Milling on a Drill Press
or, the poor man’s drill press mill — the $30 cross slide vise…
© 2011 by KV5R — Rev. July 1, 2011.
About
I keep on needing to cut blind slots in aluminum flatbar, but how? I can’t afford even the cheapest milling machine (≈$650), so I want to rig up something that will work for $60 or so. I have a little bench-top drill press, and router. The router, as you can see in stabilizer1, is too fast, too sloppy, and too hot. The drill press should turn a ¼″ end mill, but I need a cross-slide vise for it. Decent ones start at over $100, but I found one for $30 (+$15 ship), and read lots of bad reviews about it, but I decided to get one anyway and just make it work, if possible.
Notes
- The $30 cross-slide drill press vise is a horrible piece of work—it’s the worst example of casting and machining I have ever seen. You will see below.
- If you get one, be prepared to work on it for several hours (or days), and even then, don’t expect it to produce any precision results. The dovetails are not parallel, and they are not smooth! If you just want to use it to position work for drilling, it’s fine for that—but they falsely advertise it as a “milling machine”…
- I found a TiCN-coated solid carbide ¼″ end mill online for $12.75. It works well in aluminum if you’re not in a hurry; turn it slow (like <3200) and blow it with air.
- Milling with a drill press is not like milling with a real milling machine. You have to go very slowly so as to not overload the quill bearings, or deflect the cut, with excessive side-load. Also, the drill press and vise assembly will flex and vibrate some, so smooth cuts are not possible. If you make the last pass a very shallow climbing cut, it will be pretty smooth. Your slots will still need some hand-filing.
- You can see the end results in the stabilizer3 article.
Photos
I tried just pushing the piece through the jaws of a vise…
…using a 2-flute router bit. It works but…
…what a mess!
So I ordered this $30 cross-side vise. I decided to take it all apart,
wash off all the goo, then grease just the threads and mating surfaces.
It has three main parts—I’ll call them the vise, the mid-stage, and the base.
Here’s the vise jaws—simple flatstock cut with a chop saw.
The vise section. Its dovetail has a shim plate with two bearing balls and setscrews,
as well as a lock-screw knob. The balls sit in divots drilled in the shim; they don’t
roll, they just keep the shim in place.
Here’s the upper mid-stage screw that drives the vise stage across.
The mid-stage is driven across the base with this screw, using an inner and outer collar.
The screw and collars drive this threaded block that is pressed into a hole in the mid-stage.
To slide the mid-stage off of the base you need to remove the big screw then
drive the block out. It wasn’t tight and came out with one whack.
The mid-stage parts. Like the vise stage, it has a shim for the lower dovetail.
The base.
The two outer collars. Check that machining on the left!
I guess that factory doesn’t reject any defective parts…
The threaded block.
Detail of one of the shim assemblies.
Check out that high-quality machine work…
As you crank the handle along, it goes “bump bump bump…” Not smooth at all.
Rough crank handle
I decided to clean all the parts. I had this can of chem-dip that was about to rust
out, so I decided to use it. I didn’t know it’s also a great paint-stripper!
We seem to be missing some metal here… This is one of the vise’s load-bearing surfaces!
Jaws are nicely misaligned…
Check out the slot in that setscrew.
The sand-casting is very rough. Lots of missing metal here.
…and here.
Grease the threads, run them through, then wipe off the excess.
This is advertized as a 4-inch vise. This one jams at 3 inches, due to the poor machining.
Even forcing it all the way open, it’s only 3½ inches.
Greasing the setscrews.
Greasing the dovetails and setting the balls in place.
Setting the shim in place. Note that the divots in the shims are off-center; they go toward the top.
Greasing the upper shaft in the mid-stage.
Sliding the vise on the mid-stage.
I clamped the mid-stage in the bench vise and started sliding the vise stage back and forth.
At this poistion, it’s sloppy loose…
…and at this position, it completely jams. The dovetails are not parallel!
I filed on the dovetail until it didn’t jam, but this doesn’t fix it. One has to
continually adjust the shim screws while milling, because the dovetails are not parallel.
I got tired of filing, so I put the shaft in and reassembled the vise to the mid-stage.
Stupid design flaw: the fixed end of the vise will not reach the center of the mid-stage
because the crank handle runs into it. The shaft needs to be about an inch longer. You
can get around this by mouning it off-center or diagonally on the drill press.
You can’t tighten this locknut…
Preparing to mount the mid-stage on the base.
Hammer the threaded block in (make sure it’s straight!) then install the shaft.
Install the inner collar…
…then push the shaft through the base and install the outer collar and crank handle.
You’ll need to take an old screwdriver and grind it down to fit these screws, or you’ll
never get them tight. They are too narrow for a ¼″ screwdriver blade.
Of course, it won’t fit my drill press table.
I had to mount it diagonally and swing the table a little to make it work.
The diagonal mount also allows you to put longer things in the vise and miss the column.
Preparing a test cut with the carbide end mill.
The test slot reveals that the upper and lower dovetails on the mid-stage, or the vise jaws,
are not perpendicular. I’ll need to make custom jaws for the vise to correct it.
I decided to make jaws out of ¼x1x5 6061-T6 aluminum, and mill a step in them.
The step, being cut on the vise, should be parallel to it, and thus allow me make straight slots.
…drilling…
…tapping…
…milling the tops level…
…cutting the steps. Since they were cut on the vise, they should correct the run-out of the dovetails.
They did, but note that cutting too fast will side-load the whole mess and still cause some run-out.
Now I can cut straight slots! What a mess!
So there’s the poor man’s milling/slotting machine. I plan to take the vise all apart again sometime and load it up with Clover grinding compound, slide it about 100,000 times, and see if that will smooth out the rough surfaces. Will let you know if it works.
Stay Tuned!
Next, I review the Aiptek AHD-H5 Extreme camera.
Then after that, I’m gonna build a shoulder-mount, walk-around, 20-foot telescoping jib, with a stabilizer on the end, controlled with 4 fishing lines… Imagine that!
—KV5R
