Is there some reason why a rotary tool spins so that dust/shavings
are sprayed back towards a right-handed user?
Or maybe I'm using it wrong? Seems that either I need to use the
cutting tool with my left hand or to put the project on the right
side of my right hand.
Maybe because 90% of humans are right handed (dexterous) and most of the
remainder are left handed (sinister).
Somewhere there's probably a reason why drills and threads are mainly
right handed, my WAG is that came about because it's usually easier to
apply a clockwise twisting force with your right hand than it is to
apply a counterclockwise one (at least for me it is.) *
So, if most drill bits have to rotate clockwise viewed from their tail
ends, it makes sense to make the Dremel spin that way.
I've never seen a reversable Dremel, but it wouldn't take rocket science
to add a DPDT switch reversing switch in the two motor brush leads so it
spins either way.
Rigged like that you could spin cutting disks, diamond burrs and stones
the "other way", but if it's toothed burrs you're using, they gotta go
* So how come screw top containers don't use left hand threads? It's
usually harder to open them than to close them, and I'm pretty sure
being right handed that I could twist 'em clockwise harder than
counterclockwise. The only left handed opening threaded cap I've
encountered is the one on the storage can for my Curta Calculator, and
I'm pretty sure that was done deliberately to prevent inadvertently
turning the crank clockwise when closing it. [Or maybe some diemaker in
Lichenstein screwed up and they didn't realize it until they'd made
10,000 cans. :) ]
I can grip something harder palm down then palm up:
1. Grab lid w/right hand palm down
2. Grab jar base w/left hand palm up. (easier grab,
since there's more to grab.
3. Hold it about a foot from the chest
4. Grip and draw it into your chest. *pop*
That keeps the wrist stiff.
Small world I have a pair of them myself, a Type 1 and a Type 2. Really
loved the look on a guys face a couple of years ago when I told him I
use the Type 2 to check the math on my taxes. Told him I just didn't
trust the computer. Almost put them on ebay but thought about it and
decided that since they don't make them any more I might want to keep
it. They are a marvel of engineering, I'd love to own one of the cutaway
demo units that show all the parts in motion when you crank them, but
until I strike gold or oil that isn't going to happen.
Yeah, I still have my Type 1, but I sold the (larger) Type 2 when we
sort of got tired of sports car rallying some years ago.
I may well have built the world's first motor driven Curta. And if
memory serves me I built a copy of it for some fat cat in Connecticut
who just HAD to have one too. Those days were prior to the ubiquitous
solid state portable calcuator takeover.
Circa 1961 I built a DC motor driven worm gear reduced "cranking box"
for the Curta which coupled to its operating shaft through a hole bored
in the Curta's bottom plate. A one direction roller clutch in the drive
allowed also using the Curta's crank in it's usual fashion without
having to take it off the cranker box. I still have that rig kicking
around somewhere in my basement.
We used it for rallying. I coupled a geared down microswitch to the
car's odometer cable so it closed once every hundredth of a mile of
travel and triggered the motor drive into cranking one turn of the
Curta's shaft. A little relay, microswitch and transistor in the drive
unit insured it would only make one turn each time the odometer switch
closed. It had to wait for the odometer switch to open and close again
to trigger another turn.
Setting a "minutes per mile" factor for the average speed of the rally
leg we were on into the Curta made the Curta's "product" output number
tell me how much time it "should" have taken to get to that point on the
road. Comparing that number with a stopwatch let me know whether to tell
SWMBO (Who was the quite aggresive driver of our team.) whether to speed
up or slow down.
I've often thought that if some folks put as much time and energy into
their "real" jobs as they do for thier "hobby" ones, they'd be captains
of industry before they were 30. <G>
I kept some photos of those halcion days. Forgive me if I've posted this
link here before, but the years are taking their toll on my short term
Thanks for the mammaries...
I think it's because the Dremel uses tools originally developed for
stationary machines. And the reason the chips fly at you is because
you are using the wrong side of the cutter. What you should do is hold
the part in your left hand, but have it inverted so that the cutting
action takes place on the bottom of the part and the chips fly away
Wow, Eric. You must have some of them Superman genes that gives you X-ray
vision that lets you to see through the part to gauge how much you are
cutting off. Nope, I have it wrong. You are right after all. The idea is
to hold the work over your head, Then the chips fly away from you and you
can see the cut as it progresses. Maybe one should stand on their head???
The reason for the rotation direction as said elsewhere, is that not
only drills, but burrs, reamers and other cutting tools are designed for
that direction. Futhermore, arbors for cut-off discs, grinding stones,
abrasive discs, etc. would all come undone with counter-clockwise rotation.
So it's not just the motor, but much of the tooling that has to be made
The direction choice probably originated with ancient lathes. You
use the right hand to control the tool and turn the lathe with the left
hand, pulling the wheel toward's you. The idea is that the work should
force the tool against the ways rather than turning away from you and
thereby forcing the tool away from the ways and greatly increasing the
likelyhood of chatter. Now once you have the lathe set up that way, with
the headstock on the left, you could still opt to make right-hand or
left-hand threads (as do the Germans). With a right-hand thread, the work
is pushed into the chuck (towards the headstock). With a left-hand thread,
the work is pulled out of the chuck. So the right-hand thread is
inherently a safer and more rigid set up. Once you have a dominance of
right-hand threads on things, the clockwise rotation is set.
This may be yet another just-so story, but it makes sense to me.
As for the "dust in your face" problem. I've got three flex shaft
machines. I've been using them for years. I've never had a problem with
dust in my face from the rotation direction. On those very rare occassions
where it was potentially problematic, I've used my face shield. Perhaps
the poster's problem is not with his tool, but with his glasses. Your nose
just shouldn't be that close to the work.
Boris Beizer Ph.D. Seminars and Consulting
We do a lot of work with die-grinders at work. We frequently don't get to
choose how we hold the grinders because space within the dies is very
limited. I'd recommend changing the way you hold the grinder or setup the
work. It seems like a pain, but with a bit of practice, you can get very
proficient in virtually any position.
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