End of an Era
20/20 hindsight I should have seen this coming, but I didn't. It's
October 2012 and I've been designing, cutting and supplying customers
with parts packages that have included .250 thick styrene components
for a year now. I just picked up two 4'x8' sheets of what I thought
were .250 styrene from my supplier. My supplier didn't even mention
that this batch was 'different'. It wasn't until the cutting bit on my
CNC machine went thru the sheet, thru the .040 sacrificial sheet under
it, and into the top of my vacuum table that I realized the material I
was cutting wasn't .250 thick but in fact .220 thick. Fortunately I
only cut a few thousand's into the top of the
vacuum table - no real damage.
No More 1/4 inch Thick Styrene - And
a Price Increase too!!
I should have expected my supplier to substitute
6mm = .236 material at some point. It seems that the plastics industry
is moving to the metric system. Or maybe it's just that more and more
material is brought in from suppliers that are already metric. Along
with the thinner material, I've been advised that prices on styrene are
going up. It's not that I can't get .250 or .236 thick styrene it's
just not local and shipping charges make it uneconomical.
|.250 (.236 - current
|.250 (.250 - different
Under the old costs, a sheet of .250 was cheaper than two sheets of
.125 glued together. That's still true, even under the new sheet costs.
The shipping cost, not shown explicitly in the table above, but about
$60 (for 2 sheets) is what makes the difference. At this point it only
makes sense to use the thicker (now .220) plastic when it's needed
structurally. If .250 is needed for thickness alone it's cheaper to
glue together two pieces of .125. Keep that in mind.
At first, I thought
I could just compensate for the thinner material at my CNC machine and
continue on using the same designs but as I gave it more and more
thought I realized that would not work. Tabs that fit into .250 slots
would stick out. Countersunk holes would not be deep enough and the
screws heads would stick up above the surface. Furthermore,
I've been careful to make my
designs match the R2 Builders Club drawings so that my parts come out
to "club spec". I didn't want to compromise that.
What follows is a summary of the
changes I'm going to make, both short term and long term, in my designs
to compensate for the different thickness.
The Eggcrate Frame
The shoulder plates are the only components in the frame that are .250.
In the short term I'll provide a pair of .125 thick plates that will
have to be glued together to make a .250 shoulder plate.
the long term, the slots in the rings will be made narrower to
accommodate .220 styrene and the box beam that ties the two shoulder
plates together will be adjusted so that the shoulder plates stay in
the same position.
The skirt ribs are the only components that are .250.
In the short term I have enough .250 ribs in stock to fill my existing
In the long term I will obtain some .060 styrene and cut matching
pieces to bring the finished rib width to .5
The Fixed Shoulders
There is no short term compromise.
fix is to lengthen the risers that go between the shoulder hubs so that
they remain the same size. The tabs in the risers will have to be
reduced so that they don't stick out beyond the surface of the hubs.
I'm going to supply the riser parts on a separate sheet instead of
sprinkling them on the frame sheets.
The Box Beam Legs
The two ankle plates are the only components in the legs that are .250.
As with the frame, in the short term I'll provide a pair of .125 plates
that will replace the .250 parts.
I have not yet worked out a different solution for the long term. There
may not be one.
The Eggcrate Center Ankle
There is no short term compromise.
there is a relatively simple long term solution. Four layers of the
.220 styrene come to .880 instead of the 1.00 that is expected. Adding
a single .125 layer brings the total to 1.005 which is close enough to
club spec to be an acceptable solution.
I'll be working on the
short term fixes immediately so as not to delay any orders. As time
allows, I'll implement long term fixes where I can. My apologies to my
customers for not foreseeing this change and handling it better. I'll also be increasing my parts package
costs for all NEW orders. Individuals already on
the order list will not be affected.