Feb 282014

Progress is being made on the hardware. The motors are mounted, the EggBot controller board is mounted, new spools are printed and installed.

Here is the overall mounting scheme so far


I ended up printing these small spools from thingiverse.


I used a screw specifically made for screwing into plastic. It has deep coarse threads that bite well into the soft ABS plastic. We’ll see if it holds long term but it seems to have a good grip right now.

The EggBot board has an issue where the upper and lower copper planes are one power and one ground. The problem is the mounting holes do not have copper pull backs so if you put a metal screw or stand off through the mounting holes the power plane and ground planes are shorted together. So that’s no good. Mounting the EggBot board requires using non conducting mounting hardware. I decided to print a mounting platform and hold downs.

I printed reliefs in the mounting platform for the pins that protrude from the bottom of the EggBot board. The four pins in the corners go through the EggBot board mounting holes to align the board and keep it in place when held down.






I’ve done some simple tests communicating with the EggBot board and moving the motors, making sure everything is still in working order and nothing got crimped or crushed.

Next steps are to string the gondola and get some code working.

Feb 032014

I built my 3D printer from a kit a couple years ago. It is a MendelMax style and it came with a modified version of Marlin as the firmware and printrun as the host app.

One of the first things I did after putting everything together was update the firmware to the latest version of Marlin and printrun. That was a couple years ago. New versions of both the printer firmware and host software have come and gone and I’ve largely ignored them. My printer has been working fine and no need to mess with what works.

I’m in the process of building a polar plotter and I’m using my 3D printer more heavily to create many of the parts. After using the printer to print a couple parts, and remembering many of the little irritations that always bothered me, I decided to look around and see what new firmware and host apps are available.

I tried a couple different firmwares but eventually settled back on Marlin. I forked and cloned the latest from ErikZalm, created a branch for my printer mods, updated the Configuration.h, pushed my branch back to my fork, and pushed the changes to my fork. The changes for my printer are pretty minimal but pushing them to github gives me a place to stash them off box and makes them available if anyone else finds them interesting.

I added ErikZalm’s original github repo as an upstream repo so I can continue to fetch and merge his latest changes.

Fork ErikZalm’s Marlin repo into my github – do this on github.

Clone my fork onto my desktop.
git clone https://github.com/bhunting/Marlin.git

Add ErikZalm’s repo as an upstream remote.
git remote add upstream https://github.com/ErikZalm/Marlin.git

Create and checkout a branch for my feature work (support for my MendelMax)
git checkout -b bhunting_MendelMax

Fetch and merge upstream (ErikZalm’s repo), not really needed right now since I just forked and cloned it.
git fetch upstream
git merge upstream/Marlin_v1

Push my feature branch to my repo
git push origin bhunting_MendelMax

Modify the code as needed…..

Add, commit, and push
git add Configuration.h
git commit -m"configuration changes for MendelMax 3D printer - BAH"
git push

After the mods I built the firmware using Arduino 1.5.2 and flashed it to my printer.

First off I like that the annoying beep when using the rotary encoder has been toned down. Much more palatable now. I like the new menu system. Not a lot has changed but it does look cleaner and I like the wording better. But how does it print?

I upgraded to the latest version of printrun but at the same time I wanted to try Repetier Host. Printrun seems to work fine with the latest Marlin but Repetier has a more full featured interface. Repetier provides both host side software and printer side firmware. I was unsure if Repetier Host would talk to Marlin firmware but it turns out Repetier Host is more than happy to drive the Marlin firmware. In fact the two get along just dandy.

I’ve only done one print using Repetier Host and Marlin firmware but one thing I did notice, other than the improved user interface on both the printer and host side, is my print started and completed in one pass, no hiccups or restarts. It might be an anomaly but at least it didn’t crash and burn right out of the gate. So far I’m happy and looking forward to trying more prints with this combination.

Feb 022014

I just finished printing both motor mounts for my work-in-progress Polargraphic Plotter / Drawbot / Plotterbot. I decided on these motor mounts on Thingiverse. They fit a NEMA 17 motor and they looked simple and easy to print. Although I am a little concerned about the print layers being parallel to the mount bolt holes.

I printed these on my MendelMax 3D printer in ABS. I printed the mounts one at a time and each mount took a little over an hour to print. The prints needed some clean up with a pen knife to trim off the danglies but after that they look good. The motor mounting holes line up nearly perfect and the mounts are good fit to the motor bodies. We’ll see how they hold up under load but if I use a washer on the mounting holes it should distribute the stress.

My MendelMax printer

A two-for-one special, 0.5 mm printhead off of ebay. It seems to print ok.

The motor mount finished and ready to remove from the bed.





A video of the motor mount being printed

Another part down. Now on to the filament spools….