Re: Vinyl cutting knife in place of router

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Ross" <rrcarl@n...> wrote:

> Tom...
>
> Will a drag knife cut nice square corners. Just picturing the

geometry in my head, it seems like the drag knife would need forward
movement around a corner, which means that the corner would have to
be a radius and not perfectly square. Im I missing something?

>
> I'd also be interested in a source for the cutting head. It would

be neat to be able to cut vinyl should the need arise. I know how a
real vinyl cutter (rotating head) works and I would never try to
match that on my table, but if I ever need to do it, it beats a trip
to the sign shop. :)

>
> Ross

The vinyl cutters don't try to cut square corners. On 90 deg stuff
they pickup the knife and start a new line at 90 deg. I know the
head on my vinyl cutter goes up and down a LOT. One of the reasons
that most of the machines need special drivers is to be able to
control some of the things you have to like force and square corners.
My cutter has a feature called "Tangential Emulation Mode: gives
square, sharp corners in thick material".

I have cut 35mil sandblast rubber material on my vinyl cutter. I
don't know how thick photo mat is but I think the limiting factor
would be the blade cutting area (how deep you can cut with the 45 or
60 deg blades) and the amount of downforce you can apply. It will cut
stencil material (waxed cardboard).

Cutting limp material like vinyl might prove to be a challenge
without a vacuum holddown. The slightest wrinkle and it will start
to peal adjacent cuts. The challenge of cutting sign vinyl (2 to 4
mil thick) is that you have to cut completely through the vinyl layer
but NOT through the backing. Some of the guys have reported cutting
vinyl on flatbed CNC machines. If possible, I suspect the process
will be much slower than on a vinyl cutter (mine will do 48 IPS) and
the head pops up and down so fast you almost can't see it. I run it
at a more sane 10 IPS but that's still 600IPM.

I looked at building my own machine but for less than 2 grand I got a
new 24" machine with sign making software and a warranty that was
twice as fast as anything I could build in a flatbed design.

I can see where a matte cutter could be a money making machine around
a frame shop. Being able to do the complex multi-level mattes and
interesting shapes would be a snap in software.