Re: [CAD_CAM_EDM_DRO] Denford Orac CNC

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.

> Hello John,
> I will answer just to this because of the rest I have no clue:
>
> johnhe-uk wrote:
> >
> > . I went for a poodle down to the boat building area of Merseyside and

sourced some heavy U shaped channelling for the bed support rarther than
cast it like it's suggested. I took the chunk into school ...

> We had a really good talk for a while and he told me he'd put it on a
> surface grinder etc. for me,...
>
> Every piece of metal that you grind will bend because of built up
> stresses. And construction steel (better said iron) will turn into
> a Robin Hood bow. That is the reason why you normally use aged cast
> iron for suports of longer machines
> On tiny small and short machines you have no trouble with a
> ground U channel.
> But please allways check and match the contact faces with prussian blue
> and scrape or hand grind the peakes away until the machine sits flat
> befor bolting it down.
> Have fun and good luck.
> Sven Peter
>
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