Our team has been pretty stuck this year on winches and on how to pull back a catapult. We originally wanted to go for a non-backdrive winch/gearbox with a clutch, that way we have total control over the power of the shot. We have decided that this is not necessary/reasonably possible, so we decided that we wanted to use the modulox lunchbox like in the robot in 3 days video. Of course they are out of stock now, so that is no longer an option.
So, Can someone please recommend an alternative to the modulox lunchbox, like the one used in the robot in 3 days video?
We are using a modified Gen 1 Shifter but i believe those are out of stock/not made anymore. You could base it off a super shifter of a tough box. Tough box obviously needing a secondary release mechanism or integrate a shifter mechanism…a fair amount of machining.
at 2429 we were able to get a andymark sonic shifter to do the neutral and the one way drive. We did this by 1)removing the both of high speed gears from the cluster 2) putting in a pvc spacer where the original first stage gear used to be on the motor input gear 3) we used a craftsmen cross force ratcheting wrench in place of the brass that was being used as a spacer on the top of the input shaft. I will post pics as soon as i can
I would look at what team JVN did for the build blitz and maybe combine some of their features into yours. For the non back drive quality that they needed they used a 1/2 in ratcheting wrench and put it around a 1/2 hex shaft on the gearbox they were using. You could easily implement this using a touch box or a shifter box ex. ball shifter or AM Supershifter. Then you have to decide on how you release the cable attached to your shooter. This would be a neutral gear so to speak.
^^
What he said. The choo-choo works well for us (so far) and we are working on some tweaks.
If you want to drive a winch, and have another release mechanism in mind, you might take a look at this. Low cost hypocycloidal gears, packaged like a large wrench. Pretty cheap at Harbor Freight. The motor shown is not legal any more, but several good alternatives are out there including PG71 and Versaplanetary.
Its a bi-stable mechanism. Once you pass a tipping point, the mechanism releases itself.
Because there is a hard stop for the first part of the linkage on the rotating wheel, it can pull down the catapult. Eventually this hard stop no longer prevents the linkage from moving upwards, and the surgical tubing pulls it.
If you look at this video, the screw catches the first part of the linkage, allowing the catapult to be wound back. They cut away just before launching, if you continue rotating the gear further, the direction of the force on the linkage switches from against the screw to free allowing the linkage to snap and release.
We somehow got our hands on a lunch box but as an alternative to adding a shifter column we just cut down a spring and placed it between the two gears on the 3/8 shaft. A mini cylinder will disengage the gear and the spring will return it. It was a very cost saving way of doing it
Thank you very much! This clarified a lot and now the shoe thing makes sense! Are there any existing equations out there to help figure out the proper lengths of each component based on the total amount of pullback required?
It was out of stock due to the 1/2" Hex Shaft Collars which are not needed for the winch assembly. This part is not supplied by iR3 but we do keep a small inventory and will be sending this to AM as reserves if needed. You could also order the specific parts required for this assembly without a problem.
We apologize for this temporary inconvenience it was certainly unexpected.
