expanding an off center hole

Plunge cutting with a milling cutter *might* work. The best solution is to fit a boring head to your DP spindle. It isn't as hard as you might think, there exist a lot of 3MT to whatever arbors, 2MT also. Any el cheapo boring head with a small boring tool would work OK for this.

But given the low price of 1/2" end mills I'd just chuck one of those up and have at it. If you can get it to run slow enough (600-ish rpm) it should work. The biggest problem with using milling cutters on a DP happens if you try to put any side load on them. This tends to pop the chuck arbor out of the spindle.

GWE

Art wrote:

Unless ur drill press is really without slop in the bearings, runs really true, and has a really tight fit to the taper - find a guy or shop with a mill!

The local college almost always has a machine shop - the big ones have "student" machine shops... gunsmiths tend to have mills... I have at least 2 neighbors within 1 mi with mills (I have two myself now, but that's not the point...)

Oh, unless the material is soft - plastic, aluminum, brass, then the drill press stands a chance.

_-_-bear

Is it possible to adapt something else to make the existing hole work? IE think out of the box?

Drill the existing hole to 5/8" and Loctite a flush plug of

5/8" shafting in it. Remark and drill your 1/2' hole. Of course this way requires additionally a hacksaw & Loctite.

Tom

Plug the existing hole, punch the new center, and drill the new hole. Use the same material to plug the hole. Size the plug for an interference fit.

Jim

I would redrill the hole to almost the desired size and then use a 1/2" endmill with the table up as far as it would go so as to keep the spindle as rigid as possible. Use lots of lubrication.

.040" might be difficult in a press.

I'd use a milling machine.

Nuf' said?

Jim

I won't say that this will work to move the center exactly 0.040, but there are several ways to move a hole center over. One would be to drill a small hole with something like a 1/16 th drill next to the 1/4 inch hole on the side you want to move toward. It should almost be intersecting the original hole. Then drill with about a 3/8th drill and see if that moved the center over as far as you wanted.

Now you have a 3/8th hole. Use a round file to make the hole oblong with the new center where you want it. Drill with a somewhat bigger drill and see if that did not get the center where you want it.

Dan

Plug the existing hole with the same material, center punch, drill new hole. Easy, works good.

Don Young

Use a drill bushing and an end mill in the drill press is the cheap fix. The drill bushing will (should?) keep the mill from wandering sideways. I'd be inclined to use, say, a 7/16" mill to move the hole over, then work up to size after comfirming that I was on my location.

Best solution would be a boring head in a mill, though.

Cheers Trevor Jones

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Not quite. :-) How do you fit it in your drill press?

the other,

Jim

Don't even think of trying to do that. A twist drill will bend to some extent to follow the original hole whether you use a drill bushing or not. You must mill a new hole with a 2 flute milling cutter until it at least clears all sides of the original hole and you can then enlarge that if needed with a drill bit and/or reamer depending on the accuracy you require. It's not recommended but at a pinch you can use a milling cutter in a drill press chuck if you go easy.

-- Dave Baker