Why can nobody do the CNC job I need?

[Robin Hewitt]

We live in a world of injection moulded plastic, curved surfaces are commonplace and it is easy to start thinking they are easy.

CNC mills do curved surfaces as facets or use custom cutters which will cut one set curve.

There are 2 approaches for this, cut it in 2.5D with a ballnose, cut it in 3D with a flatnose.

The ballnose cuts a round bottom groove so the facets have to be smaller and there is a lot more cutting to do.

The flatnose requires one hell of a machine, an uncommon beastie.

Polycarbonate? Are you hoping these will cut shiny and see through? :heehee:

[Harry]

Hmm, I'm pretty stuck then if it's going to cost £60 to produce 1 fin!
I just don't know what the best way to go about producing these is. If CNC won't work, I cannot afford the 9k to start injection molding! Any other methods, please help!

[Robin Hewitt]

If CNC won't work, I cannot afford the 9k to start injection molding! Any other methods, please help!

It's a very simple two cavity mould, if you had CNC you could make your own. Set aside a few days to polish it though.

Mould components are fairly cheap. Follow this link and see if you feel way out of your depth...

http://www.dms-diemould.co.uk/

[birchy]

Taking a different view, have you considered contacting some of the Chinese manufacturers/injection moulding factories? For a regular order, I imagine they'd foot the costs of setup or at least meet you half way...

[Robin Hewitt]

Last time I had a mould made in Taiwan it was for a little rubber keypad. IIRC the mould was £4k, the keypads were 7p each/5k pcs, which included the contact pills and legend print.

Over here they would skin you for the mould, then skin you again when they squirted it.

Over there they only skin you once :naughty:

[HankMcSpank]

Last time I had a mould made in Taiwan it was for a little rubber keypad. IIRC the mould was £4k, the keypads were 7p each/5k pcs, which included the contact pills and legend print.

Over here they would skin you for the mould, then skin you again when they squirted it.

Over there they only skin you once :naughty:

Forget cockle picking in Morecambe bay...if I was a Chinese "Mr Big", I'd smuggle in a few guys who can whack out an injection mould in short order here in the UK ....."back of the net"!

Seriously, if this Govt want to really want a "march of the makers"...then they'd better sort out a way that "the makers" can get small plasticy bits made without having to donate a kidney.

[M250cnc]

There are 2 approaches for this, cut it in 2.5D with a ballnose, cut it in 3D with a flatnose.

3D can also be cut with a Ballnose or a Bullnose but i agree a lot of time will go into cutting.

A simple mold could be made "High Precision Of Course" where a casting resin could be added, then the mold is sealed then the mold is rotated until all the inner surfaces are covered and the resin hardens.

A similar principal is used to make Easter Eggs among other things.

Phil