Author Topic: Video - a skilled machinist shows how to turn small diameters  (Read 2212 times)

Offline Roger B

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Re: Video - a skilled machinist shows how to turn small diameters
« Reply #15 on: December 20, 2017, 05:28:07 PM »
Wish you had not shown that tool Gray.. Now I must make one :)  :happyreader:

+1  :wine1:
Best regards

Roger

Offline Graham Meek

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Re: Video - a skilled machinist shows how to turn small diameters
« Reply #16 on: December 20, 2017, 05:54:47 PM »
The semicircular pad beneath the tool bit is the clamping medium. In the view attached the clamping grubscrew can be seen next to the location slot . The hole through the Boring tool holder and through the Box Turning tool means there is no restriction on the length that can be turned. The restriction is the rigidity of the parent barstock sticking out of the chuck jaws. The material in the photos is 4 mm (5/32) mild steel. This will easily support itself with up to 100 mm (4") sticking out of the jaws.

The tool is designed to reduce the stock in one pass. Coarse adjustments on the tool are carried out by the M3 grubscrew pressing on the back of the tool bit. One full turn reduces the bar stock by 1 mm, (0.5 mm Pitch). Fine adjustment is carried out via the slotted screw. This works on the differential screw principle. The thread in the slotted plate is M5 x 0.8 P, the extreme end of the adjustment screw is threaded M4 x 0.75 P. The M4 thread screws into the main body of the tool. One complete turn of the slotted screw moves the tool 0.05 mm which reduces the bar by 0.1 mm.  Moving from one dot to the next, (10 dots), means the diameter is reduced by 0.01 mm.

The fine adjustment was an add on. I had originally tried setting the tool by turning down the end of the bar first and urging the tool bit against the turned down portion. Hit and miss would describe the outcome. More miss I hasten to add. Adding the fine adjustment means the tool can be set very quickly and be right first time.

My best regards
Gray,