Need some help with calibrating
March 22, 2015 05:42PM
Hi guys,

I tried to print a companion cube -- first test shape -- and man -- it is all messed up. I've uploaded some pictures here (forum wouldn't let me attach them, sorry!), some advice would help.

I told it to print with a raft, so that's the weird stuff you see at the bottom. It seems way too short, and also like -- it was skitzophrenic from layer to layer -- like it slowly drifts left and backwards, and the layers that are supposed to come out like go in further... some serious spatial warpage going on there...

To give some background information, it's a SeeMeCNC H-1.0 (I bought a kit a couple of years ago and just now got motivated to finish up the build) -- so it's a Huxley-like.

I can send X, Y, and Z commands and it moves the correct amount (moving 10 mm in any directions moves 1 cm measurably, and 50 mm, moves 5 cm -- this works at any height, and it moves up and down correctly as well).

I did the flow rate test -- where you mark the filament at 14 cm -- extrude 100 mm -- and compare -- do some math, update the settings until it's right -- I did all that. It's within 1 mm or so.

I printed the first layers at 230 degrees C (actual temp, measured with a thermocouple) and further layers at ~225 deg C [actual] (it's what Slic3r recommended).

The bed is ~ 110 deg C [actual]. Printing with ABS. The filament seems high quality -- I measured it at several places and my digital calipers say it's "1.7 mm" at each spot (it only displays 2 significant digits, it's advertised as 1.75 mm filament, so I told Slic3r that's what it was). Nozzle appears to be about .5 mm which is the slic3r default (kind of hard to measure it with calipers, since there's nothing to grip).

If this was your problem, what other information would you need to solve it? What else would you try?
Re: Need some help with calibrating
March 23, 2015 07:41PM
Your layers are getting all melty because it's a small object and the print head stays in a relatively small area, meaning individual layers don't get enough time to cool properly before the next is laid down. For a start, try printing two side-by-side (with a reasonable distance between) and this might bring clarity to some of the other issues, one of which seems to be missing steps on one of the axes, but it's difficult to tell with the whole meltiness issue getting in the way.

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Re: Need some help with calibrating
March 24, 2015 04:52AM
It's very melty.
Try to print a proper cube for calibration. I had to Google 'companion cube' It's quite a fiddly shape where the nozzle has to dwell over it If it's small.
How big is it?
Was it printed square to an axis or at an angle?
It looks like some layer shifting has occurred.
Have you checked belts/ pulleys?
Any nasty motor noises during print/ skipping steps?
Re: Need some help with calibrating
March 24, 2015 12:09PM
I like 3dkarma's advice to print several at the same time, so that the layers have time to cool. Alternately you could find a 40~60mm fan, make a duct out of paper, and somehow rig it to your printer so that the recently extruded filament is getting some direct cooling.

From my experience, calibration is a lengthy process. It took me about a month to get to a point where I was getting very reliable, repeatable, high quality prints.
Re: Need some help with calibrating
March 24, 2015 03:52PM
Wow, people responded! -- Thanks guys. I will definitely try more than 1 cube next time, they are very small about ~1 cm cubed (it seems I'm still getting lots of overheating -- what's the best practice with fans and ABS? -- I keep reading about a fan to cool down the extruder, or a fan to cool down the work -- which is it? -- do I need both? -- will one affect the print quality more than the other? -- Until I can print brackets for the fans, what's the best arrangement? -- Can I do anything in Slic3r to maybe give the layers a chance to cool down, like maybe retract the filament, move the head move away 50 mm, do a loop and then come back? -- Also, if we want the ABS to cool down, what's the purpose of the heated bed?)

But yeah, there was definitely some slop in my axes -- also, I didn't realize doing 1/32 microstepping was going to be a big deal -- for now I've disabled all micro-stepping (removed all jumpers from my RAMPS board and reset steps per mm). I was at about 250 steps/mm and now I'm doing about 7.8 steps/mm -- (which still seems pretty darn accurate -- especially if it's repeatable) -- I'm considering just switching to using an A4988 controllers if I'm not going to do any stepping. (Right now, I'm using two A4988's for my Z/E axes, and two DRV8825 for my X and Y.)

The other thing I did was tighten up my belts -- I installed hose clamps that I cut in half and cut the belts a little shorter and attached them to the belts -- I lost about 1 - 2 CM on each axis, but it's very easy to tension them now.

The problem is -- the motors sounded fine before (with belt slippage and 32x microstepping), but now -- the power needed to move the motors ... is much higher than the datasheet recommends for them -- and it's about 10x louder than before -- I took care to not turn them up so high that the motors would overheat or anything -- but the sound is kind of disturbing. I can hear it in the next room. It sounds like C3PO having a seizure while R2D2 is in the same room flipping out about it.

Anyway, I almost printed a regular cube -- the layers seem to be right on right now -- it's just a matter of it being super bulgey and stuff -- and I think the idea of giving it time to cool with multiple cubes will help. Also, I'm thinking of lowering the temperatures I'm using. I forgot when I printed this cube that my actual temp is different from the measured temp, and I think I printed it at like 235 - 238 degrees C [actual] (230 degrees C, measured via thermistor). Derp.

By the way -- the shapes are square to the X/Y axes -- it is not intentionally at an angle. That's how much slippage there was!

Edited 5 time(s). Last edit at 03/24/2015 04:02PM by BrainSlugs83.
Re: Need some help with calibrating
March 24, 2015 05:06PM
Mm - fans - the extruder fan is usually for all metal hotends to stop the heat travelling up to the cold end and melting the filament too far up - ie it becomes too floppy to push through. It would have less effect on the print quality than a work fan, though an extruder fan will waft the air around the part anyway.

RE cooling ABS - I think its a balancing act between allowing the part to slowly and evenly cool down to avoid warping without over melting it at the nozzle. Maybe PLA would be a bit more forgiving material to get started with.

Its possible in Slic3r to delay between layers - Printer settings - Custom G codes - Layer change G-code

I'm no Gcode wizz but you'd probbly need a G91 first to use relative coords - add a move, say G1 Z20 to move the Z up 20mm - G4 xS where G4 is dwell or wait and 'x' is however long in seconds - a move back, say G1 Z-20 and then at the end to use a G90 to revert to absolute coords.
Maybe try printing two or more cubes well spaced at the same time first.

". . . C3PO having a seizure while R2D2 is in the same room flipping out about it." Ha! lol. That's probably the result of having no stepping at all for you. I've never tried it. I've had some struggles myself with the 1/32 stepping and struggled to set DRV8825 to 1/16. I think you want some microstepping. None is a bit lo-tec. 1/32 give me problems only at higher speeds. Maybe print slower and be happy with your mechanical set up.

I think you ought to put the actual measured filament diameter into Slic3r rather than what the filament box says. Also - would be better to be sure what the nozzle diameter really is.

Good luck. Your last print was way better than the first one!


Edit: I said about just moving the print nozzle up out of the way but if its oozing goo it will land on your print, so maybe moving it away is better.

Edited 1 time(s). Last edit at 03/24/2015 05:14PM by alan richard.
Re: Need some help with calibrating
March 31, 2015 01:13PM
Thanks Alan, I'll give that a try.

I did go back to 1/4 micro stepping for now, and it seems to be working well enough @ 12V without any issues, and the noise is back to normal and it moves a bit smoother too (it was kind of getting derp'd up at a tight spot on the rod at 1/1, it doesn't have any issues at 1/4 -- haven't tried any other settings yet, but 1/4 is probably fine).

I'm still considering if I want to move to PLA or not -- I want to be able to print a replacement part for my cold end (right now, I'm holding a capacitive sensor to the X gantry with a block of wood that's killing my X-range, and my new Y end-stop is killing my Y-range...) -- but on the other hand, I'm having troubles getting my heated bed to reach and sustain the correct heat levels [just figured this out] -- I'm considering moving to 15V first (12V = 5.5A / 65W heating, 15V = 6.8A / 102W heating... -- seems like it would be a substantial improvement...)

Regarding the filament... I don't know that it's not 1.75 mm (or 1.71, or 1.79, for that matter -- I only get two significant digits...) -- for now I can try toning it down to 1.7 anyway though.

Regarding the nozzle diameter. I found a page on the wiki that seems to also indicate my nozzle is 0.5 mm -- not really sure of a good way to measure it, even with my digi-calipers... -- what's the best way to measure a tiny hole?

Also, I'm getting, way better results (even at 80 deg C on the print bed) using CuraEngine for slicing than Slic3r (still using ABS!! DX) -- at least, right up until the last few layers where it does this weird mashing thing that destroys the prints (not sure how to disable this and just print the last few layers like normal, yet) -- but Slic3r seems to be having lots of overflow and other issues, not super sure what to do about all of this. :-/

I am using repetier host, and believe I've configured all the right things in Slic3r, and there's not many options in CuraEngine that I can find -- there's certainly nothing that stands out like some checkbox that says "Don't derp up the tops of my prints..." >.<


Edited 3 time(s). Last edit at 03/31/2015 01:16PM by BrainSlugs83.
Re: Need some help with calibrating
March 31, 2015 08:02PM
You'd probably need a proper gauge to measure the nozzle. Maybe cost more than a nozzle.
See how a 0.5mm pencil lead fits up the hole. Perhaps hard to tell with filament in.
I was just throwing out ideas to fine tune calibration. If you're printing better now its not an issue.

I think you'd be safe with higher stepping 1/16 shouldn't be a problem.

I'm not sure what this means;
" instead of printing one layer at a time, decided to extrude a bunch while pulling up (on Z-axis) and make like these massive, junky, non-flat/non-uniform globs, and then it just dragged them across the print -- then it kind of used the extruder head to mash them down."

on your other post. The top layer didn't stick? or the Z moved well above layer height?

Re: Need some help with calibrating
March 31, 2015 09:31PM
Yeah, when it got to the last few solid layers, it jerked the Z axis up about 3-5 layers, and it extruded a very thick blob bead -- then it slowly ran that blob bead slowly across the top every now and then bobbing down and coming back up -- and again at the end -- kind of mashing it in.

I don't have any extra G-CODE or anything like that added. But it seemed it just wanted to finish in a hurry and go home for the day or something! >.< -- Anyway, it really f'ed up the prints. -- I wish it had just printed the top layers like it printed all the bottom ones before it (It'd be a perfect print if it did).

There's a link in the quoted text above to the thread that I opened about the issue, with more details, but so far it's just crickets -- I think it's probably in the wrong spot, but I'm not sure (and if it is, I'm not sure where it should go then!).

And Slic3r -- even with four cubes, 5 cm apart -- they just overflow everywhere. sad smiley [Also, it seems Slic3r is bad with percentages -- I tell it 20% infill -- it seems to interpret that as 110% infill -- versus Cura -- which has no issues with it.]

Edited 4 time(s). Last edit at 03/31/2015 09:38PM by BrainSlugs83.
Re: Need some help with calibrating
April 01, 2015 09:08AM
That is weird.

I think its more than just print settings or slicing. Your Z shouldn't be doing anything like that.

I never had a problem with slic3r like that. Don't think many do.

Are you printing over USB? Is it a good cable? Is your pooter busy with something else when it should be concentrating on printing?

Re: Need some help with calibrating
April 01, 2015 02:10PM
A little off-topic but I'm just amazed at that you call the printer's behaviour 'schizophrenic' haha. Great smiling smiley
Re: Need some help with calibrating
April 09, 2015 08:00PM
To be clear -- the skitzo smashy behavior was done by Cura (as previously mentioned) -- when I switch back to slic3r, it just over extrudes way too much (hence why I was experimenting with Cura). The USB cable is fine, no other software running is messing with it, lol. I'm pretty sure it generated those gcodes, I just need to try it again when I have some free time, and I can show you.

Edited 1 time(s). Last edit at 04/09/2015 08:06PM by BrainSlugs83.
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