Spinning around

Really, really almost done for now with my ‘must make’ tool list. My DW wanted to avoid looking at dark brass marks on my fingers at dinner. Since I will be turning knobs a lot while making my engine, it was time to retire the original brass handles on the carriage, cross slide and vertical milling slide. The handle design came from Keith Brooke’s excellent article on making zero-resettable dials for the Taig.

Making 1 of something is a simple task, making 3 identical units is something else. I marked out the dimensions on the first spindle, and then used that as a pattern for the other 3. Each was almost complete before moving on to the next one. The cross slide DRO was most useful. Touch the cutting tool to the material, zero the DRO, calculate diff between original and target diameter, divide diff by 2 and you get the desired reading for the DRO. (It always measures radius, not diameter). Wind the cross slide to the desired number, press zero again and now all you need to do is cut until you get to zero!

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The operation sequence: cut diameter for 8-32 threaded end, thread it. Don’t forget to undercut the thread near the shoulder, otherwise it might not seat properly on the dials later. Extend the 0.25” drill out to next length, cut the long section down to size. Finally extend the rod a bit more and cut off leaving just over .125” for the head. Those will be trimmed to identical lengths later.

Each spindle was then chucked in the collet holder, the end of the first one was cleaned up, and the carriage locked in place. The other 2 were then cut to the exact same length.2014-07-06 11.10.07

Next up is the handles. These are .375” drill rod. Because of the >2’ length of rod sticking out the tail end of the lathe, I had to first cut off 3 pieces to length. These were then step drilled to .1875. Next was to counter-bore for the spindle head. A .25” end mill does great for this, again a bit of set up to make all 3 counter-bores the same depth. I bored the first one a bit at a time until the spindle head was just below flush. I then moved the tailstock such that the lever was at maximum travel at the finished depth. The lathe cutting tool was positioned to control how far the part protruded from the collet. Two more handles went through the process. Each was then cut to exact length, such that the spindle would seat against the pulley and leave the handle free.2014-07-06 11.24.36

Last up is to cut a screw driver slot in the head of each spindle.2014-07-06 12.22.02

A bit of tidying up, some tapping of holes and we have free spinning handles. No more brass rubbing off on my fingers! The machinist clamp in the photo below was one of my 1962 Grade 9 machine shop projects.2014-07-06 12.53.58

All of this tool making has provided an excellent education on process sequence. Thinking out the workflow and required setups ahead means less fiddling, especially when making more than 1 of a part.

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