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First of all I apologize if this stack exchange site isn't the proper spot for CNC questions but I do not see any other ones that are close. If the community feels this is too far off topic then just let me know and I will remove this question. Even though this is for a CNC machine, the same issue could exist for a 3D printer. I do know this is very specific to the TAIG CNC.

Currently I have the TAIG CNC machine. Recently it has been getting bound when going up in the positive Z direction. It will go down no problem but when going up, at certain points the motor will make a high pitch noise like it normally does when it hits a Z extreme. At these points if I manually try to crank (with the controller off) it is very hard to move up. This indicates that it is a mechanical problem.

I took apart the Z axis and understand that there is a jib inside. I do understand how the jib works, tightening and loosening the top and bottom screws to move the wedge. I have tried with the wedge all the way up (biggest gap) and all the way down, along with in between in small increments. It will go up when the jib is all the way up but if I press down with my hand barely then it gets bound so I am thinking it is something other than the jib? I am not sure which other parts I can adjust or would get stuck. I did follow the directions on youtube of setting the brass insert that is attached to the threaded rod, where I tightened it to the point of where the motor couldn't move and then backed off a little bit. Has anyone had binding troubles like this?

I am a pretty new member on this forum so I apologize if I missed anything but feel free to ask any questions too.

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  • $\begingroup$ Have you verified the straightness of the Z-axis lead screws? This sounds like your machine could no longer be perfectly square. The further it gets from (0,0,0,) the more apparent the problem would be, hence why you're seeing it further up in the Z-travel. $\endgroup$
    – Diesel
    Apr 10 '17 at 14:41
  • $\begingroup$ @Diesel You're talking about lead screws but (from what I can tell on google images) the TAIG CNC only has a single lead screw driving the Z-axis. $\endgroup$ Apr 10 '17 at 18:11
  • $\begingroup$ I'm voting to close this question as off-topic, because it isn't about 3D printing. $\endgroup$ Apr 10 '17 at 18:11
  • $\begingroup$ Yes there is only one lead screw $\endgroup$
    – Eric F
    Apr 10 '17 at 19:14
  • $\begingroup$ One or two, the question remains, has the straightness and perpendicularity of the motion of the Z-Axis mill end, relative to the build platform been verified? One lead screw with a bend in it, or a slight curve would cause your cutter to become more angled the higher it gets. This would increase the friction between the bit and the work piece which would create a squeal, and increase in volume the higher the cutter moves. $\endgroup$
    – Diesel
    Apr 12 '17 at 11:35
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So inside the Z axis is a brass component that is connected to the threaded rod (lead screw). This brass component has 3 screws and depending how tight / loose, determines how much it will bind up. You of course don't want it too loose otherwise the enclosure will "jump" off of the track at times. In my case, the two screws were too tight. The way I determined how tight to go was taking the entire Z track off of the back, tightening both screws just to the point of binding and then backing off 1/2 turn on both.

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