Introduction: Easily Repeatable Drill Press Fixtures
Using my drill press I realized there was almost no way to get repeatable setups. I’ve worked on addressing this before, doing an Instructable showing how to realign your drill press table using a laser. This didn’t solve the height issue and still required you to set up the fixture every time you wanted to use a fixture. Once you set it up, if you needed to move the table you could get it back into position using the laser, assuming you didn’t have to change the height also.
Looking at the drill press, the table has too many variable components to it to use it as a repeatable locating piece between the rotation of the table on the upright post, the tilt, and I have seen some that rotate on the mounting arm in addition to pivoting. Using the upright post doesn’t work well because it is round.
But, I had a crazy notion, and I just knew it might work. The drill press housing is fixed and will have a constant position (in relation to the drill chuck and drill center. If I (literally) tapped into using it to locate the fixtures I could get a repeatable fixture mounting point, and with the design of the fixture, the height could be located as well.
- wood scraps
- tap drill bit
- thread tap
- a little hutzpah
Step 1: The Notion
So using the drill press frame/ housing would not be without its perils. I'm not a huge fan of permanently altering my tools, unless I'm removing the safety, or removing the safety, as seen here and here. However, to make this work, I was going to have to get over all that, and drill into my drill press.
First step was to check out what was in the cavity besides the light bulb. Turns out, as luck would have it- there wasn't a whole lot going on in there. The spindle way up front and the light bulb socket were pretty much it. The non light bulb wiring seemed almost completely contained in front of the casting
Step 2: No Turning Back
It was time to prepare for the point of no return.
I held up a scrap piece to see what real estate I could work with, and confirmed I would have room for fasteners behind it. Once that was done I marked the spots to drill with a punch.
Hole locations punched, time to tap drill and then tap! I decided to go with 1/4-20 since it is almost ubiquitous and I almost always have some 1/4-20 fasteners. Ironically, of course, I had some, but not the length I needed. Oh well.
Drill, tap, and verify.
I went with either 2-1/2 or 3" spacing (I can't remember which), but thankfully when I drilled the other piece with the same spacing it bolted up.
Step 3: Now for the Cool Part
I set the drill press to the right height and got the table roughly positioned, then measured down from the holes.
I put together the pieces for the part of the fixture that will go against the drill press table. Then I got the fixture positioned under the piece bolted to the drill press so that I could connect them where the fixture needed to be, in relation to the drill bit in X, Y, and Z directions.
To do this I cut the piece to length (the piece to bolt to the drill press, the vertical support), bolted it to the drill press, and lowered the drill press table to get the fixture into position. Then I raised the table back up to act as a clamp to glue the vertical support to the fixture.
Once the glue dried, I lowered the table and had a fixture that I could remove from the drill press entirely, and bolt back up to locate the fixture to the drill press in the same spot every time. With this fixture the table remained flat, so I didn't have to adjust the angle or anything, just the height. If the location is super-critical, you could use alignment bushings in the vertical support for a tighter fit to make it even more precise.
When I replaced the fixture, I just lowered the table enough to easily clear the fixture, bolted the fixture up, and I raised the table to the fixture to support it and locked the table down.
Step 4: Going Above and Beyond
The next step will be to create a corresponding fixture (either based off the locating fixture or as its own stand-alone entity) to preset the drill bit height for instances where it is not a through hole, for example, or just to be anal retentive and make sure the material will clear the drill bit into the fixture.
I haven't done this just yet, but it will be useful in some instances I can think of. Since you can not only set the initial drill bit height but the depth stop if necessary, it can be that one more step toward producing in quantity with more ease.