Z axis sliding down

Hello,
I am upgrading my cnc milling machine with better linear rails and a ball screw instead of the lead screw I was using. Now axes runs much smoother and nicely, but when I fit the spindle, the Z axis tends to slide down. I haven’t fixed the stepper motor yet, but I don’t think that will improve much the situation when it’s off.
Total weight of the axis is less than 10kg but anyway enough to create this problem.
I have seen some machines have installed gas springs to avoid this problem, but I struggle to find a gas spring with less than 100N force and 300mm stroke.
Is there anybody that have some other suggestions?

Hi Morf -
1) you can install a brake on the stepper
2) you can install long tension spring(s)
3) you can use a gas spring - the hardware store has springs that range for cupboards
4) you can use a counterweight
5) a bungee to the roof helps
6) helium ballons
7) build your own gas spring using a remote air tank

I've done a couple of these, but prefer to use a brake on the motor these days much simpler... Peter

Quote:

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Originally Posted by morfeus80

Hello,
I am upgrading my cnc milling machine with better linear rails and a ball screw instead of the lead screw I was using. Now axes runs much smoother and nicely, but when I fit the spindle, the Z axis tends to slide down. I haven’t fixed the stepper motor yet, but I don’t think that will improve much the situation when it’s off.
Total weight of the axis is less than 10kg but anyway enough to create this problem.
I have seen some machines have installed gas springs to avoid this problem, but I struggle to find a gas spring with less than 100N force and 300mm stroke.
Is there anybody that have some other suggestions?

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you can use back SUV window shocks work good or change the motor with a brake

Hi Morfeus - Also with the gas spring if there is a strut regasser nearby they can gas a spring to your force range but a brake is the go... Peter

Quote:

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Originally Posted by morfeus80

Hello,
I am upgrading my cnc milling machine with better linear rails and a ball screw instead of the lead screw I was using. Now axes runs much smoother and nicely, but when I fit the spindle, the Z axis tends to slide down. I haven’t fixed the stepper motor yet, but I don’t think that will improve much the situation when it’s off.
Total weight of the axis is less than 10kg but anyway enough to create this problem.
I have seen some machines have installed gas springs to avoid this problem, but I struggle to find a gas spring with less than 100N force and 300mm stroke.
Is there anybody that have some other suggestions?

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You can also just mount a piece of plastic against the Ballscrew, this will work like a friction brake, can be spring loaded, needs very little load to stop the screw from turning, a piece of cutting board will work, or other quality plastic can be used

Quote:

---

Originally Posted by morfeus80

Hello,
I am upgrading my cnc milling machine with better linear rails and a ball screw instead of the lead screw I was using. Now axes runs much smoother and nicely, but when I fit the spindle, the Z axis tends to slide down. I haven’t fixed the stepper motor yet, but I don’t think that will improve much the situation when it’s off.
Total weight of the axis is less than 10kg but anyway enough to create this problem.



I have seen some machines have installed gas springs to avoid this problem, but I struggle to find a gas spring with less than 100N force and 300mm stroke.
Is there anybody that have some other suggestions?

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Mount the motor first and if it still sliding down, then use brake or springs.