[TheForge] But how fast does the Alldays & Onions go?

[Bob Ehrenberger]

Mike,

They used to sell an after market cruse control. It hooked up like your bike 
computer with a magnet glued to the drive shaft and a servo connected to the 
throtle.  When you got the speed you wanted you enguaged the unit and it 
kept it there.  I don't know if they are still available, but it might be 
useful for your application.

It only took me 6 months to get my fixer-up air hammer going last year.  I 
can't imagine how hard it was for you to keep at it as long as you did, 
great job.

Robert Ehrenberger
Shelbyville, Mo.
eforge at centurytel.net

----Original message----

Date: Fri, 11 Jul 2008 00:54:53 -0300
From: mspencer at tallships.ca (Mike Spencer)
[TheForge] But how fast does the Alldays & Onions go?


The Alldays & Onions people (now doing business as Alldays Peacock
Industrial Fan Engineers) kindly sent me technical poop on my
hammer.  So I know how fast it's supposed to run: 135 beats/min.

Counting the gear teeth and knowing the pulley sizes, I should be able
to set the right speed from the engine tach.  Only the engine tach is
flaky and there would be a lot of bother or expense or both to set it
right.  What to do?

Bought a "cycling computer", an electronic widget that tells you
MPH/KPH and a bunch of other stuff and works by clipping a sensor to
the bike's forks, clipping a magnet to a spoke and "programming" the
widget with the circumference of your bike tire. By knowing what
tire circumference the widget *thinks* you have, you can calculate
the nominal MPH that goes with any desired RPM.

So I stuck two magnets out of a hard drive on the big gear of the
hammer 180 deg opposed from each other; fixed up a little bracket
(that screws into a threaded hole in the hammer that just happened to
be in the right place) to hold the sensor; mounted the cute little
"computer" using another convenient hole.  Set the (nominal) wheel
size and figured out how fast such a wheel would be going at 270 RPM
(135 x 2 because I used 2 magnets instead of one.)  Now I can let in
the clutch and rev the engine up until the widget hits the right KPH.

Seems to work fine except that the readout occasionally jumps from the
target 64 KPH to 80 and then right back again.  Maybe a little futzing
with the magnet positions or the clearance between the sensor and
magnets will make that go away.

Pics not yet available but Real Soon Now.  Gotta show off the new
paint job, too. :-)


FWIW,
- Mike

-- 
Michael Spencer                  Nova Scotia, Canada