Sunday, 3 March 2013

Mendel90 - Heated Build Chamber from Foamboard

I've been steady printing small parts for the last few weeks, but since changing to a new reel of filament (Crystal Clear 3mm from faberdashery), I've been struggling to get reliable print settings.  This has been very frustrating, as the reel of Village Green that nophead supplied in the Mendel90 kit was very reliable.

In case anyone is interested - my settings are currently:

  • Hot end: 200C first layer, 180C thereafter
  • Bed: 90C first layer, 80C thereafter
  • Everything else at Slic3r defaults (everything I tweak seems to make it worse)

One particularly frustrating problem has been large prints curling up at the corners, or failing to stick to the heated bed.  Ambient temperatures in my office have been pretty cold lately, which won't help.  So...  it seemed a good idea to build an enclosure around the Mendel90 to keep it cosy.

I had some spare foamboard which seemed like an ideal material to build the enclosure from.  I also added a 2mm glass sheet to the front (a piece of picture frame glass, approx £3) which can be slid in/out vertically by lifting the flap along the front edge.  I've only been running with it for a few hours, but it's certainly allowed me to print some larger parts that weren't possible before.  Will find a thermometer soon and check the temperature it reaching, but at a guess, I'd say it's in the 30-40 degree range.

Filament is fed through a long slit in top, the slit is covered in thin craft foam to keep the heat in and trap dust.  The foamcore is joined to itself with hotglue and to the Mendel90 with white duct tape.

I'm fairly pleased with how it turned out - it was quick to build, very cheap and appears to do the job - it doesn't even look that bad.

Alongside building an enclosure, I also put together a quick filament spool:

It's similar to many already on Thingiverse, but uses cheap aluminium tube and very lightweight parts - 6mm tube for the arms, 12mm tube for the axle (no bearings). On Thingiverse -

PS - while writing this I've been playing with the custom start GCode in Slic3r, and now appear to have a clogged hotend - just stopped a print as no plastic was coming out to discover it appears to be leaking out above the nozzle - crap :(

Here's the startup GCode that killed it...  derived from nophead's oozefree start

M190 S90
G4 P120000
M109 S200


  1. Hi Damian,

    My own experience with low to no pigment (ie transparent) filament is similar to yours. Jet PLA from Amazon uk comes in a rather translucent orange.

    My solution was to print the first layer very slowly, onto a very accurately leveled build plate. Nozzle at 200 and bed 80-90 (like you've got). It was the low speed that helped most. Some people advocate a very high nozzle temperature for the first layer (230-40). I've found this causes the PLA to bubble and lay down irregularly, creating an ugly bottom edge. On following layers I drop the nozzle to 180 and the bed to 60-65. The bed is specifically lower than PLA's glass transition temperature, which must help guard against part curling...?

  2. Hi Woodsmoke

    Good to know I'm not alone - print speed for first layer perims is currently 10mm/s (slic3r default), I thought that was already pretty slow, but will def try reducing that given your experience. I've also ordered some other coloured PLAs to see if that helps.

    Have ordered a dial guage, so will check bed level with that and see if I can get it any better - it's as flat as I could get it using a reference object and calipers :)

    Nearly finished clearing the blocked nozzle - I think it sat hot/blocked for too long and the filament started to melt above the PEEK, jamming it into the base of the geared block - had to drill it out. Have manually fed plastic through the nozzle (bypassing the hobbed bolt), but it's very hard to feed - I do wonder if something hasn't failed in the seal to the nozzle, but not sure how best to check/fix... hoping I don't have to buy/build a new nozzle :(

  3. I had similar problems and believe they were caused by too much friction in my spool feed.
    I also drilled out the filament which had swelled in the wade block and hot end. I ended up damaging the PTFE liner which is inside the black plastic part of the hot end, so be carefull.

    Next time I'd partially heat the block and disassemble it rather than drill the hot end.