- Joined
- Feb 7, 2014
- Messages
- 350
Back from vacation, so lets finish this.
The shaft for the head is straight forward lathe work. The first problem to solve is how to attach the shaft to the head. It has to turn both directions under load, so a plain screw in will not work. After casting about for a while I decided that keyways weren’t the solution, nor was a lock nut that would increase the overhang even more. So I embarked on a solution that would use a pin to keep the shaft from rotating in the head. The hole was bored first. The shaft body was turned to 5/8 to fit my boring bar holder. One end was single point threaded to 5/8-18 NF. The other end of the shaft was then turned to fit the head. I turned the shaft just a wee tad big, then let it cool before final fit. The shaft was just barely too big to push into the head. I put the shaft in the freezer rather than trying to take off the few tenths, and risk making the fit too sloppy. The next morning I heated the head on a hot plate to 300F. With head on a stout piece of hardwood and the shaft straight from the freezer, I set the shaft to the hole and whacked it with a hammer. It went in almost all the way, so I whacked it with the 3 pound hammer. I doubt that I’ll ever have to cross drill the head for a pin any time soon. Now if you have a well stocked shop with a 5/8 chucking reamer and a stout hydraulic press, you can forgo the hammer.
Next up is the tool carrier. One hole was drilled on center and another near the edge of the adjuster side. The intended cutter was 3/8 round HSS, so the holes were naturally 0.375”. The hole depth is well short of breaking through the dovetail. With the two cutter positions and the screw adjuster should make balls from really tiny to nearly 2”. Flats were milled parallel to the dovetail to ease fabricating the grub screw holes that will lock the cutter.
Nearly done now. Only one more part to fabricate. The turner needs a lever to rotate the head in operation. The 0.625” shaft is too small to directly attach a handle. Placing the handle on a carrier presents the same rotational problem as mounting the head to the shaft. The solution at the outboard end of the shaft makes use of locking nuts, one of which is the lever carrier. The carrier was made from a left over piece of head stock. The 2” round was faced, center drilled and tapped for 5/8-18 NF. The resulting round nut was chucked into my rotary table and six flats milled on it. The lever itself is a 6” rod, threaded ¼-28 NF at both ends. The hole in the carrier was not actually drilled until after the turner was assembled so that the lever wouldn’t end up at some strange angle.
To assemble the ball turner – A thrust washer was placed on the shaft, then the shaft was inserted into an AXA boring bar holder. The clamp screws are adjusted so that the shaft just turns freely. A thrust washer on the threaded end is followed by a 5/8-16 nut to take up end play. The threaded carrier is then run onto the shaft to lock the nut. The carrier is then marked on the ‘up’ flat, removed, drilled and tapped for the lever, then reinstalled and locked to the adjustment nut. This provides lock for the lever in one direction. To lock the other direction, a final 5/8-16 nut is installed and locked to the carrier.
The ball at the end of the lever was turned with this turner.
The cutter design is still under development, but this first guess works. I hope to make round knobs instead of oval ones with a bit more practice setting up the turner.
The shaft for the head is straight forward lathe work. The first problem to solve is how to attach the shaft to the head. It has to turn both directions under load, so a plain screw in will not work. After casting about for a while I decided that keyways weren’t the solution, nor was a lock nut that would increase the overhang even more. So I embarked on a solution that would use a pin to keep the shaft from rotating in the head. The hole was bored first. The shaft body was turned to 5/8 to fit my boring bar holder. One end was single point threaded to 5/8-18 NF. The other end of the shaft was then turned to fit the head. I turned the shaft just a wee tad big, then let it cool before final fit. The shaft was just barely too big to push into the head. I put the shaft in the freezer rather than trying to take off the few tenths, and risk making the fit too sloppy. The next morning I heated the head on a hot plate to 300F. With head on a stout piece of hardwood and the shaft straight from the freezer, I set the shaft to the hole and whacked it with a hammer. It went in almost all the way, so I whacked it with the 3 pound hammer. I doubt that I’ll ever have to cross drill the head for a pin any time soon. Now if you have a well stocked shop with a 5/8 chucking reamer and a stout hydraulic press, you can forgo the hammer.
Next up is the tool carrier. One hole was drilled on center and another near the edge of the adjuster side. The intended cutter was 3/8 round HSS, so the holes were naturally 0.375”. The hole depth is well short of breaking through the dovetail. With the two cutter positions and the screw adjuster should make balls from really tiny to nearly 2”. Flats were milled parallel to the dovetail to ease fabricating the grub screw holes that will lock the cutter.
Nearly done now. Only one more part to fabricate. The turner needs a lever to rotate the head in operation. The 0.625” shaft is too small to directly attach a handle. Placing the handle on a carrier presents the same rotational problem as mounting the head to the shaft. The solution at the outboard end of the shaft makes use of locking nuts, one of which is the lever carrier. The carrier was made from a left over piece of head stock. The 2” round was faced, center drilled and tapped for 5/8-18 NF. The resulting round nut was chucked into my rotary table and six flats milled on it. The lever itself is a 6” rod, threaded ¼-28 NF at both ends. The hole in the carrier was not actually drilled until after the turner was assembled so that the lever wouldn’t end up at some strange angle.
To assemble the ball turner – A thrust washer was placed on the shaft, then the shaft was inserted into an AXA boring bar holder. The clamp screws are adjusted so that the shaft just turns freely. A thrust washer on the threaded end is followed by a 5/8-16 nut to take up end play. The threaded carrier is then run onto the shaft to lock the nut. The carrier is then marked on the ‘up’ flat, removed, drilled and tapped for the lever, then reinstalled and locked to the adjustment nut. This provides lock for the lever in one direction. To lock the other direction, a final 5/8-16 nut is installed and locked to the carrier.
The ball at the end of the lever was turned with this turner.
The cutter design is still under development, but this first guess works. I hope to make round knobs instead of oval ones with a bit more practice setting up the turner.