Hi All,

I hope you're all well.

I'm trying to find a ceiling blade fan holder .STL file but found nothing
in Thingiverse and Tinkercad.

I have an old ceiling fan which works great except for this one fan blade
holder (made of some kind of metal - looks bronze-like) which cracked.

I've visited a plethora of Home Depots, Lowe's, Ace Hardware stores, fan
and ceiling light  stores but can't find the correct ceiling fan blade
holder (bracket?) to fit the holes distances in the fan motor.

The fan manufacturer no longer makes that model so they have no parts for
it.

We got a new dual Tool Head for the Lulzbot TAZ 6 (able to print metal) at
the library so we wanted to see if we could print a metal fan blade holder
with the 3D printer.

Thank you for your thoughts/suggestions.

Best,

Charles.

I don't know anything about metal printing, but unless it prints
really strong I would be very nervous.  A fan is swinging a heavy
thing around pretty fast; if it broke it could get exciting - especially
since losing one blade would then make the whole thing unstable.  I
wouldn't be shocked if it tore itself off the ceiling.

Net:  I wouldn't do it unless I was very confident of the strength of
the resulting part.

But:  I'm not a mechanical engineer, haven't done any calculations,
don't know how strong anything is, et cetera.

While I am in the camp of "need a metal part" (because even the most cheaply
made fans I have seen still have metal brackets) Nylon or Carbon-Fiber would
probably be strong enough; the blades are relatively light but moving
fairly fast.  ABS might even be worth trying, but I would stay away from PLA
because it is more brittle.  There is a significant moment force generated
by the weight of the blade, plus a shear from the spin.  I would print at
100% infill.  At least for PLA, there are annealing methods regarding
heating it in an oven that increase layer strength; I assume similar
techniques exist for other plastics.

There are going to be other factors in play.  Is the fan flush-mounted to
the ceiling or on a downpipe?  The fan failures I have seen on youtube tend
to be the one with a downpipe - the extra length creates a much bigger
wobble from being unbalanced (e.g. a blade has suddenly gone missing)
eventually building until the fan rips itself out of the ceiling.  I saw
several videos of flush-mounted fans with a blade missing and nothing bad
happened.

Objects in motion remain in motion... a blade suddenly detached from the fan
is not going to hit with enough force to kill/maim someone or - but has more
than enough oomph to go through the exotic fishtank, a window, or an LCD
screen.

You have a lovely opportunity here for SCIENCE!

--
Sent from: http://forum.openscad.org/

The reference to annealing brought forth in my alleged mind the "latest craze" for 3D printing strength, salt-re-melting of PETG. Summary: one creates salt flour by grinding ordinary sodium chloride (table salt) in a coffee grinder until it is the finest powder. One then packs it firmly in a heat resistant container and adds the 100% infill part. Less than 100% infill means heat-expansion voids that will destroy the part. The part is completely enclosed and encapsulated by the compacted salt and heated to re-melting temperatures. I've seen quite a bit of variation in the final temperature, but the people who have followed a consistent and gradual heat/pause/heat/pause/cool/pause/cool/pause program create parts with erased layer lines and nearly 100% strength increase. PETG is pretty strong as-is, but to see the near-doubling in the test pieces is impressive.

Tons of work, but for some things, quite worth the effort.

On Tuesday, November 10, 2020, 7:33:48 AM EST, shadowwynd <shadowwynd@gmail.com> wrote:  

While I am in the camp of "need a metal part" (because even the most cheaply
made fans I have seen still have metal brackets) Nylon or Carbon-Fiber would
probably be strong enough; the blades are relatively light but moving
fairly fast.  ABS might even be worth trying, but I would stay away from PLA
because it is more brittle.  There is a significant moment force generated
by the weight of the blade, plus a shear from the spin.  I would print at
100% infill.  At least for PLA, there are annealing methods regarding
heating it in an oven that increase layer strength; I assume similar
techniques exist for other plastics.

There are going to be other factors in play.  Is the fan flush-mounted to
the ceiling or on a downpipe?  The fan failures I have seen on youtube tend
to be the one with a downpipe - the extra length creates a much bigger
wobble from being unbalanced (e.g. a blade has suddenly gone missing)
eventually building until the fan rips itself out of the ceiling.  I saw
several videos of flush-mounted fans with a blade missing and nothing bad
happened.

Objects in motion remain in motion... a blade suddenly detached from the fan
is not going to hit with enough force to kill/maim someone or - but has more
than enough oomph to go through the exotic fishtank, a window, or an LCD
screen. 

You have a lovely opportunity here for SCIENCE!

--
Sent from: http://forum.openscad.org/

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