Duet3D Rotating Magnet Filament Monitor: 3D printing the housing

Scrambler73

Hello,

a few days ago I bought a Duet3D Rotating Magnet Filament Monitor. This parts had a discount because the housing wasn't included.
So I went to the Duet3D documentation page and found the instructions and GitHub page for the STL file's.

After the 3D printing I started mounting the Rotating Magnet Filament Monitor but the holes are way to big. So the problem start with the magnetic assembly that rattles in the holes. The diameter of housing = 7,40mm and bearing is 7,00mm, so the hole is 0,4mm to big.
Then I use the M2,5 to screw the parts together and again the hole is to big, I measure 2,48mm in the 3D printed housing. The PCB part is fitting in very neatly, so making the part smaller in the Slicer is not a option.
I printed the part with a 0,25mm nozzle, the printer settings are good. The print quality is not a problem, the 3D printed housing looks good. Just he hole dimensions are wrong.

Can Duet3D not only share the STL file's but also a STEP or Solidworks file, I will make adjustments to the drawing so the parts have the correct dimensions. So I can 3D print the part again and have a working Rotating Magnet Filament Monitor!

alankilian

@scrambler73

THIS THREAD has some information about that.

Lo-Fi

@alankilian

If it's helpful, I've just redrawn it myself:

Duet MFS Housing - LidV1.1.step Duet MFS Housing - BaseV1.1.step

I printed in PLA, 0.2mm layers, 0.4mm nozzle. Accepts normal bowden PTFE and plastic collets. I'm going to add some strain relief for the wiring, but haven't got round to adding that yet.

Scrambler73

@alankilian Thank you for sharing the topic :D. I used the download link and got the STEP file's I need. Today I had some time left so I put a few hours in drawing the complete housing in SolidWorks. Just turned on the 3D Printer for test printing 2 sets. So tomorrow morning I know if it's correct or not.

If everything is good I will share the drawings on this forum. I will include the STEP and SW-files.
I assume @T3P3Tony did the drawing of the parts, it's not a bad product. I just would like to know why the filament transit holes where drawn in a ellipse. It could be that the process from open SCAD to STEP would make the holes an ellipse. I personally never use ellipse and I'm curious why Tony would.

@Lo-Fi I did not mentions this but I need the V2 housing Still thank you for the effort

T3P3Tony

@scrambler73

TLDR: FDM printing hack.

History:

They are a truncated teardrop, not an ellipse. Its an old FDM trick to make holes with no support required. The original teardrop was the RepRap logo by Ed Sells from very early on.

Adrian used to say with 3d printing you get complexity for free, so this is something that would be complex to machine (a teardrop shaped hole) but easy to do with a printer and it gives an advantage because a horizontal hole prints with no support.

Later when bridging got better it became a truncated tear drop. (earliest i found reference to it was this blog post by @nophead in 2008: https://hydraraptor.blogspot.com/2008/07/every-little-helps.html?m=0

Nophead had the original library for truncated teardrops in openSCAD
looks to be part of a larger library now.
https://github.com/nophead/NopSCADlib/blob/master/utils/core/teardrops.scad

And Duet derived the teardrop part of our logo from this history as well.

Scrambler73

@t3p3tony Alright! That is very interesting Tony! ! ! This is the first time I hear about the teardrop used in 3D printing, very interesting to read about this. Thank you for explaining and sharing the history, I find it a good history to know.

For the Solidworks folks!
https://github.com/Scrambler73/Duet3D-Rotating-Magnet-Filament-Monitor.git
There you can find the SW files and a STEP assembly, open the STEP to find al the parts inside. From there you can open the STEP parts partially
This is the first time I share anything on github, so if anyone have a problem downloading please share here.