We usually use a cut list + reference cad, though we haven’t had the time to train everyone in the proper way to cut tube I guess, we’ve made a scuffed 3dp jig + added some QC checks to make sure it doesn’t happen again though.
It would probably be good practice to make drawings, but things usually change on the fly, and documentation is hard, lol.
Would you say the cost vs time saved was worth it?
Even so, I’d say it was worth the time save
We designed this jig for use with REV MaxTube precisely for the reasons you mentioned. These were inspired by something I think @Nick_Coussens posted on Discord a while back.
This uses these dowel pins from amazon. The onshape document below has an adjustable kerf setting for whatever your blade width is.
Onshape Link:
Printables Link:
https://www.printables.com/model/373487-jig-for-cutting-10-hole-patterned-box-tube
Hope this could be useful!
Finals week is approaching! As a result, we’ll be slowing down our meetings, and mostly doing programming and light manufacturing. We’ll probably sendcutsend any necessary plates for our competition robot, and I’ll post a requirement list for our competition robot
Anyway, we tested our intake today. We’re new to pneumatics and arm stuff, so we’re spending a bit of time figuring out what we are doing, so no speedrun 
Intake works! Accidentally found a new feature in which we can eject cubes w/o having to extend the intake. As a result, we could probably do hybrid cube cycles super duper fast, which I think is cool. (prog accidentally reversed the intake direction after retracting, intake should work normally)
Broke another turn buckle trying to test our arm 
will repair Saturday and send videos
Whats the point of the piece of boxtube right over the pivot of the arm? couldnt u remove it and gain passthrough ability for balls? It seems like a deadaxle for the pivot anyway so is the top piece of tube even adding much strength at all?
Cool stuff! Our team is not really experienced with running chain drives and turnbuckles. So, excuse the silliness of the question, but how hard is it to break a turnbuckle, any advice on making sure they stay as one-piece?
The top box tube adds a bit more top strength (and torsional stability) and acts as a hard stop for us not extending outside of the extension limit (oops)
Apparently pretty dang hard, I would make sure to put your turnbuckle on the side of the chain w/o loads, as well as tensioning it by hand and not a wrench
oh i see, so if u flipped the arm over, you would momentarily be too tall?
Yup
Updates on this:
Looks like plushies are out of stock, we need to do an inventory check so shop has been closed.
Oh no, I just bought a plushie through the store! Fingers crossed, but please don’t stress if you don’t have them right now. I’ll gladly accept a hand delivered plushie at champs 
Sorry about that! We should be issuing a refund shortly. Will contact our supplier about the plushies and see if we might be able to get a 2nd stock if there’s interest.
We were losing money on the plushies, so there is still a little bit of debate if we want to get another stock and sell them again. Apologies in advance.
For something like a chain run on an arm, what side of the chain run would you consider to have less or no load? If the chain is tensioned, shouldnt both sides be seeing equal (or close to equal) loads?
We’re planning to use some turn buckles on our arm this year too, and would love to avoid this type of failure if possible.
Sorry for the late response, I personally don’t understand it to the level where I can explain it well, and someone else taught me about this, but I’ll try to explain it anyway (please someone correct me on this)
Basically, one side of a chain/pulley system/whatever has to not have tension in order for it to rotate, in which the difference of the tension causes the rotary movement. If the arm ends up flipping over, the tension in the arm is flipped. (TBH, I barely understand it either)
Anyway, we were running 35 chain, which makes it slightly more impressive, but as long as you don’t slam your arm at full speed two the force of two neos (two neos can lift two robots lol), you should probably be fine.
Edit:
Both sides carry tension, but gravity makes it easier on one side of the tension, chain kinda acts like a rope in the sense that if you try using it by it self, you cant really push anything, but on a pulley system you can pull on 1 side to rotate the other, and vice versa. The problem with how we broke the turnbuckle was less about the tension in the chain, but more like slamming an arm against a hard stop at full force with the power of two neos.
Saturday meeting recap:
We finished tuning arm PID and some basic systems integration and started testing the integration of mechanisms. There are a few dead zones we need to fix.
A sponsor machined our DT tubes which is very nice, so we’ll probably paint and start working on the comp bot/beta soon, we still need to finish cad. (Will be doing a pretty similar robot with some slight variations, nothing too drastic.
Arm changes:
Swapped the turnbuckle to the opposite side of the chain side. In theory, we should be okay, WCP sent us a spartan tensioner that’s coming on Monday I think, so we’ll document our results.
Added shaft collars for sprocket retention.
Near the end of the meeting, we added some magic polycarbonate, hopefully, to fix our cube issues for the next meeting. The main issue is that you are mostly forced to have a gap due to the arm’s reach, but at the same time, you don’t want the cubes to fall out. We will try making a polycarbonate flap for the cubes while the arm passes through.
Arm works! Actuates pretty quickly, geared 72:1
Slow mo version:
Programming did a pretty good job, the arm seems to stay stable when smacked.
After cube is in the manipulator, swinging the arm up seems to cause the cube to fly out (no videos )
Cube likes to “jump” out of the robot
Something seems to be stalling in either the indexer or manipulator, we will attempt to solve this by adding another stage to the MP and doing a manipulator swap to a more aggressive cube compression. (already built, we just forgot to swap)
Our wheels are kind of an oopsie right now. The tread is worn out, so when we drive, its very bumpy right now, avoiding all driving until it gets replaced. We have tread replacements, so we should be able to replace them, but we might get more wheels, so swaps are a bit easier for us.
When the arm goes up, the spark max sometimes has a can error for some reason, but the other mechanisms still work. I don’t know why. We’ll figure it out Monday.
One of our brand new neo 1.1’s refuses to turn, we have absolutely no clue why, but it caused our indexer not to work, we replaced it with a new neo, and one of our students is disassembling it to try to diagnose the issue.
Our falcon pinions are a bit wobbly on our SDS modules, can’t figure out why either, only happens on two of our modules. Not exactly sure if it’s a falcon defect or an assembly error of the SDS module, the falcon feels pretty rigidly attached to the module and we cant wiggle the body, so we’re not exactly sure why the pinion is wobbly.
(I still really need to get around to calling VEX about our missing four falcons from fedex, I keep forgetting lol)
Other Side Quests:
We tried making this today, no videos, but it didn’t work was trying to make an indexer based on 4481’s bottle flip indexer, but flipping the cones requires too much space. I bet a team could pull it off if they tried, though.
A new designer is working on a cone shooter, mostly just for auto points, but it’s fun watching them learn.
Need to test w/ pneumatics sometimes, will require a test bench with pneumatics.
Anyway, we’re taking it slow for finals week, with none of our meetings being required, so week 3 will mostly be CAD updates as well as prog videos.
that’s unfortunate… what did they discover? any pics?
