Re: [CAD_CAM_EDM_DRO] 7 square holes -square drills

>
> There was an article I just read in a trade mag talking about some of
> the advantages offered by modern controls, both presently realized and
> being developed. One was machining square holes with a triangular tool,
> interpolating the required oscillations....
> I understand the theory, helped by the illustrations. But I have to
> wonder about the horrendous negative rake incurred when the tool is
> coming out of the corner. Neutral rake isn't achieved until the cutting
> edge is halfway along a side.
>
> Jon

yep this is the same as the polygon drilling attachment but done in the CNC
control instead of a hardware attachment

the polygon drills have a cross section more like a three flute reamer or
end mill with strait flutes so there is 'some' positive rake at the edge
and they can have more than 3 teeth ,a 5 tooth cutter would drill a hex
you always get one more side than the #teeth

if youve ever had a drill chatter at the start of the hole and stoped
you wound up with a three lobed dimple from a 2flute drill bit
the polygon attachment just does it deliberatly and with control

Brian