# Speed Indicator



## JPMacG (Nov 28, 2014)

I purchased an old Goodell Pratt No 440 Speed Indicator at a barn sale today.   It appears to be just a turns counter. It has two rubber couplings, I guess one for the indicator shaft and one for the lathe, drill press or milling machine that you want to measure the speed of.  

I guess it can be used to determine RPM by coupling it to the work for a certain time period and then doing some math.  Also I guess you could determine feed rate by using a wheel of a certain diameter on the indicator and pressing it tangentially onto you work.

Anyone know anything about this neat little instrument?   There was no information with it, just the original box.  Never saw one before.


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## petcnc (Nov 28, 2014)

JPMacG said:


> I purchased an old Goodell Pratt No 440 Speed Indicator at a barn sale today.   It appears to be just a turns counter. It has two rubber couplings, I guess one for the indicator shaft and one for the lathe, drill press or milling machine that you want to measure the speed of.
> 
> I guess it can be used to determine RPM by coupling it to the work for a certain time period and then doing some math.  Also I guess you could determine feed rate by using a wheel of a certain diameter on the indicator and pressing it tangentially onto you work.
> 
> Anyone know anything about this neat little instrument?   There was no information with it, just the original box.  Never saw one before.



I have seen Tubal Cain using similar devices.
See the video here https://www.youtube.com/watch?v=m7qyirccUeI

Petros


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## francist (Nov 28, 2014)

They're pretty common, doubleboost also just put up a video on his channel about using one to check rpm's.

-frank


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## kd4gij (Nov 28, 2014)

There was a thread on here not to long ago about them. I have a brown & sharp. It looks good sitting in the gauge drawer.:lmao:  http://www.hobby-machinist.com/showthread.php/26421-What-s-a-speed-indicator-used-for


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## aametalmaster (Nov 29, 2014)

I found one in some junk i bought. My neighbor was with me and he was 80 at the time and a retired machinist. Said he used one with a pocket watch to time it. I never tried it. Will watch the vids posted...Bob


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## schor (Nov 29, 2014)

Most of the time you don't get the extra tips with it. I have one and have used it quite a few times when checking rpm on drill presses I restore.


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## darkzero (Nov 29, 2014)

I have a Starrett one that I picked up at a local flea market. Had no idea what it was or how it was used until I saw Tubalcain's video on how to use them. Funny cause when I picked it up, Tubalcain's video on them came out just a few days later.


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