Determine bag 'back and cover' length

[HondoMan]

Right then, have the odd (to me at least) order for a man's bag. The request is for the back and cover (only and one piece) to be basketweave stamped.  The length or height of the front piece is 27,5cm.  Three gussets on this bag for a combined 20cm.  The length of the cover need be half down the front (13,5cm).  Including the leather thickness, I've calulated 62,5cm.  A length of 62,5cm will fall short.  The problem I'm on about is the wee curve across the top of the gussets.  That is an additional length to the piece and my maths seem to be not aiding me at present.

I get the very rare request for a tooled bag (more belts than anything).  Normally I simply cut the back-cover piece long and trim off the excess.  That's a non-starter this time.  It need be spot on or as exact as possible.  One centimeter short or long will be fine.

Suggestions on a solution to this?

Cheers!

[Rahere]

Tack-stitching. Make it up as you would a blank, but with a single tread, one hole in five, cut it to length. Remove the stitching (it should just pull through) and work. Make up properly.

[HondoMan]

@Rahere, have an idea what you're on about and I appreciate your input, but would rather no do that.  It puts stitch holes in the leather before tooling and dyeing, which can be problematic.  Cheers!

[Rahere]

On 10/28/2020 at 8:56 AM, HondoMan said:

@Rahere, have an idea what you're on about and I appreciate your input, but would rather no do that.  It puts stitch holes in the leather before tooling and dyeing, which can be problematic.  Cheers!

I'm a pragmaticist: theory's fine, but leather's real, and you're proving there are more things in heaven and earth than are dreamed of in your philosophy, Horatio! Another approach would be to do the same, but using card to make a template to be used kn laying out your leather for tooling, rather than the leather itself.