"Pozidriv" [was Re: Tools (was: IBM 5155 analogue display fault]

[Tony Duell]

> 
> >>>>> "Joe" == Joe R <rigdonj at cfl.rr.com> writes:
> 
>  Joe> You mean $napOn!  Checkout the ads in NutsNVolts, you can buy a
>  Joe> whole set of interchangeable bits for about $5. That's a
>  Joe> fraction of what SnapOn or the TechTool suppliers will charge
>  Joe> you for a single bit.
> 
> Yes.  The difference is that stuff that cheap typically doesn't fit
> and doesn't stand up to use.

The two main reasons that I don't buy cheap tools...


> 
> I once bought a cheap drillbit set.  What I got was a box full of
> pieces of drillrod.  They pretty much all had a spiral groove cut in
> the sides, though often only just barely.  And there usually was at
> least a trace of a bevel at the tip.  Cutting edge?  Dream on...

One major problem I've found with cheap twist drills is that the 'point' 
is not quite central. This means they wobble slightly as they drill and 
make an oversize hole. This won't matter for the average home electric 
drill (which has more play in the bearings anyway), it certainly matters 
if you use them on a machine tool.

I once wasted a couple of hours because after making a part (a roller for 
an HP9100 card reader), I drilled the central hole with what I thought 
was a 1/8" drill and then found it was a very loose fit on the 1/8" 
(measured) motor spindle. Too loose to grip on the knurled part. I had to 
make the roller again and go and buy a good-quality 1/8" bit. No problem 
then.

I can't remmeber how much that tqist drill cost me, but it was a lot less 
than 2 hours of my time at any sane rate. 


-tony