Best touch plate solution to date?

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This topic contains 27 replies, has 15 voices, and was last updated by  Ian 2 days, 7 hours ago.

Viewing 28 posts - 1 through 28 (of 28 total)
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  • #85429

    Kelly D
    Participant

    I’m about to pull the MiniRambo off the drop table and replace it with the Rambo and endstop wiring. While I do so I’d like to incorporate a touch plate so I can nail my tool changes finally. If you all saw how I do them currently you’d wonder how I ever got good results……

    What’s the best way about this according to the collective here? One of the tall disc and alligator clip things form Amazon? A diy moveable piece like Jeffe’s spatual plan? A piece milled in flush on the work surface and hard wired into the table/board?

    #85450

    Ryan
    Keymaster

    I use a magnet and some metal tape…ghetto fab baby. I do have a few super fancy high tech one here that I have not tried out yet….ghetto works so well I never walk up the stairs to get the fancy ones.

    #85471

    Kelly D
    Participant

    The key bit is knowing precisely how thick the touch plate material is, right?

    #85529

    geodave
    Participant

    I use a 4″ putty knife from Harbor freight.  It gives me plenty of room to put the alligator clip on. You can probably find them at dollar store also.

    #85534

    Kelly D
    Participant

    I use a 4″ putty knife from Harbor freight. It gives me plenty of room to put the alligator clip on. You can probably find them at dollar store also.

    I have to admit I haven’t looked deep enough into it yet in terms of how they are wired up. I assume the cutter contacting the metal closes the circuit to the end stop. So one wire from the board goes to the metal plate, the other wire has an alligator clip that you clip to the cutter? Is it that ‘simple’?

    #85537

    mulze32
    Participant

    I use a 4″ putty knife from Harbor freight. It gives me plenty of room to put the alligator clip on. You can probably find them at dollar store also.

    I have to admit I haven’t looked deep enough into it yet in terms of how they are wired up. I assume the cutter contacting the metal closes the circuit to the end stop. So one wire from the board goes to the metal plate, the other wire has an alligator clip that you clip to the cutter? Is it that ‘simple’?

    It’s that simple. You are just creating a a NO switch. The Putty knife though is a great idea. Will be using that.

    #85544

    Guffy
    Participant

    #85547

    Kelly D
    Participant

    Thanks gang.  Then once I know the thickness of the plate I add a start code that alters the z axis by that amount and I’ve got perfect zeroes for the rest of my days?

    M851 z-[plate thickness here]

    Correct?

    #85560

    Guffy
    Participant

    thickness = 0.8, safe level = 40 :
    G28 Z
    G92 Z0.8
    G0 Z40
    M400

    1 user thanked author for this post.
    #85561

    Guffy
    Participant

    you also can surround it with M0 commands to waiting with showing hint on the LCD

    M0 Attach probe
    G28 Z
    G92 Z0.8
    G0 Z40 F300
    M400
    M0 Detach probe

    #85562

    Kelly D
    Participant

    Just trying to see if I understand this.

    The end stop will trigger at .8 but set the machine’s coordinate (understanding) to 0. By using G92 z0.8 you’re telling the machine that it’s ACTUALLY at 0.8 right ‘now’ and so any following gcode will be reduced by 0.8?

    Would M851 Z-0.8 do the same thing? And if so, why use one over the other?

    #85563

    Guffy
    Participant

    By using G92 z0.8 you’re telling the machine that it’s ACTUALLY at 0.8 right ‘now’

    exactly

    #85564

    Guffy
    Participant

    Would M851 Z-0.8 do the same thing?

    i don’t think so. i guess it dedicated to hint machine how to interpret probe coordinates when you perform bed leveling with G29. I think G29 not useful for CNC application

    #86009

    Bill
    Participant

    Aluminum foil means you don’t have to allow for thickness of the touch plate, and you can set it at the top surface of your piece.

    #86029

    Kelly D
    Participant

    Aluminum foil means you don’t have to allow for thickness of the touch plate, and you can set it at the top surface of your piece.

    Just a couple of alligator clips in that case? One to the foil, one to the cutter?

    #86061

    Barry
    Participant

    Aluminum foil means you don’t have to allow for thickness of the touch plate, and you can set it at the top surface of your piece.

    Just a couple of alligator clips in that case? One to the foil, one to the cutter?

    Yep!

    #86117

    Guffy
    Participant

    Imho, foil isn’t best solution. It’s easy to get it creased and you can’t be sure that it lays flatly on the surface. I guess you can’t just hold by one hand or just drop and make homing.

    #86118

    Deek
    Participant

    I cut a square of aluminum foil out of the flat bottom of a heavy duty disposable pan, like from Thanksgiving.  To make the connection I soldered to a paperclip and slipped it on the foil.   So, far working great!

    #86140

    Tim W
    Participant

    I just use foil tape with a corner folded over and stick it to where i need my 0 and re 0 on tool changes on the face and it never moves 🙂

    1 user thanked author for this post.
    #90557

    AZ_Ron
    Participant

    I’m using a 6″ long .08mm feeler gauge.

    Works fantastic!!!

    #121199

    Justin
    Participant

    Don’t mean to revive an old topic but would something like this  (https://www.thingiverse.com/thing:1799974) work if you put aluminum tape on the places that would be used to touch off?

    #121218

    Steven
    Participant

    I don’t see why it wouldn’t work. I think I will give it a  try. I might even see if there are any filaments that have metal in them and would be conductive, as that might work too.

    #121222

    Barry
    Participant

    They make conductive filaments. Not sure if it would be enough though.  Metal infused filament isn’t usually conductive.  At least not uniformly.

    #121227

    Justin
    Participant

    I was thinking of just milling it out of wood since it’s one sided

    #121233

    Ian
    Participant

    This is mine – 0.6mm thick.  Signal connected to the base, and the common is attached to the bit (croc clip).

    Works perfectly

    Also made a pen holder with a touch switch on it. That works fine too.

    Attachments:
    #121302

    José
    Participant

    Hi guys

    How do you connect this to RAMBO? just like Z-min end stop? or there is another pins dedicated for this probe?

    My build is kind of weird. I think the earth or neutral of the tool is connected to GND on the RAMBO, but currently I’m using just a connector to Z-min signal and I have no need to clamp the bit with the other connector. In fact If I do so, the steppers start to move like RAMBO is signaling them.

    I think I will find an electronic circuit to isolate this. My other end stop are all mechanical.

     

     

     

     

    #121354

    Jamie
    Participant

    I think I will find an electronic circuit to isolate this. My other end stop are all mechanical.

    I like this idea. It’s probably relatively straightforward to incorporate an opto-isolator with a AA battery and touch plate on the emitter side and the phototransistor side would connect to the Rambo or whichever controller. Then you would be completely safe from any weird stuff going on with the ground levels.

    #121368

    Ian
    Participant

    You could very easily 3d print a sprung ‘point’ that broke a slotted opto isolator such as the diagram attached (The required 0v, 5v and signal are all on your Z-Min terminals I believe).

    Or just optically isolate the returning signal using a 4N38 opto-isolator if you were worried.  Then if the returning ground signal was a bit ‘dirty’, you would still get a clean returning signal to the controller

     

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