My money is on the this not being followed:

with a side order of this not being followed:

As far as vertical, I know Ian runs vertical without a "knocker", as do many others. You could probably compromise by tilting it 30 degrees or so - all of the benefits of running vertical, and better feed. I would not recommend a "knocker" or "buzzer", either reorient the machine or redesign the hopper.

Yes, separate power supplies would help, but not a ton. The speed actually only changes a few percent, but the human ear is very sensitive to frequency shifts. This few percent swing would work out to +/-0.01mm of error or so at most.

Yes, that is correct about heat up. Plastic conducts heat more poorly than metal, so it needs more time.

Filament manufacturers use a machine not unlike the Filawinder that walks the filament back and forth. Personally, I spool by hand with a drill, I've never had a tangle on the spool. Actually I had more tangles with commercial filament before I started using a Filastruder than ever since (0).

I'm using the vertical set up and I do find that the beads don't feed perfectly.  Right now I only have the throat on since I wanted to keep things simple and run a couple of test colors and materials.  More feed above might help it feed better.  15 seconds of tapping every 10 grams of filament gets it to feed better.  I do think after I do this that I hear some pellets perhaps 'grinding' on the hopper, perhaps between the screw and hopper.  Can you over feed the screw?

I'm thinking about printing something that would attach to the screw on the flat section and as it turns have it cyclically prime a spring driver kicker that would tap the throat.

That's why I asked about over feeding it since that would affect the design- 3-4 whacks per rotation, or just one.

I think the filawinder and the feed knocker will remove a lot of variation and make it hands off.

The only other thing I think I would do if I would get two power sources and move the heater and motor off of the same set-up. I can definitely hear the effect of the heater on the motor.   I don't know what the effect is on the filament and it definitely affect the cost.  The motor doesn't have to be connected to the controller, does it?  It could just be on a separate power supply with a switch?

Between those additions (not even the dual controller)
Either that or finding a 12V motor with an offset/unbalanced shaft and wiring that into the motor circuit to act like a constant buzz.

Distinct, larger taps or a constant buzz- What do you think will work better.

One thing I've found is that just because the extruder is up to temp doesn't mean that the plastic is ready to be extruded.  It takes my extruder about 12 min to get to 180C.  I need to let it settle for about 10 more minutes so that the plastic is melted and the extruder doesn't try to twist itself apart or slip the power coupling.  I stop and start it a few times rather than just turn it on.  That sound Kosher for ABS?

Just out of curiosity, how do filament manufacturers get the filament to wind so perfectly on the spools?  If they are doing it by hand, I understand why filament is so expensive!

I think the initial purge has metal due to surface roughness that is stuck on well enough to survive a scouring, but not a tool steel auger. Over time, the two parts wear into each other and wear decreases. However, all extruders (even industrial ones) wear, and that's why a melt filter is recommend for all but the largest 3D printing nozzles.

I was surprised by the amount of metal shavings in the filament since I had scoured the inside of the nipple pretty well to prep it.  It is bright metal, one hunk was about the size of the filament and I heard the motor strain as it 'passed' the metal.  Is this just from random hits of the auger bit on the nipple causing gouging and the metal bits?  Like I said, I cleaned up the metal parts pretty well during assembly.

It really is interesting how you get 'tuned into' the extruder running.  The more rapid on/off of the heater when it's ramped up to temp.  Like I said, the strain of the motor with gunk, or just how the pitch of the motor changes when the heater comes on.  Even how feeling the filament and its surface topography giving indications of what is happening in the there a if there is gunk.  I just run it thru my fingers and fell rough spots or bumps where there is a metal shaving.

A lot more qualitative than I thought it would be.

Thanks for all the help!

Just out of curiosity, how far up from the brass end is the plastic melted when at a steady state?

This is a great question, I'm not sure how to know for sure. There barrel gets above Tm around an inch shy of the pipe coupling, starting from the hopper.

Room between the inside face of the nozzle and end of the screw is not an exact science. Protruding about 1/4" from the end of the barrel works well, but further could also be better, Protruding less seemed to increase diameter variability.

Just wanted to give feed back on the placement of the cut since it seemed like a variable.

Just out of curiosity, how far up from the brass end is the plastic melted when at a steady state?

How much room should there be between the inside face of the brass plug and the end of the screw?  I saw your suggestions for how far it should stick out of the nipple.

Just trying to visualize what is actually happening in the tube.

Next batch will have the cutout moved more towards the middle. I was trying to get as long of an effective barrel as possible, but it seems to be more trouble than its worth.

For me, with little/nothing to grip on to when tightening it, and a hopper purchased from filastruder slid back as far as I can, Im still mis-aligned by 1/4 - 3/8 inch... the cut is just too close to the threads, I cant fit the hopper on evenly.

Might see what I can do about ignoring the instructions and putting the hopper flat-side-in... getting rid of that nubbin might give me enough clearance to line up properly.

Sure, you can trim the collar on Ian's hopper. I've worked with slightly different cutout placements, which is the reason for the variance you see. It really didn't change much.

Yes, the wooden thrust plate either needs a bigger washer to spread the load from the thrust bearing (less than a dollar at the hardware store) or replacement. If you opt for the latter, just shoot me an email at filastruder@gmail.com and I'll get you taken care of.

I'd say that the nipple cut placement at the end near the threads is less than optimal.  There is no real way to grasp the pipe and twist it securely with out damaging the threads or grabbing the nipple in the cut out area or beyond which seems to risk bending the nipple.

I thought I had the nipple tight into the flange, but I didn't.  I was testing it the garage with some breeze and the extruder got down in the mid 160s and torqued the nipple, turning it 90 degrees and slowing extrusion due to pellet starvation.

I compensated a bit for the neck of the vertical hopper by cutting the case. 

I think the nipple needs at least the width of a pipe wrench between the threads and the cut out for proper tightening and hopper placement.

Just some feedback on the cut placement experiment.

The explanation of the critical properties of the design are what I was looking for.  I've just gone thru the directions and started fondling the parts to get a feel for how everything goes together.  With your insights I feel much more comfortable.  I just see threads about improperly set up machines and not being familiar with the dynamics, I wanted to make sure I didn't suffer the same fate.

Thanks!

As for the thrust plate, any washer with a ID of 0.5" or so, and an OD larger than 1".

The other option is to move the spacers to the other side of the enclosure. This moves the flange outwards, giving you more clearance for Ian's hopper. As for the "cloud" of options, all that matters is that with the thrust bearing compressed (pushing the auger into the barrel from the hot end), the auger tip sticks out 1/4"-1/2". A variety of spacers are provided to accomplish this in different ways, as some people have reasons for doing things a bit differently (like you needing to move the flange away from the face of the enclosure to accommodate Ian's hopper).

What size washer should I use?  But I guess the bigger question is with this REV 3 kit what is the optimal set up for the Drandolph kit enclosure?  It seems there is a cloud of options of plates, spacers and layouts.