Another Backyard Shop Tip: Drilling Fairly Accurate Shaft Centers With A Drill Press
idbruce
Posts: 6,197
I am currently in the process of drilling out several shaft centers and I thought I would share my method of aligning shaft centers on the drill press. Over the years, I have attempted to drill many shaft centers, which almost always ended up in disappointment. However, during the course of the last year, I have developed a new method of centering my shafts on the drill press.
Please keep in mind, I am only advising this for imperial units of measure and for shafts that "mic" out to the nearest 1/16", such as 1/4", 5/16", 3/8", 7/16", and 1/2" (+- 0.000).
First off, you will need a small scrap piece of shaft, which is equal in diameter to the shaft you intend to drill. Secondly, you will need a small piece (approximately 2" long, however longer pieces will increase the accuracy) of seamless brass tubing 1/32" larger in diameter to the shaft you intend to drill and having a 0.014" wall thickness. In the United States, this tubing can be found at many hardware and hobby stores. Many stores stock a K&S Engineering metal rack. For an example of the tubing found in such a rack, visit this link: http://www.ksmetals.com/26.html.
Anyhow, chuck up the scrap shafting and slide the brass sleeve over the scrap. With the workpiece positioned under the scrap and in close proximity to the scrap, adjust the workpiece until the brass sleeve easily slides from the scrap to the work piece. When this occurs, the drill press should be centered with the shaft to approximately 0.00325", but probably closer.
Remove the scrap and brass, then drill your starter hole (I use a tile cutter bit for this purpose). Finish the shaft, by drilling with the intended drill bit.
It works good enough for my needs.
Please keep in mind, I am only advising this for imperial units of measure and for shafts that "mic" out to the nearest 1/16", such as 1/4", 5/16", 3/8", 7/16", and 1/2" (+- 0.000).
First off, you will need a small scrap piece of shaft, which is equal in diameter to the shaft you intend to drill. Secondly, you will need a small piece (approximately 2" long, however longer pieces will increase the accuracy) of seamless brass tubing 1/32" larger in diameter to the shaft you intend to drill and having a 0.014" wall thickness. In the United States, this tubing can be found at many hardware and hobby stores. Many stores stock a K&S Engineering metal rack. For an example of the tubing found in such a rack, visit this link: http://www.ksmetals.com/26.html.
Anyhow, chuck up the scrap shafting and slide the brass sleeve over the scrap. With the workpiece positioned under the scrap and in close proximity to the scrap, adjust the workpiece until the brass sleeve easily slides from the scrap to the work piece. When this occurs, the drill press should be centered with the shaft to approximately 0.00325", but probably closer.
Remove the scrap and brass, then drill your starter hole (I use a tile cutter bit for this purpose). Finish the shaft, by drilling with the intended drill bit.
It works good enough for my needs.
Comments
Way to go, Bruce.
Not pretty and danged expensive, but quick and dirty and you know it's a perfect fit.
However be forewarned, depending upon the fixturing and drill press alignment, it can be a bit tedious to get that brass to slide smoothly from the scrap to the shaft, but when it does, you should be in the ballpark.
I always like to choose the right process for the job. One of my favorite tools is my Servo drill press - a simple, precision drill with an 1/8" Albrecht keyless chuck. I've been really fortunate to collect some nice tools for my Parallax work. My most favorite tool is my Wilton band saw.
Ken Gracey
Definitely. For those contemplating a drill press purchase, it's perfectly fine to buy a cheap one from Harbor Frieght. Save your money for a good chuck. When the Harbor Freeight unit arrives, chuck the chuck and install a precision Albrect chuck in its place. It will probably cost more than the drill press. You won't be disappointed.
-Phil
I've said it before and I'll say it again. My favorite tool in the metal shop is our Rotex punch. Punches a variety of hole sizes (even a square or two) thru sheet metal, sheet plastic. etc. Rapidly makes holes or wheels/cams, rings, etc. Leaves a center dimple in the circle cutout so you can easily line up center if you want to punch a smaller center hole.
http://www.rotexpunch.com/2652.html
I just got tired of drilling off center, then one day, I pulled up a stool in front of the press and thought about a solution.
Say it isn't so
I save all my chucks for fixturing, threading with small taps, holding round pieces for solder, heating, welding, etc.... Don't throw them away, just put them in a drawer with other useful garbage