Saturday, August 25, 2012

Lexicon -- Backlash/Lash

Strictly speaking, the accepted term for clearance between mechanical components, especially with respect to the mating teeth of a geartrain, is 'backlash'. At, I found this etymology:

'backlash  1815, of machinery, from back (adj.) + lash. In metaphoric sense, it is attested from 1921.'

It seems to me that the 'back' portion of 'backlash' introduces a needless specificity to the term for many purposes. Hence, I'm inclined to simply use the word 'lash' as a catch-all term for any sort of clearance/play/slop in a mechanical relationship, even though I can find no authoritative support for that usage. Though I tend to be a stickler about correct, authoritative word usage, in this particular case I'm entirely at ease with taking the attitude, "Authority? We don't need no stinking authority!"

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Sunday, August 19, 2012

Immobilizing a Lathe Spindle

My lathe has no provision for locking the spindle, and I needed to lock it so I could tap a thread in something chucked in the scroll chuck. I came up with this arrangement.

There was already an unused hole in the side of the switchbox that was the perfect size for tapping a 10-32 thread. A length of 8mm diameter rod and a 5/16" cable clamp now provide an adequate spindle lock for what I need to do.

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An Improvement -- SATURDAY, AUGUST 25, 2012

I've added a second cable clamp near the spindle to minimize lash. Here's a view of that with the chuck dismounted.

Much better.

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Addendum -- SATURDAY, NOVEMBER 24, 2012

I just discovered a little glitch. When I went to mount the lathe's four-jaw chuck, the parked spindle lock rod interfered with the jaw nuts on the back of the chuck. I had to remove the cable clamp nearest the spindle, and back the rod well away.

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