# Tachometer Kits / Installs



## TX COWDOC (Sep 21, 2020)

I'd like to install a tachometer on my PM1236 while I am setting it up.  Any suggestions / guidance?


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## Z2V (Sep 22, 2020)

I use this one on my band saw, seems to serve its purpose. I use the MachTach on the mill but no longer available, unfortunately.


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## mksj (Sep 22, 2020)

Along the same lines, I just installed this one from Amazon in a recent build. At least the instructions were in English.





						uniquegoods LED 4 Digital Tachometer RPM Gauge Speed Meter Tester 10-9999 RPM with Hall Proximity Sensor NPN Switch Red: Amazon.com: Industrial & Scientific
					

uniquegoods LED 4 Digital Tachometer RPM Gauge Speed Meter Tester 10-9999 RPM with Hall Proximity Sensor NPN Switch Red: Amazon.com: Industrial & Scientific



					www.amazon.com
				




The VFD speed pot is integrated into the same Hammond Diecast box, I tap 2 holes in the back for mounting a L bracket. I typically mount these under the DRO if you have one, otherwise near the headstock away from flying oil and chips. RPM meter still has plastic covering on the display. Note that all these RPM gauge's hall sensor will only work with the correct magnet polarity, so mark the magnet as to the end that faces the hall sensor. You can check it by powering it up (can use a 9V battery) and then placing the magnet in front of the hall sensor and the LED light should flash on with the correct polarity.  You can use electrical tape to temporarily hold the magnet to the spindle. Gap between the hall sensor and magnet is around 0.1-0.2", these use only one magnet. They are surprisingly accurate.


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## davidpbest (Sep 22, 2020)

Nice bench Mark.  How about a YouTube tour with all your tool recommendations.


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## TX COWDOC (Sep 22, 2020)

mksj said:


> Along the same lines, I just installed this one from Amazon in a recent build. At least the instructions were in English.
> 
> 
> 
> ...


How hard is it to wire one of these in? I have decent electrical skills on big stuff i.e. wired my shop etc. but this is intimidating! 
Can you post a pic of how you mounted it relative to the DRO? Many thanks!


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## mksj (Sep 22, 2020)

There are 2 wires for power which is typically 12VDC (about 50 mA), so need a small DC power supply or they have 24VAC to 12VDC step down converters that one can use power from your 24VAC transformer used for lights and the contactors. There are 3 wires used to connect to the hall sensor. They are all color coded and numbered so just connect the wires per the instructions.

MachTach install, these kits are no longer available.


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## helmbelly (Sep 22, 2020)

This handheld is in my cart for $15. I just need to check RPM periodically. https://www.amazon.com/gp/product/B004Q8L894/ref=ox_sc_act_title_2?smid=A1BREQ8I6OHSBG&psc=1


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## fixit (Sep 23, 2020)

mksj said:


> There are 2 wires for power which is typically 12VDC (about 50 mA), so need a small DC power supply or they have 24VAC to 12VDC step down converters that one can use power from your 24VAC transformer used for lights and the contactors. There are 3 wires used to connect to the hall sensor. They are all color coded and numbered so just connect the wires per the instructions.
> 
> MachTach install, these kits are no longer available.
> View attachment 337891
> ...



How in the HELL do you do work and keep your equipment that clean? I just spent 2 hours cleaning my lathe and it's still bad compared the this.


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## TX COWDOC (Sep 23, 2020)

Here's the 2 parts I THINK will work.  What wire size is needed to go from the machine to the converter? 12/2 romex? (This part is a joke  )






						Amazon.com : Urban Security Group 24V AC to 12V DC Converter Adapter : 2.5A : Go from AC to DC Power : Input: 20-30VAC : Output: 12VDC 2.5A : Removable Terminal Block : Full Wave Rectifier : Camera & Photo
					

Amazon.com : Urban Security Group 24V AC to 12V DC Converter Adapter : 2.5A : Go from AC to DC Power : Input: 20-30VAC : Output: 12VDC 2.5A : Removable Terminal Block : Full Wave Rectifier : Camera & Photo



					www.amazon.com
				









						DIGITEN 4 Digital Green LED Tachometer RPM Speed Meter + Hall Proximity Switch Magnet Sensor NPN for Lathe Conveyor Belt: Amazon.com: Industrial & Scientific
					

DIGITEN 4 Digital Green LED Tachometer RPM Speed Meter + Hall Proximity Switch Magnet Sensor NPN for Lathe Conveyor Belt: Amazon.com: Industrial & Scientific



					www.amazon.com


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## mksj (Sep 23, 2020)

Wire is only carrying about .050A so use 18 or 20AWG. This is from the 24VAC (not 204VAC), wire to the converter and then from there to the input power of the tachometer. The Hall sensors are wired slightly different, essentially a negative and positive power, and a wire that electrically sends a pulse open to closed when the magnet is in front of the hall sensor. Wires to the hall sensor take about 10 mA, you can use anything from 18-22AWG, nothing special.


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## tjb (Sep 23, 2020)

davidpbest said:


> Nice bench Mark.  How about a YouTube tour with all your tool recommendations.


Ditto


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## Sparweb (Sep 24, 2020)

I recently ordered this:





						Digital Red LED Tachometer RPM Speed Meter Gauge Hall Proximity Switch Sensor for sale | eBay
					

Find great deals on eBay for Digital Red LED Tachometer RPM Speed Meter Gauge Hall Proximity Switch Sensor. Shop with confidence.



					www.ebay.ca
				




It should be here fairly soon


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## TX COWDOC (Sep 25, 2020)

Next question: Installation......What is the best way to secure the magnet to the spindle?


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## DavidR8 (Sep 25, 2020)

TX COWDOC said:


> Next question: Installation......What is the best way to secure the magnet to the spindle?



I was planning to drill a hole and just drop the magnet in. Maybe with a dab of epoxy but if it’s a rare earth magnet those things hold fast. 


Sent from my iPhone using Tapatalk


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## mksj (Sep 25, 2020)

Depends on what you are mounting it two. If to the spindle, people often just use some electrical tape, but not a long term solution. If a spider, then I drill a shallow hole so it sits flush in the hole and you can use some metal epoxy.  Many of the magnets are metric in diameter so need a metric drill to get a press in fit, then I use red Locttite. I no spider I make an aluminum ring and mount the magnet to that., use a small set screw to hold it in place.


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## NCjeeper (Sep 25, 2020)

TX COWDOC said:


> Next question: Installation......What is the best way to secure the magnet to the spindle?


I just have my magnet in one of the D1 holes. If I need to change chucks I just pluck it out.


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## TX COWDOC (Sep 25, 2020)

mksj said:


> Depends on what you are mounting it two. If to the spindle, people often just use some electrical tape, but not a long term solution. If a spider, then I drill a shallow hole so it sits flush in the hole and you can use some metal epoxy.  Many of the magnets are metric in diameter so need a metric drill to get a press in fit, then I use red Locttite. I no spider I make an aluminum ring and mount the magnet to that., use a small set screw to hold it in place.


Thanks for the replies.  Mark, that is the solution I am looking for.  I'll proceed with the aluminum collar / ring.  Thanks!


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## davidpbest (Sep 25, 2020)

Here's another example.   This is my PM1340.  The spider has the magnets for the tach sensor, the tach sensor mounts to a custom ring installed over the spindle end-mount.  More *details here*.


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## TX COWDOC (Sep 26, 2020)

mksj said:


> There are 2 wires for power which is typically 12VDC (about 50 mA), so need a small DC power supply or they have 24VAC to 12VDC step down converters that one can use power from your 24VAC transformer used for lights and the contactors. There are 3 wires used to connect to the hall sensor. They are all color coded and numbered so just connect the wires per the instructions.



I have the wire, connectors, and transformer. I plan to rough-in so to speak the transformer so that I can close the panel and finish setting up the lathe this weekend.  I will then mount the tachometer etc. at a later time.  As you know the electrical panel is a busy place.  Any guidance on where on the lathe circuits to attach the 18AWG from the transformer?  Thank you!!!!


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## middle.road (Sep 26, 2020)

After seeing the two lathes above I'm going off somewhere and hanging my head in shame...


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## Skowinski (Sep 26, 2020)

How difficult would it be to use one of these kits readouts to replace the one that came in my 833TV mill?  Now that I've used this thing some I'm finding the digital readout isn't very easy to read when the bright shop lights are on.  It's reading 394 RPM's in this photo....


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## Sparweb (Oct 4, 2020)

So far nothing as pretty as what others have installed, but here what I've done so far.  The display is "permanently" installed, the sensor, not so much, but a simple set-up to determine that it works and will run well this way:







It was working great for a while, then it started doing this:





The display goes blank for a few seconds, then the right digit fades in, then the next digit fades in, then it comes back for a while.  This cycle repeats every 3 or 5 minutes.  Any thoughts about what might be happening?


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## mksj (Oct 4, 2020)

Skowinski said:


> How difficult would it be to use one of these kits readouts to replace the one that came in my 833TV mill?


I would get some Matt anti-glare screen plastic typically used on phones screens and tablet screens. They have a self adhesive back, cut it to fit the tach display window, some have slight darkening or color enhancement filters. The plastic one for phone screens are a few $, worth a try. The tach pickup on mills varies, some use an output from the drive that runs the tach display, others use a hall sensor and magnet(s) on the spindle. The latter is doable but can be a challenge on a mill. Mills with a back gear, you need to have a tach pickup off the bottom of the spindle.


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## DavidR8 (Oct 8, 2020)

The tach I bought (the one in post 12) says it requires 8-24v 40 mA.
I have a variable voltage power supply but it produces 2100 mA.
I noticed in post 9 above that the DC power supply produces 2A 
Is it ok to 'over supply' the tach with 2.1A or am I going to cook it?


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## .LMS. (Oct 8, 2020)

I would think you'd be okay - it should only draw what it needs to.   Overkill, yea....


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## Spotshooter (Oct 9, 2020)

I need to find a nice small box to put my tach in and mount it below my DRO...


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## Papa Charlie (Oct 9, 2020)

Spotshooter said:


> I need to find a nice small box to put my tach in and mount it below my DRO...



Just do a Goggle search for "Electronic Enclosures". You will find a seemingly sea of different size, shape, materials, etc. Probably one of the easiest parts of most builds.


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## Sparweb (Oct 10, 2020)

@Spotshooter
Let me introduce you to Hammond: http://www.hammondmfg.com/EE_Index.htm
A very wide range of enclosures, many suitable for DIY kits

@DavidR8,
The power supply sounds fine.  Your tach can accept various voltages and the power supply will deliver it.  The tach needs less than 100 mA to run but the power supply can deliver up to 2A so again, it's OK.

FYI,
To get DC for my tachometer, I used a bridge rectifier across my Lathe's 24VAC transformer secondary coil.  This is producing 24 * 1.41 = 34 VDC for my tachometer, but the tach doesn't seem to like it - too much voltage it seems.  I am going to swap this for a mini-laptop power supply which will take 110VAC and produce 18VDC which is perfect for the tach and less likely to have ripple, too.  I with I'd thought of this before, actually.


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## DavidR8 (Oct 10, 2020)

Sparweb said:


> @Spotshooter
> Let me introduce you to Hammond: http://www.hammondmfg.com/EE_Index.htm
> A very wide range of enclosures, many suitable for DIY kits
> 
> ...



I also have a laptop power supply I can use. 


Sent from my iPhone using Tapatalk


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## silence dogood (Oct 10, 2020)

I went way low tech. Made a calibrated knob with a  HF photo sensor tachometer and added pointer.  Not as charming, but works fine with my LMS 3960 mill.  Sorry the picture not better.


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## rogerl (Oct 10, 2020)

When I installed my tachometer I just used a 9 volt battery to power the tach. My drive had a contact that closed when the drive was running so I used it to turn on my tachometer. The only time the tach is on is when the drive is telling the motor to turn. No risk of leaving the tach on and running down the battery. So far I have not had to replace the battery yet so I do not know what the battery life will be. Simpler than wiring a power supply.

Just my 2 cents
Roger L


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## B2 (Oct 15, 2020)

Hi Roger,
Nice idea.   I did something similar with a sensor control for turning on our garbage disposal.  There the power required was 220V 20Amp circuit.  I turned the disposal on with a Solid State Relay  and turn on the SSR with a Reed switch via a set of 4 AA batteries.  The Reed Switch is closed via a magnetic field and I placed it under the counter top out of sight and out of the water etc.   No electrical switches exposed. My wife has a very small, decorative, flower vase on the counter with the magnet inside and she just moves it over the sensor to turn on the disposal.  Anyway, the only time power is taken from the batteries is when the disposal is running. I installed it around 2011-2012 and have yet to need to change the batteries.   I also wired in a three position toggle switch so that I could turn it on manually (no batteries), turn it off completely (safety), or only allow the magnet to run the device. 

I have been thinking it would be nice to have a tach on my lathe spindle, but hate to attach a magnet to the spindle.   I am curious how you mounted your tach sensor and magnet. 

Dave L.


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## rogerl (Oct 15, 2020)

Attached are some photos of my install. I have an Automation Direct VFD in the box I made to hold it. The tachometer power is wired to a relay output from the drive the the tach only works when the motor is running. The lathe is a South Bend 11 swing. The headstock has the 7/8" hole thru it. I made an aluminum adapter that I pressed on the small hub on the gear at the end of the spindle. The magnet holder attaches to the adapter with a small setscrew. The prox switch is mounted to the guard. I needed to machine the guard a little to get a flat surface for the prox switch mounting block  to mount. Lots of work to get the magnet and switch to mount but there was no better place to put it.

Thanks
Roger L


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## B2 (Oct 16, 2020)

Thanks Roger,
Nice install.
Maybe I can try a press fit a magnet holder on my lathe.  I will have to check it out to see where I can attach the sensor.  I have not been able to find a Tach with a smaller display.  I have a purchased a volt meter type display that is about 69mm x 26mm. My VFD puts out a 0-10Vdc signal corresponding the the maximum motor frequency,which  I have set to 100 Hz.  I.e 10 volts = 100Hz.  However, this is not really the spindle RPM as one changes gears.  It will fit in my lathe control panel, but all of the tach readouts I can find are about twice this size and do not fit very well.  

Good night
Dave


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## TX COWDOC (Jun 18, 2021)

Finally got around to finishing my tachometer project.  Lots of credit to Mark for the technical advise on connecting the power supply and producing the spindle collar with magnet.  Fit like a glove.  I went with a different approach on the reader support collar and made one out of stock material from McMaster.  Took very little machining.

Multipurpose 6061 Aluminum Round Tube, 1/2" Wall Thickness, 4-1/2" OD 








						McMaster-Carr
					

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.




					www.mcmaster.com
				




As it turns out, the PM1236 spindle rotation is 10-15% faster than the chart.


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## Ken226 (Jun 18, 2021)

TX COWDOC said:


> Finally got around to finishing my tachometer project.  Lots of credit to Mark for the technical advise on connecting the power supply and producing the spindle collar with magnet.  Fit like a glove.  I went with a different approach on the reader support collar and made one out of stock material from McMaster.  Took very little machining.
> 
> Multipurpose 6061 Aluminum Round Tube, 1/2" Wall Thickness, 4-1/2" OD
> 
> ...



I installed one of these in both my lathe and mill when I did my 3 phase motor / VFD upgrades.   They take a few seconds of running before they display an accurate speed, but work rather well considering the low cost.

I found and used 120v versions from Amazon, as my lathe only had 240v and 120v ac transformers in the electronics enclosure.  My contactors all have 120v ac coils.

A short video overview.


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