OneUp V2 Build Log.

[mr_intensity]

Extruder Sub-Assembly Part I - Not the Print Head

Many mistakes, many lessons learned.  More parts needed.

So, First step was to bust out OpenSCAD, and attempt to define the missing/broken parts for a buddy of mine (with a 3D printer) to print up.  My definitions were bad.  My EIFRAME piece was a little bit small, and the holes were a hair too close together.  I was off on several dimensions on the SIDEBRACE piece.  But, I was close enough to get started, so the adventure began...

The OneUp V2 destructions have you start with the Extruder assembly.  So, for starters, I put the Tensioner sub-sub-aseembly together backward.  Then, I could not put it into the Extruder sub-assembly.  Had to take it apart and do it right.

First lesson learned:  The Melemite parts have a "front side" (nice finish) and a "back side" (unfinished), which have NOTHING to do with how the parts go together.  Sometimes, the "back side" has to show, because that is how it was cut out of the melemite.

In other words: Assemble for function, not looks.

Tip:  When I put the Tensioner Sub-sub-aseembly together correctly, I had it too tight, and the bearing wouldn't spin.  I figured this out later, and had to remove it from the Extruder Sub-assembly, loosen it up, and put the sub-sub-assembly back in.  Pain in the tukkus.  DON'T make the same mistake.  Make sure your bearing spins before installation into the Extruder Sub-Assembly.

Trying to put together the Extruder Sub-assembly is when I realized the holes in my printed EIFRAME piece were too close together.  Out came the Dremmel™ tool, and...Okay, I lied.  Out came the Drill Master™, Harbor Freight's Dremmel™ tool wannabe, and I went to work with a very thin sanding/polishing stone attachment.  I had to cut the semicircle a little larger, and I had to drill the holes out a little larger.

   

Second lesson learned:  3D printed plastic does not create "plastic sawdust" with a high-speed polishing stone.  It melts.

Then it came time to handle one of the Nema 17 motors.  For some reason, I could not screw in the set screw (in the Filament Driver Gear - FDG) loosely so "...the gear coulud be moved, but not fall off."  Either this thing was snug enough to not move the gear, or it was completely loose.  And yes, I did have it lined up with the flat on the motor shaft.  Oh well, just have to be careful with it so it doesn't fall out.

Of course, if I had actually LOOKED at the picture in Q3D's instructions, I would have seen that the teeth were pointing toward the motor, not away.  More on this in a moment.

Stacking many differing layers together (like ECFRAME, EPFRAME, EHFRAME, three EIFRAMEs and EBLOCKs 1 and 2) and then trying to run a screw through all those tiny holes that you need to line up, is like hearding cats.  Nothing wants to stay together long enough for you to get the screw in place.  The ECAPSPACER part of the Tensioner Sub-sub-assembly was exceedingly difficult to keep in place to get it into the Extruder Sub-Assembly.

Anyway, I got everything together, nice and tight, when it came time to line up the FDG "teeth" with the bearing from the Tensioner Sub-sub-assembly.

   

Hey, this gear won't slide any lower because the gear body is in the way because...the gear is on upside down!  Take the motor off (while trying to keep the screws threaded through all those layers of everything else) and turn the gear around.  Hm.  Now that set screw can "snug" FDG, without "freezing" it.  Who'd a thunk it?

Third lesson learned:  Pay attention to the instructions and stop putting stuff together backward.

I left nothing to chance.  I adjusted my gear while the motor was off.  I lined the "stack" up over the motor, eyballed the gear-to-bearing alignment, made adjustments lined them up again, etc.  I figured I would get the gross adjustments out of the way, while the gear was "snug," and make fine adjustments after the motor was situated.  It ended up that my alignment was fine once the motor was bolted down, and I could just tighten the set screw.

Important tip:  Before screwing the motor to the stack, make sure that you rotate the shaft so the set screw is pointing out the opening between the Tensioner and the EIFRAMEs, so you can get your hex key in there for final tightening.

Okay, next I dry-fit and then super glue EBELTMOUNT (which is actually labelled XBELTMOUNT in the BOM document) to the assembly.  Dry fit is good.  But my one tube of super glue appears to be dried out.  Now, I bought this small tube as part of a set of small tubes of super glue, I just don't know where all the rest of the glue is.  I'll come back to gluing later.

A thought:  According to the destructions, you adjust the tensioner assembly with the M4 nut.  Why?  That nut is kind of hard to get at, and you need a tiny wrench.  It makes more sense (to me) to super glue that nut in place, and do your adjustments at the other end, using your hex key, on the M4 bolt head.

Just make sure you glue the m4 nut to the EBASE and not the M4 bolt  :-D

Also, why only one M4 washer?  The ESPRING appears to be small enough to push against the M4 bolt head, but it also looks like the ESPRING will eventually separate around the bolt head.  Why not just have a washer on both ends of ESPRING?

I'm going to the hardware store for an M4 washer.  I am also picking up two M3x15mm screws, and probably super glue.

Why do I need  two M3x15mm screws?  I'll get to that in Extruder Sub-Assembly Part II - The Print Head.