New Dog, old tricks.
A different spin this post. I haven’t finished my shop yet,,so my tools are still residing in storage. Even so, my thoughts turn (pun intended) to them frequently. Of my tools, my gases, welder and the Chinee 3-1 are accessible. The problem with the chinee lathe/ mill is lack of change gears/QCgearbox and some serious lacking of capacity/adjustment.
I am thinking forward to when that shop is up, and I still need tooling. While I am down, I see now reason that I can’t make some of that tooling. In this instance, mandrel/arbors for turning gears and pulleys. These mandrels are so subtle in their appearance, I have seen them used for parts of machines or even large pins. They are most often,6 1/2″ long, of which 6″ is the working length. That last 1/2″ is for mounting the dog because these are used between centers. Why they are misplaced is the difference between the “big and little ends”. Say that the mandrel is set up to turn items for a 3/4″ shaft. The big end will measure .751″ amd the little .749″. Over 6″ that difference seemingly disappears.
Well here is the old trick time. Seeing how I can’t use the bend right now, taper turning is quite limited. The tailstock doesn’t adjust on the Chinee (it travels the bed, but is fixed on center with no adjustment built in..in fact, the castings are bolted on then machined to each machine by said machine for accuracy.) So I could use the compound rest but thats like swatting mosquitoes with a baseball bat. It worked for a heavier taper way back when (one of my first projects was turning a Morse taper #2 shank/live center.) This is .002″/6″ ! Thats .000333,,,”/in! That is reading in seconds of degrees! The rest measures in degrees and minutes (as in 30 minutes/division) nothing as fine as that measurement.
Well shit. How do I this one?
Actually paper is the answer. A piece of standard notebook paper measures between 2 and 3 thousandths. Good enough. A strip about 1/4″ wide placed into the backside of the MT socket before I put the live center in effectively moves the tailstock center forward the needed amount so that I can turn this taper. Being a roller bearing live center, and the fact that thrust is towards middle on both centers, I am not worried about the MT slipping.
Apparently, not an original idea but I read about it in an old 1897 manual for boring machines to “squeeze a little more” out of a machine; not for a lathe. Can’t see why it won’t work myself.
And now its time to hand feed that cross slide. (Come on shop, I want my power feed back!!!!!)