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Mechanical Resources

IFI FRC Drivetrain Reference Tables, 1.4 MB

Plexiglas vs. Lexan

When you want see-through protection…
Plexiglas is less expensive than Lexan, but Lexan protects against impacts. Plexiglas is much more brittle than Lexan and can easily break if flexed wrong and is prone to chipping and cracking. Lexan is more prone to scratching.
How-To

Center Distance for a Given Chain Length

The center distance sprocket-to-sprocket for a tight chain may be determined by:
c = center-to-center distance in inches
L = chain length in pitches
P = pitch of chain [in inches] (.250" for #25 chain and .375" for #35 chain)
N = number of teeth in large sprocket
n = number of teeth in small sprocket

c=P/8*(2*L-N-n+sqrt((2*L-N-n)^2-0.810*(N-n)^2))
Begin with a chain length approximately the distance you are looking for and solve for it, then pick the nearest whole number for "L" to get the final distance "c".

Sprockets must have sufficient chain wrapped around both the driving and driven sprockets to avoid skipping teeth. Shoot for an optimal 180° around both sprockets, but don't depend on less than a minimum of 135° unless there is virtually no-load on the system. Be especially wary of small sprockets where the number of teeth engaging the chain is very few.
Here are a couple of detailed references:
Martin Sprocket and Tsubaki Library and Tsubaki's - The Complete Guide to Chain

Planetary Gears

You'll see these types of gears in the FIRST Globe motors (if you take apart the black gear head on one end of the motor). The Globe gear casing itself is the Sun gear while the planet gears rotate against the inside.

Here are some explainations of how it all works- planet gears with the sun gear.
Epicyclic gearing or planetary gearing
University of Denver Epicyclic Gear Trains

How To...

General Tool Operating Procedures ( Adobe PDF

, 64 KB)

Guide to Using a Milling Machine ( Adobe PDF

, 470 KB)

Guide to Using a Lathe ( Adobe PDF

, 1.31 MB)

Sharpening Lathe Tools ( Adobe PDF

, 80 KB)

How to Use a Drill Press ( Adobe PDF

, 263 KB)

Bandsaw Tune Up ( Adobe PDF

, 101 KB)

Broaching Keyways ( Adobe PDF

, 108 KB)

Instruction on a wide-range of shop tools and short basic written tests complete with answer keys.
Texas Technology Education Guide ( Adobe PDF

, 1.6 MB)