3 Jan
2014
3 Jan
'14
8:05 p.m.
On Fri, Jan 3, 2014 at 7:57 PM, Mark J. Blair <nf6x at nf6x.net> wrote:
They are strong in 2 dimensions, and laminated in the third, so thin structures
like the switch cams are easy to fabricate, but not strong against
lateral stress.
The walls of any fused filament part are typically 1-3 concentric layers with a
random amount (user's choice) of fill. 25% is typical for parts that don't take
a lot of stress, 70%-90% for things like gears and extruder housings.
I'd print the drive plugs face-down so the user-visible portion is
smoothed by the heated bed (typically kapton-coated glass). The body
can be hollow, of course, and the switch cams stick up as it prints.
Put the whole thing in an acetone vapor bath to smooth the sides
(ridged from the layering) and to fuse the layers together and you'll
have a nice part. With a reasonably accurate mechanical drawing, it
shouldn't be too hard to make a solid model with OpenSCAD and tweak
the model to select the unit cams and once the shape is verified (I'm
guessing it will take a test print or two and minor dimensional
tweaks) it should be easy to print a set of 4 at once (or multiples of
the same unit if you needed them). I'd print multiples at a time to
let the cams cool (tall thin things need that extra time).
On Jan 3, 2014, at 15:50 , Ethan Dicks <ethan.dicks at gmail.com> wrote:
Sounds like you _can_ snake a round cable down into an 11/44. You
appear to be describing a BC80M or BC80J cable.
I'm not saying you _can't_ fit a round RL
cable down through the sides
of an 11/44...
I took a closer look at the cable just now. It's round all the way to the
controller card, where the wires break out to a double row header with
individually crimped terminals and a strain relief clamp. The drive end
has a cable clamp that looks like it might connect to a shield. Just by eyeball, I'd call it about a 10 foot long
cable.
Probably a good guess. It's likely to be either 6' or 10'. Total length
from controller to furthest drive has to be under
100'. Never seen
anyone get anywhere close.
The drive connector has a black plastic shell, rather
than a metal
shell like on my daisy chain cables and terminators.
That's common. Probably pre-FCC.
I didn't see part numbers on the cable.
It might be by the controller end or a sticker on the Berg connector.
My drives are all missing the sheet metal piece that
screws to the back
panel near the connectors so that the cables can be clamped to it, but
a suitable replacement shouldn't be too hard to kludge together.
It's just a Z-shaped bracket with some screw holes for the drive and
some rivnuts for the cables. Easy to kludge.
I will need to buy or kludge rack slides for at least
a couple of my drives.
Those are a little more odd. You should have runners riveted to the sides
of the drives, and those fit onto slide rails for the RL01 and RL02. Those
routinely get tossed with racks when nobody wants to figure out how to
unbolt them (it takes a few minutes). You are probably better off fabricating
shelves than rails if you can't find inexpensive surplus rails.
I would not
recommend that. Fused filament parts are not as
structurally sound as injection molded parts...
Thanks for the advice. I haven't had my hands on filament printed parts
yet, so I don't know anything about their properties. Injection molded parts would sure be nicer, but the
tooling to make them would cost a few thousand dollars.
Yep. It's not worth spinning up a full run, but at ~$10/hr for the machine or a
few dollars per cc of plastic, it might be worth fiddling some 3D shapes.
-ethan