Reverse Engineering Help Needed!

[JimRaynor]

Hi everyone!

Lately, I've been 'deconstructing' stuff that's damaged/no longer used/etc., trying to reverse engineer them, to figure out how they were made, what tools/machines were used...

It's quite fun and educational but lately, I'm stuck with a certain item and I thought maybe one of you guys can figure it out.

Attached, is a cutaway of a leather strap - about 25" long. The picture shows it but what I can add to the givens is, there's also a super-thin and super-even-spread of glue between the black and red parts

P.S.: Notice how the binding (black leather) on both sides are not individual parts but actually a single piece (sheep skin I assume) running under the red leather.

So, how do you think it was made - build order, tools, machines, attachments?

Thanks in advance.

[JimRaynor]

Here's a quick (and ugly) sketch of the cutaway, if it helps...

[johnv474]

(Sorry for formatting--always lumps paragraphs into one). Lay out strip of black. Use roller/brush/spray adhesive over entire surface. Lay masking tape parallel to edge on black leather. Fold one edge of black leather toward tape (your guide line), and press. Remove tape. Apply adhesive to red. Apply red along tape line (just slightly in to adjust for black to be folded again. Apply adhesive to edge of red. Fold same black over again to stick to red. Now do both folds on other side of black (possibly cutting off excess first). Ready to sew by itself then glue to tan... or if sewn through tan, then glue that first before sewing.

[JimRaynor]

Thanks johnv474,

I always thought it'd be impossible to center align the res piece and there had to be a machine in the process because I couldn't come up with using masking tape!

P.S.: If you're unhappy about formatting, try SHIFT+Return for new paragraphs, instead of just Return.

Edited August 4, 2015 by JimRaynor

[Nuttish]

I don't think there's a trick for perfectly centering it other than measuring the piece and accounting for the diameter of the roll.

The top piece of yours looks like it has wide channel skives under the turn. That could give a clear demarcation for where to start folding the piece on each side and makes it easy to finger press and glue a straight line.

Otherwise, it looks like it's glued bottom up, folded/glued, and topstitched.

I'd fold last so that you can see exactly where the piece will end up on the top and align masking tape so you can get a clean glue-up.

[Art]

I look at it from a modern manufacturing standpoint which (even in the orient) seeks to reduce manual labor. The products are probably not leather in the animal hide sense of the word. More than likely the parts are manufactured leather or whatever produced from maybe some percentage of leather etcetera. The sandwich parts are bought in rolls with dried adhesive applied if necessary. It is most often activated by heat and set with pressure. A assembler/sewing machine can do one side at a time or both sides at once, just depends on the machine capabilities. Many of these machines are adjustable, some are computer controlled. All have the ability to mount cutters, heating stations, have multiple needles with adjustable gauges, and most importantly, mount folding and pressure stations and pullers. It is very easy to accomplish this operation in two passes, a more sophisticated machine could be setup to do it in one pass (folding and sewing both sides at the same time). This operation would be similar to a binding operation.

That may seem like a lot of trouble for a leatherworker doing one or even a dozen of these, and it would be. But when Wally World orders 10 as an intiial order for each of it's 4500 stores, you find an engineer quick.

Art

[DrmCa]

+1 for manufactured leather.

My wife thought she was given a genuine leather purse for a present right until it melted on one summer 100+ degree day and smeared the other purses on the closet shelf with black plastic.