Serial #260

Lesson learned: a loud crack followed by no more extrusions, check your washer on the coupler:

I had another washer, just had to take everything apart right quick to get to the coupler. I had cut it with aviation shears, and it twisted pretty well where there were small stress marks from the shears. I cut this one with a dremel. Hopefully it lasts. Going on an hour now with now problems. Thankfully the PID controller instructions were on here, because I too did not get a manual.

PTC fuse:

http://en.wikipedia.org/wiki/Resettable_fuse

A regular fuse does not self reset, it blows once and is done.

Really there's no reason to fuse the motor as long as you don't start it without letting the polymer get up to temp, and you use an appropriate temperature for the polymer you're trying to extrude. Really either of the above can be disregarded if you just hang around the first minute or two of extrusion to turn off the motor if it stalls.

The new motor will trip the overload protection on the power supply before reaching stall current.

It should, yes. Stall current is 4.5A, when combined with the heater load this will trip the supply. Of course when the heater cycles off this will no longer be the case.

Again, in practice the motor should not be stalling.

Absolutely. Next version will do away with the mechanical fuse by using a motor with a square shaft, and a PTC fuse. That's about a month away, though.

What are your thoughts on a variable speed motor?  Different speeds for different material.  Or is this taken out of the equation by adjusting temperature?

Well, lets say you were trying to speed the motor to a slightly faster rpm of say 4 or 5 and with a slightly higher temperature of say 185 to 190 (basing this on the material you are extruding and the quality of the extrusion) You could potentially get more extruded in a shorter time. 

I just wonder if it is worth the effort and cost of making it variable.  Does the set rpm of 2.5 extrude at the most efficient speed?  Would going with a higher rpm have anything to do with increasing the speed of the extrusion at all at this point?  Is it just the temperature of the heating band at this point?  I've read through most of the posts and I see the ramen effect happen because of high temps in conjunction with the type of material being extruded but no mention of the speed of the motor. 

You upgraded the motor on later revisions to go faster.  I wondered what the limit would be on the rpm in regard to the current heating band and setup.  With a variable motor, you could play with it to see exactly how fast you could extrude and still get quality filament.  You obviously did tests to come up with the original motor but then came out with a faster motor later on.  Now that the filastruder has been tested more by different people and different materials and with your idea of a new motor....I was just wondering how far it could go without changing the rest of the extruder.

But slow it down, no.  I'm about trying to speed it up.  I understand about not leaving the extruder running unattended but having it set up in the workshop and just staying in the workshop all day to get a spool of filament doesn't work with my work habits.  I can't babysit the machine and I can't leave it.  I'd rather start it, work on a project for 4 hours or so and then stop it and have a spool of filament.  Maybe its just too early in developement as a process to get that kind of speed from a DIY system.  I can live with small bits of filament until then but I may have to work on a fussion splicer.