Low Cost DC Welding Using Car Dynamos: Jeph 5

Low Cost DC Welding Using Car Dynamos: Jeph 5

Low Cost DC Welding Using Car Dynamos By Peter Hanbury

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This manual gives full details of how to use car dynamos for DC electric welding. Car dynamos will give considerably more voltage and current than their rated output for limited periods of time. Since most welding is of an intermittent nature, and probably no more than 25% of the time is actually spent welding, the dynamo limitation is no disadvantage.

The current and voltage rating of a dynamo is for continuous use, and they will, in fact, give from 11/2 – 2 times this current when used for welding with an open-circuit voltage of 60 volts.

DC welding has the advantage over AC welding in that it is particularly good for welding thin guage mild steel sheeting. This makes it ideal for car body repairs and other light welding.

The dynamo requires an engine to drive it, and three designs are suggested:-

(1) A portable petrol welding generator can be built similar to the
one shown on the cover. Welding generators normally cost
hundreds of pounds, but the one shown was built using
second-hand parts in a weekend for less than £25. It is capable
of giving up to 70 amps and larger or smaller generators could
be built to this design.

(2) The dynamo can be permanently installed in a vehicle above
the existing dynamo/alternator, and driven by a second fan
belt from a double engine pulley.

(3) If the car already has a dynamo fitted, the existing wiring can
be disconnected, and it can be temporarily rewired for welding.
This is suitable for light welding only using 16 swg electrodes.

Copyright Peter Hanbury

CAR DYNAMOS
The best dynamos for welding which can be obtained for a reasonable price are heavy-duty car dynamos, e.g’s Lucas C42, C45, & C48 types. These can be purchased from scrap yards. Most scrap yards have them even though the proprietor may not recognize what they are. Ask to be allowed to sort through their pile of dynamos, they look approximately 50% larger than standard dynamos. The type and date of manufacture are stamped on the case. (take a wire brush to clean the case).

A heavy-duty dynamo, when driven by a suitable engine, will generate up to 70 amps and has an open-circuit voltage of approximately 60 volts. This will run 16 & 14 swg electrodes easily, and is ideal for car body repairs and other light welding.

If greater current is required two dynamos can be driven together and over 100 amps is then available which is ample for 12 swg electrodes. Brazing can be done either by direct heating with a carbon rod, or indirectly with a carbon arc torch.

Almost any dynamo will weld to a greater or lesser degree, and two small dynamos of similar type can always be used in place of one large one. The table below is a useful guide to welding performance:-

• ASIN ‏ : ‎ B083G6T1R4
• Publisher ‏ : ‎ Atlantean Arts (January 2, 2020)
• Publication date ‏ : ‎ January 2, 2020
• Language ‏ : ‎ English