Quote:
Originally Posted by ron
Hi Alex I dont think that there are any grinding marks on my unused track but will check it in the moring, I have quite a bit of it and will have a good look, Regards Ron
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Hi Ron,
Appreciate you looking into that.
I believe the links must have had feeder and riser and possibly runner metal protruding from them. Depending on the thickness of this attached metal from the pour, it would have been broken off or sawn off and if it was impracticle to leave it without further finishing they'd have ground the worst protrusions off the link.
Also look for fairly straight thin broken off or ground sections, often along long edges where flash may have been removed where the drag and the cope (the two parts of the mold) were joined together. This is known as the parting line. Sometimes the sharp sand corners on either side of the parting line break off a bit before the drag and cope is assembled and this results in what would have been a bit of metal protruding along that seam. These parting lines may appear not all in the same plane because a mold may consist of not just 2 but 3 or more parts (not counting cores).
[inserted 8/6/2010 - Another reason for Parting lines to not appear in the same plane is if the cope and drag faces are not in a flat plane - they may slope in plane too. As far as I can work out, in sand molding lateral thinking is the name of the game. The shape of the object to be cast dictates the complexity of the mold and so long as the basic rules of creating a functional, safe, mold are followed, and the simplest outcome (for economy) is chosen, then how the mold is comprised is left to the talent and skills of the foundryman. Just as important as the ramming and extraction of the pattern/pattern-pieces is the cutting of the feeder, runners and risers so that the metal flows in the desired manner and contaminants are trapped where they are of no consequence, and weight of the metal keeps the casting filled during cooling, and shrinking is controlled as much by design as possible.]
Look at anything cast in metal and it usually has such marks unless it was machined and/or finished all over.
Drop forged (stamped) items like spanners, etc also have evidence of flash most of the way around that is still fairly obvious.
yadaa yadaa
Alex