Warping Irony...

[ShadowX]

Its actually not that bad in terms of cost. For me it was under $45 and it completely changed how I print. I used hair spray before and now I have two full cans collecting dust. The only thing I buy now is 90% pure isopropyl Alcohol from Walmart. I use it to clean the surface and to cool the part after a print. I can’t imagine a better surface. I tried FR4 based solution like PrintBite, but I was not impressed with the holding power. It holds well at temperature and the part comes off when the bed cools down. However, I still had issues with lifting on corners on small and large parts. I don’t trust it to hold my parts especially for long prints. I have full trust in PEI since there is no way for me to take the part off without damaging the bed when its heated. Once it cools down, you can pop the part right off with no effort. The only issue I have with PEI is that its transparent to IR light, so I have to coat it with black paint in order to use my IR height sensor. Other than that, its awesome.

[wirlybird]

Sounds good. I have some stubborn ABS parts that are large and a lot of infill (still tinkering on that) that love to lift at the corners after several hours.

From what I have read on Printbite it is not great with ABS so I wasn’t going to try it.

[Iceman24k]

you can also adjust the infill pattern to help mitigate this problem…

also I swear and attest to the glue stick on glass or mirror tiles…

also but not as good as glass,… polycarbonate sheet is cheap…

[cobnut]

Just a quick update. I’m getting reliable good results with the blue tape now. Getting those results seems to be mostly about the z-height of the first layer. I’m still calibrating the bed to the glass surface so the blue tape reduces the gap. Print with too small a first layer and there isn’t enough material laid down to form a good bond for the next layer (and you get all sorts of uneven blobs). Print with too large a first layer and the ABS doesn’t adhere well to the tape.

I’ve done half a dozen prints now where there was no warp and in all but one the tape came away cleanly from the model. In the one case where it became stuck to the model (this may have been because I allowed it to cool right down to cold room temp, about 11C overnight), it was easily removed after soaking in warm soapy water.

The prints are still sticking quite firmly to the bed under the tape so need careful removal with a scraper but they’re not “welded” to it like they were with my first attempts with this tape.

So, in summary, for me it seems to be:

1. Use the right blue tape. I’m using the 3M 55mm wide version from Amazon.

2. Warm the bed before applying the tape (to about 65C so it won’t burn you). Applying the tape to a cold bed means you get gaps between the tape strips as the bed expands (and possibly reduces the tape adhesion).

3. Get your first layer height right. I can’t give any examples because I suspect the “right” height will vary from printer to printer, material to material, but essentially if the nozzle is too close to the bed/tape you get a poor first layer and/or the tape welds itself into the print and to the bed, if it’s too far away it doesn’t stick well (to either the bed or the model).

The PEI bed sounds interesting, and I might well give that a go as well. Although the tape is working, it adds time and “fuss” to the print process I’d rather not have (and is of course an ongoing expense, not a one-off, albeit quite a low one).

[wirlybird]

I should be trying the PEI this weekend. It is supposed to get here tomorrow. I am also going to run another glues stick on glass test. The last one was going good until power interrupted the print!

[wirlybird]

I was doing a glue stick test and it was going good until power killed the print. Going to try another starting tonight. I had a lot of infill on my part 50% for strength. It is two pieces that bolt around a pipe like a clamp/bracket. I think if I do even more shells I can reduce infill since many shell layers around the bolt holes should give good crush strength.

[wirlybird]

Well, this whole PEI experiment was a huge waste of money. I haven’t even been able to print with it. As the bed gets up to temp for ABS (100c) the PEI starts to curl and peel up all around the edges. The interesting this is the PEI sheet was perfectly flat as I installed it.

[Nebbian]

What adhesive did you use to stick it down? Did you really clamp it down when installing?

[ShadowX]

You need to install with the 3M 468MP double sided tape. Other types of adhesive can not handle the temperature without delamination. You can’t install the sheets on top and use clips either. It has to be bonded down to the glass with the tape to work. What type of bed surface are you using? Glass? Did you verify the surfaces are clean before you stuck the PEI sheet on it and verified all the bubbles are removed?

Here is another thing to try. Heat up the bed and put another sheet of glass over it and apply some weight over the bed to get the sheet to stick down. You will still need to put in clips along the edge to hold the glass plate down to the bed surface and it would go over the PEI sheets.

[ShadowX]

[wirlybird]

Thanks for the info. I bought exactly what I needed as you listed I believe.

I am bonding to boro glass and it was clean. A good scrub and rinse in HOT water, air dry then washed with alcohol and air dry.

I bonded the mat side of the PEI and as it heated it lifted and curled bad. I flipped it so the shinny side was down, which I really want up, and it is sticking for now.

I am going to try another later and this time heat the glue once install and then weight it. Weighting it should matter since this 3M glue and PEI are not compressible but stick by contact but it’s worth a try.

I’ll check out the video later, thanks again.

[ShadowX]

I have my PEI mounted on Boro glass and also an aluminum disk for even heating also. Make sure you wipe down the surface of the PEI also and it should help. The PEI is not compressible, but the glue underneath is. Its relatively thick and the material will press down. The trick with another layer or glass and some heavy weight is to ensure that its bonded at temperature. You have to heat the bed while you apply the force. I’m glad the shiny side is working a little better for you. You might had some trapped bubbles on the first try and that expanded enough to lift the PEI sheet. Keep us posted.

[cobnut]

Hi @ShadowX the PEI sheet I’ve ordered apparently is self-adhesive - are you saying I should use the 3M tape instead of this self-adhesion (it’s 3M - you can see the logo in the picture)?

I was also intending to put the PEI directly onto the bed - is putting it onto the glass a better idea (actually happier to do this as it’d make removal/replacement easier and allow me to use multiple beds).

[wirlybird]

What did you get, I am interested in the adhesive already on it?

[ShadowX]

I don’t know what type of adhesive they used for your PEI Sheet. If its 3M 468MP, that is the preferred material. It will retain adhesion at least up to 100C on a print bed. Some of the other adhesives may not be rated for the high temperatures. The 3M material is usually labeled on the backing tape. If the sheet already has the backing tape, you should just use that for now. If you find out that it has problems at higher temperature due to delamination, then you should remove the PEI and use the 3M tape.

Sticking directly to glass is fine. You may have to raise the temperature up slightly or wait a bit longer until the top layer gets up to temperature. Compared to glass, you can actually use a lower temperature for PLA than plain glass. At around 40C, my print is already sticking well. I used a thermocouple thermometer to measure the actual bed temperature on top since I have a high power heater and the thermistor is on the aluminum heat spreader. I have a old kapton heater layer, glass, adhesive, and then the PEI sheet. Its not the preferred method, but its a pain for me to get the old kapton heater off so I left it there.

[cobnut]

@wirlybird this one:

https://www.amazon.co.uk/gp/product/B018G59B82

Seemed like a good deal as it’s big enough to cover the FF Pro bed twice. If you look at the close-up photo you can see “3M” branding on the back. Should arrive tomorrow or the next day (I ordered the last one, hence the long delivery time shown now on that page) and I’ll report back once fitted and tested.

[cobnut]

OK… another update. I’ve just completed my first print on my new PEI sheet and… it’s “OK”, but not perfect. There was some very slight warping to one corner of the model, not huge, but enough that I can’t send it out to the customer. The print was ABS, bed temp 90C, absolutely no adhesive at all, so it was a tough test.

I’m now printing another part at 100C bed (my normal ABS temp, I reduced it in the first test as a… test) so we’ll see how that goes. I’d rather not use any adhesive, but I’m thinking a tiny spray of adhesive will probably make it 100% warp free.

Anyway, so far it’s pretty good and I’m sure will be excellent for PLA, but it’s certainly not perfect first time…

[ShadowX]

You have to bump up temp for ABS. With all the layers of thermal resistance of glass, adhesive and even the PEI, the top of the bed may be 15C less than the temp on the heated bed.

[wirlybird]

I gave up on it for now. The expense and effort was not worth it. It still isn’t working well for ABS. I get much better results with hair spray or glue stick on glass and the effort really is minimal.

I need to get thinner glass to try again with mounting the PEI or make yet another shim!

[Polo_S_mano]

I might have a solution for you There’s a 3D printing adhesive called Magigoo that works pretty well with heated beds because it sticks when the bed is hot and when it cools it releases the print almost by itself. If you’re printing ABS or PLA I’m sure it will do just fine. you can find it on magigoo.com

I hope I helped a little.

Leo