Linear Motion Breaking

[Jim Dawson]

In that case, a cam applied clamp with a solenoid or air cylinder actuator would be my choice.

[handlewanker]

So.….you need to move the linear bearing block on each position individually up and down independent of each other and hold each one seperately.....that can't be done on a single ball screw.....but you could have 2 ball screws with 2 ball nuts one each attached to each of the bearing blocks.

Then you can activate each ball nut independently as they are now independently attached to each linear bearing.

What if you did away with the linear rail and bearing block and just had each ball nut housing attached to the frames you want to move?

Having two seperate screws with a stepper motor for each means you can independently move each ball nut housing without having to lock and unlock a linear bearing braking device.

Each ball nut can be held in a precise position by the holding power of it's static stepper motor, and either ball nut can be held in position or moved while the other one moves without the first or second one moving off position.
Ian.

[handlewanker]

Also I'm not to sure what it means by mobile device because I am on a desktop computer.

A mobile device is a phone or Ipad etc...…..down in the bottom left side of the post it says …"posted via Mobile Device" so I assumed it was being sent from a phone or Ipad…..I don't really know what it means otherwise.
Ian.

[maxbest]

If i have just a ball screw with a ball nut on mounted vertically, nothing attached to the ball screw or ball nut and I rotate the ball screw, what will happen to the ballnut, will it rotate with the ball screw and keep its same verticaly postion or will it move down the ball screw???

[maxbest]

Just because I am thinking that I could then have two ball nuts on the ball screw instead and then engage and disengage them to the ball screw. Whilst still locking and unlocking them to the linear shaft.

[Jim Dawson]

It is not possible to disengage the ball nut from the ball screw, short of screwing it off of the end of the ball screw.

[maxbest]

i dont mean literally disengaging it from the ball screw but instead preventing it from moving up or down whilst the ball screw is rotating and it has a housing around it.

[handlewanker]

Reffering to post #24...….No, it will not move up or down.....it's the same as any nut on a threaded rod and 2 nuts will also not move up or down if the rod turns and they are loose.

It is also not necesssary for the ball screw to turn....if it was fixed to a base vertically you could have a stepper motor to rotate each ball nut and so drive them seperately up or down as desired......each of the ball nuts driven by a stepper motor would of course have to be rotating in a housing which is attached to the load you are driving.

A simple design for one driven ball nut could be a ball nut with a timing pulley fixed on one end and a stepper motor driving it via a timing belt.....the whole lot enclosed in a housing......you would have to have a ball thrust bearing on each end of the ball nut to transmit the load.

You have to apply the characteristics of a ball screw/ball nut combination to establish a principle on which you create a design.
Ian.

[Jim Dawson]

When free, the only thing preventing the nut from moving on the screw is whatever friction exists between the nut and the screw. I can't imagine this being a reliable method of ''releasing'' the nut with the idea of it holding position.

I do know a used (and thus looser) ball screw/nut assembly that the nut will rotate down from gravity when the screw is held vertically.

[maxbest]

In relation to my initial question about locking a linear bearing to a linear shaft, I have just found these: https://uk.misumi-ec.com/vona2/detai...0424922%3a%3af I'm trying to figure out how they work exactly, something to do with a spring and the lever but I don't quite get it. Have any ideas???

[Jim Dawson]

In relation to my initial question about locking a linear bearing to a linear shaft, I have just found these: https://uk.misumi-ec.com/vona2/detai...0424922%3a%3af I'm trying to figure out how they work exactly, something to do with a spring and the lever but I don't quite get it. Have any ideas???

Not really enough detail in the picture to tell for sure, but it looks like the lever operates a cam. Maybe something like a sprag clutch, spring applied and press the lever to release.

[handlewanker]

Yes, the clutch grips the shaft and can be released by depressing the lever to allow it to slide back and forth......it would have the same effect as gripping the shaft with your hand and relaxing it when you want to move.

As far as the actual design is concerned you will have to buy one and try it out.
Ian.