Simple cheap speed reducer

[MarlinDave]

A question on pulleys. The sewing machine belts seem to be 3/8 inch. Some companies call them L or M series. Auto zone has a 15 series. All the pulleys I have found for sale are A series (1/2) or A and  B series ( 5/8 inch). I just had the narrow pulleys on hand, one came off my clutch motor. What pulley series matches 3/8 inch sewing machine belts? 

[DonInReno]

1 hour ago, 327fed said:

A question on pulleys. The sewing machine belts seem to be 3/8 inch. Some companies call them L or M series. Auto zone has a 15 series. All the pulleys I have found for sale are A series (1/2) or A and  B series ( 5/8 inch). I just had the narrow pulleys on hand, one came off my clutch motor. What pulley series matches 3/8 inch sewing machine belts? 

3L and 3v pulleys are for 3/8” belts,  but I don’t know how much of a difference there is between them.

[MarlinDave]

https://postimg.cc/cK5THjZF

This machine for sale on leatherworker.net has a simple reducer but I am unsure what type of bearing is used.