Sunday, 27 July 2014

Die cutting with a 20 ton hydraulic garage press

Nick from CustomStuff asked a favour - she's made us plenty of playing/gaming cards for prototype projects like non-RFID poker cards in the past - so it's only fair we helped out.

Having got a rush order in, and having problems with her own cutting setup, we were asked to produce about a hundred playing card boxes, with little more than a pre-made die and some pre-printed patterned (and laminated) A3 card. What we needed was a way of squashing the die into the card with enough force to cut where it needed cutting, and to crease where it needed creasing.

Our answer was to put into use a piece of equipment we've had hanging around for a long time (in Paul's living room since last Xmas, when he used it to emboss some handmade leather gifts). It's a 20 ton hydraulic hand-operated garage press.

It took a few goes to get the process just right, but eventually we managed to get a good, clean cut on just about every one!

The process was to place a 1" thick steel plate (thanks to CNC Paul) on the press, then a sheet of mdf as a cutting mat (a regular cutting mat is just too soft, as we found from experience!) then the laminated card on top of the mdf, the die (cutting side down) on the card, then a second 1" thick steel plate on top.
Those steel plates are pretty darned heavy - each one weighs over 20kg - no mean feat to lift on and off the cutting surface, every single time!

With the steel sandwich in place, the press is lowered onto the top steel plate. A good few pumps and there was a slight - but noticeable - click, as the blade cut into the card. For the first few attempts, we stopped at this point, but found that some boxes didn't cut all the way through, all the way around. So in future cuts, we placed the die such that the cutting point of the bottle was off-centre, and pumped the handle almost until it wouldn't go any futher (without too much effort).

The result was a perfectly cut (and creased) box outline, every time.

After about 30 or so boxes, cutting performance fell slightly, with some corners of the box not cutting cleanly on every cut. This was fixed by replacing our mdf cutting mat. After cutting so many boxes, the mat started to fall apart in places.

A new piece of mdf, and cutting was as clean as the first time. After a few teething problems (and lifting a 20kg weight onto and off the press about a hundred times) we ended up with a stack of playing card boxes, each cut exactly, and each with crease lines in all the right places. It's nowhere near as quick as using a clicker press, and a lot more cumbersome, but we got through them all in just a few hours (maybe a bit more, including stopping for a brew and a chat in between every 10 sheets or so).

It was quite satisfying, not only to be able to return a favour, but to get such a successful result from something so crude and unlikely to work!