Adding PrintBite+ Build Surface to a Wanhao I3 Plus Mk2

I have loved my i3 Plus Mk2 since I bought it. Out of the box, the demo print was perfect and, for the most part I have had no issues - except for first layer quality / adhesion and auto bed levelling.

Almost all of my early prints were ABS and they went well, there was some warping, but that was remedied after a trip to Ikea :-)

I struggled to get a perfectly smooth first layer - smooshing it into the bed helped, but the Wanhao magnetic Buildtak style surfaces didn't fare well with lots of high temp ABS coverage and soon became worn and uneven.

I then switched to PLA and constantly struggled to get good first layer adhesion without a raft, trying a range of combinations of temps, z offsets, first layer widths and heights. Quality was also poor.

My auto bed levelling was also incorrect - the nozzle was always higher on the RHS of the bed than the left (I checked frame alignment and z-axis alignment). I could watch it auto level and see the sensor light come on at an increasing higher position as the x-axis moved to the right. At least it was consistent and I knew exactly how many turns of the bed levelling nuts on the RHS would be needed to correct after auto levelling.

I really wanted to use glass, but the inductive z-height sensor doesn't work through glass and as this is also used for the end-stop would cause all sorts of issues.

However I have found a solution for the build surface, which has also solved my bed levelling and here it is:

Step 1: What You Need

Please note I am in the UK, so all temps are degrees C and links are UK based.

  • A sheet of glass, cut to size. I got borosilicate from Oozenest and they will cut to size, including chamfering the corners - however you might not want to do this (not because it's a bad product, but see below)
  • A replacement Wanhao magnetic print bed bottom section from Wanhao UK
  • A sheet of PrintBite from Oozenest - also available from 3DFilaPrint. They don't do 220mm x 220mm, so I got a 250mm x 250mm sheet.
  • Not detailed here, but I would recommend installing Chad Hurd's awesome fork of AVDi3++ for the Mk2 - the github repo is here but you should join the Wanhao i3 Plus facebook group, search it for Chad Hurd and you will see his post with links to downloads and excellent references and instructions.

Step 2: Before You Start

This is for the Wanhao i3 Plus Mk2 with the automatic bed levelling - and is not neccesary for machines without - although it might work for other printers using similar bed sensors.

The borosilicate glass is NOT recommended for PrintBite and I got it after a classic case of not reading the damn instructions properly. Having said that, I have used it and done quite a few prints with it subsequently and so far, everything is OK. I'll report back if I have issues.

TLDR The role of the magnetic print bed bottom section is to provide something for the z-axis sensor to respond to - this gets sandwiched between the glass and the PrintBite. This is essential to make this work on an i3 Plus Mk2.

I would highly recommend installing Chad Hurd's AVDi3++ I have only added this print bed since I have installed it, so I don't know how this method would behave with the stock firmware - but when I was curing the PrintBite adhesive, I tried at first with 110degC bed temp, and got a thermal runaway warning - I don't know if it was serious, but glad of the extra protection offered by this firmware. I subsequently used 100degC and everything was fine.

DISCLAIMER (stating the obvious): This has worked well for me, but you do it at your own risk - as with pretty much everything to do with 3D printing, you're playing with electricity, high temperatures, glass and other dangerous stuff. I can't be held responsible for anything or anyone that gets killed, maimed, hurt, broken or caught on fire as a result of this. Please be careful.

Step 3: Clean the Glass Plate

I rubbed it down well with some isopropyl and then buffed it with a clean cloth

Step 4: Attach the Magnetic Print Bed Bottom Section

This section has a blue protective sheet on one side and a white sheet on the other, covering the adhesive. Pull back one edge of the white sheet for an inch or two and then place that edge, lined up on top of the glass plate. I then slowly pulled out the white sheet from underneath whilst rubbing back and forth on top with a cloth to remove air bubbles.

Step 5: Add and Trim the PrintBite

Once the magnetic plate was on, I peeled off the blue protective covering, cleaned it with isopropyl alcohol, buffed it with a dry cloth and then attached the PrintBite in the same way as the magnetic plate.

As the PrintBite is bigger than the glass, I lined up the bottom edge (with the logo) to the edge of the glass, so I had three edges overlapping.

I then flipped over the glass/magnetic bed/PrintBite sandwich and, using a sharp knife, trimmed down the edges of the PrintBite.

Step 6: Cure the Adhesive

Finally I followed the PrintBite instructions and left the whole kaboodle covered in a damp cloth on the print bed with a temp set to 100degC for an hour, let it cool and then repeated repeated.

Step 7: Conclusion & Recommendations

These before and after photos show the dramatic improvement. PrintBite is awesome and I particularly love the 'click' you get as the part releases itself from the bed when it hits about 31degC.

This will add an extra strain on the y-axis as it adds a lot of weight and I would highly recommend adding both a y-axis belt tensioner and a y-axis belt pulley support (options for both on Thingiverse). I have also dropped printing speed a bit to be kind to my patient and overworked printer.

For whatever reason (some kind of electrical / magnetic anomaly?) this has also solved my bed levelling issue and I am now getting first layer quality I didn't think was possible.

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