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.
