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Cam Grinding Made Easy
By Ken Hurst
All model engine builders strive to build the next engine better or to try to
improve the one's we have already built. The heart to every 4 stoke is the
camshaft. Designing a cam for your engine is easily in your ability if you have
the right equipment.
In previous issues of Strictly I.C. # 39 - 40 & 41 Gene Switzer's Camshaft
Grinding Machine article was published. The machine looked easy enough to make
so I started looking around for a gear reduction motor for the drive system
& a high-speed motor for the grinding wheel. I stuck with Mr. Switzer's
org. design; but changed the way the cam is driven; Stylus base & profile
follower; the master cams & grinding wheel dresser.
The drive system was DC 1/3 hp motor. That I purchased at a Swap meet. The
drive chain used was1/4 pitch chain and sprockets for the drive, the chain
drives the cam & cam master at the same timing. The cam & master cam
rotates at 20 RPM, the grinding wheel @ 7500 RPM.
The Stylus was changed was using a 1/2" travel micrometer barrel for
adjustment instead of the 3/8"-24 TPI adjuster & added a roller
bearing tip to follow the master cam. Roller bearing was a 3/8" OD. Trying
to Grind a Cam the crown of the cam the (lift) was too sharp and it did not
duplicate the master. Talking to Paul Bennett at one of club meetings
(B.A.E.M.) he told me that he experienced the same out come and recommended
using a flat piece of material to follow the master cam. I used a piece of
delron brown and it holding up nicely. The piece of delron is 1/4" wide X
1"X 6" .It was mounted 1/2 way between wheel and stylus. The roller
bearing stylus set on the delron follower. Using the flat follower the master
is duplicated in a smaller size at a 4 to 1 reduction.
On the master cams; instead of one master cam I made an intake, and an exhaust
cam. Each with a different profile on the crown of the lift but maintaining the
same lift & eccentric for driving the oil pump. The eccentric has the same
lift as the master cams. I installed them to alum. block that has a setscrew
for locking into position on the driven shaft. This way the master's cams can
be installed as a group. Making the masters is easy. I used 1/4 alum. plate,
used a belt sander to shape the lobes and hand worked flanks & crowns. With
good layout tools it doesn't take long.
Dwight Giles improved the dressing of the grinding wheel. I loaned him the
grinding machine for use on his Panther Pub. He installed the fine grade wheel
dresser diamond. He used the grinding motor guide shaft and a bracket installed
on the under side of the grinder support plate for positioning purposes. The
wheel dresser just slides on the grinding motor guide shaft. It does an
excellent job keeping the wheel true and clean.
This little giant does a great job; it has made camshaft for my Wall 4, V-8
Challenger & the Silver Bullets I just finished. Remember the key to making
a great cam is lob split, smooth duration & equal lift.
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