PEI sheet  

Re: PEI sheet

You really need to remove the original; adding an extra layer is going to seriously increase the chance of the PEI not being even, and if it's not level then your bed won't ever be level no matter what you do...

I've got some dimples too, but so far they haven't been an issue. When I replace this PEI I'll be putting some printbite on instead -- I've had much better experience with it over PEI on my other printer.

see http://manual.prusa3d.com/Guide/Replacing+the+PEI+sheet/133 for insrtuctions on removing the old PEI.

Re: PEI sheet

Are the dimples from air? If so would it help to puncture it with a needle and press it down letting the air escape? Could you post a photo?

Also if it is just two dimples, would it make sense to get some fine sand paper and smooth it out being careful not to damage the traces on the bed?

Re: PEI sheet

The dimples were from an issue when the print head hit the bed. They go into the bed so sanding wouldn't fix the issue.

Re: PEI sheet

Do you kapton tape you could cover the dimple with?

Re: PEI sheet

Gluestick in the hole.

It may require occasional topping up, but it works.

Peter

Re: PEI sheet

Printbite may be another option. You will need to adjust Z height and maybe the pinda probe will not work properly. Lay a sheet loose and try. Can the pinda probe sensitivity be adjusted in the firmware? I've not read the source code thoroughly. Printbite works well with my Ultimaker 2+. It does have manual bed levelling, which once set rarely needs readjusting.

Re: PEI sheet

When you say that printbite may cause the probe not to work... why would printbite interfere with an inductive probe more than PEI would? I guess what I'm trying to figure out is that since I don't know of any reason it would be an issue I'm wondering if you're cautioning to try it before "committing" or if you've actually tried it and had the issue, and if you tried it was that with or without the PEI sheet still there?

Since I just totally killed my print head with a blob of ABS that stuck and grew 'til it destroyed everything that was all caused by lack of adhesion to the print bed I'm really really wanting to get printbite on it =] The difference for me on my other printer has been night and day.

Re: PEI sheet

https://www.amazon.com/J-B-Weld-8297-HighHeat-Degree/dp/B007PP26RI

There are other high temp products out there- no reason this wouldnt work.

Re: PEI sheet

Reply about Printbite. My points are that printbite attached to the heated bed is an approx 1 to 1.5 mm thick material. The increased height and material may affect the sensitivity of the pinda probing. . It may also affect the bed heating. I only suggest caution as I have not tried it on my genuine Prusa I3 MK2 printer.. That is all, ie buyer be aware.

PEI is a thin film sheet, printbite is a hard 1 to 1.5 mm thick hard material.

Re: PEI sheet

Sooo... anyone tried print bite? Did it work?
I have some serious trouble with forcing a small ABS parts to stick to PEI.
I clean the PEI surface with isopropyl alcohol. I use ABS-T from Prusa at 255°C (nozzle) and 100°C (print bed).

Re: PEI sheet

Just to clarify there are 2 Printbite products with different manufacturers.
There is UK printbite that seems cheaper and is tough as old boots. I personally haven't heard of anyone using this on a MK2. Then theres the German Printbite that is also tough as old boots but around double the price. I have heard reports of this working on a MK2 from a contributor on the Slack MK2 group.
I'm tempted to get a sheet of the German. I have used the UK product and it was alright, but it is quite thick.

Re: PEI sheet

So I installed the printbite from mutley (bought on flex3drive.com) and it definitely complicates the probe. I've had to adjust so it's *very* close to the same level as the nozzle, just a little bit higher, which concerns me. I've sent mutley a message to find out if it's possible to get thinner printbite.

In fairness, my PEI came off so cleanly that I just left it there and put a new bed on, so my adhesive layer is probably twice as thick as the printbite; that probably isn't adding much (maybe 0.1mm?) but things are close enough that it might be meaningful.

I'll do some prints with it and report back in the mean time =]

I *love* the printbite on my lulzbot taz 5 and really hope that I can make this work on the mk2.

Re: PEI sheet

While it did take me a bit to dial it in, it's been working great! My PINDA is about 1mm higher than my nozzle, so not as high as I could get it before, but it hasn't had any issues so far and adhesion is much better than the stock PEI.