These two small pieces of G10 fiberglass have been cut into a shape that will be used to pass the igniter wires through the altimeter bay bulkheads without allowing any of the ejection charge gas to pass through.  They are 1/16" thick and roughly the size of a postage stamp.  The left one is a "cap" or "lid" that will be used to cover the other one.  The right one has two slots cut into it that are the same width as the igniter wire.  The holes are for the mounting screws.

This is the forward bulkhead for the altimeter bay.  The two white pieces are 3/4" PVC pipe fittings that serve as ejection charge holders.  The two igniter wire pass-through elements can also be seen.  The lower one has the cap removed.  #6-32x1/2" machine screws and nuts are used to mount the cap in place.  The other piece with the two slots is epoxied to the bulkhead. Two 7/64" diameter holes are drilled through the bulkhead at the end of each slot.

This shows how two igniters can be installed into the ejection charge holder and how the wires get routed through the slots, through the hole at the end of each slot, and then pass through the bulkhead.  The slots and hole match the width of the duplex igniter wire.  A small amount of grease (exactly like that used on o-rings in reloadable motors) is also added to help seal the wire in the slot.

The cap is now put in place and seals everything off.  The thickness of the igniter wire matches the thickness of the slots when the cap is put in place.  Neat and tidy!

The coupler tubing has grooves machined into it because that is how it comes in the Air-X "Black Rock" kit.  In the kit, it is intended to be permanently bonded into one end of the body tube.  The slots help the epoxy bond to the coupler tube. However, I have elected to make the altimeter bay coupler completely removable.  The grooves are not needed and in fact it might be better without them.

These are 1-inch threaded aluminum hex standoffs that I bought from McMaster-Carr.  They will be used to allow four #6-32 machine screws to hold the body tube in place at the altimeter bay bulkhead. 

I drilled a hole through each of the four standoffs so that they could be bolted to the bulkhead with #6 machine screws.

Basically these standoffs were just a simple and cheap way to add four threaded hard points for retaining the body tube.

This is an end view of the assembled altimeter bay.  It shows the aft bulkhead that has the U-bolt installed for drogue chute recovery harness attachment.  Two nuts on the 1/4" threaded rods hold the bulkheads in place.

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