Hi,
I'm starting another project and that has a type of seesaw lifting mechanism that I would like to move with a stepper motor and lead screw. I'm starting to throw some shapes in Tinkercad to get an idea of where the pitfalls are in my thoughts and I hit one with the lifting mechanism. I thought I would use a stepper attached to a lead screw but since the mechanism is done with a seesaw(like on the playground) the attach point of the lead screw will go in an arc instead of a straight line. I could leave one side of the lead screw unattached but that would wear everything out quickly and it's not a great way to do things in general.
I realize this is a little out of the scope of the forum as it doesn't directly relate to Arduino even though I'm using one to control everything but I thought with all the experience on the board someone could nudge me in a good way to go about it. I was thinking a gear type system might work but since it will lift about 15lbs that it would take a fairly large stepper and so I thought I would ask to see if there was a way of attaching a lead screw that would allow an arc type motion.
Thanks
Consider posting a drawing that shows what you actually want to do.
Also give us some idea of the dimensions and masses and required speeds.
A good general description of the project makes it much easier for us to give useful advice as it puts your questions in context.
...R
A lead screw attached to a turning center allowes the leadscrew to move. The moving part can then be made following any desired curve. Take a look at the mechanics used for the excavator arm! They use hydraulic cylinders and oil, You use a lead screw.
Assemble the lead screw things, apply the load and try to measure what torque You need. Then buy the stepper and the power supply.
The thin rectangular bars are 10" long with the pivot point around the center of that 10". The Left side will have about 15lbs of weight attached to it and I thought about adding a counter balance to the right side to make movement easier.
The left side of the mechanism is the lifting attach point where my troubles began.
The left side of the mechanism is the lifting attach point where my troubles began.
What does the left side do?
What are those troubles?
Where and how is the motor attached?
Railroader:
A lead screw attached to a turning center allowes the leadscrew to move. The moving part can then be made following any desired curve. Take a look at the mechanics used for the excavator arm! They use hydraulic cylinders and oil, You use a lead screw.
Assemble the lead screw things, apply the load and try to measure what torque You need. Then buy the stepper and the power supply.
I would do it that way if I was using pneumatic cylinders, I have done this with other equipment. The fact that both cylinder ends are floating attach points and a smooth rod I don't worry about things wearing down because there is movement in the attach points.
With a lead screw the attach points are fixed and it wants to travel in a straight line and any side to side movement is going to cause a great deal of wear on the threads and the nut. I thought I would get around it with a rotating shaft on the end of the seesaw but then the arc motion come's into play and the fact that the arc moves away from the plane the lead screw operates in.
jremington:
What does the left side do?
What are those troubles?
Where and how is the motor attached?
Sorry, I got my lefts and rights mixed. LOL
The left side is a fixed weight(15lbs) attached to the mechanism and will move up and down probably about 3" max.
The right side which has nothing attached to it in the pic is where I will connect the stepper and lead screw in some fashion. I thought of using a swiveling pin at first but with the movement of the mechanism being an arc because of the pivot placement will make the pivot move away from the the lead screw.
Perhaps an eccentric connector would work, the type you would see on a rig that pumps oil from the ground?
Railroader:
A lead screw attached to a turning center allowes the leadscrew to move. The moving part can then be made following any desired curve. Take a look at the mechanics used for the excavator arm! They use hydraulic cylinders and oil, You use a lead screw.
Assemble the lead screw things, apply the load and try to measure what torque You need. Then buy the stepper and the power supply.
I think I follow what you are getting at, an eccentric, I will have to start searching.
If the lead screw is an extension of the stepper motor shaft then the motor could be mounted on a gimbal.
...R
Robin2:
If the lead screw is an extension of the stepper motor shaft then the motor could be mounted on a gimbal....R
You don't think that will create strain on the lead screw and wear the coupler nut down?
That would be the simplest way to take up the wayward movement of the arc.
ribbonman:
You don't think that will create strain on the lead screw and wear the coupler nut down?That would be the simplest way to take up the wayward movement of the arc.
Isn't there going to be strain on the leadscrew and the nut whatever way you organise it.
The diagram in Reply #4 gives no indication of how you envisage the system working. A simple 2D pencil sketch would probably be a lot more enlightening.
...R
Let the stepper be firmly connected to the lead screw but this build have a pivot point near the stepper. The lead screw nut (lathe terminology) follows a track in a plate and You have almost any curve of movement You want.
Take a look at marble machines! Look at their lifting, elevating parts! Lots of mechanical inspiration to gather.
This will raise the demands for the stepper marginally.
Also take a lok at vobbling steam engines.
Robin2:
Isn't there going to be strain on the leadscrew and the nut whatever way you organise it.The diagram in Reply #4 gives no indication of how you envisage the system working. A simple 2D pencil sketch would probably be a lot more enlightening.
...R
You are probably right.
I hadn't come up with attaching and moving but basically on the right side of the pic I will connect something to pull the rectangular arms up and down moving on the pivot point.
Railroader:
Let the stepper be firmly connected to the lead screw but this build have a pivot point near the stepper. The lead screw nut (lathe terminology) follows a track in a plate and You have almost any curve of movement You want.Take a look at marble machines! Look at their lifting, elevating parts! Lots of mechanical inspiration to gather.
This will raise the demands for the stepper marginally.Also take a lok at vobbling steam engines.
Thanks for the ideas, they very helpful.
That's why we're here, to assist. Come back when You've gained more ideas how to arrange the mechanical stuff. The rest will be common Arduino knowledge.
ribbonman:
I hadn't come up with attaching and moving but basically on the right side of the pic I will connect something to pull the rectangular arms up and down moving on the pivot point.
If you want more help this is much too vague.
Do your thinking and then post a simple diagram that illustrates it.
...R
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