Thread/Needle size for a Yamata FY5618?

[Vhatton]

Got my sewing machine up and running today but I have a few questions-
-It seems that the walking foot is leaving marks on the leather. Is there a way to adjust it? It is a Yamato FY5518.. 
-What is the ‘normal’ size of thread for most projects? The gentleman I bought it from had a #277 in it. The gentleman that is showing me the ropes does vehicle upholstery and as a trial run threaded it with #92.. I’m not sure how to find out what size needle is in it. 
-The thread on the underside of the leather is thin, almost like standard sewing thread. Does that mean my topside of projects will have a thicker thread and the underside be thin?
I’ve been hand stitching the last 3 years so I’m hesitant about the thinner thread. 
Thank you!

[CowboyBob]

This machine is more for canvas do to fact it has feed dogs underneath that pull the material that can leave teeth marks which is the same as the feet which have teeth(which can be ground off) .There a pressure foot adjustment for the foot pressure on the top left hand side of the machine,you can loosen it by turning to the left.

Thread size #138 is about the largest I would recommend for it.

Edited June 26, 2020 by CowboyBob

[Vhatton]

Thank you so much! Will the #138 be good for wallets, journals, knife sheaths and such? 

Veronica

[Wizcrafts]

9 hours ago, Vhatton said:

Thank you so much! Will the #138 be good for wallets, journals, knife sheaths and such? 

Veronica

You'll need at least 1/8 inch of leather to hide the knots with #138 thread. It has 22 pounds breaking strength, so you may need to sew double rows on sheathes or pancakes. It is fine for journals and combining the back to the interior of a wallet. It is too thick for the interiors though. For those you'll want to stock up on #69 and/or #92 bonded thread. Get you some #18, #20 and #23 leather point needles for these threads sewn into leather and the same sizes in round points for cloth, canvas and Naugahyde, if you intend to sew those materials.