What's the secret to drilling through 1/4" angle iron?

[4570Man]

I would way rather use my mill for a large hole. The low speed on the mill is 60 rpm. The low speed on my drill press is 250 rpm. The mill is only 2 hp, but is geared so slow it has plenty of toque. If you get a catch with a bit 3/8 or smaller it will break the bit without slowing down.

 

[LD1]

I would way rather use my mill for a large hole. The low speed on the mill is 60 rpm. The low speed on my drill press is 250 rpm. The mill is only 2 hp, but is geared so slow it has plenty of toque. If you get a catch with a bit 3/8 or smaller it will break the bit without slowing down.

A drill press with a low speed of 250 isnt made for drilling large holes IMO. Sounds like either a bench top model or benchtop that they just put on a floor stand. If you look at the literature I am sure it may only be rated for 3/4" holes.

Even locking the bed down in all axis' on the mill, drilling a large hole at a lower speed you see alot of movement. Wearing things out.

Mills werent made to drill. (allthough they can). Obviously the larger the mill the more ridgid, but most 1-2hp bridgeports with 9x49 table just arent that solid for large holes IMO. Especially used and wore out some.

Not to mention, with most mill setups with R-8, you are limited to using S&D bits with 1/2" shaft. Forget about using MT3 or MT4 bits, which are WAY more ridgid than a S&D bit. A good drillpress with MT4 spindle for 1-1/4" holes is WAY better than a 2HP bridgeport IMO

 

[4570Man]

I'm not sure what size the MT in the mill is. It is pretty big. I only use my DP for woodworking, and it does fine for that.

 

[LD1]

I'm not sure what size the MT in the mill is. It is pretty big. I only use my DP for woodworking, and it does fine for that.

It is uncommon for a mill to have a MT spindle.

R-8 is common on small bridgeports.

LArger mills run 30,40, 50, and 60 taper. Which is different than morse, and even in the 30-40-50-60 series there are variations. CAT, BT, NMTB, etc.

 

[4570Man]

Yeah, it doesn't have MT. I don't know what kind of taper it is. It isn't a Bridgeport. It is a pretty big mill, it is probably 18 inches taller than I am.

 

[Buggs67]

I was surprised at 75 responses to a question about drilling holes. I expected some derogatory remarks at the OP and was glad to see only help.

 

[LD1]

Yeah, it doesn't have MT. I don't know what kind of taper it is. It isn't a Bridgeport. It is a pretty big mill, it is probably 18 inches taller than I am.

Probably a NMTB40 taper. Surprised it is only a 2HP mill though. And probably has a 10x54 or larger bed.

I am guessing you havent ran small little 1 or 1.5HP bridgeport with 9x49 table and R-8 1/2" collet and 1" S&D bit? Cause if you had, you would much prefer a decent drill press for its rigidity.

Most people, if they are lucky enough to own a mill, dont have a huge one. And on a small mill with large holes.....just dont work well in my experience.

At work, we have a 2hp BP with 9x49 table. It is pretty frowned upon if you are caught using it for anything over 1/2" drill. We do have 3 nice presses. A 5hp clausing with ~8" round column, a 3HP variable speed (powered with an internal VFD), with maybe a 5" column, and a huge 10HP radial arm that must weigh 4 or 5 ton.

Either way, a mill was designed to be a mill, not a drill press. The quill and power feed (if it has it), just arent as heavy, and you are limited by the smallish keyway on the R8 collet.

Bridgeport actually rates their mills at 3/8" maximum drill diameter for power feed, and 3/4" when drilling manually. There is a reason for that.

Most small benchtop drill presses are rated at 3/4". So why would you choose to wear out an expensive mill vs a cheapy press.

 

[4570Man]

Because I don't have a good drill press. I wouldn't consider any of the presses you listed as a "cheapy". Those presses probably cost more than my grandpa paid for the mill. The mill has a 4" or larger quill, most cheapy drill presses quill is only 2.5". One day we were drilling the broken exhaust manifold bolts out of a straight 6 Cat out of a semi truck. The head probably weighed 400 pounds. It was sure nice to just turn a lever to align the holes VS wrestling a 400 pound head around then trying to secure it.

 

[SIMassey]

You are right about the limitations with R8 collets, but a Silver Deming drill will do a good job at the right speed held in a 1/2 inch collect. I have seen plenty of welded up tangs on Morse taper drills during my career in industry with a major tractor manufacturers. Core drills included. Even larger than 3 inch.

 

[LD1]

Because I don't have a good drill press. I wouldn't consider any of the presses you listed as a "cheapy". Those presses probably cost more than my grandpa paid for the mill. The mill has a 4" or larger quill, most cheapy drill presses quill is only 2.5". One day we were drilling the broken exhaust manifold bolts out of a straight 6 Cat out of a semi truck. The head probably weighed 400 pounds. It was sure nice to just turn a lever to align the holes VS wrestling a 400 pound head around then trying to secure it.

Just to be clear, the 3 presses I described arent what I was considering a cheapy. But even a cheapy is better for hole drilling than an r8 small bp mill IMO