Underpinner question

[Ajs349]

I need to find an underpinned that can handle frames that are 1/4” wide. According to the website the alfamacchine line can handle that thin of a frame, are there any others that could handle?

 

[Jim Miller]

A 1/4" wide frame would have almost no structural integrity, no matter how you join it. My suggestion is to use only glue on the miters, and when fitting, glue matboard "dustcover" on the back of the frame.

 

[Ajs349]

Thanks Jim. Currently I glue and later add miter splines so it ends up being pretty strong. I’m trying to find a quicker method to join. Also the total thickness is around 1/2” but with the rabbit cut out the bottom is about 1/4” or so.

 

[Rick Granick]

You might possibly be able to glue and, while in the vise, use a 23 ga. pinner to help hold the miters. The pins make very tiny entry holes. But with so little "target" area of wood, you have to be careful to aim just right so the pins don't shoot out the sides. I do like Jim's suggestion to use a rigid backing to add structural strength. It would avoid having to add a paper dustcover too.
Rick