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

[MossRoad]

I finished my trailer today. With some re-engineering, I found that using 20 5/16" bolts would be just about as strong as using 40 1/4" bolts so I used the 5/16 ones. I did not drill a pilot hole.

I used a Dewalt cobalt pilot point 5/16 drill bit which was still just as sharp on the last hole as on the first. I had used some Dewalt titanium bits in the past and this bit put those to shame. I used my 18 volt Craftsman drill on the low range. I don't know exactly what speed it was, but it was probably about 300 rpm. Following advice that I got in this thread, I put as much pressure on the drill as I could and it drilled through the 1/4" angle iron making long spirals instead of little chips.

I did not use cutting fluid or coolant because at this low speed and with it cutting so fast, I could touch the bit after I drilled the hole and it wasn't even hot.

Now I understand how I burned up so many drill bits in the past by going at a high speed and not using much pressure with a hand drill on jobs like this.

Thanks to everyone who gave advice and I just wanted to let everyone know what worked best for me. This job turned out to be much easier than I had thought it would be. :thumbsup:

What? No one handed drilling while taking a video with the other? I'm highly disappointed.

:laughing:

 

[GPintheMitten]

I see you got it done. Good for you.

For future thread readers, for occasional home shop use, you can't beat a small benchtop drill press compared to hand drilling. Something like this:

Northern Industrial Tools Benchtop Mini Drill Press — 5 Speed, 1/3 HP | Drill Presses| Northern Tool + Equipment

 

[k0ua]

I read an article a long time ago when I was a young man that said that a good drillpress was one of the first things you should buy for your shop. The wife and I scrimped and saved and we bought a nice 15 inch floor stand model. I have never regretted purchasing it. I have bought many tools since, but the drillpress has been one that I probably use the most. Just bite the bullet and get a good one. It wouldn't have helped in the OP's situation but in general they are so useful.

 

[bigtiller]

I use mine on just about every project I do. I am seriously thinking of buying a second one. If one is good, wouldn't two be better?

 

[4570Man]

Look for a used milling machine. Going from a drill press to a milling machine is like going from a hand drill to a drill press.

 

[bigtiller]

I have been waiting for one to come my way but they are about as rare as hens teeth.

 

[the old grind]

I have been waiting for one to come my way but they are about as rare as hens teeth around here.

Fixed that for ya.

If you're serious, look for a used mill in KC, Chicago, or Minneapolis ('Bridgie clone' or 'mini' thereof). Big markets there, if sparse picking at times. (If you can't afford to haul it, you might can't afford to buy it.) 3-Phase power usually requires a rotary Phase converter or VFD but cost may be offset somewhat by possible lower price of smaller 3PH machines.

btw, I paid more than 4x for my ZTR mower ($5k vs ~$1K & very lucky) than for the used knee mill. Ya gotta shop hard for a good deal on a good machine when retirees like me are after 'em too.

Hope the OP doesn't mind the side-track, ... since he's done. ....

 

[BigTruckMan]

I do professional steel fabrication, and I use high quality HSS steel bits on my mill/drill .

.I sell in my opinion some of the best drill bits there are . A 1/4'' drill bit is about $5 ,but it will last forever. These are the only kind of bits that I use . I have done hundreds of holes with my bits.
It also helps if you put some pressure on the drill ,and use some cutting fluid. Also make sure that you keep your bit strait.
Also,I never do pilot holes unless I'm drilling 3/4'' or bigger holes. I would recommend going on ebay or to a local steel fabrication shop and see if they have any high quality bits ,or you can contact me and order one from me.

 

[Dwayne Oxford]

1st time I saw a Dewalt pilot point bit used it was in an oversped, over pressured hand drill and bending every which way. Got me some quick. I drill a hole in the welding magnets and rig a low pressure air blow to cool the bit which allows you to spin'er WAY faster. If you wanna get real fancy you can buy a mister

 

[LD1]

A mill is certainly a step up from the average homeowner drill press. But IMO it is no replacement for an actual drill press. For most of what us guys do here, yep a mill would be a lot handier and can handle most of out drilling needs. But when using larger bits, Like 1"+ and drilling through thicker metals, a large drill press is alot better than a small mill.

 

[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