So this year, I’m taking a more major role in building the robot. In the past, I’ve built small parts of the robot and even an entire robot in tower takeover but I always had a “good” builder next to me telling me what I missed and what to do next or it was just absolute garbage (what I built in tower takeover). Anyways, I was hoping some experienced builders could share some basic tips to ensure what I build is not horrible and maybe even considered good build quality.
This youtube channel has several high-quality videos that should help in that regard.
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It mainly comes down to your durability of your bot and how it performs on the field. 4 bars that are uneven and skip, are well, bad build quality. Drive bases that for some reason have camber - also bad build quality. I have been known to overbuild my bots a lot, and because of that, they are a lot heavier, but we went all of worlds without breaking a single part or fixing anything. Kepler electrons, as said above, is really good, but also look online for build explanations, as you can take lots of notes from how they construct mechanisms, cross braces, etc.
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Good build quality usually refers to being efficient on your usage of metal yet have the same structural stability as the status quo. Also as, that is being aware of methods of building that gives you advantageous levels of structural integrity even with minimal level of resources.
If you can build a DR4B with 30% less metal than what the status quo usually builds and yet have the same structural integrity as the status quo because of building tricks you have learned over time, then chances are you have built a lift with good build quality. Also, build quality also includes friction levels of joints as well (as in finding ways to have 20-30% more efficient joints)
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Another good measure is the amount of friction you have. Good builders tend to have less friction in everything they build including lifts and drives.
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I’m not the builder for my team but one thing the builders on my team do is take time when building. They don’t rush builds and this has greatly increased our quality with our robots.
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i second this. Rushing a build is a bad idea. Although I personally don’t like cading the robot, it does help immensely. I’m the guy on the team that if someone has some insane idea, i execute it. Usually, if it’s crazy complicated, i have to CAD it first so I can get an idea of what to do. it’s good for the journal too!
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Use locking nuts (my team’s personal favorite) and make sure you have a strong base. We once had a base that was loose, and part of the bot failed because of it.
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Dont use them excessively, only where needed. They are unnecessary extra weight.
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no, kepler build quality is trash
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Reduce friction, maximize strength.
Use this mindset in your builds. When putting a bot together, think to yourself, “is there a better way to do this that will result in
- Less friction?
- More strength?”
And as always, use the resources around you. Look at pictures of others’ robots, chat in discord servers, browse the vex forum, watch YouTube vex reveals. These sites have plenty of good inspiration for quality build quality.
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nylocks, bearing flats, and having at least two screws secure metal together, using high strength shafts when needed, and screw joints when applicable
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this is a fairly basic concept but still something I had to learn in my early years, everything you build needs to be carefully planned before it’s built. even better, make a prototype to test before you make it officially part of your robot
also just don’t use hexhead screws, it’s extremely hard to get the right amount of torque to be able to unscrew it and they strip out very easy
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I really love the spacing
First, to specifically answer your question. Good build quality is when the bot operates at the limits of the materials & design NOT the quality of assembly, the motor power is put to use moving stuff not creating friction/heat, and you don’t have to keep fixing stuff that breaks.
To achieve that, here are some guidelines.
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Bearings should be checked to make sure the shaft rotates without friction or feeling ‘notchy’. If you feel notches, the bearing is damaged (usually from overtightening). Check them BEFORE installation and AFTER.
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Shafts should be straight and free from burrs. Sandpaper or a flat file will help with this. Do NOT assume shafts are all the same dimensions. I have gotten entire PACKS of shafts that were over spec .5/100"
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Braces are important. However, a drivetrain that does not flex slightly is a liability as the competition floor is never 100% flat.
Note the braces for the lift. They are set at a 45 angle in BOTH axes. That’s all it took to hold a 4 stage lift in place that could reach over 3 feet high.
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Wire routing is important. Wires should be as short as possible. They should not rub against anything sharp. They should be tied to structural pieces to keep them tidy.
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There should be NO sharp spots on the robot. Period. File all your metal when cut. File the flats of the cuts. File the edges. File the corners. File/sand the ends of cut shafts.
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Robot take impacts. A 1x2 or 1x3 c-channel chassis should be made with the ‘flat’ facing outward. This provides more protection against bending when hit.
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MEASURE the spacing on all arms/etc to make sure they are parallel. Measure spacing on your chassis /etc also.
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Tighten all fasteners to almost tight. Then come back and do a final tightening. This keep the ‘slack’ from being pushed all to one side of your bot as if you tighten completely at first before all fasteners are in.
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Put code in your bot to check & display motor amps & temps. Temps between similar motors (drivetrain/lifts/etc) should be VERY similar. This also allows you to check gearing/load/etc to get the most from your motors WITHOUT overloading/overheating them.
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ALL shafts get at least 2 bearings supporting the shaft. No exceptions.
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ALL shafts get DOUBLE shaft lockers where needed. No exceptions.
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Shaft spacers/lockers should still have room for a fingernail between them and the metal they are against. Otherwise your friction will be too high.
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Rubber wheels should be cleaned periodically. This will help grip. Also, do NOT run your bot on the dirty floor.
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Stand offs should be tighened with a nut driver if possible. It’s very hard to get them tight using wrenches, even 2 wrenches double stacked together.
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TOOLS: Proper tools will 1) speed assembly 2) increase quality of assembly 3) protect/prolong life of stand offs, screw, nuts, etc.
a) nut drivers (you need 2 sizes, get them)
b) elec screwdriver with torx tip AND socket adapter for nuts with a torque limiting clutch
c) medical hemostats (even better than needlenose pliers, can be bought in fishing section of wal-mart or gotten from amazon).
d) cheap calipers can be a real time saver for checking dimension. this is also how we found why our out-of-spec axles were not fitting into anything.
A pair of hemostats will speed up assembly more than any single item you will ever buy. They can hold nut in tight corners. They can ‘fish’ screws through tight spaces into holes with a speed and precision you won’t believe.
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Could you explain this one; I do build in the way described but I never thought about the direction of the channel really having an impact. Many Worlds robots that I saw had the flanges facing outward.
While redundancy is great, I have not found the need for double locking shaft collars. If you put spacers on the shaft with one collar you don’t need more.
I like your metric for measuring how tight the spacers are. The way I test this is just to see if the spaces can freely rotate on the shaft/screw.
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With the edges of a ‘c’ channel facing outwards, an impact can easily bend the edge or even nick it causing a sharp spot. With the flat side out… this is not going to happen. It makes a smoother safer chassis. Also keeps your metal in great shape (no bends, nicks, etc) for future re-use.
Locking metal collars are held in place w/ a set screw. Those are famous for 1) stripping 2) fracturing 3) falling out 4) being easily overlooked when checking the bot. The consequences for a loose collar are high. Doubling up removes that problem. Have seen plenty complex bots… have not seen where double protection cannot be done.
Furthermore, when placing back to back locking collars, but sure to orient the set screws the same way so it’s easier to check them both at the same time.
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This is the only one I disagree with. One of the most important aspects of a robot being good build quality is serviceability. In my many years of vex, I’ve always done it like this ] ] - [ [ , because of how serviceable the drive will be WHEN you have to make a repair. Worried about bent metal? Pair of pliers. If your metal is bending that much though, I would recommend better bracing on your drive channels.
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Pickup a pair of hemostats and you have a robot’s that tougher AND easily/quickly serviceable. If you protect impact items… the need for service drops off a cliff.