Arguably what I didn't do today, as I've been indulging in the worst kind of armchair / chequebook engineering.
Some time back, when I had a workshop, I made a quick change tool holder for my Bridgeport clone that has a 30 taper spindle. The usual toolholders for this are NMTB30 which has a parallel shank for the drawbar thread but I had to machine about 8-10mm from the end of the shank due to the limited space in the spindle to house the collet mechanism and the pullstud. It's not a difficult operation but as the BT30 toolholder is almost identical apart from having no shank to machine away, it's a more convenient solution.
I've been acquiring a few NMTB30 and BT30 toolholders as they have come up and it's become clear I'll now require a fair few pullstuds to make use of them – a short version for the NMTB and a longer version for the BT. I managed to make up a few of the NMTB version the first time round but I reckon it would take me quite a few days to make up a dozen or so more of each type on my manual lathe. However, I've got a life to live, an armchair to sit in – and a chequebook in my pocket.
So I modelled the pullstuds in Onshape at the end of last year and got our factory in China to farm them out to a local machine shop. On my last visit in March they were ready, complete with a comprehensive incoming inspection report, hardened and ready to go. It's a blatant bit of chequebook engineering admittedly but at £3 each, I'm happy to pay for someone else to crank them out so I don't have to. To be fair, my armchair workshop doesn't have the facilities…
I now have 20 of each (£120 all in), which should keep me going for a while. Fine looking things. Here's the original CAD model (short pullstud) and what they look like with NMTB (not yet machined back) and BT flavour holders. Some other pics in my album.
Murray


