Re: Smithy Granite

--- In CAD_CAM_EDM_DRO@y..., "Chris Clough" <cclough@x> wrote:

> I need something like 6x12x2 inches of cutting area. The tolerance
> claimed on this machine is .0005, which I think is quite good.
>

Easy to do with a good operator and manually. However .0005 will be
difficult to CNC without ball screws or a very tight antibacklash nut
on an axe-me thread(which wears them out). My guess is that you need
about .015-.03 tolerance on your detail features, probably .06 on the
contours. The bolt holes need to be big enough for clearance, drilled
finish should be just fine. I would expect the flange face to
require machining for fit to gasket and weird angles. Fixturing may
end up as more critical than the milling.

Are you going to weld up an assy, or machine complete?

> In all reality, I don't even need a plasma CNC as I could free hand
> something close to a quarter inch off - I mean if looked at that

way, I

> could do the majority of things by hand and then put that rough

piece on

> the mill and clean it up and get it where I need it - is this an

idea?

>

Probably as good as anything. The CNC plasma will save you a lot of
hooded, hand work though if you have to make several pieces that are
the same or similar.

Snag grinders can make plasma cut edges look pretty nice too.

> I'm thinking the same... or think of this - what if I made a jig

that

> would hold the plasma torch onto the chuck of the mill, turn the

mill

> motor off, and use the plasma to cut roughly with it, and then take

that

> jig off, and put a nice cutting pit with coolant running to finish

it up

> - I just thought of that

Whatever you do, don't turn that plasma unit on within 6 feet of your
mill or lathe. The only thing worse is mounting a grinding wheel in
a lathe. ByeBye precision scraped and flaked ways.

Put the manual jig on a metal plasma cutting grate outside your shop,
or under a serious CFM fume hood if inside.

Best Regards,

Fred Smith
IMService