Leather press issue

[Phlin]

Hi,

we made diy press with car jacks for cutting leather with dies, but the die isn´t cutting all the way through the leather. Can someone guess what might be the issue just by looking at the photos?

We have two 20 ton car jacks.

The working are of the press is 30 x 15 inches.

The longest die is 4 x 28 inches.

The small V shape is 12 x 15 inches.

The large V shape is 12 x 26 inches.

I hope someone could help us solve the issue, thanks for any comment.

[Constabulary]

wow - what a beast! 

Are you using a cutting board of some kind made of Polyethylene or wood?

[Phlin]

Thanks for the quick replies  yes we have polyethylene clicker block under leather. So the only solution is to divide the dies to make cutting area smaller, that is what I was afraid of.

[Matt S]

Yeah that's a lot of effective cutting area. Tippmann, for instance, only rates their 15 ton press for 60 linear inches (1500mm) of cutting area on leather, and I'm not sure that it'd do that on harder veg tan like you seem to be using. Even if you're getting a full 40 tons out of those two jacks, and there's no flex in the machine, you might be trying to take too big a bite. Taking Tippmann's figure as a basis (4 linear inches per ton) you'd be looking at 160 linear inches or 4 linear metres for a 40 ton press.

It's a cool press. How are you limiting the depth of cut?

[Phlin]

Matt, thanks for the input. We did just the test cut so far so we haven´t thought about limiting the depth yet but we probably should I guess. Everything has been total nightmare so far, we have been cutting everything by hand and we wanted to speed everything up so we got the dies first and then the first version of the press which bent like crazy so we were left with just bent metal shelf, kind of expensive one, now we got this one which doesn´t flex but it would need two times more power I guess since the longest die is roughly 8 linear meters of cutting are. And the double power would mean that the press would bent because it´s calculated just for 40 tons of pressure, just a perfect situation...

Edited March 19, 2020 by Phlin

[Matt S]

@PhilN, have you tried casing/damping the leather before clicking? It would theoretically reduce the pressure required but I've never tried it. Alternatively, have you tried taking multiple "bites"? For instance if you can put the die-leather-board sandwich only halfway into the press and take a hit, in theory the press will only "see" 4 linear metres, you will double the knife pressure, and might go to full depth. Then without removing the die from the leather raise the press and put the whole die under the press and take another hit. Again you'll only be putting 4 linear metres into effect.

Depth limitation is probably something you want to look at once you've got it cutting to full depth, or you'll easily destroy your cutting board and maybe clicking dies if you press them all the way through the board.

[Northmount]

Possibly your cutting surface is not perfectly flat as well.  How do you keep your jacks in sync so they come down evenly and parallel to the cutting surface?  You make have to release and cut multiple times to make up for the added tonnage needed.

Tom

 

[MikeRock]

Try leading one side down first, by a 1/16" or so.  That way the cutting pressure is spread out.  Then bring the other end down to the same depth.  As said, casing might help. 

[Dufresne]

Try cutting two layers. Perhaps some light card board on the underside. I had new dies made a year or so ago. Had the same problem. I finally figured out the more layers I cut the cleaner the cut was. 

[RockyAussie]

Break them knives down to single or at most doubles. It will work out quicker in the end and allow less wastage. The long strap knives have VERY little chance of working as the leather has no where to move between the straps except inward which means your trying to get around 5mm per strip to condense out of the way. The knives can cut better if you give them a polish with a rag wheel and tripoli polishing compound but that won't work with this set up either. Just for your information, a proper clicker press can normally cut to cut at about 30 seconds a change and gang knifing can save a little but the right gear will save a lot more.

[Dufresne]

Might I ask where there is a good die maker in Canada.? I’ve always used  a company in Ontario but last time was not so great. I had a glove palm made and the finger tips were no where near round. They made a second at no charge and it was worse. 

[shoepatcher]

Die Max in Quebec is an excellent  die manufacturer.  Does a lot of work for the hockey companies!!

glenn

[Hasbeencowboy]

I have a 12 ton press that I made with 12" x 12" cutting area.  I have a few dies I use that are 14" to 36" long.  I make several passes with the longer dies.  It works great for the things I make