Need a new SDS drill

[Doctor Drivel]

Chris, you have it right.

[Dave Plowman (News)]

You've not been awake?

[Dave Plowman (News)]

It doesn't take too much imagination to realise a very inefficient device (drill, etc) which is using more of its input energy to produce heat rather than useful work is likely to burn out rather sooner?

[Chris Bacon]

That doesn't stand scrutiny, either. First, however, what about the figures above? Which is most "efficient"? Here's a list of the impact energy given by various the 900W drills:

3.5J 3.8J 4J (my Aldi cheapo) 8.5J 10J

Which is most "efficient"?

Which one cost the best part of £600??

[Mark]

Only two people perpetuate this,enter them in your killfile. Signal to noise then becomes acceptable.

-

[Doctor Drivel]

I agree. Put them in your killfile.

[Rob Morley]

How many impacts a second?

[Chris Bacon]

Now, now, pipe down at the back there. Mr. Plowman has boobed in a major fashion, and I'm enjoying the suspense!

Please don't come up with any arguments about why an "inefficient device (drill, etc) which is using more of its input energy to produce heat rather than useful work is likely to burn out rather sooner?", or I'll send you off to Dr. Drivel's office for a good talking to. Hang on - cruelty has been banned, these days. Sorry!

(BTW, which one cost the best part of £600?)

I'm off to the workshop to get my drill & see what it weighs and what it's bumps per minute are.

[Doctor Drivel]

That is normal.

[Chris Bacon]

Well, I've put my Aldi cheapo on the bathroom scales, and it weight a fraction short of 5 Kg. This hasn't caused me problems so far as I don't do lots of over head drilling with it, e.g. into concrete floors (none, actually!). It's OK for short periods above head height. On the side is a label mentioning the (UK freephone) service hotline. It's 850W, not 900 as I incorrectly remembered. No load speed 800 RPM, 3150 BPM, steel/13mm, concrete/26mm, "wood" 30mm, brick/core drill 90mm. The bumf says 4.2J. It came with grease, non-SDS chuck adaptor with a chuck key, 1 chisel, 1 pointed breaker, 1

22mmx200 bit, 16/12/10mm x 100 bits, a peg spanner to undo the gearbox grease plug, and a 300mm long bit of round spring steel with a crank in one end that might be a depth stop, or something, and a round rubber bellows thing (additional to the dust cover at the bit end), and a spare pair of brushes. If it came with anything else, those bit are now MIA. It's done lots of work, now this desk is a bit oily and has some masonry dust on it. I've now an absurd urge to drill a hole in something.

[Dave Plowman (News)]

Really?

Excess heat kills just about any electronic or electrical device ever made.

Don't you know nufifink? ;-)

[John Rumm]

All other things being equal then yes. If however you were comparing a

600W blue Bosch against a £25 900W power drivel, you can be pretty certain the Bosch will have more power at the output side.

[Doctor Drivel]

Do you any figures to prove this or are you making all this up?

[John Rumm]

I have results from an empirical test I carried out about two weeks ago in fact:

A neighbour gave me a variable speed NuTool hammer drill (he had plenty of drills, and got this one free one when he bought some other tool). So I thought it would be interesting to experiment with it a little, and also compare it against my old green Bosch, which on the plate at least, has 200W less power.

The results were interesting but not supprising. The NuTool demonstrated significantly less torque - especially at slow rotation speeds. In fact I could keep the chuck stalled simply holding it by hand until at least three quarters of full trigger pull was added. Attempting this with the Bosch broke free of my grip with only about a quarter of maximum trigger pull.

30 seconds of medium speed drilling under high torque (typical if using a mixing paddle for example) resulted in copious production of smoke from the NuTool, after which it was running very roughly with intermittet speed and loads of sparking from the commutator. At this point I took it appart to see what was going on, and found that the bushings that guide the carbon brushes were so poorly made, that they were in fact preventing the brush springs from keeping the brush in contact with the commutator. A bit of work with a file to get free movement of the brushes restored "normal" operation again.

From the outside the NuTool felt ok but a little front heavy. The design of the air venting was not so good (your hand when placed in the place that feels right on the grip tended to obscure the air vents. This restricted the air flow to the drill a bit). The chuck was actually not bad, although it had a fair bit of eccentricity when measured with a DTI, although probably not enough to make much differnce on bits up to

200mm long.

So all in all in spite of the NuTool being a 580W variable speed drill it usability was very limited. Torque wise it was trounced by the Bosch or even my 12 year old 9.6V NiCd drill. However drilling at max speed was ok, as was hammer. Without doubt attempting to do much screw driving with it would result in its very swift destruction. The gearbox such as it was consisted of a brass output sprocket on the motor, but all the rest of the cogs were nylon. Most of them sat in greased recesses in the plastic case - where there were any bearings they were simple sleeve bearings.

So in summary if you subscribe to the idea that DIY is all about drilling half a dozen holes for some rawl plugs three times a year then this drill would seem quite good. If you persisted in using it to drive the screws however, then it would probably melt.

[Doctor Drivel]

Where all these tests done in a controlled, monitored, logged and scientific manner? What test equipment was used?

[David]

In article , Doctor Drivel writes

Yes I'm sure they were, in the same way that you have measured the effectiveness of your electronic descaler

[Doctor Drivel]

demonstrated

They were? Can you elaborate please?

[Chris Bacon]

Oi! David! Here are some scissors to snip with:

8< 8< 8< 8< 8< 8< 8< 8<

[Chris Bacon]

Here are some scissors for you, too: 8< 8< 8< 8< 8< 8<

[Doctor Drivel]