HD extruder mount

[ehegenberger]

Yet another update:
I realized after printing that I made this 15 mm thick instead of 12, plus I put the hole for the setscrew in the totally wrong place, at least for my flange, so here's a new screenshot and stl:
extruder mount HD.zip

Here's the redesign of the extruder mount incorporating the axle flange. Because my flange is 12 mm high, that makes the mount, formerly 9 mm thick, now 12 mm thick. This will require sliding the bed 3 mm or so out along the horizontal 2040 extrusion to compensate.
Since it's necessarily thicker, I added extra material to the body of the mount and also extended the zeroing stop so it still hits the bracket as intended. I'll leave the older pictures further below since I haven't printed this yet.

From before:
I was too lazy to order the extruder mount, but I made this hopefully more robust one that incorporates the axle flange right in the mount. I had to countersink the screw holes in the flange, and now I have to go to the hardware store yet again since I don't have any more flat head screws. My flange is 12 mm high, so that's how high I made the mount. I don't have a really clear picture of how this was originally supposed to go together; hope this doesn't throw off the alignment!
I made some stepped offsets in the recess for the flange so should bridge and print nicely at a layer height of 0.15 mm (or multiples thereof). Please check the dimensions of your own flange, including the location of the setscrew hole, before printing as is!

[jyjblrd]

Looks good

I would be careful that your mount isn't too long. The extruder needs to be at the right distance from the pulley so that the nozzle is at the center of the print bed. Don't know what that distance is off the top of my head, but you can measure it on the f360 assembly.

Probably can be more than 2mm longer than my design

[TheOnlyMann]

for the latter question, the original design allows for 90 degrees outwards before getting stopped by the homing stop, and inwards ~180 degrees.
[inwards, in this case, means that the extruder face(nozzle) from the bottom swinging 'inwards' toward the 2040 aluminium extrusion, and vise versa]
however, since the inwards print orientation limits the polar printing degress up to ~90(to not be obstructed by the 2020 extrusion) so the extra degrees never gets its usage.

if you reverse that, as in, make the homing interaction happen on the underside of the revolving mount, this would mean that inwards 90 degrees and outwards ~180 degrees.
This makes the bowden tube/other connectors bit too long at times i think(since they will be oriented outwards while doing the bed leveling) however at the benefit of beign able to use the upper left quadron of the revolving extruder as a possible orientation(while printing, the head can still move in the original way, so the tubes arent going to be an issue)
this would possibly as long as the space is given make the printer be able to print on a underside of what you are printing.

this might be a marginal benefit, but since some of the questions was eliminating supports and sometimes printing underside with the extruder, it might be a idea worth exploring. thats all.

Edit: woops, thought you questioned about the latter question ive asked, which you didnt. Oh well morning brain

[xobes]

This makes the bowden tube/other connectors bit too long at times i think(since they will be oriented outwards while doing the bed leveling)

I think that we can easily incorporate some cable management.

would possibly as long as the space is given make the printer be able to print on a underside of what you are printing.

Neat idea.

[TheOnlyMann]

2. It feels like it would center the mass more rather than having things hanging out so far from the vertical axis (Z), but I suppose you're right about torque on the horizontal axis.

yeah this was more the case, as i felt the 2nd MGN12 rail was more in for "emotional support" since the most of the action happens on the front MGN12 rail and this I think it gets bit worked up
centering the weight would make it slightly better
that said it shouldn't be much that heavy so not that needed, and probably the bowden tube not being in the way is more important

[jyjblrd]

Those are some good points.

You're right the "outside" pointing angles are more useful than the "inside" pointing angles. And it should be a relatively ways to change the homing direction.

Something interesting is that you don't need to rotate the nozzle as much as your printing angle. ie. if you print a 90 degree layer, the nozzle only needs to rotate around 60 degrees. Obviously the closer the nozzle rotation is to the layer rotation, the better the print quality will be.

I've actually limited the rotation on my printer's nozzle to +- 45 degrees, because it is very difficult to avoid collisions between the extruder and the part/bed as it is printing with a non-planar slicer. The math behind preventing collisions when the extruder can rotate 180 degrees out sounds pretty rough

[jyjblrd]

I would love a drawing showing the names you use for the axis... I saw b, c, z... now there's x...

Here is a screencap from my youtube video

As for naming, there are the traditional XYZ axes which you already know. There are also the ABC rotational axes, with A rotating around the X axis, B around the y, etc...

Strictly speaking, the printer design is a "CZXB" 4 axis printer (named from the printed object to the nozzle)

[xobes]

I've also beefed up the extruder mount (diff design than above), will commit to github once I get things tested out. I figure that any offset necessary to re-align the center can be made on the bottom where things come together down there.

Printing now... still...

[xobes]

For those interested... I use FreeCAD, and I've remodelled any part I've changed, Here's my branch as it stands today, nothing tested.

https://github.com/xobes/4-Axis-Polar-3D-Printer/tree/beefy

[jyjblrd]

Small warning about this design, you will be loosing a few cm of x travel because the x linear rail will hit the B mount you created sooner, as you extended the side opposite the extruder. This is why I kept it as short as possible

[xobes]

ah... I did so for strength, as I had one break on me.

Another warning about this design, I don't think I can get it back off the rail 🤣 cause I left no tolerance -- the screws might not even have been necessary.

I don't have rails yet, cause mine require M3 T-nuts, but I don't have any.

[xobes]

I put it back (ish) -- thanks for the warning.

[ehegenberger]

So here's my final version of the extruder mount with built-in flange (final stl is at the top of this thread), slightly singed as the local hardware store was not forthcoming with the right length of screws. Here in Denmark, DIY means you buy a kit and hire a self-acclaimed professional to build it for you, so parts are not always so easy to come by. And after 20 years I still can't pronounce the names of the vegetables at the grocery store.
At this point I think the weakest link is the single 3 mm setscrew holding the flange itself on the axle, but I'll file a flat on the axle and hopefully that will be enough.

[TheOnlyMann]

Denmark sounds fun. Gonna have to singe off Aliexpress and get usable results here, least it wont cost half the buyment price to ship it here i guess..

[ehegenberger]

It actually came out better than it looks in the photo. :)
Oh and after taking off my glasses I saw there's another setscrew on the other side. If anyone asks for it I'll redesign this with a hole on the other side, but I'm done printing this thing and am just going to hit it with the drill.

[ehegenberger]

OK, I see now I made a mistake in assuming that 5 mm flange coupling was for the extruder mount. It should actually have been the 5x11x6 collet
(collar) that I totally forgot about and just now rediscovered down in the bottom of my pile of parts, right? So, um, what was the acutal purpose of that 5 mm flange coupling under "Hardware" in the BOM? It admittedly helped me to make a beefier extruder mount, but now I'm surprised nobody was asking me "flange? What flange?"

[xobes]

I like what you did. That other little piece has been irritating me quite a bit.** I tried to make it so that I could use both of the set screws, but one of them ended up getting stripped out and the plastic cracked again anyway.

** I fiddled with the pinter settings to try and get the hole sizes correct and in doing so I think I ended up making all my parts weaker.

[ehegenberger]

Oh, so you don't have any metal threads at all in there? That would crack your part most days, with the force you need to keep it on the shaft. I think I was just fortunate in having mistaken the use of the above flange.
"That's 5 points for Gryffendor for sheer dumb luck" 😆

[xobes]

Oh, so you don't have any metal threads at all in there?

The cracked one -- the metal stripped out because I've made and re-made this part so many times. Next time I'm doing your design. -- I do want to make some mods, though. Is there a way to export your model so that Adobe won't own the data? I'm really not a fan of using a free-but-proprietary file format for an open source project such as this. I'm not coming in here and mandating that everyone use FreeCAD, but I am going to use it myself.

[TheOnlyMann]

i mean wouldnt fusion be able to extract the design with step files and adobe cant do shit with that

[ehegenberger]

I'm using the free version of Fusion, which can't export STEP afik. What about 3mf, or is that the same thing? I also find it annoying that I have to essentially redesign any STL even after importing it to Fusion.

[ehegenberger]

Hang on, how about this? I've been doing "save as mesh" but there's also a file export function I didn't know about.
extruder mount v11.zip
Here are the options, any of these work?

[xobes]

Will give it a try.

[xobes]

Worked great, I was able to import it in FreeCAD. I was also able to modify it. It's worth noting, however, that all steps leading up to the final geometry are gone, but at least if something needs to be patched or tweaked slightly, it's possible.

[ehegenberger]

That's good to hear - certainly better than triangle mania. What a shame that design steps get lost when exporting from one software to another.