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  1. #1
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    Make a $25 Full 3D Probe

    ------------------------------------------------------------------------------------------------------------------------------------------------------
    EDIT: Just few points as a checklist for anyone following the instructions to make this probe:
    1 - Do not leave the Probe Plug inserted while not using the Probe.
    2 - Remove the Plug before powering on the machine.
    3 - Safest procedure is to insert the probe after the machine is powered, homing done, stock inserted and ready to probe.
    4 - Its good practice to manually check the LED on the PP page is working before instructing PP to probe. This can be done easily and fast before first probe. Once you position the probe where you want; use any metal piece, block, gauge, screwdriver or a spare piece of wire for this purpose and touch/connect the ball to the table or stock; the LED should light up in PP Probe page, this tells you everything is working fine and PP will stop the movement when the ball touches. If the LED does not light up, then maybe you have a loose connection or solder from moving the probe cable around many times. So fast check, once a day before probing can save the trouble of building another one. This is soft metal so worst case it will bend and no other damage.
    ------------------------------------------------------------------------------------------------------------------------------------------------------

    My Poor Man's 3D Probe (PM3DP). Man, i love acronyms


    I put this thing together today. The video and demo of it working with PathPilot Probe routines is at the start of the video, then full details and schematics of how to make one follows the demo.

    Simple and can't go wrong with its cost.

    Watch the video and let me know what you guys think.

    https://youtu.be/eqcJWWOrv0c

    Here are my follow-up comments;

    - I may actually fabricate a circuit for it, just to make it easier to change, enhance and so on. I send out circuit designs for fabrication almost weekly, might as well send out a small one for this one.
    - V2 could be adding a mechanism to flip the contact so it goes to NO as well. Its NC now. When I tested it directly without using Probe routines, PP gives a message that the probe was activated but it does not reset or stop anything. Just a red message.
    - I did actually use it for Z as well. Even though it does not have a spring to push it up, at 5 IPM to probe in Z looks great and it seems it does not need the push up.

  2. #2
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    Re: Make a $25 Full 3D Probe

    Nice work. A few questions for you (just the basics of any probe system):
    1) What is the radial runout of the probe tip? Is it adjustable?
    2) What is the repeatability in a single direction on the 770? For example probe in X and record the value, back off and probe again. Repeat 10+ times (30 is better statistically) and see what the max and min values are.
    3) What is repeatability when actuated from various directions (on the 770)? For example, rotate the spindle 45 degrees and take 10 measurements, repeat at 90, 135, 180 etc...

  3. #3
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    Re: Make a $25 Full 3D Probe

    Quote Originally Posted by IMT View Post
    1) What is the radial runout of the probe tip? Is it adjustable?.
    Multiple sources to buy this type of probe body claim 0.0005" accuracy. I think I saw some video showing that on a lathe as well. So it really depends on the probe itself and not the idea how to connect it. If you had a chance to handle/see one of these, they are actually well built, seems pretty accurate. My Ball dia came out to be 9.92mm. See below, I tried to check it.

    Quote Originally Posted by IMT View Post
    2) What is the repeatability in a single direction on the 770? For example probe in X and record the value, back off and probe again. Repeat 10+ times (30 is better statistically) and see what the max and min values are..
    Going to try this today. I am interested to know this now.

    Quote Originally Posted by IMT View Post
    3) What is repeatability when actuated from various directions (on the 770)? For example, rotate the spindle 45 degrees and take 10 measurements, repeat at 90, 135, 180 etc...
    I actually did try something similar, I figured the best way to set up a proper dial gauge is to level the gauge to be the same as the machine, then creep the ball to it, push it slightly so it zeros, then rotate the spindle by hand. Obviously there could be slight visual error to get the ball to center on the dial. Three tries I got 0.004" different when rotating the ball all the way around, goes 2 thousands on one side, back to zero then two thousands on the other side and then back to zero! Interesting. I've decided that I probably need to use the other type dial, not the one that pushes it, but the tiny one that came with Tormach kit. Would be great if experienced/pros build it and give it a try just to compare. Of course, the accuracy, repeatability and runout can all be checked before any attempt to build it as I've shown, this way this can be confirmed that it is suitable. Still, at this cost, its not bad!

    If you see the last note on the video, the idea, components and wiring can be used on more accurate, or even build your own spring/ball using the same machine tolerances. It needs to be conductive, and it needs to be insulated from the spindle metal body. Attach the bottom wire to it, and touch your piece. The design converts this touch from NC to open connection for PathPilot. The nice idea about this simple probe body is that the ball is pushed into the end recess, this is the only area that needs to be accurate. If the ball snug back correctly, it will always repeat the same. As you see in the video with 30 IPM, the ball does move on the first touch.

    And of course experience also plays a good part in using this thing correctly and minimizing any errors. Such as making sure the ball is halfway or lower than the top surface edge, this way it touches right on the middle of the ball rather than lower if the middle was higher than the top surface. I think one time in the video it probably was higher.



    Quote Originally Posted by IMT View Post
    Nice work. A few questions for you (just the basics of any probe system):

    Thanks. I wouldn't call it a system though . Free idea for newbie (and maybe old) hobbyist.
    It actually did not cost me that much. My cost $17.50 (20mm Collet & probe). I already have the electronic components as I buy them in bulk, and they are less than 10 cents, I had old Midi keyboard cable that was going end up in the trash next cleanup. Probe from Aliexpress was $9.95 with free shipping! I already ordered one ER32 Collet Tool holder just for that odd extra size.



  4. #4
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    Re: Make a $25 Full 3D Probe

    In addition to repeatability, what is the actual accuracy (measure a 1-2-3 block or other item of known size)? Source of the original probe?

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    Re: Make a $25 Full 3D Probe

    Just use a 123 block and measure both sides! Good idea, thanks. Will give it a try tonight when i head out to the workshop.

    The one I cut, was from Aliexpress, I see now its $12, must have been special last month!. Others on Aliexpress are the same also, http://-Probe-Electronic-Edge-Finder...810217651.html

    I also got another one from eBay (USA stock) as backup, its identical to the one from China and wanted to keep a local source for faster replacement if broken. This one: https://www.ebay.com/itm/Electronic-...72.m2749.l2649

    You can also search “Electronic Edge Finder” in eBay, AliExpress and Amazon. Here is a list on eBay. https://www.ebay.com/sch/i.html?_odk...inder&_sacat=0

    Quote Originally Posted by kstrauss View Post
    In addition to repeatability, what is the actual accuracy (measure a 1-2-3 block or other item of known size)? Source of the original probe?

  6. #6
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    Re: Make a $25 Full 3D Probe

    I owned quite a few of that style of probe, and I'd be surprised if it was good for better than a few thou, on average. The probes themselves tend to often have a fair amount of runout, due to mis-alignment of the end piece of the shaft (the insulated part just above the ball). The ball itself, once "bumped" does not always return to the same position, adding some random error. And, of course, it is unforgiving in the Z axis, or if contact is made ANYWHERE other than on the ball when probing laterally. So, bump it once more than very gently, and it's toast.

    That said, for most work, plus or minus a couple thou is "good enough".

    Regards,
    Ray L.

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    Re: Make a $25 Full 3D Probe

    I'm going to put in a big plug for the Wildhorse Econoprobe. I have used mine a lot and it's still going strong after a couple of years. If you take the time to really dial it in, and put it away carefully between uses without bashing the tip around, it has been giving me +/- .001 or better no problem. I've gotten to where I simply trust it. I use it for every single project. At $100, with the Tormach plug on it, just plug and go, it's as good as you can possibly do for a cheap probe. And far FAR better than it should be for its price. You can actually use all those fancy features in PP.

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    Re: Make a $25 Full 3D Probe

    All great feedback. I suppose even poor men need spot on accuracy sometimes!. The intention of doing this was not to make it compete with other systems

    You guys are tough crowd; expecting so much from a $10 shaft/ball. .

    I did some of the above tests, I get results between 0 and 2 thou, average of 1 thou really. I also remembered I did not clean the end piece of the shaft at all before securing the ball to the spring, making a small contamination a possibility as well.

    Though, thinking about my results, maybe it will be more accurate if its used to zero on the center of the stock. Still, as it is 2 though worst case does sounds like good enough for the purpose.

    Note to anyone wants to give this a try; I edited the first post, just to caution against powering up the mill with the probe inserted. Big chance it will kill the MOSFET as I did not include any protection circuit for the MOSFET to make it simple; the machine seems to have voltage transients when the board and/or VFD is powered up. You will just need to make sure the probe is not inserted before powering the machine. Actually, its best not to have any accessory connected to the DIN-5 before powering the machine. Some more recommendations added to first post.

    For anyone else wants to build an accurate shaft/ball; and maybe using this MOSFET connected for PP, then a protection circuit and galvanic isolation components are better; just few more components which I will prepare a V2 later.

  9. #9

    Re: Make a $25 Full 3D Probe

    I think it is cool. I might give it a shot. I already have two probes, the Wildhorse probe, which I find to need adjusting almost constantly. Then the Tormach passive touch, which by following Threadexpress videos on YT find I get excellent results with. But it's always nice to have a backup should an accident happen. I'll be using it on Mach3, but the adaption looks perfectly straight forward.

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    Re: Make a $25 Full 3D Probe

    Quote Originally Posted by narrobb View Post
    All great feedback. I suppose even poor men need spot on accuracy sometimes!. The intention of doing this was not to make it compete with other systems

    You guys are tough crowd; expecting so much from a $10 shaft/ball. .

    I did some of the above tests, I get results between 0 and 2 thou, average of 1 thou really. I also remembered I did not clean the end piece of the shaft at all before securing the ball to the spring, making a small contamination a possibility as well.

    Though, thinking about my results, maybe it will be more accurate if its used to zero on the center of the stock. Still, as it is 2 though worst case does sounds like good enough for the purpose.

    Note to anyone wants to give this a try; I edited the first post, just to caution against powering up the mill with the probe inserted. Big chance it will kill the MOSFET as I did not include any protection circuit for the MOSFET to make it simple; the machine seems to have voltage transients when the board and/or VFD is powered up. You will just need to make sure the probe is not inserted before powering the machine. Actually, its best not to have any accessory connected to the DIN-5 before powering the machine. Some more recommendations added to first post.

    For anyone else wants to build an accurate shaft/ball; and maybe using this MOSFET connected for PP, then a protection circuit and galvanic isolation components are better; just few more components which I will prepare a V2 later.

    I wish I weren't so electronically-retarded, I'd give this a shot myself. One of the many time consuming parts of any of my machining forays is indexing my stock. This would really put a dent in that time. I've found that even with my present method of indexing I can have as much as 2-thou in variance for the small parts I make. the longer my stock, the longer my variance so, I try to touch off closer to the center of my stock on both the X and the Y axis. If I were to do it the way you showed it in the video, I'm sure I'd be off more than 2-thou.

    At any rate, I think it's a good idea even with accuracy results being as they are. I'm sure tweaks could be made to compensate for this. There are many things that can affect accuracy. You could manually index your part perfectly and any number of things can happen during the normal process of machining that can give us the same 2-thou or more accuracy loss. It's just that some of us rarely ever re-check the finished part after its done to see if we were holding the same accuracy that we had indexed to. Unless there's a visibly obvious loss of accuracy, I just assume that it's all good.

    Keep up the good work; and if you decide you'll ever sell these on your own for not to much money, let me know.

    MetalShavings

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    Re: Make a $25 Full 3D Probe

    That's great, if you do please post how did it turn out. I will also be looking for a more accurate shaft/ball/spring


    Quote Originally Posted by CL_MotoTech View Post
    I think it is cool. I might give it a shot. I already have two probes, the Wildhorse probe, which I find to need adjusting almost constantly. Then the Tormach passive touch, which by following Threadexpress videos on YT find I get excellent results with. But it's always nice to have a backup should an accident happen. I'll be using it on Mach3, but the adaption looks perfectly straight forward.

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    Re: Make a $25 Full 3D Probe

    Thanks. You are right about the various places to get errors. When I finished the machine last week, I think I spent a long time making sure my 6" Kurt is perpendicular to the spindle, though I was skeptic I should not be so anal about this as machinist change workholding vises all the time. Just by bolting it in does not mean its really straight with Y. Maybe some thou off! Won't matter if you cutting around the stock anyway but if you have partially finished stock then I guess it would matter. Then there is the actual spindle runout, TTS holder and collet errors.

    As an exercise, I thought I use Tormach Touch Tool (Digital) to walk on the entire length of the 6" Soft Jaw to see how my machine level is (across x). So I touched the Jaw and pushed the tool slightly till its reads 50 though. Then walked X to see; the 50 stayed fixed all the way till it moved about 4.5" (then it changed to 49 for a half inch, then to 48.5 the last 1" or so. This still does not mean it's the machine itself, it could be the jaw, or contamination; so I am going to stop chasing these small values and move on to start cutting



    Quote Originally Posted by MetalShavings View Post
    I wish I weren't so electronically-retarded, I'd give this a shot myself. One of the many time consuming parts of any of my machining forays is indexing my stock. This would really put a dent in that time. I've found that even with my present method of indexing I can have as much as 2-thou in variance for the small parts I make. the longer my stock, the longer my variance so, I try to touch off closer to the center of my stock on both the X and the Y axis. If I were to do it the way you showed it in the video, I'm sure I'd be off more than 2-thou.

    At any rate, I think it's a good idea even with accuracy results being as they are. I'm sure tweaks could be made to compensate for this. There are many things that can affect accuracy. You could manually index your part perfectly and any number of things can happen during the normal process of machining that can give us the same 2-thou or more accuracy loss. It's just that some of us rarely ever re-check the finished part after its done to see if we were holding the same accuracy that we had indexed to. Unless there's a visibly obvious loss of accuracy, I just assume that it's all good.

    Keep up the good work; and if you decide you'll ever sell these on your own for not to much money, let me know.

    MetalShavings

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    Re: Make a $25 Full 3D Probe

    Quote Originally Posted by narrobb View Post
    Thanks. You are right about the various places to get errors. When I finished the machine last week, I think I spent a long time making sure my 6" Kurt is perpendicular to the spindle, though I was skeptic I should not be so anal about this as machinist change workholding vises all the time. Just by bolting it in does not mean its really straight with Y. Maybe some thou off! Won't matter if you cutting around the stock anyway but if you have partially finished stock then I guess it would matter. Then there is the actual spindle runout, TTS holder and collet errors.

    As an exercise, I thought I use Tormach Touch Tool (Digital) to walk on the entire length of the 6" Soft Jaw to see how my machine level is (across x). So I touched the Jaw and pushed the tool slightly till its reads 50 though. Then walked X to see; the 50 stayed fixed all the way till it moved about 4.5" (then it changed to 49 for a half inch, then to 48.5 the last 1" or so. This still does not mean it's the machine itself, it could be the jaw, or contamination; so I am going to stop chasing these small values and move on to start cutting

    Yea; I do it the same way with my vice and get basically the same results. I use a .0005" dial indicator to index my 6" vice. I still fully expect to get variances so using a device like the one you've built and getting one or two thou off is really not that big of a deal for me; especially since the parts I make are cut from a 6"x1"x.5" piece of 1018 steel.

    It's nice when I can get the indexing done so it's dead-nuts spot on but, that's a rare accomplishment for me. I do try though; mainly because I have to turn the part around and plane off a certain amount and then follow that up with a chamfering tool path. I cut six separate little parts from that piece of stick so If I'm off any more than a couple of thou it will give me unacceptable results.

    If I could get your Probe gadget to work for me at two-thou off of dead-nuts it would still be a useful item to have.

    MetalShavings

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    Re: Make a $25 Full 3D Probe

    Quote Originally Posted by narrobb View Post
    [FONT=Arial], I think I spent a long time making sure my 6" Kurt is perpendicular to the spindle, though I was skeptic I should not be so anal about this as machinist change workholding vises all the time.
    I use a 5" Tormach machinist vise with ground vise keys. I can move vise on and off table at will with vise keys using the pre aligned center keyway on the mill table. Very accurate system to align tools like 4th axis, vises and other fixtures with little effort. You can even put keyway stops in place to move vise or other fixture on and off and still locate it very close to same place each time.

    oops reading your post a 6" kurt would overhang to much if you use the key slots it has. You would need a smaller vise or mod it like others do.

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    Re: Make a $25 Full 3D Probe

    Quote Originally Posted by mountaindew View Post
    I use a 5" Tormach machinist vise with ground vise keys. I can move vise on and off table at will with vise keys using the pre aligned center keyway on the mill table. Very accurate system to align tools like 4th axis, vises and other fixtures with little effort. You can even put keyway stops in place to move vise or other fixture on and off and still locate it very close to same place each time.

    oops reading your post a 6" kurt would overhang to much if you use the key slots it has. You would need a smaller vise or mod it like others do.
    On my Tormach vice it had some threaded holes on the bottom so I turned a couple of bolts on my lathe to the exact outside diameter as the inside widths of the keyway slots. It too went on nearly perfectly for the longest time but now I think I've worn some flats on those bolt heads so i have to manually index it again. Those two bolts I turned have worn just enough to make me have to run my dial indicator across the face of the vice jaws to make sure I'm within tolerance for my tiny parts. I guess rather than whining about being off by a couple of thousands I could just turn a couple of more bolts to the correct diameter and start from scratch all over again but I'd still have to index my stock.

    Better yet would be a fix for that I came across somewhere, it may have been on this forum. It was suggested that I could either mill or buy a piece of metal that fit perfectly into the keyway slots, sticking up above the face of the table; then turn my vice upside down and clamp it onto that perfectly fitting piece of metal in the keyway slot. With the underside of my vice facing upward I could mill a shallow slot of the same width on the underside of my vice that centered on those two threaded holes. The flat piece of metal stock could then be screwed in that milled slot onto the bottom of my vice. In theory, if done correctly it would mean that whenever I needed to remove or replace the vice on the table, it would simply fit into the keyway slots for a perfect alignment every time.

    I might be able to get my vice on straight but the edges of the metal stock I use are rarely as smooth and straight as the inside of the jaws of my vice. I think a touch probe of some type would still be a useful little doodad to have.

    MetalShavings

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    Re: Make a $25 Full 3D Probe

    Quote Originally Posted by MetalShavings View Post
    On my Tormach vice it had some threaded holes on the bottom so I turned a couple of bolts on my lathe to the exact outside diameter as the inside widths of the keyway slots. It too went on nearly perfectly for the longest time but now I think I've worn some flats on those bolt heads so i have to manually index it again. Those two bolts I turned have worn just enough to make me have to run my dial indicator across the face of the vice jaws to make sure I'm within tolerance for my tiny parts. I guess rather than whining about being off by a couple of thousands I could just turn a couple of more bolts to the correct diameter and start from scratch all over again but I'd still have to index my stock.

    Better yet would be a fix for that I came across somewhere, it may have been on this forum. It was suggested that I could either mill or buy a piece of metal that fit perfectly into the keyway slots, sticking up above the face of the table; then turn my vice upside down and clamp it onto that perfectly fitting piece of metal in the keyway slot. With the underside of my vice facing upward I could mill a shallow slot of the same width on the underside of my vice that centered on those two threaded holes. The flat piece of metal stock could then be screwed in that milled slot onto the bottom of my vice. In theory, if done correctly it would mean that whenever I needed to remove or replace the vice on the table, it would simply fit into the keyway slots for a perfect alignment every time.

    I might be able to get my vice on straight but the edges of the metal stock I use are rarely as smooth and straight as the inside of the jaws of my vice. I think a touch probe of some type would still be a useful little doodad to have.

    MetalShavings

    I use these on my vise and other fixtures.
    Attachment 385222



    They align to my center t slot. My center Tslot is about 0.002 out of square limit to limit. As for probes and Indicators I have no less then 8-10 in tts holders at any one time. No electronic ones yet . I mostly use Hamier for offsets and a Best test indicator for sweeping surfaces. Then a host of other ones for holes, paper thin materials.......

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    Re: Make a $25 Full 3D Probe

    Quote Originally Posted by mountaindew View Post
    I As for probes and Indicators I have no less then 8-10 in tts holders at any one time. No electronic ones yet . I mostly use Hamier for offsets and a Best test indicator for sweeping surfaces. Then a host of other ones for holes, paper thin materials.......
    I'm curious. How do you probe for features/edges on very thin materials?

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    Re: Make a $25 Full 3D Probe

    Quote Originally Posted by kstrauss View Post
    I'm curious. How do you probe for features/edges on very thin materials?
    Standard wobble indicator that has a flat bottom can edge find down to 1/16 thick. Then a laser edge finder that Tormach sells works for something like a paper gasket thickness of material.

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    Re: Make a $25 Full 3D Probe

    after looking at the video in post 1

    I would add a 330 ohm resistor in series with the red LED indicator to limit the LED's current when the buzzer is not fitted

    Attachment 385278

    john

    PS
    not knowing what the tormach probe input circuit is like

    I would expect a 100 ohm resistor in series with the FET's drain will limit the current if the tormach DIN pin 1 (+5V) was shorted to the input pin 4

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    Re: Make a $25 Full 3D Probe

    Why would the buzzer be not fitted? If it's going to come from the source without buzzer, only LED, then the resistor would be included as part of the probe.

    But if you mean if someone wants to remove the buzzer and keep the LED then yes but no point of doing that. Notice that the Collet holder is covering the LED anyway. The probe needs to be inserted all the way in the collet to minimize any runout from saw/cutting the shaft. For the 2nd unit I made, I did not connect the +5V at all to the probe, no buzzer or LED as they are not needed and as I mentioned in the video a straight forward building of the probe as no need to remove bulk.

    Quote Originally Posted by john-100 View Post
    after looking at the video in post 1

    I would add a 330 ohm resistor in series with the red LED indicator to limit the LED's current when the buzzer is not fitted


    john

    PS
    not knowing what the tormach probe input circuit is like

    I would expect a 100 ohm resistor in series with the FET's drain will limit the current if the tormach DIN pin 1 (+5V) was shorted to the input pin 4

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