[Artemisia] sewing garmet leathers on a regular sewing machine

[Dr. C. M. Helm-Clark Ph.D.]

It's actually easy to do this without ruining the leather
or the machine.  First, use a roller foot to protect the
leather.  Second, get sewing machine needles specifically
for leather - they have a geometric cross-section of either
a triangle or a diamond that won't tear the leather once
the thread is in the hole.  Third, don't sew too fast - not 
more than 3 or 4 stitches per second - and that's fast!  
Unless you are using a machine specifically designed to sew 
leathers(and you'd know it if you had one - they are goofy 
looking) you don't want to go very fast at all.  Fourth, do 
several practice pieces first to make sure the bobbin tension 
is just right for the thickness of leather.  Last, leave a
seam allowance for garmets of 3/8ths" for garmet weight
(1 to 2 oz) and 1/2" for chap weight leathers.  For a vest,
I would assume you're using a garmet weight. To finish the
seam, with the inside of the seam facing you, spread the 
seam allowance to either side and with a light (1 to 2 lb.) 
mallet, lightly whack the 2 sides down flat on either side
of the seam and then glue them down with a high quality
contact cement like duro or barge brand.  When the glue is
set, lightly tap the entire glued-down seam allowance to
"set" the glue (if you do this, the glue will not ever
release). If you don't do the seams this way, they will 
likely look wrong when the garmet is worn (you can do the
sorts of seams you use on sails and tents and such, which
don't require the tapped and glued seam finishing, but
I think those wouldn't be right for the vest you describe).

Oh, and don't use any thread lighter than quilting weight.
Regular poly sewing thread for cloth will not survive the
greater elesticity required for leather clothing.

This is how the professionals do it.  I know - I worked in
a real production leather shop, sewing caps and car seats
and billfolds and stuff (among other things).

So why not just do this yourself?  Just make the changes
to your sewing machine set up - and otherwise, it's not
that different from doing cloth.

ttfn
Therasia, OL in LEATHER (and NOT C&I or metal, geez...)