80/20 Channel

[cmrnpizzo14]

Does anyone know of a piece that would fit into 2 pieces of 80/20 channel (the x-shaped kind with grooves) that would allow the 2 pieces to slide while the edges stay joined to eachother? I know that bolt-heads work, but I was wondering if they had a piece designed for this that would reduce friction.

Thank you!

[nathan_hui]

Are you trying to make a linear slider out of 80/20?

[JesseK]

Talk to team 357 if you're trying to make linear slides. They made a cast and molded their own plastic slides for 80/20. It was in the 2007 "Behind the Design" book.

[Anyun]

Two years (Logomotion) ago our initial placement mechanism for the inflatable pieces used a linear slider (we scrapped it later in favor of a pneumatic arm). Anyways, we did it by using brackets and a pulley system. The brackets were used to make sure the channels didn't go to far up and fall, and the channels were just slid on to each other. The pulley would force the channels to slide along each other until they hit the bracket above them, then the next piece would start rising.

It wasn't very effective for us, and I doubt it will work well, but it's a starting point if you're desperate.

[cmrnpizzo14]

Yes, we are trying to make a linear slide out of it, but it is a little more complex than that. It won't be large, but we will definitely need something as robust as 80/20. We have very limited machining capabilities, so anything COTS would be great.

[ksafin]

So... 80/20 linear slides..?
http://www.8020.net/Solution-8.asp

AKA yes they have tons of linear slide components for sale.
They're just VERY expensive.

[MrRiedemanJACC]

They are expensive, but we have worked with our local 80/20 salesperson for sometime and if you need small quantities (couple of feet) they may just be able to help you out. Our local salesperson has been more than reasonable in the past.

[Conor Ryan]

Back in the day, 1403 used bushing tubing to do a similar thing....
http://www.chiefdelphi.com/media/photos/20128

the tubes shown actually have different ODs, and then we had a bushing slider (mcmaster calls them sleeve bearings) inbetween.

Not such a teaser anymore?

[Donut]

Originally Posted by ksafin

So... 80/20 linear slides..?
http://www.8020.net/Solution-8.asp

AKA yes they have tons of linear slide components for sale.
They're just VERY expensive.

We built an extending elevator in 2005 that used the linear slides and the roller guides, they work really well as long as you space them far enough apart (we sometimes drove our rollers too close together and caused the elevator to bind). By far our highest scoring robot and we used some of them again in 2007 with success. If I remember correctly we just got the bearing pads and mounted them ourselves, not the full assemblies or bearing profiles, which saves some on cost.

Bosch also has some linear elements for use with their extrusion that is similar to 80/20: http://www13.boschrexroth-us.com/Fra...aspx?Group=112. I think the profiles are different enough that the sliders aren't interchangeable with 80/20 but don't take my word on it. It looks like they make linear bushings like 1403 used as well.

Igus makes nice linear slide elements, my senior design project used one of their slides on it. They're a long time sponsor of FIRST (how I found about them), most teams probably know them for including energy chain for cable routing in the kit every year but they actually do a lot with plastic bearings and even included a few linear parts in FIRST Choice this year. They're out of stock in FIRST Choice now but you can get a 1 meter guide rail and a sliding carriage for it for about $100.

[AlexH]

also sold as linear bearings

http://www.amazon.com/s/ref=nb_sb_no...linear+bearing

mcmaster's link to them doesn't seem to work right

[ThaneS]

I would recommend looking though McMaster-Carr's (http://www.mcmaster.com/) selection of linear rail components. Just search for "Linear Rail". They have a great selection. It may not be the cheapest in the world, but it will save you a lot of searching.

P/N 60585K18 are specifically made for sliding along 80/20. I am somewhat weary of any sleeve bearing solution though, as they are often much easier to bind. However, ball bearing slides are usually more expensive. If you call/e-mail McMaster, they may be able to give you values for the maximum moments that can be placed on the carriages. That should give you an idea of how resistant to binding the carriage will be.

[RRLedford]

Yes, 80/20 has some excellent linear slide concepts.
The three sided bearings are pricey, but the flat plate slides are more affordable.

This hard to find item is very,very useful for the 1" size framing. (Fastenal Part# 0961342 -- 80/20 Part#25-6797)
It can help stabilize adjacent sliding framing.


We used it with our FTC Kiwi bot elevator this year.
You can see it sticking out of the right rear elevator column where two 6-32 screws hold it in place. With only two stages to elevate 27" we had to go with minimum overlap of stage columns (<3"), requiring slide plates be <2" engagement.
This gave too much wobble on full extension, but this little piece solved our problem so well that we even got gravity return to work reliably.
NOTE: PICs are from when we only elevated to 16" so side plates not fully spread.




-Dick Ledford

[msheffels]

Perhaps two of these joined together, one for each piece of 80/20?

http://www.grainger.com/Grainger/802...CJ3?Pid=search

[RRLedford]

Yes, the C-shaped slider block is much stronger, but more appropriate for the heavier loads of FRC robots, and with three slide plates, also easier to be carrying the loads properly (unlike the bot in PICs above where shear is main loading on two slide plates).

-Dick Ledford

[Donut]

Originally Posted by RRLedford

Yes, the C-shaped slider block is much stronger, but more appropriate for the heavier loads of FRC robots, and with three slide plates, also easier to be carrying the loads properly (unlike the bot in PICs above where shear is main loading on two slide plates).

-Dick Ledford

How much strength you need is certainly application dependent. If I'm building a basic elevator to lift 5 pounds 5 feet up I might not be too concerned about the shear loads on the plastic sliders (don't take that as an excuse not to check what the load ratings are on the sliders). If a robot plans on climbing using linear slides then proper sliding support and connections are a must for the mechanism to survive.