min thickness for the back profile on cabinet door?

[Kevin Jenness]

The issue the OP points out is driven by keeping the raised panel face at or below the rails and stiles. This is required only if the completed doors need to be run through a panel sander. I like to have at least 3/16" at the back shoulder. I have seen plenty of production doors with 1/8", and I even made some recently at the client's insistence on using a specific thickness and profile, but it seems weak to me.

I like to run the stock through a wide belt prior to assembly. Accurate setup minimizes levelling the joints and I don't have to sand out cross-grain scratches, plus I can put the panel where I want it.

The profile JR shows reminds me of the time a customer asked the shop I was in to make a set of doors with a thumbnail bead omitting the quirk, so the cope and stick profiles met at the door face in a horizontal plane. Finish sanding was a nightmare as any deviation from flat produced a visually out of square joint. JR's example is close to vertical so it would take some sloppy sanding to be problematic in that way.

[David Kumm]

I've done what others have said. Rails and stiles at 7/8-1 1/16 depending on my profiles. Avoids all the problems, makes me happy when I open a door and separates me from the herd. I even like them on inset doors. Dave

[Robert Engel]

Andy,

Is the panel bit part of a matched set of the rail/stile you're using? If not, that's probably the issue.

The minimum would be about 1/8" on 3/4 - 13/16" stock.

Kevin brings up a good point. If you're hand sanding there is not absolute need to for a flush panel. Its really impossible to visually tell if a panel is 1/16 - /8 proud of the frame. That said, when drilling for euro hinges, its nice to have a flush panel but you can also drill prior to glue up.

[Martin Wasner]

and I don't have to sand out cross-grain scratches,

I see this frequently. And don't understand it.

How does sanding cross grain scratch differ from with the grain other than it's harder to see the scratch when it's with the grain?

I kick everything I can through the widebelt at an angle to make the scratch as obvious as possible.