Ar15 seat edge radius?

[Biney777]

I had an idea for making the rounded seat edges that run the length of the cockpit using a slice of pvc pipe. Has anybody tried this? I have dryfit it and it looks like it will work. The seams get fg taped and I will use epoxy w/ wood flour to fill the gaps, then the seat top gets glassed as well (for wear protection). I might try a test to see if epoxy will bond to the pvc well/or at all??? I would appreciate any thoughts on the idea or suggestions?.?.

[Capt UB]

I will be following, I think it sounds like a good idea.

Don't know how well the epoxy holds on to PVC in that type of usage.

Could you laminate plywood pieces then round the edge?

[topwater]

To glass PVC you really have to rough up the surface . I used 60 grit and then a good wipe down with acetone.

[Jaysen]

Why not use the PVC as a mold and make the edge out of FG laminations?

[jacquesmm]

The plans show wood but if you use PVC, use it as a mold as the previous builder has said.

[Bogieman]

I really like that idea. Seems like it would be very comfoartable on the backs of your legs. Sorta thinking about doing something similar on mine because I lowered my seats which took away the nice rounded seat edges. What I was considering for mine would be to run a 1 by 2 lengthwise along the stringer top so that it's flush with the seat top, then router a nice rounded edge on the top and bottom. It could also work as a hand grip.

Bogie

[Biney777]

The plans show wood but if you use PVC, use it as a mold as the previous builder has said.

Sorry, my inexperience with fiberglass and epoxy is showing. How exactly would I do that? I am guessing by using it as a mold it removes the risk of the epoxy not bonding well or at all to the pvc, and saves on the weight of the pvc itself. And they do weigh approx. 3.55 lbs each more than the 1/4" ply in the plans. I just weighed one and in my head I hadn't thought they added any additional weight . I get that an addition 7 lbs up really high in the hull would be bad!
What kind of lamination would be sufficient for that radius? The seats get covered with 6oz. Woven fabric per the plans. (I think)
So my plan would be to use ??? Layers of ??? Fiberglass to create the radius, then use the 6 oz. Woven fabric to cover both seams and tie it all together???

[Jaysen]

boogie, That would work. That edge is also known as a "bullnose" or "stair edge". You'd want to edge it before installing.

biney777, the lam schedule is out of my expertise since I think you need some structure there. But the mold isn't too hard. wax the mold to prevent adhesion, lay pre wetted tape in layers working wet on wet. Vac bag or use a mated mold for best glass to weight ratio.

[jacquesmm]

If you use a PVC pipe instead of wood, you need to use more glass.
That is why it is better to follow the plans.
With a PVC pipe, I would go for 3 layers of biaxial 12 oz. over the pipe with offset edges.

[Biney777]

If you use a PVC pipe instead of wood, you need to use more glass.
That is why it is better to follow the plans.
With a PVC pipe, I would go for 3 layers of biaxial 12 oz. over the pipe with offset edges.

Thank you Jacques, I know I feel your pain, every time you design something idiot proof another one(me) has to start thinking...
So maybe a better question would be. I like the thought of just one large radius edge on each side vs. 2 with a flat spot in the middle. Which to me seems like it would be very difficult to get faired decently? How would you suggest doing that? I swear I am just trying to build to plan, the thought of how badly I could make something like that look tho is why I started "thinking".