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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details.

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Old 7th Jul 2021, 6:56 pm   #21
greenstar
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Default Re: Wolf Electric Tools Ltd

PMM, thanks, so why did these early electric hand drills run at far slower speeds than the power drills made now? As I understand slow speeds have the advantage of not heating the drill bits so much. Are modern drill bits able to withstand higher temperatures? Why were these drills slow? Because it was difficult to make faster motors? Is there more torque at slower speeds, ie, the drill is less likely to jam and burn out?
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Old 7th Jul 2021, 7:16 pm   #22
mark_in_manc
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Default Re: Wolf Electric Tools Ltd

For drilling steel, you want to go slow - for a 1/2" chuck, the motor of my big old 'van dorn' drill (which is a lot like some of the Wolf products shown here) is geared down to 400rpm, and even this is a bit quick. I have been playing around with a big old pillar drill and some of my ancient induction motors, and 180-ish rpm with a 3/4" bit is still a bit quick in steel. By contrast, if you are drilling wood you want to go much much faster, or it will tear. This is the origin of those once-ubiquitous 2-speed B&D drills (where you changed gear by folding that tab-thing around) - though here, the slow speed was still too quick for large holes in steel. Then came Velleman drill speed control kits, and then came first corded, and then battery, drills with trigger speed controls built in!

To address your question about motors more directly, the old drills have a reduction gearbox in the front - that's why they're slow. It means you get full power at low speed, which is great - although modern drill-drivers are also great for loads of torque at nearly zero speed, with only a 2-speed epicyclic 'box - I don't know how they do this without overdoing the 'i' in 'F=Bli' and burning up.
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