This page documents
rotational mold on a shoe string budget by welding together pieces cut
from scrap molds. Please visit my About
page if you are curious about the weird web site name or why I
suddenly became interested in bat conservation again after a twenty
year hiatus. Possibly find out what put this fool notion of mass
producing plastic bat houses in my head.
Rotational molding, while slower than other molding processes
also happens to have much lower tooling costs than more familiar ones
as injection or blow molding. Sadly,
much lower is still not quite cheap enough for me to
afford (I'm maintenance BTW
not some high up muckety muck) However, rather than do the logical
give up on fool notions and perhaps visit
my local building supply, buy some lumber and simply build myself a bat
Nope, not me, I
went and bought two
used molds and immediately started modifying them into a bat house
mold. These were from an obsolete product and had been striped of steel
parts then pushed to the side awaiting a trip to the scrap yard that
not look much like half a bat house mold does it?
aluminum molds with
lids, 184 pounds total at scrap metal prices.
Brought them home to my 'machine
shop' (cough) a Porter Cable circular saw with a carbide blade. Bit of
stick wax on the blade and safety glasses and it is not
that much different than cutting wood. Saw dust sure does taste funny
Bit of whacking
and it is
starting to resemble something kinda sorta like a bat house mold.
Well, at least to visionaries and lunatics. Will leave it to the good
to decide which category I belong to. :)
together and couple of passes across the front. The 1/4" flat bars on
outside of the mold were temporary
and removed later as the sides were welded.
1/2" X 3/4" bars inside the mold
serve as a backer strip for the weld thus hiding my welds from showing
in the finished part. Missed by a few
inches having the bars serve another purpose. For these bat houses to
certification (a very important goal) then a horizontal vent
slot will need to be cut across the front 1/3 of the
way up from the bottom. Would have been a neat hiding place having the
vent in the
bottom of an existing slot. Addendum: The backer
bars proved to be a huge mistake. Resulting slot detracts from the
the finished bat houses even more than a visible weld would and complicate
installing the baffles. Bar has been completely removed across the
front and thinned
on the sides.
A few months
delay and the two halves are finally welded
beginning of the parting line flanges. Tried to
re-use the cast ones from the original molds, way too many short pieces to
it worth while. 1/2" X 2" bar stock was from an on-line metal store.
delay and the parting line flanges are done. Material for the lid
was acquired through trade. Swapped a large scrap of 1/8" checker plate
and $8 for a similar sized scrap of 1/4" smooth plate. Any one
who has ever seen the movie Thunderheart will recognize the quote
"Nice trade." I certainly think so!
Beginnings of a decorative dormer. Wish the roof was a little
steeper so the dormer could be larger. Also wish my molds roof had a
like a few of the professionally made molds at my work
have. However, those molds run an order of magnitude more than
I will have in this one.
of the frame being used here as an alignment jig to space the stand
offs (bosses) for welding. These are threaded to bolt the steel frame
to the aluminum mold.
welding the frame the day after Christmas 2010
standing in snow. (No 220 volt electricity in the barn / shop)
to come together in this trial assembly. Thanks to my son for
16 used auto valve springs. Saved me over $80 not buying die
springs which are the norm with most sprung rotational molds.
feature. The 'lid' of the mold forms the back of the
finished bat house. The pocket in the above picture will thus form a
pocket in the top back of the bat houses. What is it? Big thanks to
"Terry L" over at the Bat
House Forum for this idea.
side is now completely done. Full up with clamps, lifting rings and the
'pry' points to get the lid off in case it gets stuck. The 3" channel
clamps are attached to is a bit rusty since it was stored out doors
for 20 years. Most 'store bought' molds use 2" box tubing here,
however I did not want to buy a full stick just to get a few
short pieces. Rusty channel will do fine:) BTW the mystery feature
above is was a 22 1/2 degree French cleat to
hang the bat house with while remaining screws are installed.
Already changed to this longer 45 degree cleat for
safety. Found during testing that it was
possibly to force
the top of a bat
house off the mounting cleat even with the bottom securely fastened.
initial 19 prototypes have the shallower angled cleat.
Aggravating last minute detail that I had known would be a problem from the
very beginning. Quite
time consuming to remove this reverse draft step in four places with
now the inside is done. Sand blasted texture on the ends
bottom of bat house) contrasts nicely with a smooth sanded
middle. A shot peen verses polished finish will contrast even
better once I start selling a few and can afford to have this done.
finally ran February 16 2011. Yeah!
cute as I had hoped for. However, debuting as the best looking
material bat house on the market is no small achievement.
28th 2012, just over a year since the initial prototypes, my mold was
back up for a brief final beta run. Only five this time and
much better looking without the goofy looking 'belly band'. More bat
house pictures on the home page.
for visiting! As Jed Clampett once said, "Ya'll come back
now ya hear."