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[ATM] moron big rigs
Hi Dave,caution,ya got me started!
I will have my friend come by with his digital camera on Friday.In the
meantime let me give a word picture of what I'am talking about.The jack
shaft principal is strictly first generation machine shop.With it you can
obtain 8 speeds,6 in high,6 in low.Here is the power-train set-up on my 10"
South Bend lathe.It begins with a 1750rpm motor having a large and small
pulley mounted on the shaft 2 1/2",4".This is belted to the jack-shaft.A
simple arbor shaped like a 'Y" and 2 bronze bushings.The left side has a
10" and 9"pulley,(casting). To the right,(between the bushings) is a (4)
step cone pulley:5 3/4,5 1/4,4 5/8,4.This is belted to the lathe headstock
with the same cone sizes.Without back gear you have 8 speeds.With the
back-gear engaged,you get 16 speeds.
My lapping table has a 3/4hp motor with a 2,2 1/2,2 3/4.The spindle has
a 10.
Low speed is 333rpm.I checked the set-up to discover it is in fact NOT a
true jack-shaft set-up.But I do have the j-shaft assy. sitting there
waiting to be installed.It is off my 1920's bench shaper.To lower the final
spindle speed you can either put a small pulley on the motor with a very
large pulley on the j-shaft,(as in the lathe configuration) or begin with a
slow speed motor.You can also begin with a gear-head motor. I use these on
all my sphere-grinding machines.They can handle a 6"+ rock and grind it
down to a perfect finish.Here are their stats:Motor 105.7 rpm. torque 30
inch pounds,ratio 17.02,1.1 amps,115 volts,cont. duty.With some care,these
motors will last a very long time.They are $70 apiece, and can be had at
Diamond Pacific.If you put one of these on the arm and on the spindle,they
should work.The bearings you use should be just like a lathe.One thrust
bearing on the bottom.One radial P-block at the head.I made my own housings
out of 4" CRS with provisions for re-tightening and zerk fittings.Turned
down the bottom end on a 1" shaft for the thrust cone.The top bearing has a
take-up set-screw collar arrangement.It also has a zerk fitting. The rig is
made from 1" angle iron and 3/4" plywood.It is cross braced to prevent any
shucking.The upper-arm consists of a double pivot with a 1750rpm motor,2-6
pulley system .The 2" motor pulley goes to the next double pulley at the
arm pivot.This in turn goes to the head.The whole upper rig is made by
Victor Mfg. These were top of the line lapping tables probably 60's or
earlier vintage.I bought my table for $200. The over-arm head has an acme
screw adjustment for down-feed.The addition of another motor to guide the
head is the only major additional up-grade.Of course you'll want to change
pulley's around as opticians work much slower on precision glass.This rig
is a dream to use.It doubles as a surface grinder when I need it
to.Tolerances of .0001 or less are not difficult to hold.And this can be
done at 600 grit and finish with cer/ox.Your own mirror-o-matic can do
surface grinding work this fine.I will send along some pictures of the
rig.More questions are welcome.I can build bearing sets as mentioned.
regards,Ron
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