# What linear actuator to use

I want to make a project, where I put the log on a conveyer belt and at some time i want to apply linear force from the side that it would push the logs to the side. But I am not sure what mechanical device to use. I read a lot about linear actuators. They seem to do the job, but I dont know what kind of linear actuators I need, I never used one. The log weights from 10 to 40 kilograms I guess. They are about 1.5meter long.

I was thinking about using one linear actuator, which would apply force to the center of some board, that would push whole equally, and that way I dont need to worry about the dimensions of the logs. it would push no matter what size the log is.

I hope that someone can lead me to knowing at least how powerful actuator must be to do this job.

You will need to know the force required to move the log, the distance that the log must move and the speed of the movement to be able to specify an actuator. Can you measure the force required with a fish (spring) scale or similar? Do you have a drawing of the device that you can post? How to post an image.

edit to add: How often does the movement happen? Some actuators have duty cycle limitations, they cannot be continuously cycled so must "rest" some time between cycles.

Thank you for a reply. I will try to give a brief idea.

So the problem is, that my parents get older and they cannot do hard works anymore. Wood cutting is one of the hardest jobs.

I attached a drawing. Imagine that you are looking from the top at the wood cutting machine. Its construction is made from wood and the actual saw is from metal, it is marke with black waves. so everything that has black borders in that drawing is what I have now. Basic thing, is that you take the log, put it on the table, and then push it to saw and it gets cut. And this is the hardest part. So I would like to somehow make it easier. what i was thinking, is adding another wooden construction(everything that is marked as red).

So I would add a table with the same height as the wood cutting machine, which surface would be made from rotating wooden parts. I dont know english term for them, but that is not the main thing. so when you push the log(which is that black thing on red table), so that it touches the very end (red solid rectangle), i could use two pedals. that would control two linear actuators on each side. So the scenario would look like this:

1. Turn on cutting machine.
2. Put log on the red table and move it until it reaches the end.
3. Then use one of the pedals to stretch board with linear actuator that is marked as no. 3 on the drawing.
4. When the log is tightly pressed with both red boards, then press another pedal which would start stretching linear actuator marked with no. 2. at the same time linear actuator marked as no. 3 will start to release. that way, log would be pressed against the saw and start cutting.

When log is cut, again it would be possible to press pedal which controls linear actuator no 3 which would move the log at the starting position. Then you just need again to push log until it reaches the very end and repeat the process.

This is the best idea I could imagine, it would be great if someone has a better solution and would share with it.

So talking about force. I Imagine that if the log weights from 10 to 40 kg, I need to use wood to wood friction coefficient that is 0.6. And calculate needed force like this:

F = 40kg * 0.6 = 24 N

So I need a linear actuators that can apply 24 N force? Or there are any other forces that I forgot about?

I also want to mention that I am not very experienced with physics as you can see. Im a software engineer, have some experience with Arduino Uno and Mbot. So buying the correct tools is the biggest challenge for me. I do not want to overpay and buy way more powerful actuators than I need.

Edit: I forgot about what happens when log actually starts touching with saw, I guess it would apply some force against the actuator. So I would need more force than 24N when the actual cutting would start?

You are really over-thinking this.

Hire a neighbor boy to help with the wood cutting.

Paul