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Repairs to a Bandsaw

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Meldonmech:
Hi Guys
             When using my Bandsaw recently I heard a horrible sound from beneath the work table, and immediately stopped the machine. On investigation I discovered the lower blade  guide die casting had broken. The design was flimsy in the area where most of the downward blade forces were acting. I glued a piece of wood to the area that  needed thickening up, then glued the casting back together.

Meldonmech:
 
    For some time now I have wanted to attempt lost wax casting, and thought this would be the ideal opportunity. I made a wooden pattern, and added a runner/riser.
 I purchased some rubber moulding medium, and made an adjustable mould box from four pieces of " L" shaped wood I had nailed and glued together. These were held together with finger clamps. The pattern was placed in the mould box, the rubber was melted and carefully poured into the mould box. When set the mould box was removed.

Meldonmech:
 The rubber mould was then carefully cut open and the pattern removed. Casting wax was then slowly melted, while the mould was turned over to expose the pouring hole , then taped around the outsides to keep the mould closed. The mould box was replaced around the rubber mould to give added support. The melted wax was then poured into the mould and allowed to cool.

Meldonmech:
 
The wax replicated pattern was removed from the mould when cooled and smoothed off using a hot knife. The wooden mould box was reassembled, and the wax pattern placed in the box.  Casting plaster was mixed to a thick cream and was the poured to fill the mould and allowed to cure.

                                                       Cheers  David

Meldonmech:
 When the plaster had set, the mould was turned upside down and placed in the oven over a small bowl. The mould was heated until all the wax was removed. Then the mould was cooked at 220 c. for an hour to remove any moisture left in the mould.
       Aluminium was melted in the furnace and poured into the plaster mould until filled. A large bubble of aluminium rose from the mould, and then burst.  I realized I had a problem, and suspected a steam bubble.
       On cooling the mould was broken open and the casting removed. Luckily I had left a generous machining allowance on the pattern and thought I might be able to use the casting.

                                     Cheers  David

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