# Tach on a LMS 5100



## Scorn64 (Jan 30, 2021)

Has anyone figured out the pinout of the tach output on a LMS 5100 relative to the TouchDRO board tach input? I would like to integrate the RPM from my lathe into Touch DRO.

Thanks,
Scott


----------



## ycroosh (Jan 30, 2021)

Scott,
I haven't tried that particular machine, but in theory it's pretty straightforward:
There are three Hal effect sensors on the brushless motor that output 5V pulses (once per revolution each). 
If you use TouchDRO adapter for glass scales, you might be able to just connect one of those directly to the board (on my mill the inputs on the controller board are pulled up, so a direct connection work fine). For other adapter versions you will need to add a high impedance level shifter to bring the voltage down to 3.3V. You probably won't be able to use a simple resistor divider, since that will mess up the original controller board's signal. 
Hope this helps
Yuriy


----------



## llamatrails (Jan 30, 2021)

For info on the Seig tachometer, which the LMS line of mills and lathes uses, check out these pages: Hacking the SX2 Mini Mill .  Specifically, this page: Pin outs and Protocol .

Rick


----------



## ycroosh (Jan 30, 2021)

Rick,
This is the complicated way. Using pulses from the sensor is much simpler and doesn't require any decoding.
Yuriy


----------



## llamatrails (Jan 31, 2021)

The OP asked for info on the pinouts for the tach used on the lathe.  I agree that the provided tach output won't integrate easily with the TouchDRO.  Not what I'd recommend.

I used the linked macpod info to make my own external tach for my LMS 3900 mini mill as it was easier (and safer) for me than to dig into the controller to find the raw sensors.  Grizzly sold me the external tach board part for a lot cheaper than what LMS wanted for the complete tach.

On my PM 1236T I used a simple optical sensor on the back side of the spindle into the TouchDRO board and it was way cheaper and easy.


----------



## ycroosh (Jan 31, 2021)

llamatrails said:


> The OP asked for info on the pinouts for the tach used on the lathe.  I agree that the provided tach output won't integrate easily with the TouchDRO.  Not what I'd recommend.
> 
> I used the linked macpod info to make my own external tach for my LMS 3900 mini mill as it was easier (and safer) for me than to dig into the controller to find the raw sensors.  Grizzly sold me the external tach board part for a lot cheaper than what LMS wanted for the complete tach.
> 
> On my PM 1236T I used a simple optical sensor on the back side of the spindle into the TouchDRO board and it was way cheaper and easy.


Well, direct quote "I would like to integrate the RPM from my lathe into Touch DRO." (see in the OP's post), so I made a bold assumption that he wanted to integrate it with TouchDRO, but I might be wrong.


----------



## llamatrails (Feb 1, 2021)

I responded to the first sentence, and you the second.  I hope we both gave him enough info to proceed from here ...


----------



## ycroosh (Feb 2, 2021)

llamatrails said:


> I responded to the first sentence, and you the second.  I hope we both gave him enough info to proceed from here ...


Team work at it's best


----------



## Scorn64 (Feb 4, 2021)

Sorry, got tied up with work. I appreciate your help. It was to integrate with TouchDRO. I was hoping it was more straightforward.


----------



## ycroosh (Feb 4, 2021)

Which TouchDRO adapter do you have?


----------



## Scorn64 (Feb 4, 2021)

I have the DIY kit to be combined with Shahe scales. I’m still waiting on the scales. Should have them next week. I also have a launchpad. I thought I would play with it for the fun of it. My lathe was just shipped so I won’t have it until next week.

It’s not the end of the world to not integrate the tach. I was just hoping it had been done.


----------



## Hard_ware (Feb 7, 2021)

You can mount a magnet to the spindle and use a hall effect sensor to have a tach signal.
I think its the best way as its completely isolated from the lathe.
Get a sensor that will work off 5v to supply pwr from the PCB.






						Amazon.com: Taiss/ 1Pcs LJ8A3-2-Z/AX-5V M8 2mm Sensing DC 5V NPN NC 3D Printer Cylinder inductive Proximity Sensor Switch Work Voltage 5VDC Special for MCU : Industrial & Scientific
					

Amazon.com: Taiss/ 1Pcs LJ8A3-2-Z/AX-5V M8 2mm Sensing DC 5V NPN NC 3D Printer Cylinder inductive Proximity Sensor Switch Work Voltage 5VDC Special for MCU : Industrial & Scientific



					www.amazon.com


----------

