Engineeringtech
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- Jul 29, 2013
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This probably sounds like a beginner question, but I'm not a beginner. I don't do a lot of facing of large diameter stock, because I have such a small machine, a Hardinge DV-59.
I'm trying to face 2" diameter CRS. This particular bar cuts very well. Almost like a free machining leaded steel. But I keep getting a "dished" end. I'm not talking about the small nib you get when the tool height isn't exactly at center. No, there is a gradual dishing of the end of the bar. The bar end is not square.
A DV-59 does not have a saddle. It has a compound that must be adjusted to make a square cut. Mine is reasonably well adjusted. I stuck a piece of 3/4" stock in the chuck and turned a light skim cut off. Over the 3" length of cut, there is less than .0005" change in diameter. So why, when I face the end of the 3" piece, is there at least a .005- .008" variation from the perimeter of the part to the center?
The toolbit is not flexing. I have the quick change tool holder mounted parallel to the stock, as you would do with a boring bar. And I have less than 1/4" of the cutter sticking out of the holder. Very rigid. There is no play in either two slides.
I played with thespindle speed. No change.
I'm trying to face 2" diameter CRS. This particular bar cuts very well. Almost like a free machining leaded steel. But I keep getting a "dished" end. I'm not talking about the small nib you get when the tool height isn't exactly at center. No, there is a gradual dishing of the end of the bar. The bar end is not square.
A DV-59 does not have a saddle. It has a compound that must be adjusted to make a square cut. Mine is reasonably well adjusted. I stuck a piece of 3/4" stock in the chuck and turned a light skim cut off. Over the 3" length of cut, there is less than .0005" change in diameter. So why, when I face the end of the 3" piece, is there at least a .005- .008" variation from the perimeter of the part to the center?
The toolbit is not flexing. I have the quick change tool holder mounted parallel to the stock, as you would do with a boring bar. And I have less than 1/4" of the cutter sticking out of the holder. Very rigid. There is no play in either two slides.
I played with thespindle speed. No change.
