Drill bits in a milling machine?

[Linburger]

Forgive my ignorance, I'm just learning to use the milling machine. I've been told that endmills have a tendency to "walk" when boring holes because of the flat end and that it's better to use a drill bit to drill holes. I have a project that calls for very precise X,Y located holes. Is it possible to use drill bits in a milling machine to drill holes?

Also, is there a difference between boring and drilling, what about reaming?

[Turo]

I've never heard the thing about not using end mills in mills, heck that's what you're supposed to use them in. Now, they aren't necessarily the best tool for the job if you're just drilling holes. I would suggest a drill bit for that.

Boring is pretty much another word for drilling a hole, but it may be more used in the context of drilling a concentric hole in a cylindrical piece, thus creating a "bore" but I don't think that's super critical in relation to other jargon.

Reaming is cutting a hole that is more accurately cylindrical than that done by a drill bit. In general, the reaming is done after the (just slightly) undersized hole is drilled. If you look up a reamer on wikipedia, it will show you a picture of the tool for the job.

I hope that helps.
One question, just for curiosity's sake, what made you ask this on a gun forum rather than a machining forum or some other website that specializes more in machining?

Btw, my source is that my pop is a machinist, and has been for the last 30 years and he's taught me some of his trade.

[Linburger]

Well its a gunsmithing project and I already have an account here so I figured why not.

My question stands, lets say I want to drill a 0.098" hole at (1.402", 0.76"). I don't want to use a drill press because I can't get the exact location. But I don't want to use an end mill because drill bits are better for drilling holes. My best case scenario would be to use a drill bit in a milling machine, but my question is, is this possible?

[Turo]

Well its a gunsmithing project and I already have an account here so I figured why not.

My question stands, lets say I want to drill a 0.098" hole at (1.402", 0.76"). I don't want to use a drill press because I can't get the exact location. But I don't want to use an end mill because drill bits are better for drilling holes. My best case scenario would be to use a drill bit in a milling machine, but my question is, is this possible?

I see, sounds reasonable.

It's very possible. Depending on your mill you may need a specific chuck to hold the bit, but this is done all the time.

[Woodymyster]

Milling machines make great drill presses. There is nothing wrong with using a drill in a mill. What you just described is the correct approach for this job. Besides, you are not going to find an endmill with a .098 inch diameter anyways. So for your setup, your just going to need a 40 size drill in a drill chuck. I would also recommend using a spot drill or center drill to start the hole and to ensure the drill doesnt also walk.

For your other questions, Boring is usually understood as a single point tool that cuts an inner diameter on a part.

Reaming is the use of a reamer to make a very accurate hole due to the fact that drills are understood to be not so accurate ( but in most cases they are accurate enough for most jobs).

Using an endmill as a drill is known as Plunge Milling.


Jon

[elsolo]

It is very common to use a centercutting endmill to "face" a flat on the work, then switch to a drill bit to poke the hole. This prevents the drill bit from walking across the surface and deciding on a different location to make a hole.

Using an endmill to drill a hole can often result in a slightly larger diameter hole because they don't deflect and self center like a drill bit, so any runout of the spindle, collet, or mill will be added to the diamemter of the hole.

[-hanko]

Listen to Woodymyster...

Find the hole location, lock the X and Y tables. Spot the hole location with a centering drill. Drill the hole. If you're looking for best precision, drill the hole a few thou under and finish with a reamer. Unlock you tables and repeat as necessary.

-hanko

[ar15barrels]

You need what's called a center drill.
It's short and stiff so it won't wander.
You make a little detent with the center drill, then switch to the regular drill bit and the regular drill bit follows the little detent that's precisely located.
This is standard practice for almost any drilling operation I do in a milling machine.



In the picture, the largest one is about 7/16" diameter with a 5/32" tip while the small one is 1/8" diameter with a 1/32" tip.