Mould making basics for wet forming leather

[UKRay]

Although I have made many wet formed items 'freehand' I have never tried making up a mould and using it to 'mass produce' anything.

I'd like to make some knife cases to fit French made, folding, Opinel knives. Have you ever made up a mould like this or something similar? Got any tips or suggestions? Best of all, could you please post pictures of your moulds so I can get a better idea what is involved in making one.

Will I need to brace the mould to stop it flexing?

What is the best material to use?

How should I clamp my mould? What method/tools/clamps works best?

I saw a thread a while back that mentioned cling-film / sarran wrap. That seemed like a good idea to stop the leather staining but have you got any other good tips?

The radius on the mould edges is concerning me a little. I haven't seen many pictures of moulds and those I have seen have not shown this. I can see it doesn't want to be too sharp but what works best for you?

I'm also keen to see how consistent they will be as I have heard that each leather moulding will need quite a bit of trimming to make it look right.

I'm also keen to know how close to the moulding I can stitch with a machine. There seems little point in hand stitching the things unless I really have to - my idea is to mechanise these processes! I need to know the optimum distance because I think I have to allow for this in my mould design.

Any help gratefully received!

[Randy Cornelius]

Funny you should ask, I have been asked to teach a class on basic case making at the IFLoG show in Indianapolis, In this fall. In that class I will be teaching the basics of making molds for cases. I have used several different materials for molds over the years but I find that wood is the best. It will absorb some of the moisture and help dry the leather while in the mold, thus setting the form you want and keep it. Wooden molds can be made with common wood working tools, the most importaint is a router but with some patients you can make them with wood chistles, rasps and sandpaper. If you can make it to Indianapolis this fall my class will be very afordable.

Randy

[china]

I also use timber to make my molds treated pine, mainly because I have plenty of offcuts, I make an outer shape, the the size of the item + leather thickness and a inner shape, then I soak the leather, and work it into the outer mold the push the inner mold in and hold it there with a G cramp, until it is dry, I always make it oversize to allow for trimming, as for stiching one of my machines can sew right up to an edge as the needle and foot have zero clerance on one side. Hope this helps.

china

[rdb]

There's a book called "The leatherworking handbook", by Valerie Michael, that has some good chapters on 2 piece moldmaking and methods.

I'm not a master of anything, but I have to make molds once in awhile.

I just use my bar clamps and sandwich boarding to hold any molds together. Sometimes I'll make a mold and screw the top right to my old workbench.

If your molds, and leather pieces are consistent, the trimming off of the excess will also be consistent.

As far as radius is concerned, it all depends on your equipment. How close can the foot get to the crease. Holstermakers use specific feet and plates for as close as possible sewing. I don't have those feet yet, so I make do by sewing on the opposite side of the presser foot, and just getting the needle foot as close as it can fit. It just about goes right into the crease. I don't trim until after sewing, so the walking foot still grabs. This works better on small projects, but larger ones show the mistoops. I'm sure those with the proper equipment will tell you the specific/correct plates, and method they use.

Holstermakers also use their presses, and vacuum pumps over molds for larger production purposes. There's several Threads here on those discussions, as I'm sure you've read.

I don't often mold anything much bigger than a holster, or cellphone case, and that's not everyday, so I still use the old fashioned Stohlman type method with just using tacks, for the most part. But I might have 3 or 4 of the project nailed to my working bench, while they dry. With a big enough bench/ tacking board, small production levels can add up quickly. I place the tack right in the crease, and my way of sewing covers the tack holes.

I hope your questions open a big discussion on this. It could be useful to all...

[Jordan]

Dagnabbit rdb you beat me to it. I could not remember where I put my copy so I could post the info. Great book chock full of good stuff.

[rdb]

Not really related, more free form, but this is my bench this morning.....

[UKRay]

I do have a copy of that book - Valerie Michael lives a little way down the road from here and I plan to check out her courses later this year. She does quite a bit with leather moulding I understand. Her work is superb, I've seen an example in the Leather Museum in Walsall.

Sorry Randy but it is just too far to hop over the pond for your course. I'd really like to but...

Thanks, China - any chance of a picture of one of your moulds please?

I do admire the way you work, rdb. I wish I could be that 'freeform' but I'm just too darn orderly to work like that! I'd have to find myself very special bits of wood and keep them just for nailing moulds to. I even have to tidy the bench and hoover up the floor after work most days so it is clean for the following morning. Not quite obsessive, but veeery close! LOL

Badger was telling me about using fibreglass to make moulds the other day. Absolutely fascinating but he tells it better than I can. He apparently uses a pasta cutter to produce 3mm thick clay strips that replicate the space taken by the leather... sadly I only retained the bit about the pasta cutter and not how he uses it! Hopefully he'll jump in here...

[fishguy]

The Al Stohlman case making series of books, which are pretty readily available at Tandy or leather factory have quite a few examples of using plugs and two piece molds.

[rdb]

Crack me up!

Admiring the way I work? I'm a slob!

Somehow in the madness, I make a few things that work. Here's one of those "freeforms" finished up this morning...

Vinegarooned, but no finish yet.

[jbird]

I don't know how it is but I have done a bunch of wet forming some pretty odd shapes to and I do it like you would think inner mold outer mold but I use 1/2 plywood the better stuff used for cabinets works great for sure wish I had some pics but it works nice and so does the old pin up way.

Josh

Edited March 17, 2009 by jbird