Install your own PEI tutorial

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mhackney
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Install your own PEI tutorial

Post by mhackney » Fri Mar 06, 2015 12:20 pm

Over the last year I've become a bit of a PEI print surface snob. I do use other surfaces like PrintInZ and BuildTak for a few things (especially where their surface textures can be used for visual advantage) but my go-to workhorse surface for the last 12 months has been PEI. Now that I have a KITTAZ, the first mod I needed to make is a PEI surface and, unfortunately, the TAZ 5 PEI surface is not yet available for sale. So, I did what I've done with my other printers; made one myself! The following tutorial will show you how to do it. It only takes about 30 minutes and this method is tried and true - I estimate at least 100 people have used my instructions to install their own PEI surfaces.

Materials
The 0.03" to 0.04" thick PEI sheet in a 12" x 12" square is the best material to use. It is thick enough to last and not so thick as to be overly expensive. It transmits heat well too. You can get it from Amazon or McMaster Carr. I've used both (the McMaster PEI is 0.04" and works just fine). Note that the McMaster Carr PEI is glossy on both sides, the Amazon material is glossy on one side and matte on the other (see A Few Notes section below for more info). This tutorial will use the McMaster PEI since Amazon is backordered for a month.

If you are looking at other sources for PEI the only thing you need to know is that the technical name for this specific material is Ultem 1000. This is the only one I can claim works reliably.

To adhere the PEI to your borosilicate glass surface, 3M 468MP tape in 5mil thickness is tried and true. Amazon carries it in all widths of tapes to sheets. They all work and each has its pros and cons for attaching. The narrow tapes (I use 3/4" or 1”) require multiple strips but are much easier to apply. Do not apply the tape strips too closely, there should be a gap (~1mm) between them. The adhesive is very gummy and will lump if it touches a neighboring strip. The sheets go on in one piece and if you are careful, you can get it onto the glass without wrinkles or bubbles.

NOTE: you'll notice that I needed 15 strips of 3/4" tape in the photos below. The tape comes in 5 yard rolls. That is 15 one foot long strips. So, you need to leave very little excess tape overhang or buy 2 rolls if you use the 3/4" wide tape. Only 1 roll of 1" wide tape is required.

Here is my bed removed from RazzMaTAZZ, along with the tape, the PEI (note that the McMaster has both sides covered with a protective blue film), a hobby knife and a bottle of isopropyl alcohol. Not shown are lint-free paper towels and a pair of scissors and a plastic scraper. I am using the McMaster .04" PEI and 3/4" tape since all other widths are currently backordered on Amazon too.

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Installation
The #1 requirement is to make sure the glass surface is absolutely clean. I clean and rinse with isopropyl alcohol to remove all traces of grease and moisture. Once clean, do not touch the surface!

First, apply your tape to the glass. I lay down strips starting at the one edge for rectangular beds and work across the plate. The tape has a paper film on one side, leave that attached until all strips are installed. Try to keep the tape smooth and wrinkle free. Leave a 1mm gap between strips, do not overlap the edges of the tape as that will create a lump in the PEI. Allow the tape to extend about 1/4" past the edge of your plate.

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Once all the tape is applied, I like to burnish it down with a soft plastic scraper. An old credit card works fine too. The idea is to smooth out as many bubbles as possible. Finally, use a hobby knife to trim the tape as close to the glass edge as you can. This eliminates clumps at the perimeter later when you apply the PEI. Use a hobby knife and a cutting board, you can use the edge of the glass to guide the knife blade.

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Now you can prepare your PEI. If it is covered in blue protective film, it is best to carefully remove this without touching the PEI. No need for further cleaning. Otherwise, carefully clean with isopropyl alcohol.

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You'll want to do the final assembly in a clean area with no dust or dirt that might contaminate the tape. I use a clean kitchen countertop. From this point forward, you want to be deliberate and complete the installation in one smooth operation.

Peal all the paper backings from the tape strips with the plate laying on the table tape side up.

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(Don't touch!!!)

Now position the PEI over the plate/tape in the position you want it. DO NOT LET THE PEI TOUCH THE TAPE YET. You should start by applying the edge of the PEI to the edge of the bed with the electrical connectors for the heater. With a rectangular bed, you should align two edges (on a corner). I used the connector edge (which you should do since you won't need to trim the PEI later) and the front edge. Once you have the PEI in position, attach the long edge on the electric connector side.

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and slowly work it to the other edge. I bow the PEI into a curve - like you can see in the photo above - so it unrolls as you lay it down.

Once the PEI is installed, I like to use a soft plastic applicator or credit card to smooth the PEI into the tape to get it to stick well. Be careful not to put too much pressure or you might break the glass. Most likely you will see a lot of little pockets or bubbles under the PEI. Not to worry, they have no effect on the print surface.

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Here is the PEI installed, you can see it overhangs on the back and right edges. These will need to be trimmed.

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There are two ways to trim the excess PEI. You can cut it off with a fine tooth saw or bandsaw or you can score it deeply and snap it off. I prefer the bandsaw but here is how you do it by scoring. Use a cutting board and a SHARP hobby knife. Lay the bed with the PEI surface down on the board and use the glass edge as a guide for the score. The deeper you score, the easier it will be to snap off. Don't skimp on this, it is much safer to score deeply or all the way.

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Once you have the excess PEI cut or snapped off, I like to bevel the top edge with a sanding block and 400 girt sandpaper at a 45° angle. Now you can remove the protective film and clean the surface with isopropyl alcohol.

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Here it is complete and ready to install on RazzMaTAZZ.

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Don't forget to recalibrate your bed and Z height after you install!

A Few Notes
I’ve tested the tape up to 150°C on the hotbed. Please do not try this, I have a special setup and you WILL fry your heater at that temp. There was absolutely no problem for the tape adhesion at this temp. So it is more than capable of handling our application.

You do need to print on PEI with the heated bed on. I've found that I can print at lower bed temperatures than other surfaces. In fact, you do not want to print ABS on a very hot PEI bed, you will have a difficult time getting it off. I print PLA on a 50°C PEI surface and ABS on a 65°C PEI surface.

If you don’t use sharp tools to remove parts, PEI can last indefinitely.

I have two plates, one matte and one glossy. I LOVE the matte and it does stick better for persnickety parts. You can sand the matte side lightly with 1500 grit sandpaper to rejuvenate it if necessary. I do this every dozen prints or so, followed with an isopropyl wipe. You can also convert a glossy PEI to matte by sanding with 1500 grit paper or using a Scotchbrite bad (a fine works best).

The glossy side needs to be clean, you can't sand it or you will lose the gloss. I've found that a clean white t-shirt with isopropyl alcohol works best. I rub the PEI vigorously. I've wondered if the burnishing action activates the surface in some way but haven't had time to test this. I have noticed that when when the glossy side acts persnickety, a burnish rub will bring it back.

You can remove the PEI from the 3M tape and reuse the other side. It is very difficult to remove the PEI but if you start at an edge and bend it up, you should be able to remove it. Then clean the tape side and reapply as above.

Removing Parts from the PEI
Firstly, PEI is not a silver bullet. It is just as - maybe more - important to get your Z height dead on and have a well calibrated machine. If anything, too thin of a first layer will bond so well to the PEI that removal will be extremely difficult. Not a good problem. For most parts, I simply grab the part and gently pry it up by applying pressure to one edge immediately after the print is finished. Be careful if the part is still warm and soft. Once you have an edge separated from the PEI, the part will peal/pop off. The trick is to get that first edge lifted. For persnickety parts, let the plate completely cool and then pop them off or, if really persnickety, put the plate and part in the freezer. That will ALWAYS work. I'm too impatient for that so I use a can of electronics freeze spray. You don't have to chill the entire part, simply aim at an edge attached to the PEI and squirt.

Do not use sharp tools to remove parts, you can/will gouge the PEI. The divot will forever be seen on the bottom of future parts. I have attempted to fix divots with epoxy and that works pretty well but ultimately fails and needs to be replaced.
Last edited by mhackney on Sat Mar 14, 2015 3:20 pm, edited 1 time in total.
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JonathanB
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Re: Install your own PEI tutorial

Post by JonathanB » Fri Mar 06, 2015 2:52 pm

Thanks, have my adhesive applied, 12x12" sheet, just waiting on the PEI in the mail...

One question though, who is persnickety and where does he/she/it live? ;)

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mhackney
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Re: Install your own PEI tutorial

Post by mhackney » Fri Mar 06, 2015 2:59 pm

:) I'm persnickety and live in Massachusetts!
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piercet
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Re: Install your own PEI tutorial

Post by piercet » Fri Mar 06, 2015 3:46 pm

You get extra bonus points if you use a PEI pan to do the installation. A square one might still count (PEI R squared?)

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JonathanB
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Re: Install your own PEI tutorial

Post by JonathanB » Sun Mar 08, 2015 1:23 pm

mhackney wrote::) I'm persnickety and live in Massachusetts!

LOL. would have guessed hogwarts or something ;) hehe.

kcchen_00
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Re: Install your own PEI tutorial

Post by kcchen_00 » Sun Mar 08, 2015 4:26 pm

piercet wrote:You get extra bonus points if you use a PEI pan to do the installation. A square one might still count (PEI R squared?)
That actually might be a good idea to add some weight and leave overnight to ensure a tight bond between glass and PEI.

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mhackney
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Re: Install your own PEI tutorial

Post by mhackney » Sun Mar 08, 2015 9:04 pm

Not needed at all. If you read my year old thread on the SeeMeCNC forum you'll see that I started using weight but found it totally unnecessary. The tape and PEI are non compressible so weight is not going to help. If you rub the PEI down with a plastic scraper or credit card like I describe, it will be ready to print on immediately. I've been using a PEI prepared this way for 12 months without problem.
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brazen521
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Re: Install your own PEI tutorial

Post by brazen521 » Fri Mar 13, 2015 3:53 pm

Excellent post! I found this very helpful. I ordered my PEI from Amazon and it arrived at almost EXACTLY the dimensions of my print bed, but this may have just been total luck. Glossy on both sides, which is unfortunate because I was looking forward to having that matte finish. It was about 1/16 of an inch too long in one dimension, but I called it close enough.

ABS is sticking a little too strongly that I would like it to - doesn't "pop off" after the bed cools like some other people experience. Going to continue experimenting with bottom layer thickness.

Haven't tried PLA yet.

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mhackney
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Re: Install your own PEI tutorial

Post by mhackney » Fri Mar 13, 2015 3:58 pm

It's easy to turn the glossy into matte - simply sand it as per my instructions. That's what I do, I much prefer the matte finish.

Usually when you have issues with ABS sticking too well its either the first layer height is squished (print a single layer object and measure it, it should be exactly what your layer height setting is) or the filament is being extruded too hot or (and this is a smaller effect) the bed is too hot.
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drifter57
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Re: Install your own PEI tutorial

Post by drifter57 » Sat Mar 14, 2015 2:44 pm

Might mention that PEI only becomes tacky and has good adhesion to parts when it is HEATED. If you try to print PLA on a cold PEI bed it will not stick, and you'll be back here cursing all of us PEI advocates to eternal hell fire.

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