OK, I had my strap, now the fun part, attaching it.
I have posted on the USMF before about the correct bar-tack to be found on WW2 M-1 helmets (I used to work for a defence contractor that used the same machines). However, not having access to that machine anymore the problem would be to replicate that stitch on my home Janome machine.
I thought about this for a little bit and went a head and conducted some experiments using my machine’s zigzag feature. I was able to change the length and width of the zigzag until I was happy that it approximated the correct original bar-tack. I also used a correct cotton linen thread of a colour that approximated the originals.
The chin trap had been cut right across the top where it met the bail. I removed the old bar tack and the end of the strap where it had been cut (approx. 2in.) fell away. I then used this scrap piece to further practice the bar-tacks. The reason being that machines can behave one way with a material and need adjustment when using a different material. When I was satisfied that the machine would work on the correct material, I began. I pencil marked in the correct setting to my machine for future use.
I folded the strap in the correct manner and made sure that the folds would be in the right place. I then placed a pencil line over the area that I wanted bar-tack to go remembering that the correct bar-tack is a specific length.
I then positioned everything under my machine. I actually had to remove the light cover to fit it all under. I then, using straight stitch, sewed a straight positioning stitch over the strap the length that I wanted the bar-tack. This is important as it us used to keep everything together while the zigzag stich is sewn. If you were to go directly to the zigzag stitch first the 3 layers of web would go in different directions and the finished item would look poor.
In a proper bar-tack the web stays still while the machine moves, however on a home machine the machine stays still while the web moves. The positioning stitch is vital to a good job. Original bar-tacks also have this positioning stich.
Once the straight stitch was done it was now on to the zig zaging, being very careful to start and finish at the correct points and keep a straight line.