Project in place, well almost, I have to turn a soft center for centering the shaft. See pic below
I use a thread gage, magnet and indicator to lineup the compound and scribe a mark for future use.
First chips on the bicycle pedal crank arm. (I am using silicone spray for the tailstock center lubrication.) The standard Carbide tool hasn't enough angle for the cut that I want to make, I will grind an offset tool bit, or make an offset holder.
I went to Home Depot to buy a grinding wheel with the intention of mounting it someplace. Next to the wheels were this bench grinder for $40.
The offset tool bit, 3 /8 ground high speed, about a 40 degree cutting angle. Use a piece of 1 /8 shim to reach the center line.
Finish diameter, 1.372. Radius on the tool cause chatter. Lower the rpm to BE 320 (Took a little thinking to get the belt configuration right.) reduce the radius on the tool to about .005 and profiled a 1 /8 radius with both hand wheels after the finish cut. Off set threading tool next. 24 thread per inch.
BMX freewheeler threaded on to the crank arm. Also a view of the indicator I use as a stop for threading to a shoulder. A test of reflexes, watching a few thing simultaneous and reacting.
May 2004, first use of fixture to machine four flats to machine arbor for replacement crank arm.
24 tooth hacksaw blades broken off to about 1 1/2, notched to fit in hand jig saw. Six pieces from one blade got through the cuts needed for the four plates needed.
Four jaw chuck mounted according to instructions. A 1/2-13 stub arbor was turned a 1/2 hole was drilled in the four pieces of 1/8 thick by 5 inches cut plate aluminum. The OD was turned to 4.925 with 0.50 depth on each cut. Chuck is also use for a holding fixture for nine holes. The five holes bolt circle was derived by measuring the cord of two of the five and solve for the radius. The machinery hand book table of jig bore coordinates was use to obtain the longitudinal and lateral moves. The .100 dial granulation made counting the turns from center easy. Four holes are located to use fixin bolts to mount the spider to the freewheeler. The fixin bolts were measures over the BMX Teeth
Drilling before boring the ID to fit the body of the BMX freewheeler
Boring the ID.
The completed tandem independant pedaling cranks with one plate not needed. When the five hole bolt circle matched the chain ring, I breath a sigh of relief. My tandem page will show the mounted units.
I almost didn't get the bonus package that is put together by Shoptask, here, I am using the vise along with a vise I already had to rise up to the tool to mill a relief slot for the chain.