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Pattern makers shrink rule / contraction rule by J Rabone & Sons, Birmingham, 24″, imperial markings. For casting, foundry work. It has two scales, one marked CONTRACTION FOR IRON 1/120 the other marked DOUBLE CONTRACTION FOR IRON 1/60 The inch markings are down to 1/16 for most of the length, there is a 3″ section marked in 1/32s at the beginning of the ruler. Good quality steel, edges clean and straight. The ruler is in good condition with some discolouration but with clear markings incised into the metal. Please see photos Please see photosWeight 200 gTracked post UK £3.50 EU / World 1 / World 2/ World 3 (USA) £11.55 / £18.90 / £ 21.40 / £21.30 Dispatch time stated 3 working days to allow grouping orders for posting, will often be sooner than that. Skip this bit if you already know what a contraction rule is: a pattern is needed when a product is made by casting e.g. by pouring molten iron into a sand mould. The sand mould is made by a embedding a pattern, that’s a wooden prototype of the required item, in sand and then removing it when the metal is to be poured. The metal will shrink when it cools so the pattern has to be made larger than the final item will be. The amount of contraction is known for different metals. So if it is to be 12″ long, the pattern needs to be just over 12″. The rule is slightly longer than the marked length to allow for this so using it saves calculating every measurement on the pattern . Double Contraction:”With repeated use, a wood pattern gets beat up as well as suffering from the moisture in the sand. Where significant numbers of castings are to be made, but not enough to justify production patterns (like machined metal matchplate patterns), a “master pattern” can be used. This is a wood pattern with “double shrinkage”. From it, a series of metal castings are poured which have “single shrinkage”- these castings then are cleaned up with a light buffing/polishing and used as the patterns for the actual castings. “

Pattern makers shrink rule / contraction rule by Chesterman Sheffield, 24″, imperial markings. For casting, foundry work. It has four scales, one is normal measurement and the other on that side is marked FOR IRON 1/120 . The other side has FOR BRASS 1/70 and FOR STEEL 1/64. The inch markings are down to 1/16 for most of the length, there is a 3″ section marked in 1/32s at the beginning of the ruler, this is the same on both sides. Good quality steel, edges clean and straight. The ruler is in good condition with clear markings incised into the metal. Weight 200 gTracked post UK £3.50 EU / World 1 / World 2/ World 3 (USA) £11.55 / £18.90 / £ 21.40 / £21.30 Dispatch time stated 3 working days to allow grouping orders for posting, will often be sooner than that. Skip this bit if you already know what a contraction rule is: a pattern is needed when a product is made by casting e.g. by pouring molten iron into a sand mould. The sand mould is made by a embedding a pattern, that’s a wooden prototype of the required item, in sand and then removing it when the metal is to be poured. The metal will shrink when it cools so the pattern has to be made larger than the final item will be. The amount of contraction is known for different metals. So if it is to be 12″ long, the pattern needs to be just over 12″. The rule is slightly longer than the marked length to allow for this so using it saves calculating every measurement on the pattern . Double Contraction:”With repeated use, a wood pattern gets beat up as well as suffering from the moisture in the sand. Where significant numbers of castings are to be made, but not enough to justify production patterns (like machined metal matchplate patterns), a “master pattern” can be used. This is a wood pattern with “double shrinkage”. From it, a series of metal castings are poured which have “single shrinkage”- these castings then are cleaned up with a light buffing/polishing and used as the patterns for the actual castings. “