I have broken the door preparation into several sections to keep
the individual pages smaller and give some logical sections.
An arm rest is not a necessary addition if the standard
door latch/lock is used but, the handle supplied with the door latch from
Lyle Hendricks would stick up higher and further into the cockpit. I
did not want the handle to be in an exposed position which might be caught
on a shirt sleeve and opened by accident. By fabricating an arm rest
where the handle is recessed, it can be protected. I also like the
idea of having the arm rest for the comfort factor while working the throttle
controls.
I used the standard technique of shaping the arm rest with blue foam and
covering it with tape to form a mold. This is then covered with the
fiberglass bid, allowed to cure, and then popped off the mold. The
mold is then removed and discarded. In the past this technique
has worked well but without a vacuum bagging system it may not form well
to a complex shape. This time I tried a slightly different technique
with very good results.
Before installing the door glass I have followed the lead of other
builders and decided to do the preliminary work on installing larger arm
rests and the door locks from Lyle Hendricks. I used pieces of blue
foam and 5-minute epoxy to buildup the basic shape for the arm rests.
The blue foam has been filled in and sanded into the desired shape.
I plan to have the throttle and prop controls on each side of the
instrument panel so I wanted the arm rest to extend a bit further forward.
A little bit of duct tape and the arm rest is ready to lay up glass
over the form. This would be one place where the vacuum bagging would
be a great aid.
I could not justify the time and expense of a vacuum bagging
system for the few molded parts that I needed. I tried on a couple
of prior parts to just tape everything in place but had limited success since
multiple layers of glass do not tend to follow shapes real well. The
problem is always how to hold the glass against the form while it hardens.
My idea was to come up with a method of holding the glass
against the form while is set. I first placed everthing in a couple
of flat boxes. I covered the forms with the Glass Bid and then used
SARAN WRAP to cover the glass. The one mistake I made was to not smooth
out the Saran Wrap over the glass which resulted in a less than smooth
surface.
Next I covered the layups with a thick cover of sand and
patted it down tightly against the form to ensure that the BID was held tight
against the form. Now we wait to see if it was a bad idea.....
After curing the sand was removed. The Saran Wrap peeled off
easily without sticking.
IT WORKED!
It took some work to get the part off the mold since it stuck to the duct
tape more than I thought it would.
After a bit of sanding and trimming the arm rests fit like a glove. All
that is needed now is a couple of mounting brackets and some upholstry.
The arm rest is positioned on the door and the cutout for the inside
latch handle has been made. A balsa wood block was bonded to the inside
of the armrest and shaped to the opening. Once the arm rest is padded
and covered the handle will be recessed from accidental contact.