Hello, me and my team are trying to use the GreyT elevator from WCP, but we want it to have both a shorter starting height as well as a different maximum height. In the past we have tried vertically scaling it, and ran into many issues.
I’d highly recommend you design your own elevator around the WCP components (blocks, rigging etc) if you want real control over the length and width. It also helps with understanding the intricacies of putting it together- and with fabworks and punched tube, you can totally get away with 0 in house fabrication if that’s your jam.
Pretty in depth tutorial on designing one here but I’m sure people can answer any specific questions you might have.
Otherwise you can try to import their model and replace the tubes with shorter ones from MKCad but from personal experience this would be pretty tedious.
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Is the total extension distance of a 3-stage elevator is just 2 times the distance from the inner stage to the top of the second stage? As long as no other pulleys/blocks are getting in the way.
We just today made a copy of their onshape document and adjusted the dimensions to what we wanted it to be. Would be good if some of those variables are exposed as configuration options.
The total extension distance of an elevator depends on the stage overlap at full extension, so I don’t think that formula is quite accurate.
On a cascading elevator, that’s set by the range of the carriage inside of the final stage (because all the stages move in sync), so you can decrease overlap by making the carriage larger or that stage shorter.
On a continuous elevator the overlap just depends on where you put the end stops. 5-6 inches is decent, the more the better.
Really you’ll want to do a mastersketch to figure this kind of thing out. I’d recommend this video: https://m.youtube.com/watch?v=Bd_XzBw5V_U
We have purchased the v4 GreyT kit. Fabricating in our shop is a pain. So I might turn around and purchase the AL tubing from WCP…
I am confused after staring at the Onshape file as to which sort of tubing to purchase. I assume this [2" x 1" x 0.125" Aluminum Tube Stock 1" Pattern (47") (WCP-1024)] would be fine, but I am unsure.
Any advice or corrections would be a appreciated.
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You have a few options.
First, you can choose between 1/8 wall and 1/16 wall. If you’re not super concerned with weight, all 1/8 is fine and probably a little easier to work with, since the tube plugs go directly into it and don’t need a sleeve.
Next, as you noted, 2" x 1" x 0.125" Aluminum Tube Stock 1" Pattern (47") (WCP-1024)] would work just fine. However, note that the GreyT elevator does have some holes on the two inch faces:
If you get the 1" pattern, you’ll have to drill those holes by hand, which is not a big deal if you have a drill press and some patience. In particular, 3D-printed jigs can help with hole alignment. Just note that tube plugs do rely on good hole alignment for strength, so take your time with it.
However, if you opted for 2" x 1" with 2" Pattern (WCP-1025, WCP-1428, WCP 0895), you would not have to drill any of those holes, making assembly a bit easier, and allowing for easier modification down the road (say if you wanted to shorten the base stage). The disadvantage is that you have a hole grid across the whole tube. This doesn’t tend to matter much on elevators, aside from looking a bit less clean, but ultimately it’s up to you.
Okay, a novice question from a novice.
We built it and tested it without a gearbox, just a drill hooked up to the 1/2-inch hex shaft. Goes up beautifully, but dropped way too fast. Is the proper gearbox really going to slow decent down, or did we miss something.
So a drill will likely be underpowered going up. Gravity of course helps going down.
Driving down as fast as if not faster than gravity isn’t a bad thing. But you can always add constant force springs to help counter balance and make the power requirements for up similar to the power requirements down.
FRC motors have enough power that this isn’t usually a huge issue, provided that you set up the controls properly (Kg term in the control loop is used for this exact thing). In certain cases teams have used constant force springs to balance elevators, especially if they’re not serving a second purpose as a climber.
Those can be dangerous and annoying to deal with though, and usually unnecessary.