This will likely be of interest to owners of British-built Vandercooks: Chip Coakley (the Jericho Press) emailed me with the serial number on his No. 4 made by Pre-Press Ltd. and to let me know that its original brass bearing blocks had British Standard Whitworth interior threads. When he bought replacement blocks from NA Graphics, he found that he had to make a supplementary order for the bolts and screws. Does this means that BSW screws were used on the other Vandercooks built under license: Pre-Press Ltd. (formerly Western Mfg.), Hunter-Penrose Ltd. and FAG Equipment Ltd?
BSW screws, used for British machinery from the 1850s into the 1970s¹, have a thread form with a 55° angle and a rounded crest. Chicago-built Vandercooks used the American Standard² thread with a 60° angle and a flattened crest. Even though the pitch (threads per inch) may be the same, if the the angle between interior threads on a block and exterior ones on a screw don’t align then either the screw wont advance or becomes stripped if forced.
I have yet to see a British-built Vandercook or an operator’s manual, so here are my questions:
- Do these presses use BSW screws on some assemblies and American screws on others?
- Since FAG Ltd., was a subsidiary of the Swiss firm, did their Vandercooks have metric screws?
- Is it difficult to find common American screws in the UK, continental Europe, or Down Under?
¹ During WWII the British embraced the American Standard thread, but the transition took many years, and before industry could comply, the European Common Market adopted the metric system. Parliament urged metrication in the mid 1960s, prior to joining the EU in 1973.
² American Standard threads, now regulated under the Unified Thread Standard (UTS), are divided into two main categories National Coarse (NC) and National Fine (NF), which refers to the size of the threads relative to the screw diameter, not threads per inch. A screw or bolt is specified by diameter, pitch and length. For example, the set screw on the Vandercook hand crank is ½-13 NC x ½ and the lock screw on an SP15 form roller bearing block is 8-32 NF x ¾. Often the category is omitted in the spec.