Doors Preparation - Arm Rest Construction


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.