Digit

I have a Singer HD 4423 for fabric, but I haven't used it for leather, nor will I ever now that I have a triple transport machine. That singer only has single transport (barbs at the bottom that pull the fabric forward), so heavier fabrics can slip and shift under the presser foot, giving an uneven or crooked stitch. It also probably can't deal with the thread size you typically use for leather. Other features that I've come to love about industrial machines is that a household machine (at least this specific Singer) doesn't have electronic needle positioning that makes it easier to sew stitch by stitch.

What is 'the right leather'? As for thickness, 1.5-2 oz converts to .6-.8 mm. I've ordered two half-hides of .7-.9 mm chrome tan horse nappa last month. So that thickness is certainly obtainable, at least here in Europe. Note that horse nappa is sturdier and less stretchy than sheep or lamb. When I bought my cheap Chinese manual splitter off of AliExpress I tested splitting down both a piece of 3.5mm (8-9 oz) veg tan harness leather and that horse nappa. As long as the blade is razor sharp both worked a treat.

I had a similar problem on my 69-373. Solved it by threading around the tensioner in the opposite direction so that the thread travels +/- 400 degrees (slightly more than a full turn) instead of +/- 300 degrees (less than a full turn).

I've bought some stuff from Lederhaus in Germany (lederhaus.com). They have a large choice of leather (veg and chrome), but you do have to order in commercial quantities (half hide, full hide, croupon, ...) not in small cuts. They also sell catalogues with leather samples for which they offer constant colour. And they have tools and supplies (rivets, glue, buckles, ...).

I've bought a cheap leather splitter from AliExpress which works surpisingly well. Splitting down 3.5mm veg tan is super easy and it even works on 1.5mm chrome tan. It's basically just a holder for cutter blades, so a dulled blade can be easily replaced (or sharpened if you like). The width of the leather that can be split is limited to the length of the blade, so +/- 9cm. This is the one I got: https://www.aliexpress.com/item/1005005967041306.html There's plenty of similars and the price constantly varies, but I think it bottoms out at around 35-40 euros.

I've got a similar issue with an old piece of riveted leather. In the past I've tried to scrape off that sticky green stuff, but it keeps coming back. Since recently I have a spindle press for setting rivets, so I'd like to replace all the nickel-plated brass rivets with new ones (either nickel-plated brass again or nickle-plated iron, wdyt?). What's the best way to remove rivets? Drill through them? (I do have a press drill).