Model Engine Maker
Help! => Hints, Tips & Tricks => Topic started by: mklotz on March 26, 2013, 10:14:20 PM
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It's seldom that one needs to know the rotational speed of the lathe accurately but, if you do and you don't have a tachometer about, here's one way to do it.
Get a length of all-thread and a nut to match it. Grip the all-thread in the chuck and make two marks on it a convenient distance apart. Thread the nut on up to one of the marks. Now, with the lathe running, grasp the nut (use needle-nose pliers) and time how long it takes to move to the next mark.
Given:
d = distance between marks (in)
p = pitch of all-thread (tpi)
t = time for nut to move between marks (sec)
then:
speed (rpm) = 60 * p * d / t
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You don't reckon smarts like that might have come from eating those calf brains and aigs, now do you? I remember before I smelled nitro, burning rubber and perfume, there was a group of us that would work practical problems like that. Now, I enjoy the practical problems so I can try to remember the rest.
Yo Redneck,
Eric
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It's seldom that one needs to know the rotational speed of the lathe accurately but, if you do and you don't have a tachometer about, here's one way to do it.
Get a length of all-thread and a nut to match it. Grip the all-thread in the chuck and make two marks on it a convenient distance apart. Thread the nut on up to one of the marks. Now, with the lathe running, grasp the nut (use needle-nose pliers) and time how long it takes to move to the next mark.
Given:
d = distance between marks (in)
p = pitch of all-thread (tpi)
t = time for nut to move between marks (sec)
then:
speed (rpm) = 60 * p * d / t
What a great tip, thanks.