What is it?
The chain connects the drill pipes (string) to the lever arm. The chain takes a repeated, large, jerky force and therefore must be strong and grip well. The chain must also be shortened or moved every 30cm or so as the drill pies (string) moves downwards. It must therefore be quickly and easily moved or shortened.

Used Ideas

The Original Practica Method

Consists of simply wrapping the chain around the lever arm and weight. Additional grip is given by nails to the lever arm and by thick wet sisal rope to the drill pipes. See page 13 of the practica manual. The chain is shortened using small 17mm bolts which often break.

Petro's hook

Replaces the 17mm bolts and is quicker to use when shortening the chain.

Your Ideas

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Subpages (1): Petro's hook