'spingy' cutting on turning Aluminum - SB 9a

D

dansawyer

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I have a 2 inch diameter aluminum cylinder, 2 inched long mounted on a steel shaft. The cylinder is bored to 5/8 and the shaft is 5/8. Additionally I have drilled and tapped a hole for a set screw to retain the cylinder firmly on the shaft. The shaft is acting like an arbor, it is held in place on the spindle by a collet and by a live center for good measure on the tailstock end.
I am turning the diameter of the cylinder down from 2 inches to 1 inch. The cutter is a 1/2 inch carbide 'square' end, the tool post is an AXA.

Cutting is smooth, the surface is clean. However if I don't change any settings and run the apron back and forth it keeps cutting very thin chips for up to 10 passes.
Why does the tool keep taking these very thin cuts? (I am holding the cross slide and compound slide firmly away from the work just to keep it from 'walking')
 
All machine tools have a certain amount of spring to them. The set up can also give some spring. This is normal and we learn to compensate for it machine by machine.
 
I doubt that the cutting tool is suitable for the job, or it would not be springing away from the workpiece.
 
The square ended brazed carbide tool bits, the "C" series have no side clearance nor do they have side or back rake as I suggested, the tool may not be suitable for the application. They are intended for applications where they are ground to special shapes, such as radius or form tools. You would likely be much better served by a HSS tool bit with a generous ground in chip breaker.
 
I agree. Switch to a good HSS or insert tool. The brazed carbide tools are not intended to be used out in of the box. They need to have the clearances ground in and be honed before they can make decent cuts. Particularly on small lathes like we have.
 
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