Here is a 20 Ton Jack update, it has been 20 months since I first posted the master parts for these jacks and I am now finally at a stage that I can finish them. Over the last 2 months I have been able to fix the gearing problem I was having for the functional jacks which is explained below. Jack should start shipping by the end of the month.
On top of working on the jacks I have also been working on parts to complete orders. See separate post on orders update.
After many hours of trying to make the gearing on the functional jacks work I found I had two problems. The first was the jack bodies did mot match and the gear axle holes did not line up when the bodies were fitted together. The second error was that the large gear was oval shaped and caused the gears to jam. These two error were the result in mold expansion when the parts were cast. This is not normally a problem with casting from vulcanized molds as the rubber is very firm. However as the jack masters were made of a material that cannot be vulcanized I had to make the molds with a cold pour rubber which is very flexible and allowed the mold to expand when the hot metal was poured causing the part to misshape. To rectify this I had to put a wood jig around the mold, see pictures below. This resulted in all jack bodies and gears already cast had to be melted down and recast, around 30 sets.
Here are the new parts that were recast, these bodies have all been drilled and tapped for assembly and each one is held by two screws to keep the parts together until final assembly.
Jack body parts, parts for assembly have been cleaned.
Jack mounting brackets, parts for assembly have been cleaned and all holes drilled.
Jack small parts, parts for assembly have been cleaned.
Picture of original and new body castings, the short casting now lines up the gear axle holes and ends of body.
The original body casting that did not line up.
Pictures of the original and new large gear.
Jack gear mold.
Jack body mold.
The original jack body had casting bubbles at one end, when recasting to parts I figured out a way to stop these bubbles forming, how I did is a secret, don't want to give the re-casters the heads up on this.
Regards
Mike
