Duncans Metal Pages
Casting #3
Last updated: 30 Nov 2016

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Casting #3 - A vertical bracket for my rotary table.  This page shows the casting detail, the project itself can be viewed here.

27-Dec-2002: There were some 19mm thick scraps of spruce plank lying around which were recycled into the pattern shown here, so it will be a fraction thinner than the 20mm shown in the drawing above.

All the necessary draft has been sanded in.

I couldn't find any car body filler (it must have been thrown out in the last tidy up), so the fillets have been slicked with ceramic tile grout.  This may prove to be a mistake. 
31-Dec-2002: The filler cracked up all over the place, and had to be dug out with a chisel.

The fillets have now been blinded with P38, sprayed with primer/filler and lacquered.

02-Jan-2003: The picture on the left shows a false cope, which is the ideal way to cast something this shape.
The drag has been rammed and separated.  The cope will now be shaken out and refilled.
The casting after shaking out, shown upside down from how it was cast.
 

There are a few problems with the casting (but it will probably get used anyway).

  • Sand not riddled fine enough over the sides.
  • The drag experienced a drop out, hence the crack you can see.
  • Riser in the wrong place, there is a shrink cavity of around 2.5mm (0.1") on the other side, but this will probably machine out OK.  Putting it at the apex would have been a better idea.

I used de-gas tablets for the first time which should result in less pin holes, and I'm getting a better feel for the constituents of the sand in terms of clay and water.  Here's hoping casting #4 will turn out better.

Click here for casting #4

These pages are maintained by Duncan Munro.  All content on this site is Copyright ©2002-2017 Duncan Amplification.
Warning: These pages consist of images and descriptions of equipment which can reach high temperatures creating hazardous and potentially dangerous situations.  These pages should not be taken as a step by step guide on how to construct any items or carry out any particular procedure, nor should any references to safety contained herein be taken to guarantee safety in all situations.