# Propellor :- Laser Roller Install Part 4

Permanent install of laser/photo transistor brackets and circuit walk-though.

As the laser needs to be pretty "Solid",  i decided to install it using metal brackets.... so ......

..... it aint gonna move and miss-align whilst i hit 60Km/sec

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If the spokes are too thin, you can always just put a card or something on the spoke for a bigger 'beam breaker'. Then you'll only need to count each revolution.

Much love on the epic omlet flip...

Much math on the wheel --I am using my bike as reference (Gary Fisher Hoo-koo-ee-koo 26" wheel, 36 spokes)

26" dia = 81.64" traveled per rev

1 mile = 63360"

1 mile = 776 revs.= 27939 spokes went by

pretty fast on a bike = 30mph

@30 mph (for one hour) 23280 revs of the tire = 837870 spokes went by

***staying with 30mph but breaking down back to minutes/seconds --and only worrying about the spokes***

@30mph for one minute = 13964 spokes per minute

@30 mph for one second = 232 spokes per second

Actually, I just did this math for fun (and it should be checked) but A) 232 spokes per sec seems really fast to me (for a human) and B) the prop can certainly keep up with 232 counts per second --not very fast at all for a uC.

I am a bit concerned about the actual spokes being too skinny to break the beam...

I always love the fortune cookies you include at the end...

I am only saying that .... i am more proud of my interlude @ 2:40 into the film

60Km/sec (as noted above)

=37.26 miles/sec

= 3600 km/min

= 2235 mi/min

=216000 kph

=134100 mph

That's pretty fast, yo.

Must have been a slip when i converted from Mph - .......you get "more for your money" with Kph

Perhaps i should make it with "Rocket - Brand" boards..........

The funny thing is i have not calculated the time-ings between the spokes yet -  i hope that the prop is up to it...........

if you apply a bit of light oil.

Yes , particularly if it starts Squeaking ..... my chrome metalwork is hollow square section , so only just enough threads to hold the posts.