Hi Ned,

Thanks for your reply.

The AutoCAD drawings are all to 1:1 scale. I always draw everything in
model space just like it is in the real world. I never really
understood why some people draw things at odd scales in model space
when designing. I only use scales when printing in paper space if I
have to get something large to fit on a certian size paper, or blow
something small up so it can be seen better. I have not had the
pleasure of trying Inventor yet, but it looks like a neat program.

Regarding your question about the conjugate nature of the design, the
relationship between the rollers is constant, but I guess it's not a
true conjugate in the sense that the inner roller is mounted on a
slider that allows the roller to move linearly if needed, and the
slider "pivots with" the follower about the pivot point.

There is no real sliding of the slider, any sliding would only be a few
thousandths of an inch, equal to manufacturing tolerance variances on
the width of the cam "rib" that would tend to cause the rib to bind
in-between the two rollers, if both rollers were rigidly fixed. I could
not find such small rollers that would be accurate enough to use with a
very accurate ground cam, which would allow both rollers to be fixed
without any binding of the rib between the two rollers as the cam is
rotated.

Referring to the drawings, the two rollers create opposing torque's
on the cam after leaving the centered dwell position. After the cam has
been manually displaced Clockwise from the mid-point neutral position
dwell via a lever connected to the cam, and then the lever is released,
the sole purpose of the inner roller force is to return the cam to it's
centered neutral position dwell.

After the cam has been displaced Counter-Clockwise from the centered
neutral position dwell via a lever, and then the lever is released, the
force from the outer roller returns the cam to its centered neutral
position dwell.

I had thought of using a single roller in a cam track or groove, but
decided against it because I thought I would have problems with
clearances between the roller OD and the track. That's usually not a
big issue, but on this design I thought I might have problems.

The roller forces actually bring the cam back to the start of the
one-degree mid-point dwell and then opposing extension springs
connected to the cam return the cam for the .5 degree distance to the
center of the one degree mid-point dwell. This is done since the roller
forces can't create any torque on the cam once they are in contact with
the dwells.

Note that the drawings show different springs, spring forces, and
spring rates for the inner and outer rollers. The outer roller force is
generated through a .419" moment arm. However, the inner roller force
is created solely by extension springs and the force is not acting
through a moment arm, it is strictly linear. In the drawings, I listed
the actual inner and outer roller roller force at the cam low, mid, and
high point dwells and listed the spring rates.

Thanks again Ned, I really appreciate your help.

Sincerely,
John