# INFO WANTED on (Tachometer for under $25 dollars)



## oldgascar (Mar 3, 2013)

Aboout a week or so ago,  I read with excitement, a posting about setting up a tachometer on a lathe etc.  for under 25 dollars. 
The original post and and others adding to it seemed to have disappeared.(wierd) 
 I was either  smart enough or lucky enough to have printed out the ebay listing,  so I have that info to  make the tachometer purchhase. (no optical sensor included with the tach) 

But now I am looking for the info on the actual sensor whhich was  was used by the original poster, or if someone knows if another will work.  I think I have an answer , but I would liike to see any of the orig. post.   I know one group member, I think he is from Australia (spelling ?) anyway, his name is Martin and he wrote about his setup & I beleive he even had posted photos of the sensor setup on his belt driven bench lathe.
So, Martin , if you see this ciould you re post your info or send mme a privatee email ? 

Thanks,

Bob Ferry


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## pdentrem (Mar 3, 2013)

The sensor was from Littlemachineshop.com. I will see if I can find it for you.
Found my copy in the files.

Quote:
I posed a question last week concerning installing a tachometer on my HF 7x10 lathe.

I have it built and thought I would post a thread showing what I did.
I can't show you what the installation looks like because I don't have my lathe assembled, so the tachometer isn't on the machine yet.
I did put the interrupter wheel on my ShopFox 6" lathe (Sieg C1) to test it and it worked great, but I had to hold the sensor in place.

I got the tachometer unit for $10 here:

http://www.ebay.com/itm/280938832325...84.m1439.l2649

Of course, since I bought mine a couple of weeks ago, it has gone up to $11.49.
It's still a good deal.

I bought the sensor harness for $10.51 here:

http://www.littlemachineshop.com/pro...1945&category=

These sensors are also available in several different styles, including some that are reflective instead of slotted, on eBay for as little as $1.50. Search for opto interrupter. I bought mine from LMS because it included the bracket.

I also bought the interrupter wheel from LMS for $5.95 here:

http://www.littlemachineshop.com/pro...1946&category=

None of these parts are absolutely necessary, except for some type of sensor. They just made the build easier for me.
If I had been out to save money, I would've just bought the sensor and fabricated everything else. The tachometer is programmable, so you can use whatever number of slots that you wish, including just one. You can also use the reflective type sensor which would require the use of small pieces of reflective tape, if you don't want to use an interrupter wheel.

I also found an old 12 volt wall transformer to use as a power supply.

After I got the parts together, I came up with the schematic.


tachometer Input.pdf. (PDF DOES NOT WORK SORRY)

The box marked "Original Circuit" is the circuit in the harness I bought from LMS except I had to change the resistors.
R1 is to bias the detector. R2 is to bias the LED since I changed the power supply to 12 volts.
The rest of the circuit is an amplifier to increase the current for input into the tachometer.
I had to play around with the resistor values. I did current calculations and the values weren't quite right, so I had to adjust the values. I was able to get the tachometer to work without the additional amplifier (just using the original circuit) but the current was near the limit of the detector, so I didn't know if it would last for extended run times.

Below is the amplifier circuit I built.


If you look at the picture, you will see an LED that is not in the circuit.
I put it in adjacent to R5, between tachometer pin 1 and pin 5 connections.
It is there as a test display to make sure the circuit is working.

It is a very simple circuit. It only has three resistors and a transistor.

Once I get my lathe assembled, I plan on installing the tachometer inside the motor control circuit box.I believe there is room right under the switches and speed control. Once I get to the permanent installation, I'll cut the empty space from the board. It's going to be a tight fit.

If you fabricate your own interrupter wheel or use a reflector sensor, I think it would be possible to build the whole thing for under $20.
End Quote:




Pierre


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## oldgascar (Mar 3, 2013)

The sensor is a reflective sensor only. I will not be using a wheel to pass thru a sensor head. I want yo use reflective tape. I will try to contact LMS to see if they have available a sensor for reflective tape.


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## pdentrem (Mar 3, 2013)

Martin listed Omron EE-SPY as his sensor.
Pierre

PS I hope I did not step in it by posting what I had found in the earlier reply.


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## Rbeckett (Mar 4, 2013)

Pierre,
If you would like, you can email me the PDF and I will get help to post it into the archives so that it will remainn available for others to see and use.  You can PM me and I will give you my street email address and you can do a cut an paste of the info and I will do the rest for you.  Hope this helps.

Bob


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## pdentrem (Mar 4, 2013)

The PDF is the one item that did not get copied properly, so it is lost on my system.
Pierre


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## JoeSixPack74 (Mar 4, 2013)

There was also a nice write up that a guy from down under wrote.  He was using this sensor:

http://www.ebay.com/itm/140569354266?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

I already have the tachometer from eBay and once I get the sensor I will post how I hooked it up.


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## Splat (Mar 4, 2013)

Here's the no-contact sensor I ordered after reading many good reviews on it. Either affix the reflective tape to your chuck or maybe put a threaded collar on the outboard side of the spindle and affix it there. Remember, we're talking about RPM, not SFM, so diameter of chuck doesn't matter.


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## iron man (Mar 4, 2013)

I have one of those and it is not worth the plastic it is made out of. You can get ten different readings after ten different trys at the same speed not knowing which one is accurate. I also tried it on a known RPM and it was off by a little over 200 rpm. Ray


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## Dr.Fiero (Mar 4, 2013)

Aha!  Being a file-pack-rat FTW....

(hope that's what you wanted anyhow!)


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## Splat (Mar 4, 2013)

iron man said:


> I have one of those and it is not worth the plastic it is made out of. You can get ten different readings after ten different trys at the same speed not knowing which one is accurate. I also tried it on a known RPM and it was off by a little over 200 rpm. Ray



Well yours is the first I have heard of anyone having a problem with that one. I've heard all positives but you can get a lemon in anything.


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## iron man (Mar 4, 2013)

Splat said:


> Well yours is the first I have heard of anyone having a problem with that one. I've heard all positives but you can get a lemon in anything.



 It could be a lemon sometimes it reads right but it is so inconsistant I never know for sure what is correct and what is not. Maybe there is not as many complaints because the user is taking the reading there getting as correct if you dont have anything to check it against or compare then I guess there would not be a problem.... In that case mine would be fine.. Ray


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## oldgascar (Mar 4, 2013)

Thanks to all who helped me find the info. I placed my order for the tachometer & sensor.(Actually 2 of each). 
I hope they work out for me.

Again thanks to a great group of people of this group.:goodjob2:

Bob Ferry

"oldgascar"


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## Dr.Fiero (Mar 6, 2013)

I got my sensors and wheels in the mail from little machineshop the other day - but the tach(s) it/them selves are still in transit. Usually takes about 3 weeks from HK to me.

The wheels from LMS are far too small for my machine (they're less than 3 inches OD), so I'm going to just mill out a set on my CNC router (it's only thick sheet metal, so should be pretty easy at a slow feed rate).


I also just today ordered up a mag pickup like this -> 
	

		
			
		

		
	



	

		
			
		

		
	
 , so I'm going to play with that route as well and see how it works (I'll report back either way!).


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## Splat (Mar 7, 2013)

Down the road I might get a *Tachulator *from MKC Tools. Nice little setup and will do SFM or RPMs. It ain't under $25 but from all the reviews I've read it's a competent setup.

PS, forgot to say that I'm curious about the Arduino stuff and might build my own if I can find reliable plans. Anyone got any?


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## Dr.Fiero (Mar 13, 2013)

Partially just to keep the the thread alive....  but...

My tach displays showed up in the mail today!

I got 'carded' on another package  (that the posty didn't even TRY to deliver!  And I have security camera proof - grrrrrrr) that could have been the other parts.  
Won't know until tomorrow now when it becomes available for pickup at the post office.

I'll post some play by play photo's when all the parts are here.


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## oldgascar (Mar 13, 2013)

Dr.Fiero said:


> Partially just to keep the the thread alive.... but...
> 
> My tach displays showed up in the mail today!
> 
> ...






I also  received my 2 tachs in the mail today.
My sensors are still on their way from South Korea.

Bob


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## oldgascar (Mar 14, 2013)

Does anyone know the group member MARTIN in Australia who posted pictures of his set up of his tachometer and sensor?. i would love to see those pictures again.

This is kind of "WHERE'S MARTIN" instead of "WHERE'S WALDO"

Thanks, 

Bob


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## Dr.Fiero (Mar 14, 2013)

Nope. Wasn't the other sensor (but it was some engraving bits I've been waiting on!).

I did bench test the tach though. Powered it off a bench supply with ~13v.
Fed it a 3.5V square wave from my signal generator.
Ran it from about 50hz, up to 100khz.  Worked fine! Almost perfect 1:1 ratio.

Now...  anyone have the poop sheet on setting it up? Can't seem to find it...


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## toolman49 (Mar 14, 2013)

Hi Fellas,
I haven't been eaten by a feral kangaroo, just busy with real (paying) work, just guessing, but maybe the post was deleted due to oversize photos. Have re sized them, sorry about the quality of the wiring diagram it's a back of an envelope job.
Regards,
Martin
Oops: RL should be 1000 ohms


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## oldgascar (Mar 14, 2013)

Hello Martin,
 It's Great to hear from you. I was getting worried and was just about to send out Crocadile Dundee to find you  :lmao: .  I am so glad you reposted the pics and the drawing is fantastic.

I just received my sensors from Korea today &  I received my tachometers from China yesterday.  I will place one of these on my mill drill, and one on my lathe.

I am trying to fit in (and finish) these projects and a few others before my grandson is born (due on March 29th, but I beleive he will decide to come early). Then Grandma and Grandpa will be on baby holding duty & loving every minute of it. )

Anyway, thanks so much for reposting the info and adding the drawing.


Bob


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## toolman49 (Mar 14, 2013)

Hi Bob,
For a living I service Mail processing machinery, with billing cycles, the first and last weeks of the month are fairly busy. hence the delay in replying.  I have also fitted a tacho to my RF 31 mill drill, it runs off a reflective sensor mounted to the under side of the belt cover looking at the spindle pulley which is polished and painted black for 50% of it's surface. the main reason for fitting it even though it has a fixed speed motor is that I am pretty lazy about changing belt speeds and it is a nagging reminder. If you let me know I will post some photos. I have the luxury of a 1 1/2 H.P. variable speed D.C. motor on my lathe and when I get my hands on another decent quality motor I will do the same to the RF 31.
Regards,
Martin


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## oldgascar (Mar 15, 2013)

Martin,

My lathe is the same as yours. How much reflective tape do you have on the spindle , how long and how wide is the tape?
 Did you pant the rest of the spindle black? If so, I presume it is a dull flat black, is that correct ?
If you can post the mill drill pictures I would like to see them. The casting on my mill drill had a few cracks on it.  I just got it back from a frirend who welded it up. Now I need to clean it up, paint it and reassemble it.

Thanks,

Bob


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## toolman49 (Mar 15, 2013)

Hi Bob,
The black on the spindle is just a wrap of black electrical tape, the reflective tape is about 15 x 30 mm. The sensor on the RF 31 is a Sick that was in the junkbox.
Regards,
Martin


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## oldgascar (Mar 20, 2013)

Martin, what is the distance you keep between the sensor and the spindle ?
When you turn on the lathe, does the tachometer have a quick response time ?

Are you sure of the value of the resistor RL being 1000 ohms ? I set mine up with reflective tape on the chuck of my drill press just to test it out . I held the sensor with my hand and I had very erratic readings . Does your tachometer  always give the same values (or very close) if you turn on and off the spindle mutiple times.

Anyway, if you get a chance to give me a few answers, i would appreciate it.

Thanks,

Bob


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## toolman49 (Mar 22, 2013)

G'Day Bob,
The spindle to sensor distance is about 3 mm, the load resistor could be replaced with a pot of say around 5 K ohms if you want play around with the load. My tacho stabilizes within about 2 seconds of start up and remains constant, when changing speeds the tacho responds and stabilizes within about 1 second. One of the guys down claims his was more stable after he fitted 4 reflective strips around the spindle and adjusted the multiplier to suit. Hope this helps,
Regards,
Martin


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## Dr.Fiero (Mar 25, 2013)

Since things tend to get lost over time, I thought I better grab, edit, and archive the info on the digital tach itself - after realizing it had never been mentioned!

Measurement accuracy
0.1%±1digit / Special: 0.01‰ @ 25℃
Measure Range
0.15HZ—100KHZ
9r－999.99Kr/m
input signal
Signal Type
Dry contact、PNP、NPN、Pulse
amplitude 3－30V or 30-300V(High Voltage)，this could be changed via adjust the Short circuit
Measurement Method
Full synchronization period measurement
Input Resistance
100KΩ
Power Supply
DC9-12V
Vibration Frequency ：10－55HZ，  Acceleration: 50m/s2     X、Y、Z, each direction 5min X 10
  Operating Temperature  and Humidity
Temperature:－30℃－＋70℃ Humidity:　25－85%　RH
Panel Dimensions(mm) 79X43X25（L×W×H)
Cut-out Dimensions (mm ) 75X39.5


Function Selection:

    •    Frequency and Rotate speed display Set
         (Please disconnect the input signal before setting when the input signal is High level voltage signal)
Open the back cover of the meter,
Press "S2" key to enter "SET" model and then press "S1" to change display mode,
"0" means Frequency display with filter ;
"1" means rotate speed with filter;
"2" means Frequency display without filter ;
"3" means rotate speed without filter.
10 seconds later, this meter will automatically return to the measurement mode, or power-off and restart, this meter still could return to measurement mode too.
    •    Divider Value Set
(Please disconnect the input signal before setting when the input signal is High level voltage signal)
Open the back cover, press the "S1" key to enter the Sub-frequency Value Set interface,"S1" key   is the shift key, "S2" key is the value plus key, the divider value must be set in 1-99999 or 0.0001-9.9999 figures, and   other value is invalid;After the set of the desired divider value via "S1" and "S2", wait   10 seconds and the meter will automatically return to the measurement mode, or power-off and then restart to return to the measurement mode .
Divider concept:
The number of the signal the gears get for one circle. For example, a gear can take  20 pulse signal for one circle , the divider value could be set to 20.
    •    High and Low voltage signal input switch
The default set for this meter is the low voltage input, if you need high-voltage input, you need to open  the back cover the more the short jumper from the "L" part.            
1: SIGNAL INPUT     
2: SIGNAL GND
3: NC
4: INPUT VOLTAGE "-" : GND
5: INPUT VOLTAGE  "+" : VCC


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## arlo (Mar 30, 2013)

Splat said:


> Down the road I might get a *Tachulator *from MKC Tools. Nice little setup and will do SFM or RPMs. It ain't under $25 but from all the reviews I've read it's a competent setup.
> 
> PS, forgot to say that I'm curious about the Arduino stuff and might build my own if I can find reliable plans. Anyone got any?



Are you interested in using an Arduino with a Hall Effect sensor as a  tachometer?  I've put together a prototype that seems to work although I  haven't yet done a thorough job of checking it out.  Also, I'm still  experimenting with magnets and sensor positioning.  I'm concerned about the reliability/repeatability, too. I use an LED that flashes when the Hall Effect sensor is triggered.  That let's me position the sensor and get immediate feedback on whether it's reading pulses or not.  
	

		
			
		

		
	




	

		
			
		

		
	
 The first photo shows a ring magnet on a brass rod.  The sensor is to the left.  This configuration doesn't work as well as some others I've tried.  The second photo shows the LCD display.  The green LED on the left is the power indicator.  The Blue LED on the right indicates when pulses are received.  I think typically tachometers allow a selectable period of time to elapse and count the pulses during that period.  My approach is to count some number of pulses ("Samples" on the LCD) and then figure out how much time has elapsed.  The switch on the box allows changing the number of samples.   The default of 100 is okay for RPMs of 600 or more (for 600, it takes 6 seconds to get a valid reading) but for a rotation of 100 RPM, it would require a full minute and I thought this would be too slow.  The switch allows changing the sample size in steps of 10 from a minimum of 20 to a whole bunch.

If this is interesting, let me know and I'll post my conclusions when I'm satisfied with the tach.  I use the Arduino IDE and the program is in that format.  The circuit is pretty simple and, except for the LCD and the Hall Effect Sensor, all the parts came out of my junk box.


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