Monday, February 16, 2015

MendelMax3 - Upper LED Mount

This compliments the MendelMax3 - Lower LED Mount that I created earlier.

The upper mount is quite a bit bigger, so I need to have my MM3 working well enough to print something large, and I've finally reached that point.

Similar to the lower LED mount, this one is made up of 3 parts: a back, an LED Holder and a Shield.

I initially had problems with one end of the shield lifting when I printed it, so I created a variation with a brim at either end.

It turns out that the white plastic piece is about the same thickness as the U-channel that runs across the top of the printer. I wanted the white plastic piece to be right up against the metal, so the way I designed it you need to cut the bottom off of the white plastic. This shows a side view of everything mounted and you can see the notch in the shield piece:


I used a sharpie marker along the edge:


and put a score mark using a knife blade while the platic was held in the shield:


I then scored the plastic a half-dozen times using the knife:
 

and was able to break off the lower pieces using some pliers:


I wound up with this in a few places, and used a file to get the edge smooth:

The trimmed plastic piece should then look like this in the shield:

 I also puut a strip of black electrical tape across the top (this is to cover a light gap that I found after putting everything together):

Oops. The slot isn't quite wide enough (the LED on the left is partially covered):

That's what a nibbler is for (I'll revise the model to make the slot a few mm wider):

Here it is with all of the pieces together (except the diffuser):

This is what it looks like once its all installed. I used 4 M3x25 bolts and nuts to mount it:

This is the light leak I was talking about earlier (that I covered up using electrical tape):

I ran the wires in the back channel of the 2040:

I used one of these clips at the top and bottom:

And cut a piece of black posterboard to cover the wires (you can see the posterboard in the rear slot, just to the right of the leadscrew):

My STL files and FreeCAD file can be found here.

Wednesday, February 11, 2015

E3D Bowden Coupler Clip

I started to get some jams on my all metal e3d hotend that came with my MendelMax 3.

I think I found the culprit. When I cut my PFTE tube, I made it very close to the hob:

and after using it for a while, I noticed tiny little PFTE shavings around the top of the hotend. At the time, it didn't really occur to me that this might cause a problem.

After I started getting the jams, I ripped about the extruder and didn't find anything obvious wrong. I had done several cold pulls using some cleaning filament. But then I noticed that the PFTE tube could move up and down a bit.

When the black clip at the top of the hotend is positioned like this:

then the tube is secure and won't move. However, if the black clip gets pushed down, like so:

then the PFTE tube can move up and down by about 1mm. If the top of the tube is less than 1mm fro the hob, then the tube will run into the hob, and the hob can grind off small shavings. If one of those shavings goes down the tube then it can cause a jam. The PFTE has a melting temperature between 260C and 327C (ref), and my hotend typically only runs in the 190C to 240C range.

I decided that a small clip which held the black clip in the "out" position was called for. Here's a photo of the clip:

and a couple photos of it installed:


My STL and CAD files can be found on thingiverse.