Does anybody have a solution for creating linear motion without using steel parts? I intend to place a vertically sliding rail at the front of my claw, and therefore cannot afford to have the weight of the steel linear slides on my claw. I have seen one solution online, in the form of 99371A Dreadnought’s In The Zone cascade lift, but I don’t currently have the means to cut my own spacers. I have been experimenting with cutting through all the middle holes in aluminum c-channels and having a bearing flat “ride” along the track created. The results were promising, but the method was far too time consuming, involving cutting the channel with a rotary tool, and lots of filing with needle files.
I’ve never tested it, but I came up with a concept where you tie some rope between two holes in a c-channel or plate and zip tie two holes of another c-channel or plate to the string. That way the metal can slide up and down.
You know the black spacers that are 4 and 8 mm long? Until you can cut 0.25 wide ones, those ones will work fine. I used them on my cascade lift last year.
We have a cascade that uses a metal sleeve that is a bit thinner than the black spacers. TBH I have no idea where they are from, but it’s vex apparently and it works
I’ve been out all week, so I’m just now getting to this. Apologies, because I do think I have a good alternative to Dreadnaught.
This cascade uses string, aluminum channels, pulleys, and some other components that can easily vary. (Stops, pillow bearing cases replaced with standoffs connecting both halves of the lift, etc.)
I know there are lots of issues with this design, a big one being that it uses string. Alas, here it is. I know the pros and cons of this design, so nobody really needs to lecture me about why it’s so bad.
I have an idea similar to this but it’s much more compact. In order to reduce friction, you probably want to use lexan in some areas where the metal makes contact with other metals. Particularly on the inner part of the c-channel where the “lips” of the metal interconnect (idk if that makes sense)
It makes perfect sense, but the point of that design was to be a proof-of-concept without putting too much work into doing the whole lexan thing.
It uses some basic material coupled with that linear motion kit for those who want to adjust for the weight of the slide tracks (which is what I thought the thread was about). The pulleys can just be basic standoffs or screws, and it’s not a real high barrier design.
Perfect? No. Functional/effective? Yes. But it does have obvious flaws.
I really like this idea. Thanks. I do have one question however. the string is not necessary for the linear motion, correct? As I understand it, the string only provides a mechanism for driving this contraption, which I am actually not intending to do for my linear slides.
I noticed some people talking about using lexan for the contacting parts. Would this really be necessary? As in the dreadnought ITZ video, it seemed that simply greasing the contacting parts would be sufficient.
Correct. The string and pulleys are just to power it.
Also: Dreadnaught did some crazy stuff to get friction minimal. It might not be necessary to go as far as they did with laser-cut spacers and all. But there is slop in my design that might be fixable with spacing, however kind of unnecessary in such a passive system as I’m imagining you’re shooting for.
You’ll just have to go for it and tune as needed. Keep us updated!
Danny, one of the kids on Dreadnought, often tells people to just not build a linear lift due to the friction and other issues, so any improvements friction or otherwise that can be made on a lift like that are likely a good idea.
Using poly to lower the friction is a good thought. If you go this route remember that there is a max thickness of poly that is legal but not a minimum thickness so you could use thinner poly to make the lift more compact.
Good luck building.
High friction is almost always my team’s reason for abandoning the idea of a linear lift. In this case, we are not actually building a lift, but simply a structure that we can extend passively at the end of our claw such that the manipulator can hold more cubes. Sorry if that was not clear in my original post
In that case you can just go the route of making stuff as light as possible using lighter screws and nuts as a way to make the linear. It is possible to do Dreadnought’s lift out of 2x instead of 3x which lightens the overall lift. You can also make the design more viable by making the claw itself stronger to compensate for the linear’s weight as there is a limit to how light you can make them while still being semi rigid.
The linear sliders themselves would not necessarily require tight bolts, correct? I am wondering whether it would be beneficial to use nylon screws on the sliders as a way to reduce weight. My team had found that switching to nylon screws saves a reasonable amount of weight.
There will likely be certain places on the lift where you want to have a cantilevered screw joint where if there is any large amount of load on it I would still use steel screws. If the cantilever’d screw is for free-spinning spacers as a type of roller you could likely use aluminum screws. For things like bearing flats and polycarbonate mounting nylon screws and nuts work well.
