Too much plastic with Cool and Slow Down?

Too much plastic with Cool and Slow Down?

nhand42 12 Aug 2012 14:29

I have a ToM with MK7 and recently upgraded to the latest Replicator-G, Makerbot firmware 3.1, skeinforge 50, etc. Everything seemed to be fine with the test prints.

However then I tried printing a fairly tall piece (60mm) that tapers to a thin edge, so the Cool plugin kicks in (it's set to 5 seconds) and activates Slow Down.

Now the Slow Down activates as it should, but it seems to be laying down too much plastic. It pushes out so much plastic that eventually the nozzle is swimming, and the print is simply a write-off. I moved the Minimum to 10 seconds and the extra-plastic started lower than the tapered edge. Back to 5 seconds and the extra-plastic is higher up.

I've tried Skeinforge 47 with no difference. Then tried the Jetty 3.4 firmware with no difference. Thought it might be the z-hold bug but the off/on trick and a reset didn't make a difference.

Is there a known bug in Cool and Slow Down where the extruder's flow rate keeps going at full speed? That's what it looks like to me, even though I know that sounds silly.

Re: Too much plastic with Cool and Slow Down?

Jetguy 13 Aug 2012 00:21

That sounds like an error in the script so post your gcode section with the problem. Just measure the object and grab the section of gcode with Z heights before the action. It should not take very long to figure out

I'm betting money the generated code is the problem and adjusting firmware does nothing because the gcode is what runs the machine.

F is the feedrate so you will see the difference, the idea is that the change in flowrate matches the feedrate as a percentage, so a little math and you'll have the answer that yes, the plugin at those Z heights screwed up.

I would say if an operator wants to learn the true art of printing, you should be able to read gcode like it's a first language. It's the secret to success because once you understand it, you can do anything with the machine. Just like the scripts to make gcode music, you can get the bot to hit switches, activate stuff, eject parts,change tools,just about anything you can think of. I'm just saying, make it a personal goal to master gcode and you will be suprised how easy it is.
Sorry, I know that doesn't solve your problem but I would check the rep-g bug reports. This is really a rep-g error and nothing wrong with stating it here and asking the question so other users don't get tripped up on the same error,but you need to open a bug report there to get it fixed. Again,please don't take this that I'm saying go someplace else, you should ask questions here and all are welcome. I just see with this error, I think this needs to go to that forum too.

Re: Too much plastic with Cool and Slow Down?

Jetguy 13 Aug 2012 00:25

Nevermind, it slipped past me

have a ToM with MK7 and recently upgraded to the latest Replicator-G, Makerbot firmware 3.1

Known bug with 3.1 firmware. Makerbot got this great idea to reduce heat in the z motor since it's locked most of the time and only moves a few steps and uses a threaded rod. Except, they forgot the high speed threaded rod on T-O-Ms has enough pitch that if the motor isn't locked between moves then the z can slid down and smash the previous layer.
Thus revert back to firmware 3.0 problem solved.

The function is called Z-hold in motherboard preferences, but it's broken in firmware 3.1 and any firmware derived from 3.1, thus why you saw it on multiple recent firmwares, the source is flawed.

Old related thread http://wiki.makerbot.com/forum/t-420264

Why it's not as known, because some guys bots have enough friction, the z hold when disabled in firmware 3.1 still keeps the z axis from smashing layers. Point being, it was a bad idea given the mechanics of the machine.

Last edited on 13 Aug 2012 00:31 by Jetguy Show more

Re: Too much plastic with Cool and Slow Down?

nhand42 13 Aug 2012 08:36

Jetguy wrote: Known bug with 3.1 firmware. Makerbot got this great idea to reduce heat in the z motor since it's locked most of the time and only moves a few steps and uses a threaded rod. Except, they forgot the high speed threaded rod on T-O-Ms has enough pitch that if the motor isn't locked between moves then the z can slid down and smash the previous layer.

The first 100 layers or so are perfect - I mean, absolutely perfect - it's only when Cool kicks in that it starts looking nasty. Also I did think it might be z-hold so I…

nhand42 wrote: Then tried the Jetty 3.4 firmware with no difference. Thought it might be the z-hold bug but the off/on trick and a reset didn't make a difference.

But even Jetty doesn't help - although I've never had accelerated printing before and I'm never going back to stock firmware! It's like having a new printer.

I will take a closer look at the g-code. I need to get better at reading it anyway, so I'll see if the E values match the X-Y values for the "puffy" layers.

Re: Too much plastic with Cool and Slow Down?

nhand42 13 Aug 2012 12:47

I would say if an operator wants to learn the true art of printing, you should be able to read gcode like it's a first language.

Happy days. I took your advice and read the g-code for the layers where it started getting messy. I noticed the M108 (extruder speed) was commented out. Hey, what?

Found that SF47 and SF50 both have a replace.csv that comments out the M108 g-codes. Possibly because these SF versions are aimed at 5D boards, but my Gen4 board needs the M108 g-codes. Fixed the replace.csv and the print is now perfect, top to bottom.

Even happier days, because of the problem I finally got around to trying the Jetty firmware and it's great. My ToM is now faster, quieter, and smoother. The print quality is off the charts. Best upgrade I've ever done.

Re: Too much plastic with Cool and Slow Down?

Bluemetal 13 Aug 2012 13:29

A few questions since you have successful making the jump:

When you moved from Makerbot to Jetty Firmware, what parameters in SF did you change if any?

Are you using altshell.py?

What speeds are you achieving?

Re: Too much plastic with Cool and Slow Down?

nhand42 13 Aug 2012 13:47

When you moved from Makerbot to Jetty Firmware, what parameters in SF did you change if any?

I turned off Dimension, turned off Raft, changed the flow-rate to 5.0, fiddled replace.csv to remove the comment (but kept the S -> R conversion), feed-rate to 80mm/s, travel rate to 150mm/s, and I don't use Print-O-Matic.

Are you using altshell.py?

Nope.

What speeds are you achieving?

80mm/s feed and 150mm/s travel. The test cube printed about 3x faster.

But I like it mostly for the whoosh sound it now makes.

Re: Too much plastic with Cool and Slow Down?

Jetguy 13 Aug 2012 14:41

Very cool and thanks for sharing your full setup and info.

Re: Too much plastic with Cool and Slow Down?

Bluemetal 13 Aug 2012 14:51

Thank you very much. I have to try the newer SF versions.

I have been working on this "jump" for a while and I agree with you on the side benefits like how cool it sounds when is running properly. I guess the stepper frequencies used in Jetty are much more pleasant to the ear. :)

Last edited on 14 Aug 2012 00:04 by Bluemetal Show more