"Mounting a square piece between centers

[NP317]

'Looks like WORK!
...not play!
~RN

[Harold_V]

Nice job, Glenn. Any trouble with chatter?

H

[GlennW]

I was going from 1/2 square to .390" round in one pass, then a finish pass to .375".

The first twenty pieces went smoothly with zero chatter and the twenty first piece started to chatter so badly on the roughing pass the machine started to shudder. It turned out that the edge had chipped on the HSS form tool from the interrupted cut. I figured it was a good time to stop and go home. I came in the next morning and re-ground the tool and finished the rest with no issues.

I did pay attention when I backed off the tail stock to change parts, and could not see any movement in the part as the center was backed out.

I was using an internal stop in the collet so that the stock would not push back when cutting and keeping minimum pressure on the tail stock to not deflect the stock.

Thanks, Harold!

[Harold_V]

I did pay attention when I backed off the tail stock to change parts, and could not see any movement in the part as the center was backed out.

Nice. That doesn't always happen, even with round stock.

I'm amazed at the results you achieved. Chatter for slender items like you made tends to be a problem. Speaks volumes about the design of your tool. A good balance of relief and rake. Very well done!

H

[GlennW]

Did you notice the tool is upside down and I am running the spindle in reverse?

I went to grind the tool and got interrupted, when I went back to it my brain cell failed and I ground the form tool backwards. Too lazy to grind another one so I just flipped it over.

It made the chips fall straight down and pile up nicely on the bed though...

The finish came out very nice and they are all out being flashed with hard Chrome right now.

[Harold_V]

Did you notice the tool is upside down and I am running the spindle in reverse?

No, I missed that, but I did wonder why the chips had accumulated so orderly.

I went to grind the tool and got interrupted, when I went back to it my brain cell failed and I ground the form tool backwards. Too lazy to grind another one so I just flipped it over.

One of the options not at my disposal. I use a square block (O.K. Rubber Welders), so I can't use tools in alternate positions. Can't get them on center.

When I worked at Sperry Utah, Albert Van Woerden was one of the journeyman machinists, who later became a lead man. He promoted the use of upside down tooling, often with chatter elimination in mind. Your mental lapse may have been part of the reason you achieved success. They sure look good!

H

[whateg0]

Like many things, there are more than one way to get a skinless cat. I don't understand why one would go to the effort of setting up on a mill to center drill an item like this, when centering it in the 4 jaw on the lathe can be done just a accurately, far faster, and in a single setting. If the part ends up not being turned between centers, the chuck end will need to be indicated in anyway.

Dave