First time noob in need of help calibrating and such

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First time noob in need of help calibrating and such

Postby rangua » 2013-Aug-Wed-19-Aug

Hi, i'm an all time noob in the world of 3d printing.
I have ordered an assembled printrbot simple and it arrived yesterday, and so far i'm liking it. There are a few issues that confuse me and maybe you guys can point me out in the right direction.

First thing's first, i'm working with a printrbot simple and 1.75mm PLA. The extruder is set to 190 on the first layer and 185 on the rest. My bed is a wooden one with masking tape over it (can't find the blue one, but it sticks just fine)

- The first thing i've noticed is that after a print, the head will go "Home", except that it ends up a few cm away from it (on every axis) so that the first print would be centered, the second one a bit more to the corner, etc.. and the Z axis just makes it all a mess. My fix to this is to adjust manually the extruder head every time i finish a job, but i think there should be a proper way of doing this.. It feels unproper to twist the z axis threaded rod by hand to adjust the z axis.

- I've tried printing a calibration cube steps and a yoda head. On both i find that on the corners of each layer (specially the ones higher up) the plastic tends to warp up. On the cube it's barely noticeable, but on the yoda head it made the filament drop out at certain points in the cheek. Am i extruding too much? too little? too hot? maybe i need a fan or something to cool it off faster? so many things to calibrate :?

Any help on these two points would be greatly appreciated. Here are some pics of the prints so you can get an idea of what's going on. Now i'm gonna start measuring the cubes and try to calibrate the axes.
btw, the yoda head suffered an abrupt stop because the lights went out in the middle of the print.. is there a way to resume the print when this happens?
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First time noob in need of help calibrating and such

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Re: First time noob in need of help calibrating and such

Postby Mochaboy » 2013-Aug-Wed-21-Aug

Welcome on board.

The more I see those first prints with the supplied PLA - the more it appears we're printing too hot. Try dropping the temps 5 degrees and reprint to see if that makes a difference...if you don't have a fan - work towards incorporating one into the extruder assembly.

Drop your speeds in the slic3r configs and work up from there until you've found a happy balance between speed and quality.

The initial calibration gets you very close to perfect, but at least in my case, the extruder calibrations needed some work.
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Re: First time noob in need of help calibrating and such

Postby rangua » 2013-Aug-Thu-08-Aug

I'll try doing that when i get back home.
As for the fans, can i get a cheap pc fan? how do i connect it to the board? i can see many unused ports on the board, but i can't find specifications that tells me what each port is for.
in the meantime, i'll try turning on the A/C in the room where i have the printer.. maybe that'll help.. or else, i could put a fan of my own nearby, buy i'm not sure if the fans are supposed to be always on or if there are fan directives in the gcode.
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Re: First time noob in need of help calibrating and such

Postby Tdeagan » 2013-Aug-Thu-09-Aug

Here's a Printrboard image from RetireeJay with the fan connector labelled:
Image
(from this topic: viewtopic.php?f=6&t=3922)

Most smaller 12V PC fans will work. 40-60mm fans are the most popular. There are lots of thingiverse models for adding a mount (try these).

People have even had some success with positioning floor fans to blow on the print bed.

Try to get the fan to blow as evenly as possible rather than hard on one edge.
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Re: First time noob in need of help calibrating and such

Postby rangua » 2013-Aug-Thu-10-Aug

nice! i'll try to get a decent print of the mount with a foot fan of my own :)
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Re: First time noob in need of help calibrating and such

Postby rangua » 2013-Aug-Thu-13-Aug

I tried setting up the temperature at 185 for the first layer and 180 for the rest. I calibrated all axes and the extruder (now i'm having much less troubles with the "home" position thanks to this) and i set up a fan.
After doing that i printed the stepped cubes again and got much nicer results (photo to come), but the last cube still comes off ugly and deformed (which is an improvement. last prints got two last steps deformed).. My print speed was 30 mm/s for the usual parts, reducing it to 70% on the outermost perimeters and 15 mm/s on the small perimeters. Now i've reduced it even more to 15 mm/s for the usual prints and 5 mm/s for the small perimeters.
I'll post a photo when it finish printing, since my laptop webcam is uninstalled and i'm lazy right now to get my phone and email me the photos.
Still, i think the deformed last cube comes off like that because it's not letting the layers cool before printing the next. I've read somewhere that you could put pauses between layers, but i don't want that for the first ones.. is there a way to tell the printer to do this only for the small perimeters? Maybe i'll need to do it for every layer in the end (since the yoda head had troubles at the middle parts where the perimeter was not small, but for now i don't need it for every layer.
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Re: First time noob in need of help calibrating and such

Postby rangua » 2013-Aug-Thu-13-Aug

i think the problem with the last cube is that even tho the perimeter prints at much slower rates, the fill prints at normal speed... is there a way to change this when printing small areas?

EDIT: also, i've noticed that i can't really see a separation between the extruder and the printed part, although it doesn't seem to be dragging material... could it be that i'm just missing the dragging? The skirt does seem a bit flat..

EDIT EDIT: yup, there's some dragging happening at the end. i'll have to adjust the initial Z height..

EDIT EDIT EDIT: don't know if you can see it on the pictures, but the longest edge of the figure came out a bit deformed at the middle of the print, where the square gap is. Why could this be?
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Re: First time noob in need of help calibrating and such

Postby eckerput » 2013-Aug-Thu-15-Aug

The last cube is always a problem since it is such a small area the nozzle basically sits on it continuously making it soft. Cooling can help some, but with the head in direct contact with the surface you can't really cool that much. The best thing to do is print two of them so the head is working on something else for a while during each layer giving the surface a chance to cool.

The sag you see on the top layers of the cut out box is also very common. Printing unsupported into free air will always sag a little due to the extruded filament being soft for a bit until it cools and hardens. Using the lowest possible extruder temperature and a fan can help a lot with this. It is best however to avoid parts with significant overhands or use support when printing them.

Be careful trying to get the last little bit of prefection from this shape. It is really a test piece and can push your settings into some borderline conditions which may not be optimium for more straightforward prints.
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Re: First time noob in need of help calibrating and such

Postby rangua » 2013-Aug-Thu-17-Aug

well, i'm starting a print for the spool holder. I've noticed that even tho my calibration was close to perfect, it came off quite wrong when printing widely spaced holes, so yeah, i can see whats your point eckerput. I think i'm on a printable level now so let's see what comes out of this really big model.
Later, i'll redo the yoda head, luckily with my new spool holder in place :D

EDIT: oh well, i corrected the Y calibration so the holes would fit nicely, but forgot about the X calibration.. now im getting ovals xD i don't mind it tho, but it occurred to me that printing circles could be a good idea to test your X-Y calibration
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Re: First time noob in need of help calibrating and such

Postby rangua » 2013-Aug-Thu-19-Aug

OK, this is my final post here.
Here's a pic of my first fully (and correctly, almost..) printed big item: a spool holder for my printrbot simple|
now i got the hang on calibrating and how too much hot affects the print..
thank you guys for the help :D
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