Occasional loops on underside of work - Singer 31 clone (Pfaff 34)

[ElfLeather]

I have an old Pfaff 34 that I'm having trouble with. I'm setting up to make a hip purse, and no matter how I set the tensions, the top side of my work looks fine but I'm pulling occasional loops on the underside. At best, I can get 5-6 stitches between instances. See left picture. Top thread is white Amann bonded nylon in 138, bottom is black Amann bonded nylon in 92. Needle size is 22.

The thread is moving gracefully through the thread path, no apparent snags or burrs. I tried it with some soft combination tan and some medium-soft oil tan and it sews beautifully (see first picture) but this stiffer stuff, no dice.

Anything else I can check? Or is this stiff leather asking too much of the machine?

[Northmount]

19 minutes ago, ElfLeather said:

top side of my work looks fine but I'm pulling occasional loops on the underside

Increase top tension. 

If that won't do it, try a larger needle since this is hard / stiff leather.  On 8 oz or so veg tan, I've been using #23 needle for 138 thread bottom and 207 top.

[Wyowally]

What kind of needle? Round holes in stiff leather pinch the thread. If you are using a leather needle, just ignore me!

[ljk]

I just finishing working on my Singer 44 (9" version of 31-15)  had same problem.  There was a burr on throat plate and needle was not adjusted on the scarf.  Now if I can get it under the foot it will sew it.