Scissor Lift - Help Needed

[Paul B Technic]

I am in the process of building a scissor lift (http://www.coateshire.com.au/access-hire/scissor-lifts-hire/scissor-lift-electric-hire/).

So far this is what I have built.

Now this works well but it is VERY unstable when extended to the maximum with a lot of side to side movement at the top, even when the base is held solid. Other than making the whole thing lower or "double beaming", can anybody offer a way to reduce the movement at the top?

[Alasdair Ryan]

Ideally you really want beams on the other side too, three studs wide in total instead of currently only two studs.

Cool project.

[BusterHaus]

I built one that was five studs wide and found that the use of friction pins helped a lot. It eliminated quite a bit of the slack in the system. Here's the only picture I found, sorry about the potato quality - it was in the background of a quick picture. It's pretty wide but wasn't that wobbly.

[Saberwing40k]

Look at a real scissor lift, like this Genie unit, and look at how the beams are arranged.

Also, i have found out that using pins, particularly frictionless ones makes connections that are really flexible, so try using axles for joints instead.

Also, thinking further, the scissor lift you are looking at only has four scissor sections, whereas you have seven, so it's a little out of scale. Also, I have seen real scissor lifts in action, and they can flex a frightening amount at maximum extension, which is why they have really low side load limits.

Edited March 12, 2016 by Saberwing40k

[DrJB]

Lateral stability depends primarily on the gaps/ clearances in the pivot connections. It got not much to do with the beams arrangements. when it comes to Lego, the two factors neded to make it stable have already been stated above: make the distance between beams as wide as possible, and use friction pins. There is also bending rigidity of the beams, but that comes into play only if u're carrying heavy loads that cause the beams to deform.

Edited March 12, 2016 by DrJB

[dr_spock]

You should have arms on the other size. Mounting the arms to a platform frame at the top will add some rigidity too.

Day 091 of 365: Catenary Maintenance by dr_spock_888, on Flickr

[Paul B Technic]

Thanks for the replies and suggestions, I hope to get working on it in the next few days.

[Lakop]

Nice lift. Just needs fine tuning. good luck with it.

H

[Kman860]

I built one that was five studs wide and found that the use of friction pins helped a lot. It eliminated quite a bit of the slack in the system. Here's the only picture I found, sorry about the potato quality - it was in the background of a quick picture. It's pretty wide but wasn't that wobbly.

I hate low quality potatoes too :laugh:

[Paul B Technic]

Thank you. I hope to get a chance to work on it in the next few days.

[Paul B Technic]

I have spent a few hours on it tonight, had to change to large LA and rebuild most of it but now it is much better. Next step is to add PF :)

[paul_delahaye]

I confirm, having driven a 12m scissor lift at full height, they are very wobbly, look forward to seeing your progress, and definately one I've been waiting for Lego to produce for a while. There were early ideas on the back of some of the expert builder sets in the 78 - 80's era. but not a lot since.

[JDL1967]

Maybe you can to try it with double beams on each side, and place some actuators in it.

[Paul B Technic]

Thanks for the suggestions. Once I test it with PF I will know if it needs more work.

[Paul B Technic]

PF test went well tonight, still not as stable as I would like but it is getting better.

[wissamms]

What did you modify?

[Paul B Technic]

What did you modify?

Changed to friction pins on the cross arms

Changed to axles for the top and bottom

Added some extra bracing

Changed to a large LA so had to modify the base to support this.

[Paul B Technic]

Here is a "progress" video. I had to change to the L motor as I manged to kill the M motor :(

[oracid]

Very, very, very good !

May we have some pictures as clear as the first one, on the top of this thread ?

[Paul B Technic]

Once I am happy with it I will be taking a heap of photos :)

[Paul B Technic]

I have ran in to some issues with this so it is going back to the design stage. I wont have much time to work on this for a while, life is getting in the way...