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Power Hammer from South Africa


Tom Nelson and Bertie Rietveld with their newly built mechanical hammer (Tom is on the left).

Tom and I have been exchanging ideas about hammer building since the question of the Junk Yard Hammer came up. The design is Tom's with just a few suggestions from me.

Bertie was one of the naysayers that said the EC-JYH shock absorber linkage wouldn't work!

Tom noted that the first blow was too hard then the machine settled down. I sugested that the spring was not stiff enough.

Tom,
We're running off a single vee belt and also fitted a band brake on the flywheel which is linked up to the foot pedal along with the belt jockey roller. Control is great. We can consistently deliver single blows, soft blows, and full force hard blows at full speed.

Drawing by Tom Nelson

Some technical details
Hammer mass -- 30kg (66 lb)
Anvil mass -- 200 kg (175*175*800mm solid bar) - clamped to column with a block of wood in between
Speed -- 180 /min
Motor -- 960 rpm 3hp (probably too big, but it was available)
Hammer slide -- 2 off 20mm square brass bars
Flywheel stroke -- 160 mm
Spring -- 4 leaves 5mm by 45mm -- 600 mm semicircle - precompressed 10%
Column - 4" by 6" m/steel - absolutely no sign of flexing
Copyright © 1998 by Jock Dempsey, DEMPSEY'S FORGE