Countersinking the bulkhead for the #8 screws concerns me. I just had the one baggage floor crack on me, which is easily replaced however if I have the same issue on the F-706 bulkhead after its installed it will be devastating to me. To make matters worse, one hole on the bulkhead is through 2-layers. I really wish I had done this back during the F-706 bulkhead assembly.
I was determined to solve this sooner than later. So first step I removed the primer from the holes in question on the bulkhead. This will allow me to lube then dies when dimpling. Next I opened the factory holes to #19 using a MDF backing block and stepping up drill bit sizes. I then carefully polished the holes with #600 grit paper on the dremel mandrel and buffed the holes with 3M maroon scotchbrite.
I then lubed the dies and material, took a deep breath and started to dimple. Thankfully all dimples turned out perfect, including the ones through the double layer of the bulkhead.
Feeling good from dimpling the #8 screws, I dimpled the #40 holes on the seat and baggage ribs.
Next was the very long and tedious process of deburring the corners, nooks and crannies. Went through a lot of 3M maroon scotchbrite squares on the dremmel but the job is done and done well.
