CNC: Morse taper – the inside story
Morse tapers are very commonly used in both CNC turning centers and CNC machining centers. Here is an explanation on what a Morse taper is.
A taper is of course the best way of achieving concentricity between two components. Mating cylinders necessarily need to have a clearance, the male being of smaller diameter than the female. This clearance causes an axial shift between the parts. Mating tapers with the same angle, on the other hand, are forced to be on the same axis.
Holding tapers are of two types – self-holding and self-releasing. In self-holding tapers the male is pushed into the female with force and the two parts bind with each other because of friction. The forces of hole machining operations (drilling, reaming, etc.) can be resisted without a drawbar, and the tool will stay in the spindle when idle. It is driven out with a wedge when a tool change is needed.
Reamers with Morse taper shank
(I wonder if people not connected with Mechanical engineering think “These Mechanical engineering types are obsessed with sex, even at work – disgusting people”).
In self-releasing tapers, the male will not stick in the female without a drawbar holding it in place. The Morse taper is a self-holding taper, while CAT, ISO, BT, etc. are self-releasing tapers. The Morse taper was invented in 1864 by Stephen Morse, a mechanic who was looking for a better way to drill holes in the USA. He patented the method and started the Morse Twist Drill and Machine Company. It still exists, as Morse Cutting Tools. In fact, 2 sets of master gauges of the taper were initially made. One is in the Bureau of Standards in Washington, D.C., National Standard. The other remains with the Morse company.
Morse tapers come in 8 sizes, #0 to #7. The angle is approx. 1.5 degrees, and is different for different sizes. The large dia. (dimension A in the picture) varies from approx. 9 mm to 83 mm, 9 corresponding to #0.
While browsing the web one day I found to my surprise that Morse tapers are commonly used in orthopaedic implants too, like in the artificial hip joint in these pictures.
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