Celma PRCb - retro drill from electro-junk - simple repair and teardown - is it worth it?

I inherited the green two-speed Celma from my father and the older metal one, but both were lost in action somewhere ("good practice - don't borrow"). All I have left of the old ones is the AEG UEB 12/15 zweihandbohrmaschine, which is supposedly only 150W.... However, these watts are stronger than today's ones, and I am afraid to use it with drills of larger diameters, because if it gets blocked, it can be difficult for the operator. No one borrowed this because it's hard to find a use for it, probably only as an agitator, but you may also have concerns about insulation - the whole thing is metal including the switch housing, the internal design of which doesn't look very inviting either.

I also have one from my father. It's mounted in a stand and does stationary. I have it connected via a speed controller. The machine is not worn out (I only replaced the brushes and grease in the gearbox). Continuous work is not a problem for it. It's a bit of a pity that Celma doesn't still produce, because it used to make good equipment.

Hello.
Someone wrote that in the new ones the electronics supposedly keep an eye on the power and don't slash your wrists.
Rubbish.
Someone also wrote at the beginning that this customs had 680rpm and the modern ones 4000rpm
Here is the reason for its power. Gearbox.
I would also add that I use something strange myself for mega holes. But it works. Mortar mixer 2 speed adjustable and fur 16.
Maybe not precisely bale good grip and does the job.
At one time I even made holes for garden posts fi 2500mm with it.
Regards.

BBElektrotechnik wrote:

398216 Usunięty wrote:

It has and it goes with the power.

Do I know. That drill had a power output of 300-400W and it was breaking hands. Today's appliances have wattages that go into kilowatts. A 2.5kW cordless mitre saw? No problem. Cordless drills exceed a kilowatt. But they have safety features. All you have to do is turn the drill quickly yourself and it shuts down. Some still have overload clutches.

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But these are now mostly Chinese wattles. Just like the Chinese horsepower in cars and the Chinese mAh in 18650 rechargeable batteries.

strikexp wrote:

Today you can buy a thyristor speed controller on allegro for a few tens of zlotys. (...) And a universal softstarter on allegro costs less than 20zl.

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Do these softstarts and speed controllers work on the same principle as dimmable lighting only possible with ordinary incandescent or halogen bulbs? That is, behind the regulator, the voltage is a sine wave with clipped biases, making the rms value of the voltage lower? An incandescent light bulb will shine dimmer on such a thing, and discharge lamps and LEDs are not sure how they will work, as these are not designed to work with dimmers. I understand that an asynchronous motor on such a truncated sine wave works correctly.

andrzejlisek wrote:

Do these soft starters and speed controllers operate on an identical principle to dimmable lighting only possible with ordinary incandescent or halogen bulbs? That is, behind the regulator, the voltage is a sine wave with clipped excursions, making the rms value of the voltage lower? An incandescent bulb will shine darker on such a thing, and discharge lamps and LEDs are not sure how they will work, because these are not designed to work with dimmers.

Yes.

andrzejlisek wrote:

I understand that an asynchronous motor on such a truncated sine wave works correctly.

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Not.

I'm the one who doesn't seem to understand something.

For the sake of clarity, here is a drawing I found on the internet of the voltage waveform that is on the bulb and the motor when a dimmer or regulator is used https://en.wikipedia.org/wiki/File:Regulated_rectifier.gif If the output of a speed controller is just such a truncated sine wave as shown in this drawing, and the device is used to power a variable speed motor, which motors is such a controller suitable for?

Unless I am mistaken, there are only two types of AC motor:
1. synchronous - its speed depends only on the frequency of voltage variation, such a motor will not start on its own, an auxiliary motor is used for starting or an inverter that smoothly changes the frequency of voltage variation.
Asynchronous - its speed depends on the supply voltage and the load.
I omit stepper motors because its power supply, control and application is a completely separate topic.

I conclude from the above that there is an asynchronous motor in every AC drill.

Asynchronous motors are in these large (stationary) drills - in industrial drills they are usually three-phase. Commutator motors are used in hand-held electric drills (i.e. portable hand-held drills), as the latter are much lighter and smaller for the same power than synchronous or asynchronous motors.

Zbigniew Rusek wrote:

(commutator motors are high speed

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Series motors rather. Commutator motors which are currently used in screwdrivers use commutator motors with permanent magnets. The speed of such a motor does not depend on the existence of the commutator itself, but on its design - the number of rotor windings. In the case of a series motor (also a commutator motor), a lack of load may result in the motor "coasting" to such a high speed that the rotor windings may break down or the bearings may be damaged. It is true that in the case of series motors in drills, the load (sufficient to prevent the motor from coasting) is already introduced by the gearbox, but I would not advise switching on such a motor (especially a high-powered one) removed from a drill or other device without a load on the shaft. The drill motor is unlikely to run out even then, but its speed will certainly increase significantly.

Added after 11 [minutes]: .

Zbigniew Rusek wrote:

(commutator motors are high speed

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Series motors rather. Commutator motors which are currently used in screwdrivers use commutator motors with permanent magnets. The speed of such a motor does not depend on the existence of the commutator itself, but on its design - the number of rotor windings. In the case of a series motor (also a commutator motor), a lack of load may result in the motor "coasting" to such a high speed that the rotor windings may break down or the bearings may be damaged. It is true that in the case of series motors in drills, the load (sufficient to prevent the motor from coasting) is already introduced by the gearbox, but I would not advise switching on such a motor (especially a high-powered one) removed from a drill or other device without a load on the shaft. The drill motor is unlikely to run even then, but its speed will certainly increase significantly.

Zbigniew Rusek wrote:

Asynchronous motors are in these large (stationary) drills

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Here it would also be appropriate to specify what kind of motor we are talking about - an asynchronous motor is, after all, a squirrel-cage motor - with short-circuited rotor windings, and it is a type of asynchronous motor which can be found both in a gramophone (e.g. the Bambino, as well as in table drills, but in the larger ones - stationary ones, because such a motor, compared to a series motor, has a much greater mass for the same power), but also in, for example, industrial fans with a power output of several tens of kW. An asynchronous motor is basically any DC voltage motor - in such motors, there can be no talk of synchronisation with the mains frequency, because there is no frequency in the mains supplying the motor. It is not even possible to talk about the dependence of the voltage on the number of revolutions, as this also depends on the load on the shaft.

I know that I am simplifying and perhaps (certainly for professionals) confusing this, but let's remember that the forum is read also by young people who do not know all these dependencies, therefore if someone can systematise all types of motors in a kind of table taking into account the supply voltage, mechanical construction and all other performances and dependencies, they have a chance to prove themselves.

@p.kaczmarek2 beautiful monument you saved admittedly there are better ones now, but always what monument is a monument.
Not one of us in the 1980s dreamed of such a technical wonder.
There are a few of these drills at every major flea market.

I also have a metal one, it works, the fur is a bit rusty, but I rarely use it.
The push-button speed control and overload clutch is nice though. As is the lighter weight.
With that said, I rarely drill large holes in thick steel.