Our was looking into which kind of COTS elevator/lift is the best and I couldn’t really find a lot of info online. Last season we used the Andymark 2x1 Single Stage HD Elevator Bearing and Structure Kit which is now discontinued, however, we were kinda disappointed by it and we are looking into other brands.
Right now we’re looking at two different elevators, the thrifty bot elevator, and the greyt lift from WCP. If there’s any other good brand of lifts we’d love that to know that as well.
The Thrifty Bot Elevator seems to be the better of the two primarily due to the inclusion of constant force springs to counteract chain backlash, which is not present on the GreyT elevator. I can’t imagine it would be incredibly difficult to modify the GreyT elevator to include a counterbalance, but out of the box compatibility would be easier.
Those are the only 2 complete kits for modern FRCFIRST Robotics Competition elevators. Both AMAndyMark and REV also sell elevator bearing blocks. Many teams ran both during the 2023 season to great success. I can’t necessarily recommend one over the other as I’ve never used them, you would need to dive into the specifics to see what fits your team’s specific design style/philosophy or else hear the testimony of others, however I think you’llLimelight, an integrated vision coprocessor get a great elevator kit either way.
115 used the Greyt 3-stage elevator last year, and it was mostly fine. Once we set it up, we found it very reliable. We did have to modify it slightly to suit our robot design. The large bearings on the slides made it more attractive to us than the TTB design.
Things we struggled with:
Ultimately, we ended up replacing the rope with steel wire rope and steel wire ferrules which we crimped on to make the loop. This resulted in the rope clamp blocks not “biting” deep enough into the rope, so it would slip over time. We had to retighten the blocks each match, and overtightening them would crush the tube because the bolts go through the thin crossbar 2x1 at the top of the elevator.
If I had to do it again, I probably would use the TTB elevator or use better rope tensioners on the WCP elevator or modify the clamp blocks to be tapped and screwed together for better clamping performance. I did enjoy the stock 3-stage kit that TTB did not have native support for, and I like the WCP bearing block design more overall. Probably easier and cheaper to make modifications to the cable routing on the WCP than to add a 3rd stage to the TTB.
Do you know what type of knot you were trying? While we didn’t use the greyt elevator for 2023, we copied many of it’s design elements including the same tensioning system (same rope pulleys and ratcheting hex shaft with hole drilled into it).
Browsing through the documentation I see that it just says “tie a knot” without any indication of what kind of knot should work in this application, which is pretty important:
The FRCFIRST Robotics Competition rule of thumb and what we’ve used on all of our elevators is a bowline knot. I spend a good 30mins to an hour every build season when it’s a lifting game walking a few students through tying bowline knots correctly precisely to avoid the issues you’ve described.
I wonder if it would be a good idea to update the documentation @R.C to be a bit more specific/link a guide/video on knot tying. Just an idea.
We had great success with the TTB elevator last year. We did end up customizing a few of the parts based on our specific design needs, but it provided an excellent base kit and really helped us get off the ground (we had never done an elevator before). I would definitely recommend it.
We used the TTB elevator and it was good. The only item we had issues with was on our carriage that would occasionally slam into walls we would bend or snap the shoulder bolts that held the bearings. We ended up redrilling and tapping these to 1/4-20 and did not have any issues after that.
I also wish the bearing blocks would have used a more standard hole spacing as the extrusion had to be drilled where WCP bearing blocks have a hole spacing that lines up with standard .5” hole patterns. Not a huge deal, but a slight inconvenience.
Overall we were happy with the TTB elevator and will likely use again if the challenge suits it.
We did only do a single stage so I do not have direct experience with using multiple stages on the TTB system.
For 1 I pretty heavily rely on importing a giant assembly, grouping components in place, deleting or suppressing what I don’t want, and then repeating for each sub as needed.
It’s not zero hassle, but sure easier than reassembling from raw parts.
Good suggestion,
We’ll do that and all elevators are moving to the ratchet plate tensioners. This will help teams that struggle with tying knots to the right length.
It was a bowline I believe. Maybe we’re just very unskilled, but I’ve been on way too many unskilled teams not to care about this. We had a mentor and a few students working at this before giving up. It’s not like we didn’t know how to tie the bowline, but getting all the lengths just right was a massive game of guess-and-check.
That’s what we ended up doing. Unfortunately due to how the parts are assembled, it’s surprisingly difficult to get every single screw and ball bearing selected when trying to group the parts. Also, while I was using OnShape to just validate the geometry, the students were all working in Inventor, which I do not know how to use well. I don’t know if it has an equivalent “group” tool. If I was in Solidworks I’d move parts into subassemblies to get them to stick together.
As a general heads up here, as WCP gets all the raw components on onshape. We’ll be working on making the assemblies like greyt telescope and others dynamic so you can generate the width + height needed. This is a longer term goal but on our roadmap.
This way you can generate a file in onshape and download it as steps for other programs (inventor, solidworks etc…)
Configuring the tube lengths was definitely a holdup, because it meant we had to delete the existing tubes and re-mate everything.
My experience:
We used elements of both the Thrifty and WCP elevators on our 2023 competition robot. Specifically we used the WCP bearing blocks because they allowed for narrower gaps between tubes as well as a sturdy mounting method and large bearings. Everything else (motor mounts, chain system, cable tensioning) we used Thrifty because it was easy to understand, assemble, and maintain. We built a full spare elevator and never needed it.
Team 111 used these from AndyMark and I think they look great: Compact Elevator Bearing Kits - AndyMark, Inc
I’d consider trying them for a future game with an elevator.
Ok I see now what you are talking about nailng the lengths with the turnbuckle.
We ran a version with a racthet which I believe has a much more user friendly tensioning routine since you can tie the bowline on 1 side and leave the other end however long you want since you just need a simple knot to prevent it pulling through the hole in the hex shaft. Now that the WCPWest Coast Products ratchet plates are here I wonder if the Greyt Elevator will use this in favor of a turnbuckle beyond the single stage version? Confirmed by RC.
This is a rope installation guide I wrote for 3512 for getting our 2023 elevator tensioned:
Here’s a colored diagram and some close up pics of the clamping blocks and carriage hex shaft w/ hole:
One thing to keep in mind with WCP kits, is to ensure you’ve ordered EVERYTHING that you need for it.
WCP lists a majority of their kits by individual parts, and leaves it to the customer to ensure they’ve added everything they need to their cart. I’m told it’s to allow teams with a large inventory of existing parts to be able to order only what they need, but I find it generally rather confusing/frustrating.
We’ve ordered multiple kits from them over the years, and each time we’ve ended up missing critical parts from the kit (that had to be ordered separately); Something that can be a rather big problem in the middle of a chaotic build season. Often times I’ve found mention of what’s needed to be ordered, but buried in a 50+ page manual (and not listed on the product page).
Because of these ordering issues, we’ve actually *sworn off buying kits from WCP. Things may have improved over the last couple years, but this has been our experience, your mileage may vary 
.
*We still happily place orders for some of the amazing individual components offered by WCP, just had too many issues with the kits to rely on them in season anymore.
Brian,
Thanks for your honest feedback. We’ve gotten similar feedback over the years and have attempted to fix it/make it better. Fast forward to now… This is we are doing:
I’m always open to feedback and we’ve made changes over the years. Some are easier to implement than others, but I think the experience is getting closer to ideal.
WCP makes some awesome prodcuts, so glad to see the company taking steps to address some of the weaker areas pointed out by their customer feedback. Im looking forward to seeing what else you guys have in store.
Keep up the awesome work!
We personally use a mix between the 2. We went with the bearing blocks from WCP because it supports both 2x1 and 1x1 on a 1/2" pitch. We also use tube plugs from WCP because we didn’t want to deal with plates. We then use the pully kit and motor mounting brackets from thrifty because it’s easier to use and faster to put together.
Speaking from team 6081’s experiences with a Thriftybot 2 stage elevator, I would 100% recommend it to anyone who is looking for a COTS elevator kit. We have over 130 competition matches and over 100 hours of drive practice on our original elevator, and all of the original parts. We have absolutely abused our elevator to no end, done absolutely zero maintenance, and had absolutely zero issues.
We used a combo of WCP and Thrifty parts and loved both of them. We wanted to use the WCP inline blocks to get a narrower elevator and it’s easy serviceability (never hat to touch them), with no riveted components. We also took advantage of the 10-32 tapped thru holes to mount our yoshi tongue/laterator
We used the pulleys, sprockets, turnbuckles, and chain mount from the Thrifty kit, all of which worked flawlessly.
