Z-axis uncoupled

[D. Joe]

tl;dr: 3 issues, one note: Z-axis coupler was screwed up, now
fixed, I think. Heated bed isn't heating. Power supply
previously used for fan is gone. Printer & Yoda was a big hit
with a youngster visiting during LUGOR Workshop Saturday.

Finally sorted out the Z-axis problems that have been vexing me.
Turns out one of the the Z-axis couplers was so loose as to have
completely slipped off the bottom of the bushing on the stepper
motor. There are two Z-axis motors--this was the one on the
same side as where the filament feed mechansim is (on the right
as we usually look at it).

I don't know how long that has been developing, but I'm hoping
that's been the problem I've been seeing: The hot end would run
too low when starting the print, dragging across the tape when
printing preliminary the skirt around the part,
clogging, popping out the PTFE tube from the ferrule on the
filament feed mechanism and so on.

It looked like it was turning, though. Once the print got
started, it seemed to do OK. sometimes it would help to use
pronterface to jack up the Z-axis by a few fractions of a
millimeter. We repeatedly tried adjusting the height on that
side by just twisting the Z-axis screw a turn or so. So, maybe
it was failing intermittently.

When I tried adjusting the Z-axis screw on that side last night,
I noticed the Z-axis motor axle didn't even turn, and then that
the coupler had slipped down about a centimeter, so it was
finally very obvious to me.

Anyway, I put that back in place and got it tightened up. I
printed yet another keychain fob, as a quick check that we were
back in business, and then I printed:

http://www.thingiverse.com/image:106172

and that seemed to do OK. If this in fact has been the problem,
I'm sort of amazed that it worked so far as well as it did with
just one good Z-axis drive.


I noticed since last week the power supply we had been using for
the cooling fan is gone. I'm guessing that was Alex's and that
he's just taken it to use for something else. Alex, can you
speak to this? Or did someone make off with your PS? I
borrowed one Saturday from the ham shack marked WBD
(I guess that's Walt) but put that back into the ham
shack. Ben and I futzed around a litle with trying to find a
wall wart that would drive the fan but didn't settle on
anything. Another thought is that the PS was borrowed for
B-sides and just didn't make it back to the right place--maybe
it's buried underneath all those chips and stuff.

Finally, the print bed seems not to be heating. I'm not having
much trouble so far with the first layer sticking so I haven't
focused on that yet, and might not hit it too hard unless I
start having trouble, but wanted to mention it. With a set
point of 60 the temperature reading will go up to the mid 30s,
but I'm not sure that that just isn't heat from the print
material diffusing into the bed.

LUGOR regular Warren brought his son Phil to the workshop
Saturday, I guess for a repeat visit, only this time I was
running the printer. He seemed pretty impressed with it,
especially with the Yoda print. At his suggestion, I looked for
a Death Star model on thingiverse, but had no luck.

--
Joe

[Brian Boucheron]

On Tue, May 22, 2012 at 7:29 AM, D. Joe <inte...@etrumeus.com> wrote:
> Another thought is that the PS was borrowed for
> B-sides and just didn't make it back to the right place--maybe
> it's buried underneath all those chips and stuff.

This is the likely explanation. I did grab the PS for B-sides. I
thought I unboxed everything when I brought it back, but it might be
lurking in a box somewhere. I'll take a look tonight.

I've got an annoyingly tall part to print tonight, and I'm worried
that our newly-short ptfe tube will bunch up too much, as it had to be
rerouted from in between the two top bars. I may make an executive
decision and move on to our second ptfe tube so I can route it the
right way, and then we can just cross our fingers that the damn thing
stops popping out due to secondary issues (I think during normal use
the new fitting is working quite well).

-B.

[Alex Sojda]

I did borrow that power supply for the weekend, sorry guys. I'll be
bringing that back tonight and I'll figure out a suitable wall-wart so
that supply can be used for prototyping, I think I'll also put another
one of those supplies on order, you can never have too many lab
supplies.

-Alex