Here's how I made an 82 degree countersink cutter. It took three tries and two days, well maybe not 2 days but I worked on it two different days. The wobbler I'm building calls for a countersink on the base plate for 2-56 screws that hold the frame to it. I know I had a counter sink but didn't realize it would be to big. What to do?
Well, why not make one. I got some .375" drill rod and proceeded to make one..........or two.............. or three.
The first picture shows, from left to right, the hex fixture for cutting from one sided to six sided cutters. It has a .500" hole through the center, a sleeve to bring the .500" hole to a .375" hole, the blank .375" drill rod with an 82 degree point turned on it and the large counter sink I have.
I wanted to cut 3 cutting edges on it. I set it up in the Sherline mill, and proceeded to mill out the excess stock.
Attempt one was a failure. I got the cutter lined up to far beyond center. When I started to cut the second edge I broke through to the first edge I had cut. Dam
Ok, lets try again. Second attempt. Since I had the Sherline set up to mill I used my Grizzly lathe and a spare 4 jaw to make a new blank. This is a fast way to get the part to run as close to true as possible. The blank only wobbled about .010". In no time I had a second blank to cut.
Second blank, NO GOOD. Dam!
The cutter slide down in the collet because of vibration and cut below the center line of the cutter.
You can just make out the cutting edge beyond the center line on the failed cutter on the right.Time for a beer and some thought. So I retired to the lazyboy with a beer and a Model Engine Builder magazine.
Second day. Another blank made in the lathe. Only this time I used my Grizzly Mini-mill and a larger cutter. Seems like it worked this time.
But as I look at this last picture I realize that the cutting edge is on the curved part of the cut. :P Well maybe it'll still work.
Going to hand file the relieve on it and give it a try.
I'll report back with a pic or two when I'm done.
Isn't machining fun?