Z Axis Mechanism (Concept)

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Z Axis Mechanism (Concept)

Postby BJenkins » Fri Mar 30, 2012 3:01 am

I don’t know if this concept has any real merit for a simple low cost Z table movement design but I throw it out there for anyone who may be interested. The only thoughts I have on this are included in the video description. Feel free to give the video a thumbs down if you don’t think it’s a worthy solution and also feel free to make comments. I would like to have a laser cutter in the future and maybe I can talk someone into building me one at some point. I have a friend who is planning to build one soon and I showed the concept to him but I thought it would be a good idea to see what kind of input good or bad that the group may have. It could be a big waste of time to consider this. I have a tendency of coming up with wild ideas. Ha!

http://www.youtube.com/watch?v=toiOsMDTmLk

Thanks,
Bill
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Re: Z Axis Mechanism (Concept)

Postby bdring » Fri Mar 30, 2012 3:21 am

Without doing the math, it looks like it would not be linear. One revolution of the shaft would not be the same Z movement at different location of the Z. EMC can handle this with some special machine coding, but it might be more trouble than it is worth.
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Re: Z Axis Mechanism (Concept)

Postby BJenkins » Fri Mar 30, 2012 4:08 am

(Interesting point) I didn’t think about that. I was thinking it would be a manual system. If it was only a manual system using a knob to rotate the screw then do you think this would be an issue?

Please keep the comments coming. I'm not sensitive about this concept and I would appreciate all potential problems being pointed out.

BTW; I am impressed with the buildlog designs that I’ve seen on YouTube and in the gallery. I’m kind of excited that I may be able to afford a laser cutter before long thanks to the open source efforts made by this group. I might even find the guts to try it myself. Ha!

Thanks,
Bill
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Re: Z Axis Mechanism (Concept)

Postby bdring » Fri Mar 30, 2012 12:45 pm

For a manual system, where you do not care about a linear system, a lot of people use a scissor jack style lift.
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Re: Z Axis Mechanism (Concept)

Postby BJenkins » Fri Mar 30, 2012 5:33 pm

I simply don’t know the advantages of a computer controlled Z axis vs. a manual system but I can see that a digital Z read out being a nice plus.
I do see other potential issues that I haven’t attempted to solve. Example; a. what method would be best to guide the table perfectly up and down, b. how to insure that the table stays where you put it. This is definitely an abstract concept but I would find it interesting and appreciate other problems being pointed out.

Thanks,
Bill
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Re: Z Axis Mechanism (Concept)

Postby daveczrn » Fri Mar 30, 2012 6:32 pm

i think it would be very hard to keep the table parallel to the laser. you would need to have one of these setups at each end of the table to keep it parallel and it would be a royal pain to get both sides aligned to move at the exact same time. you would also need to make the cone out of metal as it would most definatly wear out depending on how heavy the table is. and you would need to make round wheels to ride on the cone, these would also need to be metal, and all forces would be on a small spot on both the wheel and cone. there would also be a high thrust load on the bearings in the wheels.

its a very intresting concept and i am sure you could get it to work. but with how simple the 4 threaded rod system is i find it hard to replace it with something that still needs 4 rods for the table to ride on to stay straight up and down.
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Re: Z Axis Mechanism (Concept)

Postby BJenkins » Fri Mar 30, 2012 7:01 pm

Thanks for taking the time to go through this. Your points all make sense to me.

I do like the 4 screw belt and pulley system. I don’t particularly care for the scissor jack systems I’ve seen and I just decided to take a shot at what I wanted to be a simpler manual system. I was thinking that delrin would be the material to use for the cam and that may be more expensive than metal but I don’t know. I was thinking that the cam and lever system would only serve the purpose of height adjustment and therefore there would only be a need for one cam (if) the table was (somehow) configured with guides so that it could only move straight up and down. I have to admit that I thought there would be very little force on a laser bed because the material is usually light weight.

I’ll leave the video up just in case someone else wants to take a look.

Thanks,
Bill
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