On Thu, 14 Jul 2005 21:23:37 +0200, Philip Pemberton
<
philpem@...> wrote:
> Hi,
> Well, I'm getting rather sick of my Expo Reliant breaking drill bits.
> The
> chuck seems to be quite badly worn, and the bearings are utterly fried
> (not
> that they were any good to begin with. I'd hazard a guess that the drill
> bit
> really shouldn't look as if it's vibrating...
> Anyway, long story short, I'm after a new PCB drill. I've come up with
> a
> shortlist of three:
> 1) Dremel MultiPro. Saw it in B&Q for £35, looks like a nice drill.
> 15kRPM-33kRPM, two-speed (IIRC), mains powered. Couldn't find any
> suitable stands for it - with a bit of luck it might fit the stand
> I've
> already got.. with a little modification that is.
> 2) Expo (www.expotools.com) Zircon. £40 including transformer and
> accessory
> kit. Build quality looks a little suspect, but it will fit the stand
> I've already got.
> 3) Minicraft MB1012 "High Precision" (see www.shesto.co.uk). 18,000RPM.
> £38
> for the drill, plus another £55 for the speed controller, then
> another
> £39 for the stand. Hideously expensive for what it is IMO.
> What PCB drills are you guys using? Anyone got any recommendations?
> Later.
I'd put the proxxon IB-E on the shortlist.
It has good bearings, and more importantly good hardened precision ground
collets.
It doesn't take large sideloads well, esp. with long tools, because the
bearings are close together in the front and not at both ends of the motor
like in the cheaper tools. But for drilling this isn't an issue.
I think the precision of the chuck/collets might be more important than
the bearings, even cheap tools often have acceptable ball bearings at both
ends of the shaft and those could be replaced for better ones too. But if
the drill isn't exactly straight and centered the bearing runout doesn't
matter at all. The cheap grinders i have either have jacobs chucks, or
brass collets, that don't really center well. I've thought about buying
the collets only from proxxon to convert one of the cheap grinders to a
permanent PCB only drill, but haven't yet tried it (one would need to
grind the shaft of the drill to accept the more tapered collets from
proxxon correctly).
For a drill stand, i have very good results with a pivoting drill press,
bascally an arm with bearings at the back end and the drill at the front,
about 40cm long and with either a spring or a counterweight for balance.
Haven't broken a drill with it so far (ok i have broken some while in the
press, but not during proper operation, always operator fault.
You need to align the drill so it enters straight, then it is a very
reliable drilling concept.
It has practically no friction to move up and down, and you can really
feel it drill.
If you want to build one, ask for more details as there are a few tricks.
ST