WHEN WILL THEY EVER LEARN ?

They, in this case, being me.   When I figured out that the Mystery Singer was actually an Improved Family modified for leather use, I thought it would be fun to use it to make a bag.
http://mysewingmachineobsession.blogspot.com/2013/07/why-mystery-singer-is-not-improved.html

older photo, the machine is now in its nice refinished stand.

It took me a while to adjust the tension, again.  Finally I declared it ready.   I started on the bag yesterday afternoon, late.  First I made the strap. That was pretty thick for this little machine.  The rest of the bag went together pretty quickly since I had so much experience with the pattern.  But I had an awful time making the final seams.  The machine just wouldn't handle the bulk.

I thought, some, of trying the 31-15 but by the time dinner was over and I had taken my cholesterol lowering, heart disease prevention medicine, I was spent.  Besides, I wanted to watch The Princess Bride.

This morning I surveyed the machines in the sewing loft; Singer 237, Singer 201, Kenmore 1760 and, of course, the Singer 15-90.

I popped it in the treadle stand, swiped the bobbin from the Non Improved Family and started to sew.  That machine went through the four layers of the strap and the two layers of the seam plus the lining with ease. I also gave up on the leather needles. I went through two, and the points on both needles failed. IOW, they became burred.  Back to microtex sharp Schmetz.

I think I will be able to use that Non Improved Family class 15 Gloversville Machine for sewing very fine leather.  I have some nice soft stuff.  I could try making little change purses.  I suppose I should keep the machine for the "museum."  Likely there aren't many of them around.  I wonder if this guy would want it. 
 http://www.nytimes.com/2009/10/22/fashion/22GLOVERSVILLE.html?pagewanted=all

Gloversville isn't THAT far from here.  Maybe on a lark I will load it into the car and trek up there to see.