notes on the process here.

Are there any favorite resources that people have for writing custom g-code? I know there's a list of commands on the knowledge base, but I want to make sure I'm actually doing it right. I don't *think* I'm going to crash firmware in a major way by messing with retraction in g-code. But I'd also like to know that I'm doing what I think I'm doing, so I can gauge the results appropriately.

You're unlikely to hurt anything, but unless you really enjoy writing parsers to decipher gcode, it will be tricky identifying which retract moves correspond to which test models. You do need to be careful to keep track of relative and absolute extruder moves.

You can insert custom gcode to be inserted at the start of a print, end of a print and on each layer change within PrusaSlicer. I've got notes on doing this here. Any calculations or conditional code is interpreted by the slicer (PrusaSlicer) when generating gcode. Keep in mind that the printer itself is profoundly stupid, so can't do any interesting calculations or branching on its own.

RE: New guy jumping into the deep end: favorite G-code resources?

I gave up on trying to stop PETG stringing, it's just a minor downside of using an otherwise excellent material. Its amazing the way strings melt away with judicious use of a hot air gun.

Too much retraction can lead to clogging. (although I have no idea what is "too much")

RE: New guy jumping into the deep end: favorite G-code resources?

@towlerg

I have not idea either, but I have found it a couple of times.  

RE: New guy jumping into the deep end: favorite G-code resources?

Posted by: @towlerg

I gave up on trying to stop PETG stringing, it's just a minor downside of using an otherwise excellent material. Its amazing the way strings melt away with judicious use of a hot air gun.

Part of the "stringing challenge" is that you need to tweak it for each filament and nozzle combination. The light bulb for me was realizing that getting your slicer settings to accurately reflect my real-world filament and printer settings makes the biggest impact. If the slicer is sending gcode that under- or over-extrudes the actual stuff loaded into the printer, it makes sense problems result. Once I averaged my filament diameter and entered it into the slicer, then did a quick extrusion multiplier calibration, most of my stringing disappeared. 0.2-0.4mm retraction, minimal z-lift and no wiping works very well, even for PETG.

RE: New guy jumping into the deep end: favorite G-code resources?

@towlerg

I assume that you have already let the fan run at full speed and/or used a modified fanshroud?

Temptower?

Some filaments are stringy, just like my PA12 filament. But the strings can be easily removed with a heat gun.

Good question, what is too much retraction. I would keep testing until you find the limit. You can't lose anything. I had already used values (3-4mm) on the MK3 like a bowdenextruder. By default I have 0.6/0.2(z-hop).

RE: New guy jumping into the deep end: favorite G-code resources?

First and foremost, thanks to all for your responses so far. I'm new, and I appreciate the community support. I'm also 46, and so getting out of my comfort zone is a little harder than it used to be. So the support really makes a difference.

@karl, I've been working my way through the settings, for sure. My chief frustration at the moment is that printing the little 9 tower test pieces takes half an hour, each, plus bed cleaning, etc in between prints, to see if I'm getting anywhere. Plus getting each test to release from the bed without breaking up the strings, so I can put together a visible matrix of the results. So far I'm up to 16 iterations, which is a lot. And I have to do a few of each to see if each variable is making a difference. I was hoping to be able to set something up that would allow me to print a larger test that would allow me to make changes to one variable in stages during the print, like a temptower would. Only, a tower, for example, that changed retraction instead of heat, or retraction speed. Or, yes, fans. Or whatever else. One test, instead of the same test over and over, that will display the effects of each variable individiually.

One of the things I noticed is that the little 9-point torture test is a lot stringier than the bigger, blockier temp towers are. More oozing, too. I've worked through different temperatures, and different retractions and retraction speeds. I haven't messed with fan just yet. I clearly should if I'm seeing this as a temperature issue.

I fully confess that most of this is driven by my own frustration, which is getting in the way of a methodical, scientific approach. (albeit a sort of 'brute force,' way of going about things.) But to date I've read numerous articles, each of which will tell me that it's one variable or another, and I still don't feel any closer to an 'ah-ha' moment. Staggering from one variable to another, without feeling like I'm getting anywhere, is challenging for me.

--

@bobstro, the links you gave have provided a lot of information for me to play with. I'm still waiting for the light-bulb moment... but you've given me a LOT to think about and play with. So, I've started with dropping the extrusion multiplier, and we'll see where that takes us.

RE: New guy jumping into the deep end: favorite G-code resources?

@james-watriss

I think you're fighting against wind mills. Tiny strings can't be avoided under some circumstances. Especially with PETG  you will have it. Changing retraction speed and distance is not really helpful anymore. With Linear Advance you actually changing the K-Factor instead if retraction settings. The idea is to have no back pressure at the end of the move.

Feel free to post some pictures, so we can tell if there are any issues to fix.

RE: New guy jumping into the deep end: favorite G-code resources?

I am really surprised that Prusa has not made a resource that explains what the settings do in the slicer.  

RE: New guy jumping into the deep end: favorite G-code resources?

I’m on the fence. I think the basic mechanical explanations might be easily explained. But their effect on the print seems like it would vary, both as a result of the material, and in combination with other adjustments. 

I was impressed, as a beginner, with the fact that the settings on the slicer are at least is tabbed as beginner, medium, and advanced. Some of that I bypassed almost immediately, but if it was just a big spreadsheet monstrosity of labels and values, I’d have blown a gasket. Or maybe just developed a really leaky gasket.

RE: New guy jumping into the deep end: favorite G-code resources?

I haven't found any tutorials for the PS yet and probably only those exist which were written by users.

to the original Slic3r there is something: https://manual.slic3r.org/

S3D does not offer much and is completely outdated. To get along with PS you have to fight your way through with the help of youtube videos, forum tips and a lot of experimentation.

RE: New guy jumping into the deep end: favorite G-code resources?

Posted by: @charles-h13

I am really surprised that Prusa has not made a resource that explains what the settings do in the slicer.  

They've started, but it's very much early days. I was actually contacted about providing some content right before COVID hit. I'm sure their plans have been completely derailed, but Prusa seems to be willing to commit resources to documentation, even if it's not their top priority.

RE: New guy jumping into the deep end: favorite G-code resources?

Well, I suppose that's as good a place to learn as any... writing up such a thing.

I'm out of my day job, at home with the kids, thanks to COVID school schedules. I'm also taking calculus, but I do better when I have a project. So, maybe I'll start digging into this.

I'd obviously be relying heavily on the community here for corrections and insight, but I don't know many better ways to learn...

RE: New guy jumping into the deep end: favorite G-code resources?

I've got some PrusaSlicer notes here, but it's far from complete. I had started doing screen grabs of all the settings screens right before the 2.2 release, so they're all out of date. Keeping up with the pace of change within PrusaSlicer is going to be a challenge.

RE: New guy jumping into the deep end: favorite G-code resources?

I assume that you have already let the fan run at full speed.

Avoid this like the plague. OK not strictly true, but start off with a highish fan speed with PETG, and you will get nice prints with no strength!.

Gradually tweak your other settings whilst reducing fan speed and you will get increasingly stronger PETG prints.

Biggest result I had was drying PETG and getting my calibration absolutely spot on. I now print with the minimum fan speed I can run the fan at without it stalling, minimal to no stringing and strong prints, I only use high fan speeds for the first initial bridging layer.

Oh, and use Bobstro's PETG settings, then play with increased temperatures and speeds, but keep fan speed down as low as you can for strong parts.

I don't even bother with PLA anymore, PETG for 90% of all my printing.

RE: New guy jumping into the deep end: favorite G-code resources?

Posted by: @chocki

[...] Gradually tweak your other settings whilst reducing fan speed and you will get increasingly stronger PETG prints.

I'm looking forward to PrusaSlicer supporting separate fan speeds for external perimeters. During the COVID PPE push, I had to enable 40% fan on overhangs for the larger shield frames printed in PETG. I would have liked to only use the fan for external surfaces. I believe SuperSlicer allows this now. 

RE: New guy jumping into the deep end: favorite G-code resources?

@bobstro

I'm sure that updates will throw things all out of whack on a regular basis, but I have to believe that the core functionality won't actually change. So, it might be a challenge to find them, but less of a challenge for beginners like myself to do that, than to figure out what they're for in the first place.

RE: New guy jumping into the deep end: favorite G-code resources?

Thanks for the info Bobstro, this will be a useful feature.