jsc wrote:Tim is going super geek on you, and there's really no need. You probably have r2. You can verify by checking the text that gets spewed out when you start up the printer and looking for the PID settings. They should correspond to the default PID settings for r2.
Ahhhh, thanks! That is what i needed to know to proceed with my personal setup.
PID is a common control algorithm often used to maintain temperature. It relies on three parameters labeled, oddly enough, P, I, and D, which need to be tuned for the particular system being controlled. An autotune attempts to give you some appropriate values by measuring how the system reacts under certain conditions. It is only necessary if you feel the default settings aren't giving you good temperature control. Here's how you run one:
http://reprap.org/wiki/PID_Tuning. Instead of 200, use whatever temperature you normally like to print at as a target temperature (but not too high, as the autotune will overshoot the temperature you set as the target as part of the tuning process). Remember to save the results with M500.
If your system is tuned well, you should see a small overshoot on first heat rapidly setting down to your target temperature with minimum oscillations.
You can read more about the details of the PID algorithm on Wikipedia and elsewhere, but the short version is:
P(roportional): how far from the target value are we? The farther off, the more power we give (or remove) to try to get on track.
I(ntegrative): how long have we been off target? The longer it's been, the more power we give or take.
D(erivative): how fast are we coming up on the target? The faster we're approaching, the less power we give or take.
P is pretty intuitive. I is for when you're consistently running a little low or high and P isn't giving you enough change to fix that little error. D works to reduce overshoot, so that if you're screaming up to the target value you take it a little easier, and if it's rapidly going the wrong way you nudge it a little harder back in line.
You shouldn't have to know any of this unless you want to tweak your values manually. The autotune works pretty well.
Also ,what i needed to know, and a good explanation of it. But probably not something that a beginner with the dual is going to need to mess with. I'm perfectly serious about putting together a starting guide, similar to the one that i cobbled together from all of you guys' How To's and Suggestions for the single machine. (I have been asked to compile one for the dual.
) But there hasn't been as much written up on the dual. I can puzzle it out myself over the next several months, but that is an unnecessary delay, and a terrible waste of time - you boys already know what you are doing. It looked to me like you and Tim had gotten the farthest along with testing and using this thing, and probably a few others as well, but I've only read through the contents of the Dual Extruder thread once.
There were several places where you guys were proposing starting sequences and methods, I guess what i need to do is ask whether you are still using those, or if you have dumped them by now in favor of something that works better?
How would you guys feel about writing up some brief "How-To" guides for specific bits of the puzzle that you feel very comfortable with? We can link to those in the general guide like we did with the first one. i would prefer to link to actual How-To's , so that you guys can get the cred for it, instead of having to comb through the bits of wisdom that show up in response to various questions across the forum and then paraphrase them to get them into one place.
1. I know that there is a certain amount of G-Code knowledge involved - I'd like to make it easier for someone to use who doesn't have that knowledge base. (A little more detailed than the Wiki - which assumes that everyone is going to understand the specific steps on how to compile something and get it loaded into the firmware before flashing it. Or if it's even necessary to flash it into the firmware - is it better to just load it in through S3D scripts somewhere?)
Cura's dual extrusion support is pretty good.
2. If you understand Cura - a little Quick Use guide for certain specific issues would be
fantastic if you have time to knock one up.
Something along the lines of: If you want to create a wipe tower, do this. If you want to use the second extruder for support only, do this. If you want to print with 2 colors, do this. etc. etc.etc. Anything you feel is important.
S3D's is getting better, but as Tim said, it still does a lot of boneheaded things that it's annoying to have to workaround. If you're just going to use the second extruder for support, the situation's a lot better.
If Tim does grace us with a data dump of his current procedures, I would just adopt that wholesale as he's looked into it more than I have.
3. Oh yes, I plan to. I'd like to have one for each method below, for both Cura and S3D. (One might be better for a certain process than the other.)
Processes:
a. Using 1 extruder for support and the other for finished print.
b. Using the two extruders for different colors - same filament. How does one create the separated parts of the design in order to make the slicer treat the parts correctly? Is it necessary to do anything special, or do you just design it that way to start with? Doing it by layers is easy enough to figure out, but do you have any alignment problems if you have separate parts on the same layer? Color bleed problems? (That kind of thing.)
c. Using different nozzle sizes for speedy infill.
d. And the easiest thing, which is how i will probably start - using two different filaments in each nozzle, to avoid having to change out filament. (Well maybe i'll wait on that and do the two colors. I'd prefer to get things set up with PLA.)
e. Any others?
And then the problems:
a. Oozing issues. 16mm retraction for the un-used nozzle? Lower temps while inactive? Adds too much time to the process? Wipe towers? Dribbling off to the sides? Shields? You guys know a lot of sh*t, but it's scattered all over the place and it takes days to find it.
b. Alignment issues? Color Bleed?
c. Keeping the inactive nozzle from knocking the print?
d. Fine-tuning tips?
Anyway that's the idea for the guide. It's going to be a heck of a lot harder to put this one together, because like you said - it's harder by about a factor of ten. But eventually MG is going to want to release the dual more broadly, to people who don't have your level of experience. So input from the early adopters is needed, and we need to make it a bit more....basic. We don't need to make everybody experts with it, we just need to get them started, like we did with the other guide.
An example of an ideal startup sequence, assuming you're going to start printing with the left:
purge right, retract a ton, purge left, begin print
An example of a tool change sequence, switching from left to right:
retract left a ton, extrude right a ton to bring it back to zero, squirt on the priming tower, go back to printing
I can write these up if they are still good. If you've got suggestions to make them better, that's what i'm looking for.
Soon as i find out if these are the latest and greatest.....do you feel happy enough with your Marlin M2 configuration to have beginners start with it?
None of this is going to happen immediately, so no need to jump on it right away. I was just hoping to enlist some help with this thing. You boys are the experts.
