Marking stitching holes on leather thats wet formed/not flat?

[RipDyna1991to2017]

Im making a gusset thats wet formed, similar to a U gusset.  Im having a hard time figuring how to punch straight holes/make straight cuts once the leather is no longer flat. 

Im starting with a piece of veg tan thats close to the shape i need, but after wet forming and cutting off the excess, the gusset edges arnt perfectly straight.  Once glued, i would sand the edges flat/equal to the body, but i wanted to count and pre punch the gusset holes so theyd be equal the holes on the case.

I tried using the exact shape i need, but the leather stretched and dried different then how i had planned with my pattern.  

I hope this makes sense, its a simple problem i believe, but im struggling to come up with a solution.  Thanks for your time, any help is appreciated. Usually i would just punch the holes on the other side of the piece, but it would be awkward because theres only a small lip.

[Matt S]

This is one of the several reasons why I like using a pricking iron and awl in the traditional English technique -- you just need to prick the front while flat, glue the gusset in place, then sew. The holes are opened one at a time with an awl as you sew.

If you prefer to punch your stitch holes, you'd probably have to do it after the gusset is bent in place to avoid having to match up holes in gusset and front. You just have to get creative in how to back up the lip of the gusset when punching.

[zuludog]

Have a look at these YouTube videos -

Making a Moulded Leather Possibles Bag by Ian Atkinson

How I Make a Large Wet Moulded Leather Possibles Belt Pouch by John Wellings - Variety Channel. There are probably other similar videos, just Search around on YT 

They clearly show that firstly you wet mould the leather; then trim the border or flange; then glue it in place; then make the holes through both the front and back with a stitching chisel or an awl; then sew it up

I don't think you could pre - prick leather that is to be wet moulded because, as you have seen there would be too much distortion and the holes would no longer line up

I would cut the moulded part to the approximate shape, then do the final trimming after the sewing as that would literally give you more margin for error 

Nigel Armitage has several videos on making pouches where he explains about pre - pricking, though these are with plain gussets, not wet moulded

However his Vimeo channel does have a video on wet moulding. There are nearly 100 videos on all aspects of leatherwork, from the seemingly simple and basic like how to cut leather or place stitching chisels to more advanced projects, and he is constantly adding more. For £3/$4 per month you get first class information and instruction

Edited August 15, 2020 by zuludog

[chuck123wapati]

If i'm correct you said you already punched the holes in your bottom piece. Form your gusset with extra leather for trimming, glue your two pieces together then you will have to punch through the existing holes on the bottom piece with an awl or some such, sew it together then trim the edges straight. Thats about the only way i can think of fixing your problem. You can pre punch leather if you are using a pattern and diamond chisels but even then its ify especially of wet forming.

[Frodo]

Drill the holes