I have been summoned…
While in theory, the idea of a Linear slide or a cascade lift seems to be a good idea, in truth it is not. There are many examples of it working in situations outside of vex. For example, you have FRC, which has countless examples of successful lifts; a more practical example would be large forklifts. We spent a full season testing and optimizing our lift to keep up with dr4bs. We first started with a lift that was wheel driven as a proof of concept. While this did work it used 6 motors, which would be impractical. Our next prototype was to attempt a string lift, which was mentioned above, but it had many issues. The first issue that you will run into is that first string stretches over time giving inconstancy results. This combined with the fact that as the season goes on the string will become more brittle and stretch. Another thing to take into consideration with string is it getting caught in something which we decided was n to worth the risk due to the fact that’s our lift could be pulled over. Furthermore, the issue of winding string at the bottom has the issue that the string would be uneven causing unlined acceleration which once again would interfere with the accuracy need to place cubes.
Now on to our final we spent about 5 months perfecting our lift and making sure it was working to its peak. We firsts started with McMaster spacer, but while these do work they were 1 mm too big so we custom made our spacers, which was alluded to in our video explaining our lift. Then we moved onto reducing friction. The first thing we had to do is find the optimal type of Lube to use and what proportion to mix them in. We then had to figure out if there was any way to smooth the metal which was sanding it down with 1000 grit sandpaper due to intolerance due to vex’s poor build quality. Then to one of the largest success of out lift binning motors, batteries, power expanders, and, chain. Our team found that motors have a difference in performance ranging plus or minus 20 percent when voltage is held constant. The next thing we binned was batteries while the stated voltage is 7.2 volts we found that batteries can go up to 10.2 volts we ran our autos on 9.8 volts for maxim output on our drive and lift motors. Power expanders pics have tolerance once again around 10 to 15 percent which was needed due to the high power draw of our motors. and finally, the chain was manually inspected to see for imperfections to reduce friction.
Another issue is the amount of depredation on the actual parts. we had two robots, one could be practiced with while the other lift and robot could be rebuilt. We had to rebuild our bots every other week due to the parts falling apart. We went through 92 motors 2 power expanders and all of out metal on the two bots can never be used again (not just because they are in the display case).
Now while I do not regret doing any of this, in fact, that year was my favorite year in vex from sack attack to ITZ. However, the time we spent could have been cut down to 1% in the time and would not have created so many issues. So while on the surface it does look like a good idea to have a linear lift I would throw extreme caught to the wind. If you want to keep up with the stacking speed and constancy that we will once again see this year from teams with dr4bs be ready to invest 100 hours a week for a whole year just to lose your first elimination match because of b01.
Sincerely Danny Team 99371a
PS.
If you do attempt to make a lift this season I am not very active omg the forum, but more on the vex discord just ask for someone to tag me and I will always be willing to give my opinion
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Here are some (pre-Dreadnought) pictures of my cascade from a couple of years ago (2017). The design is much simpler than Dreadnought’s and works just as well. In addition, you should be able to lift it with 4 393 motors or 2 V5 motors.
you used locknuts as bushings?
I am not one who worries much about the weight, but I doubt that it can lift that effectively with lots of extra weight from 5x35s and all of the nuts.
Im not sure that using 5x’s instead of 3x’s is beneficial to the OP’s question which was how to make linear slides that are lightweight and smaller to fit on a claw.
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