Precision steel touch probe for CNC machines

2015-05-28 20:58 | Categories: CNC, In English, Projektai, Užrašai

IMG_4710_tStarting new project – LP0018D – best in the class digitizing touch probe/edge finder. After long research and many adjustments finally preparation is complete. Time to review first samples. Like all of my previous projects it is funded completely from my pocket, so should be reasonably priced and I am not rushed by crowdfunding bull*hit.


This touch probes is made of tempered steel and electroplated, reference surfaces are grinded after. If this is not enough, it is completely hermetic, and filled with special dielectric fluid (which also enhances contact, stops oxidation, …). And if this is still not enough – all contacts (pins, balls, springs, and PCB will be coated in gold at least). So if you don’t crash it – it will be immortal.

For testing I have made metric 8mm shank. I it will be good enough for most of machinists, but in future if there will be demand I will introduce other accessories.

At first let’s take a look at parts involved in this design. Did I mentioned – all parts are custom made from my carefully selected vendors/manufacturers. To be precise 7 of them.

  • Steel base – hardened and black electroplated and grinded for precise reference surfaces
  • Silicone gaskets
  • Main compression spring
  • Gold plated contact springs
  • Gold plated dowel pins
  • Gold plated steel balls
  • Plastic parts to contain parts
  • PCB (not yet from professional PCB house, but it will be ok for testing)
  • Quick release snap action aviation grade (rated by manufacturer) connector
  • Stylus with 3mm Ruby tip and M3 thread. (Renishaw compatible)


Can be purchased on Kurokesu e-shop







Assembled view


Touch probe external dimensions

Today I just assembled one of these touch probes. Will test later and publish results. Initial tests seems positive. Stay tuned.


3 dowel pins glued unevenly (hey, first try to assembly), so trinocular part is slightly unbalanced. Good chance to calibrate, which is done via 3 set screws in the upper steel part. Here are some results.


Calibration test

Also, did I mentioned I am in love with this aviation grade connector. It makes a pleasant snap when connected.

Snap action connector

Snap action connector

  1. Hello,
    It would send one probe to the Czech Republic?
    Thank you for answer.

    • Saulius Lukšė
      2015-07-21 11:06

      Hi Mirek. Sure, no problem. Please check your email for more details.


  2. Russell
    2015-08-02 16:56

    I bought one of the pre-production units from EBay and I’m very pleased with it.

    I did have a USA made probe but it was poor (impossible to centre and the repeatability was never better then 0.06mm no matter how much I played with speed and debounce). Fortunately(!), I crashed that into my vice and bought one of these probes to replace it.

    I managed to get the new probe on centre to .002mm (the best I can measure with my DTI) with a few minutes tweaking and the repeatability is within 0.008mm probing at 500mm/min.

    Probing at 50mm/min the repeatability goes up to 0.005mm (both figures obtained from a loop of 100 probes writing the result into a file and finding the maximum difference) Perhaps it could get even better with some debounce tuning in LinuxCNC but that’s good enough for me.

    The only thing that confused me slightly is that the probe is not an isolated switch and has both wires grounded through the tool holder when the probe isn’t activated. This meant a slight change to my wiring to use a pullup resistor.

    I’m very happy with this probe and pleased I bought it.

    Well done Saulius.

    • Saulius Lukšė
      2015-08-02 18:32

      Hi Russel,

      I am really pleased you are happy with your new touch probe! Please let me know if you run into some unseen issues. And don’t break it :)


    • 2015-09-04 17:35

      Hi Russel, could you help me with the configuration on LinuxCNC please. I have a couple of touch plates on my Router and don’t like invert the Sauliu’s probe signal by the relay solution.

  3. Paolo Bernardelli
    2015-08-05 16:44

    It’s possible to interface your touch probe with heidenhain tnc 370

    • Saulius Lukšė
      2015-08-05 17:32

      Hi Paolo, my touch probe has closed circuit in 0 position, and circuit breaks when it moves out of resting spot. I am not familiar with TNC370, so please check if it has similar interface.


  4. 2015-08-30 10:43

    Hi, I bought a probe from Wildhorse and I am very saddened by the fact that it is virtually useless, poorly assembled at that point that I was impossiblile calibrate it. Desperately seeking an option with good accuracy and that there is no need to calibrate it every time it is mounted on the spindle. I love LinuxCNC and I would preferably use probe normally open, otherwise I’ll appreciate a help to use your probe without the need to add the classic relay, I mean with a more secure solution like Arduino. I have another normally open fixed probe mounted on my Router that I would like keep with its setting. Can you help us setting your touch probe inverting the signal with Arduino in LinuxCNC. I found this site and suppose you understand russian language.
    Thanks so much in advance.

    • Saulius Lukšė
      2015-08-30 11:14

      Thank you for notes and link. Been in your shoes :) Was looking for a decent touch probe, and decided to make a better one. For me first time calibration procedure took about about 5 minutes. I know some electronics for signal shaping could be implemented, but I decided to go one step at a time. Also there are ideas on implementing wireless (optical) link.

      • 2015-08-30 11:50

        The following lik shows an example “” on CNCzone on how to implement the probe with Arduino in Mach3, it would be very useful not only a tutorial on your touch probe on Windows but also on Linux, with the advent of Mach4 there are more people that pass to LinuxCNC as a more valid alternative to control the CNC. If you are willing to give it a try I would send you an Arduino for the solution that I asked you.
        Thankyou for the promt reply.

        • Saulius Lukšė
          2015-08-30 11:54

          No need to send arduino, have bunch of them in my drawer. Could you please tell me why you need to invert signal?

          • 2015-08-30 12:21

            ,because I have two touch plates on the router, the first is fixed and measures the length of the tool, I need the second plate to find the workpiece zero in Z axis. Both works only NORMALLY OPEN on my BOB, the ground wire is connected to the body of Router and the router bit closes the circuit when it contacts the touch plate, this solution is very simple and effective. In the past I setted the NORMALLY CLOSED Wildhorse probe inverting the signal by a relay circuit, but I don’t like this solution because I had bounce issues on the mechanical switch.

  5. Peter
    2015-08-30 13:36

    Hello, you got a very intresting looking product there.

    I’ve got a couple of questions:

    The probe tip: Where caould i get replacements if it brakes? Is it a standard part?

    Is it able to probe both axial and Radial?



    • Saulius Lukšė
      2015-08-30 13:58

      Hi Peter,

      thank you for kind words.

      1. Probe is Renishaw compatible with M3 thread (exact part number is A-5003-0057) made by telesmetrology. Slightly cheaper but I have no issues with it’s quality.
      2. That’s right probe opens connection on axial and radial contact.


      • Peter
        2015-08-30 15:12

        Very nice, Thank you for fast answers.
        Last questions:

        What kind of cable(if any) is attached to the connector?

        Do you have a scope diagram of the swiching waveform (im looking for bounce, to be precise).

        Best regards,


        • Saulius Lukšė
          2015-08-30 15:45

          Hi Peter,

          Cable has markings [TASKER @ C 123 1×0.25 SPIRAL SHIELDED CABLE LOW CAPACITY MADE IN ITALY]. I provide 2m cable already soldered.

          Take a look at few combined pictures at different time scales:


          • Peter
            2015-08-30 15:51

            Nice, Thank you.

            I will place the order on ebay right away.


          • Saulius Lukšė
            2015-08-30 15:56

            Glad to hear! Will ship on Monday.

            Please drop me a note when you test it.


    • Peter
      2015-09-04 17:26

      I jsut opened the package. Everything looks in order

      • 2015-09-04 17:31

        Hi, mate you are feeding my OCD!!! Don’t forget me please.

      • Peter
        2015-09-04 17:32

        Hrmm.. press the enter a bit to fast there…

        As i Wrote:

        Everything looks in order. Comes packaged in (what appears to be, havent measured) ESD protective bubblewrap, Not really nessesery, but a nice touch =)
        Fast shipping to Norway. 5 working days since I placed the order. Good work!

        Build Quility looks as described and teh probe has a nice “feel” to it.
        Supplied cable is acording to spec and the cute ööittöe connector is to die for <3

        I havent had a look at the soldering, but will do so after im finnished playing around with it.

        So far, it looks and feels just as promised. Thumbs up.


  6. 2015-08-30 15:55

    Hi Saulius,
    I can’t pay the probe on eBay. The transaction is blocked, can you help me please?

    • Saulius Lukšė
      2015-08-30 16:02


      this is probably because none is left on eBay. Please check an error.


      • 2015-08-30 16:06

        Good for you mate! Are you planning make some more in the next days. Please if yes notify me, I’m interested in buying and setting your probe with Arduino. Thanks

        • Saulius Lukšė
          2015-08-30 16:17

          I should have some more next week. Will reserve one for you.

          • 2015-08-30 16:44

            Nice, Grazie tante!

          • Saulius Lukšė
            2015-09-09 19:35

            Hi, it took a little bit longer. If you still need one, I sent you details to email. Please check.

  7. Marc
    2015-09-29 19:45

    Hi, I got my probe.
    can you provided instruction how to assemble to my cnc router.



    • Saulius Lukšė
      2015-09-29 19:58

      Hi Marc, would you please be so kind letting me know what router/setup do you have?


  8. 2015-09-29 20:21

    Hi Saulius,
    This mornig I received the probe and order the following part to invert the signal:
    Thank you again.

    • Saulius Lukšė
      2015-09-29 20:33

      Hi, glad you received it and interesting finding. Please let me know how it performs and how much does this inverter cost?


  9. Ard Verhoef
    2015-10-02 13:43

    Hi Saulius,

    I am interested to buy a probe from you, are they still available for purchase?

    As I understood these will work fine using MACH3?


    • Saulius Lukšė
      2015-10-02 16:34

      Hi Ard, I am setting new batch which will have much better surface plating instead of black oxide. New samples should be available in a few weeks. And yes – this touch probe is fully compatible with Mach3.


  10. Ard Verhoef
    2015-10-07 08:16

    OK, could you send me an email when you have them again?

    Thank you!

    • Saulius Lukšė
      2015-10-07 08:17

      Hi Ard, no problem. Will inform you when it will be available.

  11. John
    2015-10-13 13:04

    How do you wire it to the control unit. I have a x6-2200 china router by omiocnc

    • Saulius Lukšė
      2015-10-13 13:10

      Hi John,

      Connecting touch probe to machine running Mach3 or LinuxCNC is pretty straight forward. You define pin which is responsible for this function and connect it to your controller. While I can help configuring Mach3 I can’t tell where exactly you should connect to x6-2200 machine.


  12. David
    2015-12-13 18:15

    Hi Saulius,
    I may be interested in using your touch probe on some of our machines in the near future. Currently we are using Tormach passive probes, which are not sealed as yours are. The probes see pretty heavy use, and have to be cleaned every month or so.
    Assuming the connection points on your probe would have to be serviced at some point, what is involved in accessing the points and replacing the fluid?

    • Saulius Lukšė
      2015-12-13 18:29

      Hi David,

      Thank you for your interest. This probe was designed to minimize need of service. It is pretty easy to take it apart and put back. Unscrew bottom cap and you have access to all parts. I use deoxit fluid over gold plated contacts, combined with sealed case under normal usage it should take long time until service is required.

      All information and sales moved to Feel free to visit.


  13. Valery
    2016-01-11 23:32

    Hello, as I saw on ebay descrption, it is 5-way probe. Is that correct? I assumed that using 3 pairs of ball it is 3-way?

    • Saulius Lukšė
      2016-01-12 08:28

      Hi Valery,

      This probe 5-way. You are correct it is based on classic design rods seated on 6 balls.


  14. Thomas
    2016-02-06 15:45

    I’m having an ER11 collet chuck and the 8 mm shank would force me to use an oversized collet so I would prefer a smaller size.
    Will there be a smaller sized shank available in the near future?
    Is the shank just screwed for easy replacement?


    • Saulius Lukšė
      2016-02-06 19:24

      Hi Thomas, I can reduce shank to 7mm. For more details please check email.

  15. 2016-02-24 19:40

    Can this be used with Tormach PCNC1100 and PathPilot controller?

    • Saulius Lukšė
      2016-02-24 19:52

      Sure, it will work perfectly with PCNC1100 and PathPilot.


      • James Kao
        2016-03-21 20:01

        With the PCNC1100, will the supplied electrical cable connect to the probe port on the Tormach out of the box? Or is some cable adapter required?

  16. Peter
    2016-04-13 20:21

    Hi again Saulius!

    I have been working with your probe for a nice while now and its really good!
    During a re-wiring of my machine i accidently pulled GND and +24 in to the probe…which melted the plastic part that holds the 6 small springs..or rather heated the springs so much that they damaged the white cup they reside in :( TOTALLY MY BAD.

    So now i’m wondering if you would sell me a new plastic part (the one with the springs) and 6 springs along with it.

    Best regards Peter

    • Saulius Lukšė
      2016-04-13 20:46

      Hi Peter,

      Sorry to hear you damaged plastic part. While working on new wireless design and switching to another manufacturer have only defected parts left. Maybe you can you recondition spring holes (2.0mm)? I can send you new springs and defected plastic part. Will write you email soon with more details.


  17. Iwan
    2016-07-17 08:02

    Wow your second round probe looks and design are absolutely superb from what I gather on your blog. Then I see the above comment of a wireless one in the works – can’t wait- if you need a paying tester of the wireless version please ping me as I have been searching for a wireless one with good precision and repeatability to leave in the ATC on the PCNC1100 series 3 with path pilot. Hope to hear from you soon.


    • Saulius Lukšė
      2016-07-17 08:05

      Hi Iwan, appreciate your interest. Will inform you by email when there will be anything to test.


  18. Josh
    2016-10-04 15:45

    Good morning. Do you have numbers for the activation force of the probe? I’m primarily interested in Z activation force, but X and Y (and I guess then 120°, 240° and 0/360° – in line with the internal pivots) would also be valuable.

    Thank you for any information you can provide,

  19. John
    2016-10-13 06:43

    Hello. This looks like a beautifully made probe. Are you planning to manufacture another batch of wired (non-wireless) probes? If you are, do you know when these might be available for sale?

    Thanks for your time.

    • Saulius Lukšė
      2016-10-13 06:45

      Hello John. Actually I do. Waiting for last pieces to arrive in a week or two. I will let you know more details as soon as new touch probe will be functional.

  20. eFalegname
    2016-10-13 09:00

    Hi Saulius, mate don’t forget me please! WiFi x1.

  21. Saulius Lukšė
    2016-10-25 07:21

    I would like to let you know that new CNC touch probe TPA2 is assembled now and being tested for any flaws. First units will be assembled and put on stock soon. Meanwhile feel free to read short introduction:

  22. Valery
    2016-11-09 13:59

    Hello, Saulius, are the 2nd edition available for sale?

  23. Adrian
    2017-01-21 08:20


    Just stumbled across your TPA2 and it looks like exactly what I want… I see the product page says pre-order only, but I am unable to actually do a pre-order as I can’t add to cart.

    Any way to sign up for notification or pre-order with you?


    • Saulius Lukšė
      2017-01-21 11:43

      Hi Adrian, thank you for contacting. My CNC house is late to deliver parts – probes should be available first week of February. Will notify you personally as soon as I have them on stock again.

  24. 2017-02-08 22:15

    Hello Saulius,

    Could you send e-mail notification when the 2nd edition will be available for sale?


    • Saulius Lukšė
      2017-02-09 07:28

      Hello Andrew, sample batch of TPA2 disappeared instantly :) Now I am preparing for larger order. I think it will take bit longer than a month.

  25. 2017-04-10 13:57

    p. Sauliau,
    mes prekiaujame metalo apdirbimo įrankiais CNC staklėms.
    Labai įdomus prietaisas.
    Musų klientai klausinėja apie tokius.
    Ar galima butų jį apžiūrėti ir pasiūlyti musų klientams?
    Gintaras Urbanas

    • Saulius Lukšė
      2017-04-12 06:38

      Gintarai, žinoma galima. Parašiau laišką, galėsim pasitarti.

  26. Dear Sir, my name is Renato Oliveira from Brazil, could you send me price and delivery time, please?

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