Back in 2012, I purchased the plans and construction notes for the Worden tool and cutter grinder from Hemingway kits. At the time, we were living in France and I decided against purchasing the kit of parts, mainly due to the freight costs. Now that we are back in the UK, I have ordered a kit and anxiously await its arrival. Whilst waiting, I have been re-appraising the drawings and evaluating the possibility of converting to all-metric, both dimensionally and fastener-wise. Hemingway have partially gone down this route but have stopped short of complete metrication. (Apparently a lot of their customers still prefer to work in imperial measurements.) Nevertheless, I want to go metric if I possibly can. Having looked carefully at the drawings, I was amazed to find that, in addition to the (already changed) metric fasteners, there was a call for six different thread types and/or sizes, not to mention the need for a ¾ inch reamer for the slider block. I investigated the cost of one of these from my local engineering suppliers and was shocked to find it was the thick end of £100! I had to find an alternative. Most of the thread sizes can be quite easily swapped for metric, for example, M5 for 2BA, M3 for 6BA and M3.5 for 4BA (at a pinch). Some of these are slightly oversize and as a consequence don't leave much "meat" around them. This I can undoubtedly get around. My main concern is the ¾ inch diameter sliding bar and its associated block, which I am stuck with, unless I replace it with 20mm Ø ground stock . I have in mind boring the block to 20mm and making two bronze or brass bushes, each 25mm long pressed into a counter-bored recess at each end of the block. I appreciate that not many of the membership will have built the Worden and so will possibly not know what I'm on about ( a not infrequent occurrence!), but for those who have, what do you think of my proposal?
If anyone has already made the conversion to all-metric, I'd be pleased to hear from them. If only to stop me a) making any mistakes and b) re-inventing the round rolling thing.
Sorry for the long-winded preamble. I got there eventually.
John