Our team wants to build an 80/20 climb. We know how to rig it etc… but what we can not figure out is to connect them. We found some linear Teflon mount UniBearings but they are really expensive and heavy. I saw in another post by Dawgma 1712 https://www.youtube.com/watch?v=Nrn9cZYY__4 that they somehow connected the 80/20 extremely low profile. Does anybody know how they connected them? or a cheap and effective way to move the 80/20 linearly. P.S we are not looking to lift using the 80/20 just a way to deliver a hook. PP.s we have never built an elevator and we are running out of time to build and that is why we like the 80/20.
Hiiiii 1712 member here. I’m not in mechanical personally, but when I saw them building the 80/20 climb they did something with screws? will that help?
Edit: screws or bolts sorry
We used a combination of 80/20 nuts in one rail and drop-in nuts in the other rail to “sandwich” the two rails together (but not so tight that they are actually clamped together). The 80/20 nuts are essentially serving as washers, rather than nuts. Excess material was trimmed off the drop-ins to help reduce friction. There was also liberal use of 3-in-1Oil as a lubricant.
This prototype was developed as a hook delivery method, and this screw-based set-up may not be sufficient for bearing the whole weight of a robot. Given the risks of orienting the robot such that there are no >12" protrusions beyond the frame perimeter while climbing, we have since moved away from the detachable hook concept. As such, there may be evolutions to our design ahead in order to find sufficient load bearing surfaces. If you’re confident in your ability to route the winch cabling for your detachable hook such that you can lift your CoM without your cable extending >12" beyond your frame perimeter, this design should (hopefully) work for you as a hook delivery mechanism.
I will try and have some of our members get detail pictures at our next meeting on Tuesday.
Thanks so much! I am a bit confused about your point of the hook protruding outside the perimeter. Our plan is to rout the cables directly over the drive motors in the center of to robot. We will have 2 points of contact when hanging. We haven’t decided if we will need to lower the lift when pulling up w/ the winch.
If you’re using standard 10 series t-slot extrusion, then this Linear Bearing Pad is what you need for a very smooth working low-profile bearing pad between the extrusion sections. We used this on our elevator last year (and will use it again this year for our own version of a hook delivery elevator) and it was brilliant. You bolt through the central hole using a flat-head bolt into the t-nut in the t-slot to hold it in place. Two of them bolted to the opposite extrusion sections (one top and one bottom) give you the perfect slide with only about .16" between them. They’re made from UHMW, so no lubricant needed and they’re incredibly tough. The fit is tight enough to eliminate any wobble but still move quickly and smoothly.
This hang from a 2018 robot would be an example of a >12" extension beyond the frame perimeter as it climbs.
And consider the illustration in the blue box beneath Rule G18
OK thanks for your help I understand now! We originally planed to rout the cables so the bot would not do that. I took time to calculate the CG and we think we can make it hang somewhat level with our design.
Person who built it here, previous responses are mostly correct; each “bearing” is literally just a 90° 80/20 connector held in place by a bolt seated in a tapped hole in the 80/20. The bolts are used to clamp the stages together enough to control their motion but not enough to seize up. The bearings are arranged so that each stage has 2 points of contact with the previous stage at all times. I had played around with something similar to the linear bearing pads mentioned above and didn’t find them to be compact enough so I tried to make as clean and compact a slide mechanism as possible by hiding it all inside the slots, and that’s what you saw in the video.
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