Archive for December, 2013

Upgrading Mendel 90 to E3D hotend

After a few months of frustration with the Magma hotend, which can print ABS and nylon but not PLA, I decided to try the E3D hotend.

That's a big heatsink

That’s a big heatsink

Unfortunately, it didn’t just drop in. The heatsink on the E3D hotend doesn’t have the same groove as the Magma (the magma groove matches a J-Head). The lip on the top is thinner and the groove is larger. With the Mendel 90 wades extruder, the groove thickness isn’t important but the lip being thinner means that the E3D hot end isn’t fully secured with the narrower lip. I modified and printed a new wades extruder by changing to “function jhead_groove_offset() = 3.8;” in scad/vitamins/hot_ends.scad

Shallower indent on new wades extruder (red)

Shallower indent on new wades extruder (red)

The included 30mm fan duct also doesn’t fit on the Mendel 90 right next to the wingnuts. I redesigned the X carriage in the same vein as this modified one on thingiverse. My X-Carriage uses LM10UU so I couldn’t go with that x-carriage.

Fan mounted on new X carriage.

Fan mounted on new X carriage.

Fan and hot end. The wingnuts were replaced with M4 nuts later.

Fan and hot end. The wingnuts were replaced with M4 nuts later.

I created a new fan duct in OpenSCAD inspired by the used with the X-carriage above, except mine ducts the fan directly to the E3D fan heatsink. It took a few iterations to get the shape correct and fitting, and with reasonable support material. The Cura auto-generated support material was fine for the print, but I broke the duct in half trying to remove it.

Fan duct with support material.

Fan duct with support material.

Fan duct assembled on printer.

Fan duct assembled on printer.

My first print was ABS because it’s what I had on the printer. PLA also prints well. I figured I’d test my 2nd PLA print with this hotend by printing at 60 microns (0.06mm layer height).

IMG_2772

Head from “Black Dynamite Bust” on thingaverse printed at 0.06mm layer height

This was printed at 50mm/sec using a fan off to the side of the printer. I need to get a fan duct if I’m going to do PLA much more.

So far this hot end has been working well for me. I perhaps have too much cooling on it with the high-airflow 40mm fan. The increased length has reduced my Z height by about 12mm though.

 

My Mendel90 modifications for E3D hotend and LM10UU are now on thingiverse.

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Prusa i3 Modifications for SB hackerspace printer class

I did much of the work to get the Santa Barbara Hackerspace to have it’s first printer build weekend with a Prusa i3. I wanted to note the modifications I made and other things here.

I initially was going to do this with the Mendel 90 because of how much care and detail Nophead put into the instructions, bill of materials and more, but I had some trouble building my printer and getting all the parts. Soldering ribbon cables is pretty terrible and I was never able to fully build the electronics board that goes on the extruder.

I looked at the Prusa3-vanilla but ended up going with the master branch of the Prusa3. This means I was bit by some bugs, such as the lack of room on the extruder for nuts on the hobbed bolt.

I also initially planned to go with the larger, more sturdy box frame. Aligning and building this is more difficult, and it did not end up happening because the space got their laser cutter just as I was about to start building. This meant on my prototype printer the X rods stick out an extra 70mm, but oh well.

I went with the grabber laser cut frame, modified to work on our 12″x20″ laser cutter (by shortening the frame to 12″) and extended the top Z rod holders to compensate for the lost Z height. My prototype has a max Z of 185mm which is quite respectable.

The configuration setting for the aluminum frame expects the screws to go into tapped holes in the aluminum, but at least on the Y carriage I wanted the bolts going the other direction, so I’ve tweaked the Y belt holder to have captive hex nuts.

You can see these changes and others I’ve forgotten on my fork: https://github.com/sphereinabox/Prusa3

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