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AR15.COM
1/30/2017 6:52:42 PM EDT
Any ideas what this thing is? I figure it's for measuring RPM but what was it used on? Seems like it's from the early 1900s. Thanks in advance.
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1/30/2017 6:55:07 PM EDT
[#1]
Harmonic Tach?
1/30/2017 6:55:36 PM EDT
[#2]
Definitely an antique dikfer, with its original case and accessories, which is rare.
1/30/2017 6:57:56 PM EDT
[#3]
uncle spinny dervish.  it measures rotating.
1/30/2017 7:03:19 PM EDT
[#4]
Quote History
Quoted:
Harmonic Tach?
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It's some kind of tach, but why does it need 3 different inputs? They are all geared together but roatate at different speeds
1/30/2017 7:09:49 PM EDT
[#5]
Old machinist tach, typically used on a lathe to calculate SFM
1/30/2017 7:13:55 PM EDT
[#6]
Quote History
Quoted:


It's some kind of tach, but why does it need 3 different inputs? They are all geared together but roatate at different speeds
View Quote


We use them to get elevator speed.
1/30/2017 7:15:30 PM EDT
[#7]
It's a "hand tachometer" from the 1920-30's - similar to this one:

http://www.worthpoint.com/worthopedia/wow-antique-hand-tachometer-mm-m-ashcroft
1/30/2017 7:16:14 PM EDT
[#8]
It is an old Machinist tool, my Dad's former employer collects them he has dozens of different ones.
1/30/2017 7:18:06 PM EDT
[#9]
Quote History
Quoted:


It's some kind of tach, but why does it need 3 different inputs? They are all geared together but roatate at different speeds
View Quote



to measure 3 differernt speed ranges
hence the 3 different scales

use the scale associated with the input selected.

could be used for a numerous applications from mechanics to machinists, and beyond.
1/30/2017 7:22:39 PM EDT
[#10]
Quote History
Quoted:
It's a "hand tachometer" from the 1920-30's - similar to this one:

http://www.worthpoint.com/worthopedia/wow-antique-hand-tachometer-mm-m-ashcroft
View Quote


Yeah that looks just like it
1/30/2017 7:25:14 PM EDT
[#11]
Looks like it might be a "vibra-tach" or similar. You hold it on the engine and it reads the rpm through the vibrations.
1/30/2017 7:42:55 PM EDT
[#12]
I have one of those.  I'm pretty sure it was given to me since it doesn't look like something I'd buy, much less steal.  I no longer have any idea who gave it to me, when, why, or what it is.  I still have it, though.
1/30/2017 8:15:04 PM EDT
[#13]
Quote History
Quoted:


It's some kind of tach, but why does it need 3 different inputs? They are all geared together but roatate at different speeds
View Quote View All Quotes
View All Quotes
Quote History
Quoted:
Quoted:
Harmonic Tach?


It's some kind of tach, but why does it need 3 different inputs? They are all geared together but roatate at different speeds


It's  an old mechanical tachometer. Mechanical gages, (of all sort) tend to be their most accurate at mid-scale. That one has three scales judging by the face and the selector on top.  It probably has ( or had) a few removable rubber tips for the business end.