254 Robot

I saw that you MF your pulleys. When cadding the pulley, where do u get your tooth profile from? VEX?


One more interesting thing that we might reconsider doing differently next time was our decision to make a single stage elevator and double jointed arm, as opposed to something like 3476’s architecture with a 2-stage elevator and linear extension, allowing for purely prismatic DOFs. Having the arm made for weird singularities and dexterous work-space limits, particularly with reaching rocket disc level 2, that drove a lot of the arm and intake geometry. The intake and arm for champs were designed use a massive top level master sketch that coupled all the driving parameters from the scoring and intaking states to determine all the dimensions.

Requirements such as size of ball, reaching a disc with a ball in the way, scoring on all 3 levels, etc, provided plenty of constraints for the sketch.


Yes. You can simply get the pulley profile from a VEX or McMaster pulley by opening it, cut extruding away a flange so you can see the profile, sketching on that surface and using “Convert Entities” to grab the contour, saving that sketch as a Sketch Block and importing that sketch block into your new part, where you can add you own extra thin flange, bore out for 1/2" hex, add nubs to ride on bearing inner races, etc.


Thank you for taking your time and effort for writing up an in-depth analysis on your robot, I really appreciate it.
Although it’ll take some time as I try to digest your design! Thanks!!


Yes I meant that they cannot continuously rotate because of the wires in the tower. The tower in the video is not yet wired to the base.

Thanks @Veqic

Reminds me of a ballerina… No wonder the bot was so beautiful to watch play! :heart_eyes:

@Torrance what program do you guys cad in?

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Also what drive train do you guys use?

Did you plan to only be a cargo-only bot when you designed the first intake?

I believe that 254 CADs in Solidworks.

They used a west coast drive train.


Of course not, we planned on having a two-roller ball intake with a disc system mounted above it. The bottom roller of the intake was to be Velcro and pickup the disc from the floor and then the low jaw of the intake would articulate up and handoff the disc from the Velcro roller to the disc system on top. However, we ran out of time and didn’t really build a full intake prototype with all the systems, so just had to send what we had for the robot photo and plan on redesigning for SFR.


West Coast Drive composed of 2x1x1/16” tubes, no tensioners (added like 0.017” or something to the nominal chain cc).

6 WCP aluminum wheels with blue nitrile tread. Custom 2 speed gearbox with unadjusted free speeds of about 7.5 and 13.4 ft/sec (slowish high gear to optimize for high accelerations and covering short sprints).


Is there any reason why you ran a chain underneath to the power the turret instead of a timing belt?

Okay, that makes a lot more sense, thanks!

I noticed you were using very thin air tube for some parts of your robot. What is the ID/OD and where did you get it?

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:astonished: do you end up with dents, bending, etc? do you reinforce the bearings at all?


254 NEVER gets dented. Period.


1/16” side rails? Even with no tensioners, do you still use bearings blocks or some other reinforcement around the bearing holes?


Yes, the siderails have 1/4” plates with 1/16” deep counterbores and thru bores to hold the bearings. This means that the bearing is held by the plate and the tail end of the boss is held by the tube too, keeping the bearing plate concentrically aligned with the tube and thus the other bearing block (since holes in both sides of tube were milled in one operation on CNC mill).

The plates on the outer side of the tube (near the wheels) have countersinks for #10-32 FHCS, and the inner plates (near the chain) are tapped so the plate can clamp the tube like a bearing block setup. Also, one set of inner plates has extra tapped holes for #8-32 to mount a 3D printed bracket which holds an encoder to record wheel rotations.


We used 5/32” OD 3/32” ID, tubing from McMaster to minimize the size of the tubing in the IGUS runs and overall weight. We found a negligible change in flow rate for switching to the smaller tube, and it actually improved our time to achieve vacuum for our suction climber since we reduced the overall amount of air in the long tube lines from the vacuum foot to the pump.