Z Axis Binding. No idea where to start ...

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Z Axis Binding. No idea where to start ...

Postby bloq » Sun Oct 25, 2015 1:38 pm

Hey,

i am still struggling with my 2.x laser build. Most parts are working (waiting for the tube) but my z axis table does not work as it should. I use the solution with the nema on the bottom and the lo x7 controller. When i try to move my z table up and down it only works for some milimeters before it gets stuck. The table seems to be level but i do not now how much accuracy is needed to prevent binding. If i remove the large belt from the z table and check movement of the nema which is then only attached to the small pulley and the first rod everything works fine. As soon as the other rods are involved things start to get stuck.So where do i start? How did you align your rods? If i try to make them perpendicular i need some force to get them in place? Any hints are welcome ...

Thank you very much,

tm
bloq
 
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Re: Z Axis Binding. No idea where to start ...

Postby rsm5178 » Sun Oct 25, 2015 4:20 pm

I just measured over from the left side to make sure the top and bottom rod holders are vertically true. It doesn't matter the spacing between the rods, just that the rods are vertical.

Are you using the floating PEMs? There is the added angular and x-y tolerance gain with them that definately helps with binding.

See if you can rotate it by hand and it's just not the stepper stalling.

Maybe a picture would help?

Rich
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Re: Z Axis Binding. No idea where to start ...

Postby bloq » Sun Oct 25, 2015 5:41 pm

Hey Rich,

thank you very much!! I loosened all screws so i cannot try movement by hand but know at least i know how to align the rods. I will put them back togehter tomorrow and will tell you if i can move it by hand so maybe we can solve this step by step?

thank you!

tm

P.S: Yes i use the pem nuts ...
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Re: Z Axis Binding. No idea where to start ...

Postby mpeele » Tue Oct 27, 2015 11:43 am

How I aligned Z axis screws for 1.x laser:

1. Place bed in absolute lowest position.
2. Loosen top end screws brackets of Z axis.
3. Tighten bottom end screw brackets of Z axis.
4. Pick one Z axis screw and align it as vertical as possible using measurements from a frame member and then lock down its top end bracket.
5. Tighten all 4 table screw nut brackets.
6. Tighten belt so it drives all lift screws.
7. By hand using the belt raise table to absolute top position. Top end brackets should be loose enough such that they will move and not bind the screws.
8. Tighten three loose top end brackets.
9. Align bed to X/Y axis. I used a dial indicator attached to traveling car and a piece of 12" X 12" 1/4" float glass. Loosen timing pulleys so each screw can be turned by hand and adjust each screw such that you get the same indicator reading in four corners. Depending on how out of alignment bed and X/Y axis were you might have to do this step a few times.

After leveling bed you might get some binding and have to realign the screws again starting with step 1. If you do you'll need to do step 9 again.
If you don't have the skins on and the base your laser is sitting on is not rigid the frame may flex if the laser is moved so you might get binding in the Z axis.
If this happens you need to construct a rigid base or put the skins on tight. I built a dead flat 4" thick torsion box top for mine.
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Re: Z Axis Binding. No idea where to start ...

Postby bloq » Wed Oct 28, 2015 11:05 am

Thank you very much guys!! With your help it was possible to make the z axis work. It is still not perfect but this is a matter of fine-tuning.
There is still a little bit binding at the hightest position but this position is way beyond the limit which is set by the limit switches / the laser head.

thank you very much!

tm
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