Nearly there, but am coming a bit unstuck!

Hi guys

After a lot of hassle first with firmware, then various other things (latest until now was snapping the hot end while unscrewing it to clean it, then waiting weeks for a new one to arrive!), I've just about got to the point where I'm getting usable prints.
It's exciting, but I'm not quite there yet due to a couple of things.

If I print a 20mm test cube it sticks ok and prints alright except bulging slightly round the edges. I think this for some reason is the thickness of the extruded plastic. It's a 0.5mm nozzle and set to 0.4mm layers, but when I measure the thickness of the extruded plastic it's around 0.8mm!! Not sure what is set wrong. The step calibration seems ok (ie 20mm told to extrude equates exactly to 20mm of filament moved through the extruder without the hot end attached).

But the worse issue is that other than the test cube, and a spool bracket I managed to successfully print, all other models are coming unstuck suddenly when they're about 3 quarters done. Very frustrating!

Initially when I tried using PLA I could not get it to stick on the glass of my heated bed, no matter what I did (mostly trying with kapton and various temps), so I removed the kapton and tried blue tape. It's the correct tape and sticks well with the test cube and the spool bracket, but all other things just come unstuck.

Here's two gear type models I tried tonight. As you can see they got mostly done then unstuck and began to push around.




I still have the bed heated even with the blue tape, and have tried it very hot but currently not so much, maybe 50-60C.

Anyone got an idea what I'm doing wrong that is causing these to come unstuck part way through?

Many thanks indeed!

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Prusa Mendel i2 - Melzi V2

i didnt have much luck with painters tape
i use 3mm glass, make sure its very clean, heat to 60 then coat with 8/1 water pva mix, let dry for a couple of mins
i start print at 60 deg and drop to 50 after 1st layer
if using a fan make sure your not over cooling as this can loosen the grip
make sure 1st layer has some "squash" (although the bulging you mention could be to close for 1st layer?)
try printing with a skirt "0" distance away.
i would also check the filamet length over a greater distance than 20mm, the longer the distance, the more accurate
i did 100mm using vernier calipers

Thanks for the input - appreciate your suggestions

I suppose there's no harm in trying a PVA juice instead of the blue tape. I don't have any kapton to try with as the glass plate came ready covered and I removed it when I could not get PLA to stick at all (ABS stuck nicely but the print quality was not great). I'm tempted to try ABS again but not quite yet - I'll try the pva thing first.

I haven't really bothered with the fan so far. Didn't see a need.

Re' the squash factor, the first layer seems to do this ok from what I can tell, and the bed is setup so that I can just fit a sheet of paper beneath the hot end.
I heard that there might be a setting to spread the first layer very wide (ie lots of extra footprint for more grip) to prevent prints coming unstuck, but not sure where in repetier or slic3r this is.
Would be nice to try though.

The bulging is across all layers on the test box, but it might have been when the Esteps were set too high, so extruding too much plastic perhaps. Will double check!
For the extrusion length, yes I know that more would be better but with verniers it was within about 0.2mm over 20mm so I figured that was accurate enough for now.

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Prusa Mendel i2 - Melzi V2

Well I tried the PVA juice and I don't think it really helped as I got the same fault after a while, and it broke loose. It had progressed further than previous attempts though, so perhaps I just need to experiment with the mixture.

Anyway, I tried adding on a 10mm brim, and it printed out no problem thanks to the extra grip! So I got a half decent print of a cog/gear/wheel thing at last!

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Prusa Mendel i2 - Melzi V2

Have you set your nozzle gap? should be 0.1mm max (thickness of a piece of copy paper) The paper should drag lightly under the nozzle when homed. Spotless clean glass at 60C is all that should be required then for PLA.

Edited 1 time(s). Last edit at 04/03/2014 02:36AM by waitaki.

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_______________________________________
Waitaki 3D Printer

Yes, I'm sure I checked this after it was last adjusted and it's set so I can just slide a sheet of normal paper under the nozzle.
I calibrated at 4 corners and the centre.

I'll double check tonight though since I must be doing something wrong!

Is it possible the PLA I'm using just has bad properties when it comes to sticking?
It was pretty cheap stuff...

Edited 1 time(s). Last edit at 04/03/2014 03:46AM by Mr Joshua.

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Prusa Mendel i2 - Melzi V2

Maybe try using acetone or nail polish remover first then a good clean up with window cleaner finishing with a dry paper kitchen towel. At 60C, my prints are unmovable until the plate cools down and even then, the parts tend to hold on through suction. Turn the glass over if the other side is unused and prepare as above.
Hard to say whether your PLA is dodgy?

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Waitaki 3D Printer

Same as above my prints are unmovable using PVA diluted in water, I was having the same issues as you described before I brushed glue on the glass

I'm new to this and have seemingly cracked the adhesion problem. PLA at 185 (190 1st layer)

I use a mirror with a heated bed underneath.

- clean mirror with a razor blade between prints. Wipe dust free (but often leave "memories" of old print behind - doesn't seem to matter
- heat bed to 60 (PLA) - I dont' change the temp mid print as it's working as it is.
- print.

I've not needed to clean the class meticulously.

That's it!

I get peeling with larger objects without the heated bed on.

When it draws the skirt and the 1st layer, I manually twist both screws bars (Z) together a little if it needs adjustment. I let it lay a rather squashed 1st layer, but I make sure there is plastic across the whole line - i.e. if it's so squashed that the nozzle pushes the middle of the line away, then I lift it a bit to get an even squished line. If it's totally round, I twist it down to start squashing the line. Then once I'm happy I leave well alone.

If your skirt peels off with varying resistance then either your bed is not level, your glass not clean, or your heating not even.(well, that's what I reckon anyhow!)

Edited 1 time(s). Last edit at 04/03/2014 08:05AM by Dodgey99.

my method is pretty much the same as Dodgey99 although my hot end temp is slightly lower at 180

i clean my glass with washing up liquid, rinse with hot(ish) water and dry with paper towel
my pva was a 2 ltr tub i had lying around from wickes
also try hairspray as that sticks well as well

The glass was absolutely spotless as I clean it with acetone and it looks like fresh glass. I've tried many temp variations of both hot end and bed, to no avail. Currently I have the hot end at 200 and bed about 60.

As mentioned the models stick nicely until they're about 2/3 done then they suddenly come free.
I've picked up some cheap 'ultra hold' hairspray today so I'll try that next. If it doesn't work then the mrs gets a thoughtful free present from me!

But at least in the meantime I know that printing a wide brim/raft seems to solve it.

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Prusa Mendel i2 - Melzi V2

is it with anything you print? or only certain items?
are you using proper acetone? and not nail polish remover (which has conditioners in)
is there any warp on the bottom of the parts when they come off?

i wonder if you are extruding too hot and the lower layers are staying hot as you have no fan but gradually contract while the top is hot
maybe try a gentle fan across the print to cool the layers quicker. i used a normal house fan before i fitted the duct, just stand some card in front with a gap in the middle to direct it to the print. if it works you could fit a proper one. i would def use a fan for pla anyway

Thanks - it does seem to be certain items yes. But I've only done limited prints anyway. The 20mm test cube never seems to unstick, which seems odd since it has a relatively small footprint compared to the cog thing (forget the filename but was a file that came with my repetier install) which is much wider but unsticks every time without printing a brim.

Interesting theory and there could be some mileage in it. I've got a fan fitted but I had the notion that I only really needed it for overhangs etc.

I've tried hairspray and it didn't help this time but I need to tweak a few things physically and in repetier etc so I'll try then report back.
If that doesn't work I'll lower the hotend temp a bit and deploy the fan. I'll stick it at maybe 50% as an arbitrary starting point.

I don't get any warp though, and the acetone is proper stuff that I buy by the gallon from an industrial fibreglass supply shop.

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Prusa Mendel i2 - Melzi V2

Have you confirmed your bed is perfectly level ?

I've now completed two more quite large prints - large footprint, tall bits, quite a few overhangs, and both went without issues.

I tried one without heating the bed for a test and it peeled at 2 corners and eventually became unstuck.

I'm still only wiping the glass over with a cloth (a tv screen cleaning dry cloth - the one you get with a TV - it's lint free).

Each time the print sticks perfectly, and then when the print is done, is hard to budge, but, if I let the bed cool, it pings free itself - obviously as the plastic contracts a tiny bit.

I'm using a 4mm mirror.

I'm now assuming if you have a lot of problems that it must be different types of PLA?

I also only have the fan blowing on the print if there are bridges or if a layer takes less than 20 seconds (I'm having to increase that 20 if it's a small object where the fan never gets a chance to get up to speed - but that's about overhangs, not adhesion). I certainly would not recommend blowing across the whole bed in the early stages. I tried that and it had no chance of adhesion.

This is my PLA: [www.ebay.co.uk]

3DFilaprint, marked as 19-240 print temp, I print at 185 (default in Pronterface/Slic3r)

Oh, and I'm printing with a .35mm nozzle is that makes any difference

Edited 2 time(s). Last edit at 04/04/2014 05:58AM by Dodgey99.

Quote
Mr Joshua
Well I tried the PVA juice and I don't think it really helped as I got the same fault after a while, and it broke loose. It had progressed further than previous attempts though, so perhaps I just need to experiment with the mixture.

Anyway, I tried adding on a 10mm brim, and it printed out no problem thanks to the extra grip! So I got a half decent print of a cog/gear/wheel thing at last!

This may seem a silly idea to some of you, BUT it WORKS.
I normally use Elmer's glue stick on my glass heated bed for printing PLA, it works really good as long as you let it cool down after printing. The part just pops off by it'self if you let it cool down.
I have several glass sheets that I can use, so I have continued printing.

The other day I ran out of Elmer's glue stick, and living in a small country town where there are no shops that sell this product I had to either wait until I when shopping again in the "Big Smoke" or use something else. (BTW: I have tried many different glue sticks and they all work well)

I thought about it and came up with this idea and tried it out and it works really good also.
I mixed some sugar with water (a lot of sugar) and made a thick syrup.
I spread this on the glass with my fingers and made it as even as possible and then left it to dry.
It took a while to dry, so I put it on the heated bed to speed things up a bit. It dried so I could almost not see it there any more, very thin and flat.

Well I gave it a go and it printed even better than the Elmer's glue stick. When it cooled down a little, the printed part popped off. I tried another print and it worked OK again. I did this several times with no problem, then it started to come loose at the beginning of a print. I sprayed a VERY SMALL amount of water on the plate (almost nothing) and rubbed it with my fingers and started printing again for several times. I guess I would say this experiment was a success.
Wont cost you much to try it out, maybe you can come up with some extra info on how it works or ways to make it work better.
I use just standard window glass for printing on, no special glass that costs a fortune.

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

Quote
Dodgey99

3DFilaprint, marked as 19-240 print temp, I print at 185 (default in Pronterface/Slic3r)
/quote]

I always print PLA at 210, never had a good print at 185.
Heated bed at 65, use Elmer's glue stick or sugar to print on.

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

I also have had great success with Elmer's washable gluestick, been using it for some months now and works great every time. I use it for both PLA and ABS on glass. Only needs a light coating, and I usually get a number of prints between applications too.

Cleanup couldn't be easier, wipe down with a damp paper towel, then i usually wipe the glass with some Isopropyl alcohol.

Quote
regpye

Quote
Dodgey99

3DFilaprint, marked as 19-240 print temp, I print at 185 (default in Pronterface/Slic3r)
/quote]

I always print PLA at 210, never had a good print at 185.
Heated bed at 65, use Elmer's glue stick or sugar to print on.

Strange isn't it? Clearly different PLA works at different temps (OR... our thermistors are not entirely accurate).

I'm continuing to print perfectly at 185 with PLA and no glue.

Going to try ABS next.....

Thanks for the replies & suggestions again.

Mine has been subject to an odd and coincidental turn of events that has turned out well.

I spent time a few nights back tweaking slicer settings and firmware adjustments etc.
When I then loaded a model to test the changes it errored on slicing. The error related to a file it wanted in an assumed default directory, which was odd since I'd not changed any filepaths etc. I pointed it where I thought it should be looking instead, then it worked.

Here's the odd bit though. It completely changed how it prints, and with WAY better results.
For instance on fill-in it now does a snakey slalom type fill instead of a grid at 90 degrees (shakes the machine a lot!), and it's controlling the fan as it sees fit.
And, it's sticking! To be fair I spent ages leveling the bed and narrowing the gap of hot end to bed.

Presume it's picked up a config file intended for a Prusa now, that maybe it should have had all along.
Not too important but it's printing on blue tape now and sticking like sh*t to a blanket, if you'll excuse the phrase.

Print quality is the best I've had yet, but room for improvement for sure. The layers print ever so slightly offset on x or y (didn't check which), so the test cube has a very slight slope on the side.

So as a thank you to the machine for behaving I've tidied all the wiring today by cutting to exact lengths and putting in spiral wrap.
Actually feels like I have a usable machine now rather than a bunch of expensive frustration!

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Prusa Mendel i2 - Melzi V2

I only want to point that when you finetune your printer try to buy pla from more then one dealer.

I bought my first 20 meter to test with from one dealer that seams to be pretty bad pla that whas super hard.

It gave me the same results you describe and my printer sounded like a stone masher

I took my printer apart and got clogged nozzles a bunch of times until I got some samples from another dealer and my printer start to give me great prints.

Here is a video I uploaded before I understood wath the problem whas

[www.youtube.com]

And this bad pla gave me so much trouble before I understood that the extruder whas great and the pla whas awfull.

I have a thread with my build where you can so how it works with good pla

I love the reprap community that helped me a lot with finding a solution to my build problem.

Thanks Cliff - I'll have a look at your stuff to see what's what.

It'd be interesting to try the stuff my friend uses as he gets very neat results with his.
This is the PLA I have (I got the grey 3mm stuff). It's the cheapest I found, and usually we all know what the cheapest equates to in terms of quality.....
[www.ebay.co.uk]

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Prusa Mendel i2 - Melzi V2

By the way, here's a pic with an earlier print on the left and a current one on the right. It's showing on the wrong side though as it doesn't show the slightly offset layers:

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Prusa Mendel i2 - Melzi V2

Wow, I just watched the video Cliff and it sounds terrible!

Your printer looks very nice though compared to mine.
So that horrible noise etc was due to the quality of the PLA somehow?

I haven't been a member here for long but I've found it to be a very pleasant and helpful community. I think think it's because everyone is trying to learn and improve and achieve something.
I run a couple of forums and it's hard work to make sure it stays with a good atmosphere etc, but it's fulfilling too. But this forum is a pleasant place to be so far.

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Prusa Mendel i2 - Melzi V2

Quote
Mr Joshua
Wow, I just watched the video Cliff and it sounds terrible!

Your printer looks very nice though compared to mine.
So that horrible noise etc was due to the quality of the PLA somehow?

I haven't been a member here for long but I've found it to be a very pleasant and helpful community. I think think it's because everyone is trying to learn and improve and achieve something.
I run a couple of forums and it's hard work to make sure it stays with a good atmosphere etc, but it's fulfilling too. But this forum is a pleasant place to be so far.

Yes!
The sound comes from when the extruder tryes tooo feed the pla but it digs in to it instead and the slamming noise whas the extruder pinch making the pla slam to the sides of the extruder making that sound.

I did not see this until I took of one of the sides of the extruder so I could see the inside while feeding pla.

So until I switched from cheap bad pla to better pla so did I have a toon of clogged nozzles and when it feeded pla so whas this noise here.

I would recommend this guys pla as its high quality and it also bends a bit like abs instead of snapping off with normal pla.
It also only neads very low temps to give good results.
[stores.ebay.co.uk]
I still have 4 pieces 5 meter samples left from this guy as I ordered 1 kg when I tested the first sample

I also ordered from this dealer that have a pretty good working Chinese pla.
[stores.ebay.co.uk]

ps....
I noticed that you use 3 mm pla ?
I use 1.75 that is a bit more expensive to use for printing also

Edited 2 time(s). Last edit at 04/07/2014 02:45AM by Cliff Mellangård.