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Basic PLA printing with Mendel

Posted by TerryKidd 
Basic PLA printing with Mendel
February 04, 2013 07:13AM
My question, how do most people print PLA succesfully?

Plain glass or tape?
Heated bed or cold?
Skeinforge or slicer?

I completed my printer (Reprap Pro Mendel) just before Christmas and after some intial success with my first prints I'm now a little frustrated by still not being able to get consistently good prints.

My problem this weekend has been, PLA, first layer is not sticking properly.

I've tried heated bed on plain glass with the bed at 60 C (indicated) and extruder temp at 200C and the extruded filament just curls up behind the head and doesn't stick down at all. Plain glass seems to offer the best bed side down finish but it's not consistent for me.

I started off with the bed heated to about 45C and Kapton tape and this was OKay but it's difficult to get a nice finish on the bed side down of the part because of gaps or overlaps on the strips of tape.

I tried with a heated bed and blue Tesla tape and this is not bad, this tape goes down easier, but it seems like the Tesla tape needs to be replaced after every print.

Here in Germany I'm having trouble finding acetone for cleaning. The nail polish remover either has some kind of oil mixed with the acetone or else is acetone free. So I'm stuck with soap and water to clean the glass.

I'm also struggling to get Skeinforge to do what I want it to do. Changing the temperature setups do not always seem to change the set temperature in the GCODE. I'm using a Mac. Is there an executable only version for the Mac? I'm not sure if I've got all the Python stuff set up correctly.

I had a go with Slicer but although the user interface is great I miss not being able to analyse the output and see what the tool paths are.

How do most people do it?

Re: Basic PLA printing with Mendel
February 04, 2013 07:27AM
I had similar problems with the RRP Mendel (though I'm sure it applies equally to any heated glass bed)

Acetone is not enough - I occasionally had to take the glass off and wash it using bathroom cleaner. I suspect that some contaminants are just spread around by the acetone.

I now use a thin layer of PVA glue (mixed with water - probably 2 parts water to 1 glue) - wipe it on the glass and it works for several prints. Only problem I've had is getting the parts off if they have a large surface area - generally a sharp blow from something slid along the glass or a scalpel blade under an edge will free the part.

I like Slic3r but I get better results from Skeinforge - still trying to work out why :-)

Have fun
Re: Basic PLA printing with Mendel
February 04, 2013 08:09AM
Thanks for replying.
>I now use a thin layer of PVA glue (mixed with water - probably 2 parts water to 1 glue) - wipe it on the glass and it works for several prints.

And are you still heating the bed?
Re: Basic PLA printing with Mendel
February 04, 2013 08:17AM
Yes - the bed is heated to 50C - I haven't tried without heating. Parts come off more easily if you have the patience to wait until the bed has cooled :-)

You only need a small amount and many glues are PVA based (I'm using Araldite waterproof wood glue as I had it lying around) so it should be an easy one to try.
Re: Basic PLA printing with Mendel
February 04, 2013 08:51AM
I use pla on pva coated glass too, and I'm really happy with it. I use a 70C bed, extruding at 207C. I use repraper filament, which is not amazing quality, and it never stuck to plain glass (it seems slightly oily). However, I can print huge bases with no warping or curling with the pva. I resurface the pva sometimes, if I'm doing the same print again I rub a damp sponge over the bed quickly, otherwise I do that every 2-3 prints. I also add a drop of pva and wipe it around with a damp sponge every 5 or so prints, and every 10 or so I scrub off the residue with a damp sponge, and start again. I've had zero problems doing this for months, before that I used tape which wasn't so good.
Re: Basic PLA printing with Mendel
February 04, 2013 10:52AM
Thanks James.

I think the variable quality of different manufacturers PLA may be playing a part in some of my problems. I started off with my sample from Faberdashery and then bought some 1kg reels from a German source.

Additionally, I'm forming a suspicion that the weather conditions, maybe slightly damper of late, may also be part of it. I had a 1kg reel of PLA and it's been sat out of its shrink wrap in my, resonably dry cellar, for a few weeks now. Maybe it's become more problematic over time.

Does PLA absorbes moisture over time? If so, can it be dried out again?

Has anyone tried to characterise filament from different manufacturers? Are there any specifications for PLA published by any of the filament manufacturers?

I listened to a video talk recently where someone, who seems to be in the know, suggested that filament was like wine. Which I took to mean - somewhat undeterministic. Are we oblidged to expect good years and bad years? Or can someone point me a supplier who's product behaves consistently?

Edited 2 time(s). Last edit at 02/04/2013 10:53AM by TerryKidd.
Re: Basic PLA printing with Mendel
February 04, 2013 10:58AM
Terrykid, if you have problem with objects sticking, try using brim (for Slic3r) or raft (for Skeinforge). I had similar problems with objects slipping off and destroying the print until I started using brim. I prefer brim over the raft because it is much easier to remove. Look in the skeinforge sub forum, there is a plugin by a member of our community that does brim in Skeinforge as well.
Re: Basic PLA printing with Mendel
February 05, 2013 05:22PM
Acetone is easy to find in Germany - check Bauhaus or Max Bahr. Both have it for around 4 euros, but it wont help you (in my opinion) with PLA.

I have had good luck with Tesa Malerkrepp for outdoor. Be careful there are two kinds, one is shiny and thin, the other is more papery texture - use this one.

My best luck is with:
-205 C nozzle
-55 C Bed
tesa tape

I use slic3r on the mac, and I use Pronterface to examine the toolpath. If you have skeinforge installed, you can still use the skeinforge tools to analyze the gcode from slic3r. I would recommend slic3r 0.7.2b (really old version, but very reliable) as well as 0.9.8 (newest version), though it has a number of bugs most specifically with generating too many moves for a given line segment.

I have also heard that the tesa tape with kapton tape on top works well, I have not tried it.

I tried PVA mixed with water and so far no success here. I tried uhu, and recently I hit up Bauhaus and got a different brand. I am going to try this soon.

Some people suggest using Borosilicate glass, and occasionally running it through the dishwasher.
Re: Basic PLA printing with Mendel
February 05, 2013 06:28PM
Hi Terrykid
I have found the same as you, having completed my Mendel pro just before Christmas. Initially no problems at all with sticking to glass base heated to 85 PLA extruded 205 Then all of a sudden it started curling up behind the head, no chance of laying any plastic down at all. I had been using isopropyl alcohol, which Seemed to work ok until thent. I tried acetone, but that seems even worse. My wife, who has an objection to any chemicals, suggested lemon juice, I ridiculed the idea, but amazingly it works, It seems that if you can get the surface to squeak whilst wiping it, that's the best - I guess it's an ultrasonic cleaning effect (no idea really). I seem to have to use it regularly, must get a new lemon, it's going a bit mouldy now, but still works. Having read other comments above I to wonder if it has to do with the plastic. I originally used Faberdashery,, but now I' on a cheaper 1kg reel . I'll try a bit of research.
I use Slic3r only because it's faster and seems to have an easier user interface, but I haven' investigated Skeinforge much.
Re: Basic PLA printing with Mendel
February 06, 2013 02:53AM
Thank you, demetris,mitchese and Core Storage(great name, I too wrestled with magnetic core many years ago)

Re: Basic PLA printing with Mendel
February 07, 2013 02:31AM
mitchese Wrote:
> examine the toolpath. If you have skeinforge
> installed, you can still use the skeinforge tools
> to analyze the gcode from slic3r. I would
Thanks mitchese but how do I do this?
How do I select a 3rd party(slic3r) generated file for skeinforge analysis?

Terry Kidd
Re: Basic PLA printing with Mendel
February 08, 2013 07:59AM
I also have had some problems with this on my RRP Mendel. I ended up removing the glass and clean it. When I put it back I noticed that there were some burr around the holes in the aluminium plate and I figured it could not do harm to remove them. This should make for a better contact between the glass and the aluminium plate which I guess will give a more accurate reading on the bed temperature. After that I start using white wine vinegar to whip the glass clean and I felt the problem wasn't that big any more. Now I have bought some Chines filament and seams to stick much better than the faberdashery filament. I print PLA at 65C on the bed and extruding at 175C.

/Markus Tenghall
Re: Basic PLA printing with Mendel
February 08, 2013 09:11AM
Thanks Markus,

another useful tip. This reminds me how indeterministic, with these layers of alluminium and glass, the actual bed surface temperature probably is. If the bed heater is rising towards the target temperature the temperature on the glass must be cooler.

Then, 5mins, say, after reaching target temperature on the thermister the temperature of the actual glass may have caught up hmmm.

Re: Basic PLA printing with Mendel
February 08, 2013 08:15PM
Lemon juice, that's genius!!
PLA = poly lactic acid. It's organic and can decompose overtime.
Lemon juice is a highly acidic blend of citric, ascorbic, and malic acids.

Maybe it eats away at the PLA just enough to grip it. Awesome find. smiling smiley
Re: Basic PLA printing with Mendel
February 11, 2013 07:36AM
The temperature on the glass surface can be quite different to the bottom. I have a thermistor on the underside which reads 90C, I then used a thermocouple on the top side which reads 68C. It's easy enough to compensate for this 20C offset now I know what it is!
Re: Basic PLA printing with Mendel
February 12, 2013 02:28AM
I can testify to the effectivness of lemon juice, straight from the lemon, for cleaning glass.

I cut a lemon in half, gave the glass a wipe over with the lemon and then polished the glass dry with a kitchen towel. The extruded PLA then stuck to it nicely. (and what a nice fluid dispenser the lemon makes, you couldn't make a nicer one in a factory.)
Re: Basic PLA printing with Mendel
February 26, 2013 07:24AM
lemon could be a quite good idea and chemically not so offensive. lemon juice has sugars inside so by heating it up you probably create a nice gluey caramel that sticks to PLA smiling smiley

as you can see in the picture I also have problems with sticking PLA on the heated glass. I also have problems of infill popping up during the first layer as you can also see.

my settings are
hotend 205C (first layer, subsequent layers 201)
bed 70C (subsequent layers 65C)

I used a small 4cm fan to cool the surface, I think it works in order to keep the infill unmessed, but the cold air makes the edges curl.

maybe its another problem in my Slicer but in every big surface I get problems smiling smiley
I ll try the lemon approach (but I ll buy some lemon juice as the lemons in germany are expensive) and see what happens
open | download - IMG_2365.resized.jpg (371.3 KB)
Re: Basic PLA printing with Mendel
February 27, 2013 05:01AM
Firstly you must print your first layer slower than the other layers. I use 30mm/s on my heated bed, but back in my blue tape and cold bed days I had to use 5-10mm/s.

Then to guarantee a strong stick mix a strong solution of sugar and water (1cm of sugar in 3cm water), use a kitchen towel to spread some on a hot bed, keep wiping to make a smooth layer, wait a minute for it to dry and that print ain't going anywhere!
Re: Basic PLA printing with Mendel
February 27, 2013 05:50AM
thanks konwiddak I already use 35% of regular (27mm/s) speed on first layer.

your sugar suggestion seems nice. I used a slightly more expensive one, ie the lemon approach discribed in previous posts and YES i can attest it works wonders. even the biggest print stick to the bed very hard.

probably the sugars in the lemon juice (i bought readymade lemon juice) have the same effect as the suggary solution you provide. Maybe the acid also has something to do with it. I think I should add it in the recommendation section of the wiki as it really provides a very repeatable solution to PLA not sticking well , and I havent found it else.

another small question .

with the heatbed the rule goes the higher the temperature the better?

I experiment with 70-65-60 C and as the heatbed is the real energy consumer in reprap I would want to go as low as i can. maybe with the lemon juice the print sticks with even lower heatbed temperatures

Edited 1 time(s). Last edit at 02/27/2013 05:53AM by waste.
Re: Basic PLA printing with Mendel
February 27, 2013 07:17AM
Hmmm, interesting to see this one pop up again.

I had some success using a lemon to clean the glass but I switched to just taking the glass off and using hot water and washing liquid then drying with a paper towel. When it's sqeaky clean the glass is well and truly degreased.

Now using that (rather pricey) Faberdashery filament I struggle to even remove the print from the glass. I had to turn the 'lift' on because if the extruder head snagged the print it would tend to make the motors stall and miss steps rather than knock the print free. I'm also running with lower extruder temps to try and improve the quality of bridges so the topmost layers of the print get harder sooner.

I've had filament not stick down, even on new tape, as in the picture waste posted, but this was with brand X filament.

For me it's very clean plain glass. Bed heated to 50C extruder temp 200C for the first layer and then 190C for the rest. Faberdashery filament. I've not had chance to go back to brand X to see how well this works.
Re: Basic PLA printing with Mendel
March 24, 2013 03:52PM
Generally I use a heated bed with clean glass, bed set to 70 deg as the glass is around 10-15 deg lower than the bed. Before each print I clean the glass surface with household glass cleaner and the prints stick really well. When the glass cools a bit after the print, it does just pop off. I've tried a few different filaments and all have worked with these settings so far.
I have found Acetone cleaned glass or 100mm Kapton tape to work best. But I am going to be trying some of the methods above (especially the lemon) to see how they compare. I buy my Acetone from Boots in 100ml bottles, you have to ask for it as its a seriously strong solvent and prone to abuse, sometimes you may even have to prompt the checkout worker that its kept either in one of the drawers under the over the counter tablets etc or in the dispensary area. Either way it is always out of view. Chemists are the best source of Acetone as the behind the counter stuff is 100% acetone, it doesn't even have Bitrex in it (stuff to try and prevent misuse). All the nail varnish removers, even ones that are pretty much nothing but acetone, are all not very good at all. Boots have a policy to not sell more than 1 bottle at a time/a day and if you go in every day buying it then they can refuse to sell it to you (particully if you are young or are even slightly scruffy looking!). My local Boots store staff all know me and the pharmacist is a fellow Arduino/RasPi and BeagleBone electronics hobbiest and knows about 3D printing methods so I get no hassle there but I have had problems buying it in other Boots stores despite being 35 and tidily dressed!
Most small chemists/pharmacy's also stock it hidden away behind the counter but they can be seriously picky about who they sell it too I have been told by younger people who have been refused despite being 20-25 with ID etc...

I use Faberdashery filament with an RRP Mendel and I have found Acetone works really well for short and stumpy prints (with a brim a few layers high and very close to the model edge (if using Slic3r or a raft can work just as well in SF) but you need to wipe over the glass a few times and let it evaporate each time (make sure you are doing this in a well vented room and no where near any flame or spark -- Seriously) then go over again. I find 3 times is the charm, for doing it I use a Tesco Value dishcloth (The white ones with a red or blue stitching around the edge) or similar to apply the Acetone (double or triple the cloth over then put over the top of the Acetone bottle, put your thumb over then give the bottle a quick turn upside down just long enough to dampen the cloth around the bottle top and your thumb, then just give the glass a nice firm wipe over (don't just dust it over, use some force), then just leave for 30-60 secs for the liquid on the glass to evaporate then repeat.
On the 3rd (or Last) time, use another cloth or 2 pieces of kitchen roll/towel and give the glass a good firm wipe over just as the last of the Acetone is evaporating and you should hear the glass start to squeek (like you hear when cleaning windows), this means the glass is 100% grease free and ready to go. Just dont put any thing on that print side of the glass except the plastic out of the hot end!
After every print I give the glass top a quick blast of air from an air duster for cleaning keyboards/computers etc.. Even after just a couple of hours of being idle it is supprising how many tiny fibers and pieces of dust can settle on the glass.
DONT Leave the acetone bottle open as it quickly evapourates into the air that you are breathing, a full 100ml bottle can evaporate in 15 mins of you forget to put the lid on tightly!

For taller and bigger prints I use 100mm wide Kapton tape to put directly across the middle of the printing area (so the majority if not all of the print area is covered in just a single piece) then if needed I use 40mm Kapton tape above and below the 100mm piece (But have only ever done it a few times when I havent been able to fit the print into the 100mmx210mm print area created by the 100mm piece.
I find that works a charm and if you take your time, put the glass onto a clean and flat surface to apply the Kapton and use kitchen towel or a white dish cloth to smooth it and push it down as you apply and get the strip on carefully and without any bubbles, give the tape a good firm wipe over with a cloth as mentioned above once all the tape is laid on just to flatten any spots and remove any dust etc. (if you get a bubble that you cant avoid then use a pin to bust it then flatten the area where it was) then it becomes easily the best surface to print onto! It takes some patience tho to get such a wide piece of tape straight and flat but it is worth the time to get it right.

Both these methods give you a 100% flat print surface and have given me excellent results. I originally used 40mm Kapton in strips which worked ok but as soon as I switched to 100mm kapton or just acetone cleaned glass done properly my print quality went up dramatically!

I have the Tri-Colour/Material add on kit for my RRP Mendel due this week and am not looking forward to having to set up 3 extruders, hot ends and nozzles to all work in harmony! I also have a couple of 0.3mm nozzles coming so will be interesting to see how plastic extruded through those bonds to the print surface compared to my current 0.5mm one.

I really love Faberdashery PLA as they have the best range of colours by far, its overall great quality and available by the meter BUT my one gripe is the fact that the different colours vary so dramatically with the temps needed to work with! Some of their colours need MUCH lower hot end temps then others and some need a hotter bed and a couple of their colours are a real pain to work with and you need to spend quite a lot of time just testing temps (which normally need to be stupidly high or much lower then the general zone the majority of the colours work at) and extrusion sizes to get them working right (Teal is the one I have real problems with as it just wont stick to acetone cleaned glass whatsoever how ever many times you have scrubbed it and even has trouble on a Kapton taped bed. It even has issues sticking to itself on the previous perimeter or layer, its the only colour of theirs that I just cant seem to get dialled in).
Generally tho I would always pick their PLA for quality and range of colours every time but would also have a couple of drums of cheaper PLA in Green and White for big prints that need a test run and for making parts.

I have only recently started using ABS which despite stinking the house out, is much much simpler to work with and has the benefit of being able to be made to look much better by a quick Acetone dip or brush on! I think ABS is much better for finer and more detailed models.

I have also found (as someone else mentioned above) that the Aluminium heat spreading plate between the PCB Heater and glass plate can sometimes have little burrs or raised bits that prevent 100% contact with the glass which can have a HUGE impact on bed temps! I had one on my plate and didn't know for quite a while until I noticed prints failing in the same location over and over. I removed the glass and then used my 'Work Finisher' (Awesome ceramic bladed hand tool every 3D printer should own, Google "Work Finisher Ceramic Tool" and you will find them, well worth the investment!) to deburr it then smoothed it down so the plate was 100% flat at it should be. When you place the glass down it should kind of be pulled into the plate and when lifted the same thing, it should require a little side or back to front movement when lifting it to be able to lift it up and away.

When ever I get a new roll, drum or length of material now, I use a meter or two just printing lines and small disks to find the best temps and widths.
Re: Basic PLA printing with Mendel
March 31, 2013 01:56PM
You can get larger quantities of acetone, much cheaper on eBay than in Boots. It doesn't matter how scruffy you are then smiling smiley

Re: Basic PLA printing with Mendel
June 12, 2013 06:20AM
I have to report on the marvels of lemon juice. We have to give kudos to the girlfriend of the guy who suggested it

For PLA , no kapton tape or anything, just lemon juice on glass, it sticks so hard you have to use leverage to force it out of the glass. The lemon juice lasts for 3-4prints and then you re-apply. no bad solvents, no nasty smell no anything. bed temperature at around 55-60C smiling smiley

For ABS I had some problems with small footprint stuff unstucking, and even used hotglue to hold down a funnel I was printing.
I was ready to use acetone with ABS , but the smell is pretty bad already with the abs extruding, so I said to myself lets try lemon juice again. And surprise lemon juice works also with ABS at bed temperatures around 75-80C
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