Re: [CAD_CAM_EDM_DRO] Re: Making a punch die?

Hi John,

Yes, I've got a couple of round punches that work that way - no problem in
aligning them but I thought it was worth while emphasising the potential
difficulty of aligning a DB25 punch and, more importantly, the need to
profile the face of the punch to relieve the cutting stress enough for the
screw to cope with.

Ian
--
Ian W. Wright
Sheffield UK
www.iw63.freeserve.co.uk

----- Original Message -----
From: <machines@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: 13 July 2001 11:04
Subject: [CAD_CAM_EDM_DRO] Re: Making a punch die?


> --- In CAD_CAM_EDM_DRO@y..., "Ian Wright" <Ian@i...> wrote:
> > Hi,
> >
> > Just a thought on this - how are you intending to hold the punch
> and die
> > while using them? Most of the simple 'chassis punches' use an allen
> screw
> > through a pre-drilled hole to pull the two parts together but this
> would not
> > be very convenient for a DB25 shaped punch because of alignment
> problems
> > between the two halves. I suppose there would be a chance if you
> used two
> > allen screws towards the ends of the die but would you be able to
> use strong
> > enough screws to withstand the forces needed to drag the whole
> length of the
> > side cuts through the aluminium. At the very least you would need
> to shape
> > the bottom of the punch so that the cut is progressive i.e. it
> starts at the
> > middle and finishes at the ends or vice versa.
>
> Ian,
> That's the correct way to do it.
> Your die is just a hole / slot in a piece of metal with a bottom
> secured to it. The punch is a mirror image but you grind the top face
> away from the centre, both sides at about 10 to 15 degrees.
> You then need three holes in the punch and die, one centre one that
> does the pulling and two small ones at each end to locate the set.
> You then need a drilling jig for the chassis or part you are doing.
> Idealy this should be the same jig that used to make the punch and
> die.
> To use drill the three holes using the jig then assemble the punch
> and die on either side locating with pins through the small holes
> then just tighten the centre screw.
> We used to regrind the simple bought round punches this way as it
> made things easier and less pressure was needed. I've put 2" holes
> through 1/16" thich steel sheet this way with no problem.
>
> John Stevenson
>
>
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