raveney
Well-Known Member
Often a family member will see something, and ask if I can make it. Yesterday I was challenged to fabricate a Christmas count down similar to this....
While I discussed the design constraints with the customer, we said " wouldn't it be neat if the star was brass?" I had a leftover 3" cast brass flywheel billet" in the scrap bin. I attempted to sketch and use trigonometry for the dimensions but couldn't remember the secant formula. Resorting to the "Google it" process of memory, I just opened up CAD and sketched it there.
Set up the blank in the lathe and roughed it out, then used a rotary table for indexing the teeth. One pass on the left side every 45 degrees, then same depth and off center dimension on opposite side, but changed the angle 20-ish degrees to give the points the obtuse angle we wanted. I just eyeballed where the cutter intersected the tip while rotating the table. Then set the dial to an even repeatable number. Parted it off the stem, milled flat and then deburred and polished using red rouge. It has porosity, but looks homey.
The "rack" was cut out of some left over 3/4" red oak scrap on the table saw. Several practice cuts while adjusting depth of cut and blade angle were used so the gear/star rode smoothly but remained stable. 0.800" centers was chosen based on 25 days and the 22" length of the scrap. The customer, my daughter, was well engaged cleaning up the swarf and texting her incredulous work friends as the job progressed. She sanded the rack with 220 grit and applied boiled linseed oil as a finish. Tomorrow she will apply a coat of paste wax and then paint the numbers on.
Brass was chosen as it is very heavy and stable. It will set on her bedroom dresser top, and her curious chocolate lab enjoys "booping" things with his nose. Happy Holidays!
While I discussed the design constraints with the customer, we said " wouldn't it be neat if the star was brass?" I had a leftover 3" cast brass flywheel billet" in the scrap bin. I attempted to sketch and use trigonometry for the dimensions but couldn't remember the secant formula. Resorting to the "Google it" process of memory, I just opened up CAD and sketched it there.
Set up the blank in the lathe and roughed it out, then used a rotary table for indexing the teeth. One pass on the left side every 45 degrees, then same depth and off center dimension on opposite side, but changed the angle 20-ish degrees to give the points the obtuse angle we wanted. I just eyeballed where the cutter intersected the tip while rotating the table. Then set the dial to an even repeatable number. Parted it off the stem, milled flat and then deburred and polished using red rouge. It has porosity, but looks homey.
The "rack" was cut out of some left over 3/4" red oak scrap on the table saw. Several practice cuts while adjusting depth of cut and blade angle were used so the gear/star rode smoothly but remained stable. 0.800" centers was chosen based on 25 days and the 22" length of the scrap. The customer, my daughter, was well engaged cleaning up the swarf and texting her incredulous work friends as the job progressed. She sanded the rack with 220 grit and applied boiled linseed oil as a finish. Tomorrow she will apply a coat of paste wax and then paint the numbers on.
Brass was chosen as it is very heavy and stable. It will set on her bedroom dresser top, and her curious chocolate lab enjoys "booping" things with his nose. Happy Holidays!
