Celma PRCb 13 Drill Revival - Rotor, Stator, Bearings, Rust Removal & WD40 Usage

Dear Gentlemen,

I have such a drill from my father, it broke several times, including the rotor, so when I found one on scrap metal and its cost was 2 bottles of hops drink, I bought it for parts.

I was positively surprised during the dissection. Long brushes, commutator in good condition, rotor wrapped in string (good old job?). The gearbox works, but approx. 1 liter of water came out when unscrewing. From the beginning I suspected the bearings because it was impossible to spin the rotor, and they were actually caught by rust

Currently, the engine is disassembled. During the demolition work, I used WD40 to unlock the bearings and to loosen the rotor from the stator, as well as when I was tapping the stator

Now the questions:

1) Should WD40 be washed off the stator and rotor? If so, what? And will this washing damage the rotor / stator insulation?

2) There is some rust on the stator and rotor - how to safely remove it and with what?

3) On the commutator and el. there are some brass (scale like limescale) or remove it, e.g. with a brass wire brush

4) Can I get the motor, before inserting it into the housing, it can be folded and connected to check if everything is ok. Inserting and removing the stator is quite laborious

They count on your knowledge and, at the same time, the popularity of the model, I think that with the help you can either bring the drill back to life or decide what is wrong and leave it for parts

Thank you in advance

You can wipe the rotor with gasoline, e.g. extraction gas or white spirit. Remove rust from iron parts with emery cloth so as not to touch the windings.
Wipe the commutator with fine sandpaper and blow it off. It is worth drying the rotor, e.g. let it lie on the radiator every few hours. The rotor, despite its nice appearance, may have invisible damage, which will become apparent only after starting. It is possible to check the rotor, but only in a specialized workshop. At home, only after putting it together and running it all you will know if everything is good.

Hello, the stator coils can be checked by a primitive but effective method. AC voltage +/- 50V is given through an ammeter to one of the stator coils, we look at the current flowing through it, and then we compare the results with the other coil. If the currents are about the same, the stator should be OK. When writing, I should mean the fact that not always a short circuit of one of the windings to ground appears on low voltage. For this purpose, it would be best to test it with an inductor megohmmeter, but your friend does not have one.

From the preliminary tests of the rotor, only what you can check for a short circuit, but it can be done by colleagues, gentlemen in the service of power tools.

I support the opinion that it is better to check the elements before assembly than to disassemble it later, especially since in PRCb you have to struggle a bit with the stator :)

I would suggest changing the bearings. It would be good to check the fastener, they like to be damaged often, in this type of "deck chairs".

Regards Kamil

Thanks for the hints

I cleaned the commutator with 320 paper and the rotor from rust. The bearings will be replaced anyway, but so far the old ones have been able to start working. I have a question about washing in gasoline - how does it look technically? Put the rotor in the bowl and wash it thoroughly with the brush. Do you have to do it differently? And can the stator also be washed?

From the stocks, I prepared a new switch (switch) - I checked it, it works.

On the electrode, I found how you can make a device for checking rotors from a washing machine pump and I will try to do it. I hope the rotor won't be too big.

I will try to check the stator according to methods with this voltage. Currently, I do not have the necessary equipment.

In the meantime, I have come to the conclusion that I have to buy new brushes because the old brushes, although not too worn, are too soft. Because on a working drill they sparkle and dirty the commutator. I have never used pumice stone on brushes what kind of pumice must be - natural or artificial and at what tension?

best regards

So wash yes, but do not soak. Gasolines have an insulating enamel dissolving component. No exaggeration with that pumice stone and similar things. The commutator has to be clean and that's it. And the brushes are not supposed to be hard at all, so why replace them? Urychom and evaluate the effects.

Welcome back,

It does not have to be a pumice stone, it can be an ordinary piece of sandpaper, suitably stiffened (I use this method successfully), grammage, probably 100 or 120. It is best to "lap" the commutator surface at full voltage, because when it flattens out on the lower one, later after switching still sparking at the rated point.

I recommend replacing the bearings, do not delay with it.

Could a friend send me a link on priv how to make a device for checking impellers from the washing machine pump? Thank you very much

One more thing came back to me. Regarding checking the stator windings for short to ground. I will explain it on priv because this method is a bit dangerous, but it works :)

best regards