I had an interesting logic problem today. So I have some 1 7/8” 6061 aluminum round stock. I wanted to flatten two faces and then make it accurately round. I chopped off 40mm chunk. It was my first time playing with my Saunders plate and mod vises.
So I assumed that my cut wasn’t square. So I’ll cut two soft jaws at the current 1 7/8” If I make fusion centre the cut on the soft jaws in the middle of the jaw face and offset 10mm, then I can run my machining origin from the corner of the soft jaw and know my round stock centre.
But the vertical side won’t be guaranteed to be orthogonal to the top face. So I’ll face the top,contour the vertical sides with a -0.1mm offset for half height of stock. Now I have a face with orthogonal vertical sides halfway.
Now I’m thinking I flip the piece. Only clamp the orthogonal vertical sides in the jaws, and face the new top. This should guarantee that both faces are parallel.
But now it gets difficult. If the stock wasn’t exactly round, which it wasn’t, then I’m not sure my second contour on the other half vertical walls will meet.
I think I need another set of soft jaw cut, which measure the new diameter of the orthogonal vertical walls.
I feel like I’m doing something logically wrong.
My end product should be a “perfect” aluminum solid cylinder.
Thanks for this. So I tried again and realised that if my stock isn’t too deep then I can cut all the vertical wall from the top, then just flip and do a horizontal face until I remove the bottom part of the wall.
However I’m trying to learn the correct way rather than make anything.
The shim stock? I assume that’s to give some gap in the soft jaws when boring do that they can then tighten in the piece, but also to keep the jaws parallel?
The machine is going well with the horizontal faces, but the vertical are not great. I tried a datron 1 flute and a shapeoko 3 flute. I increased rpm to 25k, I tried reducing cut per tooth to 1/2 thou. More finishing passes at 0.01mm. I’ll try again.
They never will. There are too many variables. Particularly with this type of machine. (Runout, Tram, parallelism & perpendicularity of all the axes, slop in drive mechanism…) Even on a very rigid high precision machine like a Grob, I would not try this. You might get it within a couple tenths (0.0001"), but you will still see the step line.
I think your best bet would be to cut your stock a bit longer than what you need & clamp only on the part that will get machined off when you flip it.
What Tenacious D said as well as, think about upgrading to a router with an ER collet system. Ultra Precision collets is what I buy from Rego-Fix. The collet you are using is not a compression collet and no matter how tight you try to get it, it will never grip the entire length of the tool shank.
