Play in pen lift hinge



  • Is anyone having problems with play in the pen lift hinge I am finding a lot of play and the small spring does not seem able to cope. I have made a new arm and used a 3mm pin in a reamed hole which is a lot better but still not perfect. I am thinking of trying a version with two small bearings in the arm and two pointed set screws to sit in the bearings. Has anyone got any other good ideas. 0_1492956507312_image.jpg


  • Active Member

    @pledgy the arm mechanism needs to be completly redone. First the pen should be held at the lowest point. Second, the whole arm assembly should be adjustable on an imaginary Z axis; this allows the pen to held at the lowest point AND it allows the whole arm assembly to be adjustable to the object.


  • Developer of T2Laser Software

    I disagree about holding the pen down, it is much better to allow gravity to follow the shape (it could be assisted by a small spring but I haven't found it necessary, yet).

    On my machine at least, the small spring in the arm limits any play but the pen holder does need some improvement - mainly because it doesn't hold most pens very well.


  • Active Member

    @pledgy said in Play in pen lift hinge:

    Is anyone having problems with play in the pen lift hinge I am finding a lot of play and the small spring does not seem able to cope. I have made a new arm and used a 3mm pin in a reamed hole which is a lot better but still not perfect. I am thinking of trying a version with two small bearings in the arm and two pointed set screws to sit in the bearings. Has anyone got any other good ideas.

    0_1492981928675_spherebot - Copy.jpg

    0_1492981939541_spherebot2 - Copy.jpg


  • Developer of T2Laser Software

    The Z-axis adjustment is the pen itself, just set it so the pen is vertical when down. I don't see the need for more complexity (which typically means cost).


  • Active Member

    @Zax said in Play in pen lift hinge:

    The Z-axis adjustment is the pen itself, just set it so the pen is vertical when down. I don't see the need for more complexity (which typically means cost).

    Adjusting the pen to the object makes the pen unstable, and creates additional problems; it is poor design in my opinion. The further that the pen body extends to the object means that the pen is not held firm.

    And considering that pledgy remade the pen arm and is specifically requesting ideas, any associated cost is minimal to pledgy's specific project. The materials required to create the stepper motor shaft attachment is probably 1 cubic inch.



  • Thanks for all the ideas. I have not had a problem with pen adjustment yet as all my trials have been with the same size ping pong balls. I can imagine there could be an issue with the taper on the pens and it would not be hard to change the vertical pen arm to have a slot and thread two holes in the disc that goes on the stepper, I might give it a go on my next attempt. The plastic springy servo connector is interesting but I can see problems forgetting to set the correct S value and giving it a good stretch, I am playing with a few different bits of software to generate the gcode and in some I have to replace the Z moves with the correct S values. so far I have not had a problem with the pen going down and have tried a golf ball and it coped with the dimples ok, being aluminium and not plastic it has some weight to it. My major problem was with the play in the hinge, I am getting acceptable results now with my new version but I am sure it can be improved on further. I am lucky that I have access to CNC machines at work so I can try these ideas out in my dinner times and as its all just a hobby the budget is not such an issue, if it helps improve future versions then that's even better.


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