Why righthand threads?

[Neil A]

On Neil A Said:

Did Maudslay’s screw-cutting lathe have a left hand thread lead-screw? Most of the screw-cutting lathes I have seen have a left hand thread on the lead-screw so that the saddle moves toward the chuck when the lead-screw is rotated clockwise.

From the photographic images of screw threads that I have seen that predate Maudslay, it would seem that the right hand thread had been in common use for a long time. That is not to say that left hand threads were not used, many of the woodcut images of presses show a left hand thread, but I could not guarantee the accuracy of these images.

Perhaps a visit to one of the science museums to view the exhibits might give a clue as to when screw threads came into common use and which hand they were.

Neil

Having now seen the ‘Master-Thread’ cutting machine, I doubt we can draw any conclusion … The full-circle Goniometer surely indicates that it could produce either Right-hand or Left-hand threads.

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https://collection.sciencemuseumgroup.org.uk/objects/co46546/machine-screw-thread-making-tool-by-henry-maudslay

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MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

From the link that Duncan kindly provided:

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MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

With a little help from Google AI

https://www.gutenberg.org/files/31756/31756-h/31756-h.htm

MichaelG.

[Mark EasingwoodParticipant @markeasingwood33578]

Just for interest:-

Vacuum extractor hoses have left hand treads.

Many other things have left hand threads, circular saws, planers, the outboard end of woodturning lathes and one end of your bench grinder, to name but a few.

Why are they called “right hand threads,” and not clockwise for instance? Is it because, when looking at a bench grinder for example, they are at the right hand side?

[bernard towersParticipant @bernardtowers37738]

The left hand threads on the items you mentioned is mostly that due to the rotation direction they tend to be self tightening, for instance truck wheel nuts on the left hand side

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