Square Face Tachometer

Elroy · May 18, 2008

About 25 years years ago Elroy was moving into a old apartment house and found this "tachometer" abandoned in the basement. Always thought it was kind of cool and it is an "old tool". So here are a few pictures for your viewing enjoyment. Elroy would also be pleased to attempt an answer to any questions and would like to hear any comments.

Elroy has two other "mechanical" tachometers as well, and if it meets the approval of the board will post pictures of these as well. Comments please.

JayL · May 18, 2008

So how do you interface it ...and what do you use it for.

Elroy · May 18, 2008

JayL said:
So how do you interface it ...and what do you use it for.

There is no "interface" other than just physically setting it on the machine you want to test.

bchee · May 18, 2008

????????????

krusty the clown · May 18, 2008

we used to use those for diagnosing vibrations........its called a reed tachometer. drive down the road with it on the dash and read the rpm of the vibration so you could tell whether it was wheel speed, driveshaft speed, or engine speed related. i haven't seen one of those in 20 some years! thanks for bringing back nightmares!

JayL · May 18, 2008

I wonder how accurate it could be ...

krusty the clown · May 18, 2008

they were surpisingly accurate although not as accuarate as the electronic vibration analyzers we use now. they actually read frequency and used it to infer an rpm.

Kevin54 · May 18, 2008

One for $50 on evilBay at the moment http://cgi.ebay.com/Frahm-Tachometer-biddle-instruments_W0QQitemZ130202372620QQcmdZViewItem

Here iis a site that kind of explains how it works on a concrete ******** http://www.wes.army.mil/SL/MTC/handbook/crd_c521.pdf

wilbilt · May 18, 2008

I used to have a guitar tuner that worked on a similar principle.

eschoendorff · May 18, 2008

wilbilt said:
I used to have a guitar tuner that worked on a similar principle.

Yup. and the old Strobe tuners were a hoot too. Unfortunately, too many people tune instruments with machines instead of with their ears... which is why so many people play out of tune!

Elroy · May 18, 2008

krusty the clown said:
we used to use those for diagnosing vibrations........its called a reed tachometer. drive down the road with it on the dash and read the rpm of the vibration so you could tell whether it was wheel speed, driveshaft speed, or engine speed related. i haven't seen one of those in 20 some years! thanks for bringing back nightmares!

Excellent Response there Krusty, Elroy can tell you have some very solid experience. Good for you, this country needs more good people who know how to pay attention. As you say, a reed tachometer. Each reed having a small weight at the end of a cantilever spring. Each "beam" having a different spring constant and thus a different natural frequency. And yes it is accurate though some what difficult to use.

Now for a real antique. Elroy was surprised to find out just how accurate this thing is and good to 20,000 RPM using the best technology 1918 had to offer. This piece actually works like a stop watch that runs for 3 seconds. It counts the revolutions in this time period and displays the RPM or Feet per Minute if using the "wheel". Elroy thinks it's a neat piece. Good friend of mine gave it to me for Christmas a few years back. Enjoy

Serial numbered case:

All the literature:

Dial detail:

Serial number "52" dated 1918:

Elroy has one more "Mechanical Tachometer". I'll post that one up as well, but I need to find it first. Haven't seen it in a while and can't recall exactly where it is. I'll post it if there is interest in these old "precision tools"

krusty the clown · May 18, 2008

very cool stuff elroy.....keepem coming!

GDA · May 18, 2008

I really like reading and learning about mechanical devices and tools from posts like this. Please keep them coming. Thanks!

Elroy · May 22, 2008

Elroy enjoys his limited amount of free time and has always enjoyed his visits to the "Garage Journal". I wish I had more time to contribute to the general knowledge base and general success of the board. One area Elroy can contribute is by posting on select issues. I simply don't have the time to visit on a daily basis.

Elroy mentioned that he had one more mechanical tachometer to post. This tool came from Elroy's father. It has been "in the family" for about 40 years or so. Just a few years ago this particular tach was still available new through McMaster Carr. The new "photo eye" non contact tachometers have rendered these old time meters obsolete. Your comments would be much appreciated.

This is not the original case. The original case was lost one spring day about 1970 or so when a quick rain storm soaked the card board and it fell apart. Elroy recalls catching a fail about of hell over that one.

The speed range is selected by turning the black ring to the appropriate settings. The maximum on this tach is 12,000 RPM.

Nothing like "Swiss Made"

Uncle Buck · May 22, 2008

Elroy, very fine examples. It is threads like this that makes me wish I had a camera to take a picture of my old Stewert Warner mechanical tach likely from the 50's or therabouts. My SW came in a yellow and blue tin can complete with instructions and literally looks like the old SW dash gauges from the same era. Man I wish I had a pic to post! Thanks Elroy!

wilbilt · May 22, 2008

hholmberg said:
Elroy, very fine examples. It is threads like this that makes me wish I had a camera to take a picture of my old Stewert Warner mechanical tach likely from the 50's or therabouts. My SW came in a yellow and blue tin can complete with instructions and literally looks like the old SW dash gauges from the same era.

I think I have that same tach, UB. I will try to find it and post a pic.

Uncle Buck · May 23, 2008

wilbilt said:
I think I have that same tach, UB. I will try to find it and post a pic.

That would be very cool Wil, I now owe you an icy cold one! :bowdown:

eschoendorff · May 23, 2008

Elroy said:
Elroy enjoys his limited amount of free time and has always enjoyed his visits to the "Garage Journal". I wish I had more time to contribute to the general knowledge base and general success of the board. One area Elroy can contribute is by posting on select issues. I simply don't have the time to visit on a daily basis.

Elroy mentioned that he had one more mechanical tachometer to post. This tool came from Elroy's father. It has been "in the family" for about 40 years or so. Just a few years ago this particular tach was still available new through McMaster Carr. The new "photo eye" non contact tachometers have rendered these old time meters obsolete. Your comments would be much appreciated.

This is not the original case. The original case was lost one spring day about 1970 or so when a quick rain storm soaked the card board and it fell apart. Elroy recalls catching a fail about of hell over that one.

No third person? Elroy must've been pretty excited!

All joking aside, those are some really neat pieces. Amazing what they had before computers...

russlaferrera · May 23, 2008

hholmberg said:
Elroy, very fine examples. It is threads like this that makes me wish I had a camera to take a picture of my old Stewert Warner mechanical tach likely from the 50's or therabouts. My SW came in a yellow and blue tin can complete with instructions and literally looks like the old SW dash gauges from the same era. Man I wish I had a pic to post! Thanks Elroy!

UB , Does it look like this one on the right? The left one is a Briggs & Stratton tach used for lawn mower engines.

Uncle Buck · May 23, 2008

russlaferrera said:
UB , Does it look like this one on the right? The left one is a Briggs & Stratton tach used for lawn mower engines.

Yes it does, you beat Wil to it. I have only used it a couple of times, but I think it is really cool. Now that I think of it I believe you can still buy them new! :thumbup:

Phatsub · May 23, 2008

eschoendorff said:
No third person? Elroy must've been pretty excited!

That was my first thought as well.

wilbilt · May 25, 2008

hholmberg said:
That would be very cool Wil, I now owe you an icy cold one!

I'll take a rain check on that cold brew until I figure out how to take decent close ups....

Uncle Buck · May 25, 2008

wilbilt said:
I'll take a rain check on that cold brew until I figure out how to take decent close ups....

Pity so much of the plating is gone, I am sure it came to you that way. Do you still have the storage can and instructions etc? I lucked out, mine is like brand new! Thanks for posting pics Wil! :beer:

wilbilt · May 25, 2008

hholmberg said:
Pity so much of the plating is gone, I am sure it came to you that way. Do you still have the storage can and instructions etc? I lucked out, mine is like brand new! Thanks for posting pics Wil!

I got it just the way you see it. The back was painted black and most of the paint is gone. There was a rubber cap on the drive end that has since disintegrated. I have some brake line plugs that fit, though.

Uncle Buck · May 25, 2008

wilbilt said:
I got it just the way you see it. The back was painted black and most of the paint is gone. There was a rubber cap on the drive end that has since disintegrated. I have some brake line plugs that fit, though.

What a shame, they make a tidy presentation when in like new condition with the rubber tips and what not. :beer:

Elroy · May 25, 2008

Handy little tool you got there. Any tool box would be would look better equipped with such an instrument. Thanks for posting.

Uncle Buck · May 25, 2008

Elroy said:
Handy little tool you got there. Any tool box would be would look better equipped with such an instrument. Thanks for posting.

No thank you for starting the thread, I never dreamed that hand tachs would ever be a topic of discussion on the board. I also have a Starrett hand tach is anyone else familiar with their version? :headscrat

eschoendorff · May 26, 2008

hholmberg said:
No thank you for starting the thread, I never dreamed that hand tachs would ever be a topic of discussion on the board. I also have a Starrett hand tach is anyone else familiar with their version?

No, but I'd love to have one.

Okay, a little off topic (WAY off topic

), but these older tachs got me thinking of this...

one of my vintage musician's tools is an old wind-up pocket metronome given to me by my (now deceased) mentor and friend:

Elroy · Apr 18, 2009

If any one would be interested a fine Stewart Warner tachometer, there is currently one being offered by BWM here:

http://www.garagejournal.com/forum/showthread.php?t=34339

sk farmer · Apr 18, 2009

when i purchased my atlas lathe at auction, there was a pencil shaped tach of unknown origin with the accessories and attachments. sometime between the purchase and loading someone thought they needed it worse than me.

i have never seen another like it. i also have a s-w tach. only mine came in a round styrofoam holder and plain box. :headscrat

it appears to be of the same quality though.

Mezzanine · Apr 18, 2009

There is still one old steam turbine at work that has a reed tachometer on it... Doesn't appear to have been functional in some time though. I might have to pull it off and see if I can make it work! Or perhaps post some photos.

speed bump · Apr 18, 2009

One of my favorite professors started out in life as an ME at Colstrip Montana coal fired power plant and thus when he taught Kinematics that Frahm Tach in the first picture was one of his demonstration tools on some of the tools you used to balance machinery.

Square Face Tachometer

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