On 10/8/22 13:25, Chris Albertson wrote:
I am a big fan of "plain old PLA" The problem is not the plastic you are
using but the engineering design. The part looks like you are used to
designing with metal or wood, where you start with flat stock and screw
parts together. If you need good rigidity with 3D prints, then fill all
the air space around the part with plastic. Use thick skin and 30% or more
infill.
PLA is not "tough" because it is rigid and will not bend. So it breaks
like glass. But as long as you do not break it, PLA has the least flex
I would think that being in close proximity of thehot block, like 2mm away,
that PLA would soften and bend or stretch at that bar across the bottom of
the big vent hole.
I've had the hot end mounting bosses break off clean at the surface despite
their being buried a mm into the surface, but there is room at the
bottom of
the boss to expand that, so since the boss is a cylinder that can be
tapered,
its now tapered up to 12mm at the bottom and the hole is expanded .1mm
to ease
the torque of self threading the screw. I'd already buried a 3mm hex nut
in the
back of it. The boss holding the prox switch is hell to clean out the
hole, so it got
expanded .1mm to ease inserting the prox switch, which IMO beats the pants
off a bltouch.
Very poor access to the bottom eccentrics to adjust how tight the
POM wheels grip the X transport extrusion bar, but I did add a 10mm tall
fin to
both edges to stiffen that. So another is now making on the prusa mk3s.
And the
Ender checked, Z re-zeroed and restarted as the jerk was too high on the
Y and
it lost a few steps about 4 layers up on the last start, so jerk was
reduced about
20%, as was accel, so maybe it might work at 350mm speeds this time. If
not, a
42 volt psu for the Y motor is next, along with a higher voltage driver.
That motor
will be hard to source in a stronger version as its a double shaft.
Drives both ends
of the x crossbar from one motor. And that is the heavyweight piece in
this puzzle.
I'd love to find a carbon fiber sub for that extrusion. Even a square
with a linear
rail s/b lighter, but bring a little red wagon full of cash for that.
Actually, I found the bug in cura that is a showstopper for a tronxy
400mm cubed
printer I bought, and it would be far far easier to swap its puny xy
motors for 1NM
3 phasers I already have. Then the precision will be limited by the
length of the belts
it uses as its a doofy arrangement where both motors drive both x and y.
So to move
in straight y, the motors run in sync but opposite directions, and move
the same
direction for a straight x motion. Both belts go over a slew of pulleys,
and are around
9 or 10 feet long.
But the tronxy doesn't use POM wheels, they are all steel, running on
round steel
rods set into off center grooves in the extrusion.
So the potential for increased accuracy is there. I put small casters on
it so its on
the floor, but so is the tiny little controller display. There's enough
ribbon cable to
move it up some so I will, and I'll probably unload the bed from the psu
in favor of
an SSR with a line voltage feed. 80C takes it over 10 minutes from room
temp on
the tronxy.
The head is quite similar to the enders so another Spider 300C hot end
will be here
Sunday, and I've 70 watt heater resistors for that. W/o the bed, the psu
should
handle that. The ender psu is handling both, but the bed is slow, 5 to 6
minutes, the
plus model is 350mm square heated. So I heat its bed before hitting the
70 watter
in the hot end. And I've found a better way to calibrate flows, look at
the infill. Thin
and puny looking, increase it 5%, thick and lots of sloppiness, reduce
it to suit, with clean
infill the target. 690 is recommended for the ldo, and its actually
about 100 too much.
I'm currently running at 670, and flow is still being turned down to 85%
to get nice, but
fat and clean infill. With jerk lowered to 45, and accel at 3000, accel
is still too slow,
taking around a 6 inch move to hit full speed, but its otherwise running
well for now.
The other things I always say is to use compound curves.
Those are not as easy in openscad. Variations of a cylinder and sphere
are available as macro's but true beziers take much longer to render,
after you study up on the library that does that. I haven't gotten that
familiar with it yet. There also is not that much room to play in. I'm
modified
somewhat, the png I sent, and the prusa will have another done in about
4 hours.
I concentrated on stiffening up the left and right edges, where the warpage
was showing,but there is no real room to get artsie. And since that's
all flying
weight, every gram counts.
Thank you for the advice. Take care and stay well, Chris.
[...]
Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/>
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