Z axis sliding down

[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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[peteeng]

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

[gio666]

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?

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

[peteeng]

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

[mactec54]

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?

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

[jannos]

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?

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