Putting the Vee's on the edges will still give you an exposed edge. I
guess in the perfect world there would no more of a transition from one
sheet to the other than butted edges would give. Given that you can
control a sheet this large while feeding it past the cutter.Now do that
for both sheets. Remember that you have to control x,y, and z axes or
you will get a gage step, an crooked edge, or both. I'd suggest that the
mill edge, maybe with some careful deburring will be about as good as
you can get without setting up on a mill to do a single pass.
Check with your powder coater to see if they can coat the seam several
times to give a filling effect. I know that there is a practical limit
to how much it can be built up, but it may be enough to smooth out a few
thou. of mismatch. Also, inquire about using a primer, maybe it can be
"built up" to fill the gaps.

Ernie Leimkuhler wrote:

I have a theory about how to seam panels of aluminum, and was wondering
if anybody has heard of such a device.

I am bidding a large aluminum job right now, and part of it is
a 10' x 10' panel that needs to be powder coated.
The panels are 0.090" 5052 aluminum.
The largest sheets I can get to skin it are 5' x 10'.

I have not been able to find any suppliers of a spot putty that can
take the 500 degF of the powdercoating oven.

The powder coaters I have talked to say that it is very hard to make
panel seams not show up under powdercoat.
The eletrostatic effect hat clings the powder to the metal tends to
accensuate edges, not hide them.

I had this idea for doing a tongue and groove on the panel edges.

I was wondering about making a small milling device that could V-groove
the edge of one panel and shape the other panel edge into a knife
edge.

I am thinking about 1/4" overlap.

The problem is the grooving cutter.
I would set these up in a router table and simply feed the metal past
it.
I am worried about milling 5052.
It is a bit gummy.

It is approximately a 20 deg included angle for the groove I need.
I would need precision roller giudes to capture the sheet edge, but
that is still not that difficult.
I am thinking of adapting a small horizontal miling cutter for this.

So to use it I would mill one edge as a groove and the other as a knife.
The 2 would be nested together and attached to the backing frames using
flush aircraft rivets.

After a little sanding it should be a pretty tight joint.

I have thought about just skiving the edges of both panels to thin
knife edges and lapping them, but that woories me more.