Re: [CAD_CAM_EDM_DRO] Denford Orac CNC

If I can't have the lathe from school I may, but this is more out of
interest as to how it's done.

John H.

> Hi John,
>
> If you insist on playing with this lump of steel there are a number of
> things that need to be done. The lump must first be normalised which
> involves putting it in a kiln and bring it to red heat, then letting it

cool

> over night as slowly as possible. the underside is then machined flat to
> avoid clamping it down and warping it. If you are going to remove 1mm of

the

> material from the top surface, remove .75mm with a fly-cutter or

face-mill.

> Then normalise it again and then surface grind the rest off. You should

end

> up with a flat, as near as it can be, surface. There should be no

machining,

> grinding marks left at this stage. The next process is to blue the surface
> and scrape to a good surface plate.
>
> Regards,
>
> Terry
>
>
> | I'd really like to have a go on a surface grinder. He mentioned milling

it

> | flat first and then grinding it. Is the surface grinder much more

accurate

> | than a good knee mill? The mill we have in school is a Bridgeport Series

I

> | Textron, I've not seen one of these before (Anyone have a link to some
> | pictures or details on them?). I can see how a surfer grinder could

create

> a
> | more parallel surface over a distance if it's travel is more accurate

but

> if
> | the grinding wheel is aluminium oxide does it create a grain effect on

the

> | surface it's ground? Is it smoother or rougher than a face milled

surface?

> | Also, about how long does it take to level off say a piece 50mm by 200mm
> | down by about 1mm?
> |
> | Thanks Sven,
> | John H.
>
>
>
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