Tuesday, April 2, 2013

Cobalt Butterfly Straitjacket Part 3 - Setting Rivets

The next step on our project is attaching the rings which will become the attachment point for the removable straps. To do this we first need to figure out the correct size of rivet to use... You don't want to use a rivet that's too short - it won't seat properly. You also don't want the rivet to be too long, or it won't snug down and hold the parts securely. 

I had an assorted package of rivets, and just because I'm anal and obsessively organized, I needed to sort them by size first: 

I also have the need to convert everything to decimals to make it easier to add the proper allowance to the rivet to get the right size. You want the rivet to be one-eight to one-sixteenth of an inch longer than the thickness of the material you are riveting. 

Since there's a rolled edge on our project that keeps me from being able to measure it directly, I need to make a mockup using the same number of layers on the jacket. There are 5 layers total:

It turns out to be just under a quarter-inch thick. 

Add the minimum 1/16" (0.0625") plus the .247" and you get a minimum rivet size of 0.3095". If you go with the 1/8" maximum (0.125") plus the .247" you get a maximum rivet size of 0.372". The closest rivets to those sizes are the 5/16 and the 6/16" sizes. 

Before riveting the straps, I want to glue a reinforcement to the back. This is a tough nylon ribbon, very low-profile, with no stretch at all. It will back up the leather and add a lot of strength. 

Both parts get glue...

Fortunately the nylon strap is slightly under one inch wide, so it shouldn't be visible. 

 Once adhered, this gets divided into four parts - one for each of the connecting rings. 

It's time for the hardware loop. For this jacket I'm using these really nice heavy-weight nickel loops from Sav-Mor Leather in LA. Compared to the typical "strap-keeper" loop, it's much heavier and about 5 times the cost (60¢ vs. 13¢). But worth every penny! I'm not sure if they are cast, but they don't have the visible "weld" or gap that you see in the cheaper, lighter-weight loops.  (I totally recommend these loops, and yes, Sav-Mor can handle mail-orders!)

I normally backstitch when sewing to secure the threads at the beginning and end of each line of stitching, but in this case I want to sew through the leather as little as possible - I don't want to weaken the leather by perforating it more than absolutely necessary. So these thread ends all get knotted and tied by hand. 

 I make a cardboard template so all of my holes are consistent and aligned. (Hole alignment=very important!) I noticed I get better results when riveting (especially through many thicknesses) with a pilot hole. 
The straps are centered on a mark 5 inches apart, 2.5 inches from the centerline. 
Pilot holes punched:
 I also want to use the template to mark the hole position on the straps. It makes the centering and alignment easier than using a ruler or tape each time. 
 First loop riveted in place!
 From the inside. Looks good...
 Second one down...
I measured and marked the positon for the rear rings, on either side of the zipper. Holes punched, and rivets set...
 This part of the jacket is done!

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