Hatch rebuilt

[P69]

I rebuilt the forward hatch.
I didn't want to spend $50 - $100 for a replacement riser arm, so I made one.

http://bodylens.com/Gallery/thumbnails.php?album=30

Ground/sanded/wire wheeled all paint off both frames
Painted with Moeller zinc chromate paint (green)
Painted metalic silver spray paint made for automobile wheels. We'll see how long that lasts!

Gasket. I searched and tested a lot of materials and could not find a good, inexpensive replacement.
Gasket has to be round and solid. If any other shape, it will not turn the corners. 
Diameter: 9/16
I ended up buying the ~$4/ft gasket made for that hatch. Huge ripoff, but I couldn't find anything else.
Bought 8' and have a little over a foot left over.


1/4" Cast Acrylic 24" x 24" piece
Cut to fit with a skinny 3/16 gap between the edge of acrylic and the frame
http://www.mcmaster.com/#8505k94/=w0fp51
Color: bronze

Dow 795
Color: black
http://www.mcmaster.com/#catalog/121/3446/=w0fq9x
Used about 3/4 of a tube and had a lot of cleanup. Probably could have used 1/2 has much.
used Blue tape to mask off all surface.
within minutes of placing acrylic in frame, I began the cleanup with mineral spirits

Knob: used from old riser arm.
Arm where knob threads is threaded entire distance. the 1/2" schedule 80 pipe was not thick enough, so I welded a piece of 1/4" SS flat bar, then drilled and tapped that hole for the 5/16 x 18 knob

The support arm. Two pieces, one tube and the other round bar with notches ground into it. The lenghts are about 6 or 7" each

tube: schedule 80 pipe, "1/2" inch diameter
  Nominal   0.5", OD 0.84", Wall 0.15", ID 0.546"
  http://www.onlinemetals.com/merchant.cfm?pid=959&step=4&showunits=inches&id=59&top_cat=1


Round bar:
1/2" dia 304 SS round bar
http://www.onlinemetals.com/merchant.cfm?pid=78&step=4&showunits=inches&id=6&top_cat=1

Fittings connecting riser arm to the frame (both ends): made them out of SS flatbar.