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Old 07-15-2017, 08:08 PM
Peter Bowles Peter Bowles is offline
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I would urge you to find a way to vibrate the castable as it goes into the mold - it will make a significant difference to the final density of the casting.
It does mean you have to have the mold very securely braced and any gaps filled, but you will get a much better result than by just tamping alone. It also means you can use the specified quantity of water too - which as already mentioned is a critical aspect of these materials.
There are many inexpensive pneumatic vibrators available now - a seriously worthwhile investment I think. I used to set molds up on an old reciprolap with great success, but now use a wee hand held thing.
Once you see these castables flow under vibration you'll understand how tamping just won't cut it - particularly for structural castings.
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