I’ve really been lagging on my blogging. Here’s a quick update.
I’ve recently found myself working out of the Beaverton office again, so late one night after finishing up I hopped onto the company’s aging, crusty lathe:
These are custom captive screws for the Benro quick-release plates I picked up in Hong Kong. I’m mounting the Benro plates to a piece of 8020 1010 extrusion, and the T-slots are a little bit deeper than an ISO standard camera mount. So, for my application, a custom screw would be needed.
I’m actually pretty happy with how this turned out; the machine is old and the hand-ground parting tool isn’t the best for cutting stainless steel.
To chuck the screw into the chuck without damaging it, I took a page from an old machinist trick of slotting a nut with a hacksaw and clamping it in a 3-Jaw chuck. I started with a 1/4-20 x 0.5″ SAE button head socket cap screw.
(Note: Yes, I am aware that the standard tripod thread is a 1/4-20 British Standard Whitworth – cut with a 55 deg angle instead of a 60 deg angle. I challenge the reader to find one here in a hardware store in the good ol’ USA. A 60 deg SAE thread is “close enough” for this application with some very minor interference)
The resultant screw is a bit too long, so I trimmed it down a little bit with my motor tool.
The tool is a Taiwanese made version of the Foredom – a 600W motor on a flex shaft and a foot pedal for actuation. It takes all the standard Dremel accessories and it’ll slice through stainless pretty easily. I lined the jaws of my Wilton vice with some engineering paper scrap, and used my pano clamp as a clamping base for the tripod plate. Then, using another machinist’s trick, I put a nut on each of the screws to be cut. When removing the nut, the nut acts as a tap and cleans out any debris on the screw threads and restores the proper thread form. :-)
And BTW – at 20,000+ RPM and with 600W of power behind the disc – any slip up is … painful. Warning: somewhat graphic picture ahead:
The wound looks A LOT worse than it actually is. I think the heat from the abrasive blade cauterized the wound – it didn’t bleed much. Digging all the abrasive grit out under running water was a different story – good reminder to be more careful the next time.
And here’s the finished rig! Now, I need to order some 3D glasses…