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

[chim]

I don't have tons of experience with drilling holes, but I'm not entirely without some experience. I can't say I would normally use a pilot for 1/4" or smaller holes. Where I do use a pilot, I go by the advice of an instructor years ago. He said if you use a pilot, use one approx. 1/3 of the desired hole size.

We have a project that has involved drilling in unusual positions and through stainless and high strength alloys. The Superintendent on the project asked if I could come up with something to make life easier for the crew in a couple instances. The first was drilling a 1/4" through a high strength steel part under a train car. The part was at an angle to any reference and the only access was standing in a pit under the car. He said he could really use an upside-down drill press that can drill on an angle. For that I fashioned a "jack" type affair from a bar (load locking bar) in the warehouse. Clamps secure an 18V DeWalt drill to one end. The other end still has a rubber foot that pushes against the concrete in the pit. Works nicely.

Another situation was drilling into the end of the locomotive for a device that mounts on the exterior. It requires two small holes and one large hole. Picture a Mickey Mouse head pattern. The car is stainless and a mag drill won't stick. The material being drilled is two pieces of stainless steel about 3/16" thick and separated nearly an inch of air space. There is a very substantial rain gutter above where the holes go, so I sent a CAD sketch of the plate with the slots to a nearby laser shop and had them cut it out. Then had the guys in our weld shop make an adjustable mounting bracket. It uses the rain gutter at the top and secured via load binder strap on the bottom.

The plate is positioned for one of the holes with the mag drill stuck in the appropriate scribed footprint. The plate has scribed footprints for each of the three holes that automatically position the bits where they belong. An 1-3/8" annular cutter is used for the larger hole. A 3-jaw chuck equipped with a Weldon shank with twist bits is used for the smaller holes. Sounds more difficult than it is.

For the annular cutters we use lube that comes in what looks like a grease gun tube of ear wax. For smaller holes / twist bits we go with Red Lion made by Chromate Industrial.

 

[DFB]

Right rpm speed ...lubricant if gets to hot...its all been said already.

I'd be surprised to do a step up into that size hole on angle iron. Center punching certainly helps with skating.

Oh god most of the cheap import bits are so bad they are just totally worthless!


Not the same situation but I do a lot of cross thru drilling on thick round tube steel for our commercial greenhouse frames.

These bits have worked very well for me...its what my hardware guy stocks. I buy them individual.

black-oxide-coated-high-speed

Pretty reasonable price too.

 

[tallyho8]

I thank everyone for their responses, many more than I thought I would get. I've learned a lot and plan on drilling Saturday using some of the information I have learned here.

 

[the old grind]

Prob with angle iron is the high carbon content, which contributes to work-hardening. (key stock is another one that'll give you fits as if going too fast with a hacksaw)

Brandi, Larry, & LD1 share my views for the most part. When drilling, milling, turning always read the chip. Keep rpm down and coolant applied (even water works) you want to keep the metal/tool cool cool all the way thru. 1/4" a bit small to pilot, IMO, although that 1/3 ratio is a good criterion to spare weak drill lips/corners, as suggested.

Rendered (pork) lard oil is still among the best cutting lubes ever. If using bacon grease, remember that it's saltiness will corrode stuff if not cleaned off well enough. Don't use 'fresh' lube oils unless desperate. 'Used' will have had its longer molecular chains and EP additives broken down but is full of hydrogen and thus as laughable as briney sausage drippings as a rust inhibitor. (You knew that ...) tog

btw, 'Cool Tool II' (<1$/oz) is good for drilling or tapping, sticks well, and will also work with soft (copper, alum) alloys without staining them. (Drill patiently vs rushing. You'll get there. )

 

[DarkBlack]

Look at this!!!! http://www.fnal.gov/pub/takefive/pdfs/Drill_Press_Speed_Chart.pdf

I'd throw that chart in the trash if it was printed.

 

[bindian]

Prob with angle iron is the high carbon content, which contributes to work-hardening. (key stock is another one that'll give you fits as if going too fast with a hacksaw)

Brandi, Larry, & LD1 share my views for the most part. When drilling, milling, turning always read the chip. Keep rpm down and coolant applied (even water works) you want to keep the metal/tool cool cool all the way thru. 1/4" a bit small to pilot, IMO, although that 1/3 ratio is a good criterion to spare weak drill lips/corners, as suggested.

Rendered (pork) lard oil is still among the best cutting lubes ever. If using bacon grease, remember that it's saltiness will corrode stuff if not cleaned off well enough. Don't use 'fresh' lube oils unless desperate. 'Used' will have had its longer molecular chains and EP additives broken down but is full of hydrogen and thus as laughable as briney sausage drippings as a rust inhibitor. (You knew that ...) tog

btw, 'Cool Tool II' (<1$/oz) is good for drilling or tapping, sticks well, and will also work with soft (copper, alum) alloys without staining them. (Drill patiently vs rushing. You'll get there. )

The old grind,
Boelube is close to lard, without the smell. I like to get the bit warmed up just a little, then poke the bit into the boelube.
hugs, Brandi

 

[the old grind]

tog,
Boelube is close to lard, without the smell. I like to get the bit warmed up just a little, then poke the bit into the boelube.
hugs, Brandi

Thanks for the suggestion! Will try. (I don't cook much, anyway )

 

[SandburRanch]

Read reply #11 again. One of the few that has much value. Recommended RPM for mild steel. CS ( cutting speed ) x 4 divided by the diameter. 90 x 4 * 0.250"

 

[LD1]

Read reply #11 again. One of the few that has much value. Recommended RPM for mild steel. CS ( cutting speed ) x 4 divided by the diameter. 90 x 4 * 0.250"

I would say MOST of the treads have value. Thread 11 only talks about lube. Nothing else. There is ALOT more to drilling a hole than slapping on some cutting oil and hoping for the best.

And those recommended cutting speeds are only good IF you can apply the correct pressure (feed). So those charts IMO are worthless for a hand drill. Excellent for a mill or sizable press.

You HAVE to read the chip. If it is turning blue, you either need more feed, or slow down. More feed pressure is hard to do and control on a hand drill, thus you need to slow down.

 

[the old grind]

Post #11:

You would do yourself and your drill bits a favor by buying cutting fluid. Cutting fluid is different than lubricating oil, and in fact, lubricating oil can impede a drill bit from cutting easily because it has anti-friction, high pressure additives that keep a fluid film between the metal and drill bit cutting edge. This keeps the drill bit from cutting easily.

Cutting oil has sulfur as the lubricant and some include chlorinated paraffin lubricants. Cutting fluid allows the chips to slide away which would otherwise generate heat. It's formulated to not stick to a heated surface and pass away with the heat unlike a lubricant.

I use LPS Tapmatic #1 Gold for steel. I have a PVC 2-inch diameter end cap that I fill with the cutting fluid and feed onto the drill bit with a flux brush as I'm drilling. If you're using a hand drill, then I'd brush the drill bit and stop 2-3 times during drilling to clean the chips out of the cavity in the steel, and fill the cavity with cutting fluid.

If you haven't used cutting fluid, you'll be surprised at how much easier it makes drilling holes.

:thumbsup:

And good point, LD1 . 'Speeds & feeds' can go out the window when cutting 'dry'. Angle iron 'works' more like 1050 than 1018, 1020, or some of the 'leaded' steels. Also, not easy to know rpm when using a hand drill.

 

[LD1]

Lean on it enough to keep a curl of metal coming off the bit. Too little pressure is as bad as too much.

as others have said correct speed, pressure and cutting fluid/oil all count towards success.

Masonry drill bits would require sharpening to the correct cutting angle before they will cut steel, I've used them occasional for difficult jobs on welded stainless that has toughened during fabrication.

Punch the hole locations first with a center punch so the drill doesn't wander.

tallyho8, Drilling a pilot hole for a 1/4 bit is a verry special case and only applicable to get around problems with hard material. And [bummer] the small pilot hole itself would be difficult to accomplish reliably. IF your angle is just regular steel it should be possible to drill reliably by hand in one pass.
... To give yourself an advantage I would try to buy one of the 1/4" DeWalt pilot point drillbits. They drill extremely well with lo effort. To lube / cool, dip the tip in a shallow pool of lube about every 30 sec. ... As LD1 said, read the chip. Press hard enuf that the tip makes constant progress - no skating because it will dull it. Ill guess that you need 20 or 30 lbs pressure and 300-800 rpm. Learn to read the feel of imminent break thru and ease pressure so you dont chip the drill tip.
larry

Right rpm speed ...lubricant if gets to hot...its all been said already.

I'd be surprised to do a step up into that size hole on angle iron. Center punching certainly helps with skating.

Oh god most of the cheap import bits are so bad they are just totally worthless!

Brandi, Larry, & LD1 share my views for the most part. When drilling, milling, turning always read the chip.
1/4" a bit small to pilot, IMO,

Best advice in the thread IMO. Pretty much sums up my first post in the thread.

But to each his own. Drill them however it is easier for you. If you want to risk breaking a bunch of bits and making the 1/4" bit real grabby, then by all means drill a pilot.

I am not against cutting fluid either. Use it if you like. But for what you are drilling, I dont think it is necessary. IT wont hurt, just not a necessity.

Bottom line is read the chip. If its blue, you need to change what you are doing. IF there isnt any chips, you need to change what you are doing.

 

[4570Man]

He is drilling 40 holes. He can drill a few with and without a pilot hole, and see what works best.

 

[SandburRanch]

A pilot hole should be smaller than the distance across the web of the next size bit. A pilot hole for a 1/4" bit would be a waste of time and resources. Apply cutting oil not lube oil. Water would be better than any lube oil. For best efficiency run at or near the recommended RPM.

 

[pat32rf]

Not too much into tech stuff, but as an apprentice my mechanic showed me that just the way you stand can make that 110v drill a lot easier to push. Keep the rear leg straight and control pressure by lifting the close leg.....(drilling about waist height) This way your weight does the work, not your muscles....

 

[tallyho8]

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:

 

[LD1]

Nicely done.

Probably just how I would have done it, be it 1/4" or 5/16". I assume dewalt saying "pilot point" is just a fancy name for split point bit?

You were probably going a but faster in low speed too. Most cordless drills are somewhere around 500rpm on low and somewhere around 1600-1800 on high. Be careful using low. Dont know just what kind of power your craftsman has, but on my 18v Milwaukee if I use low, I put the side handle on or make darn sure I got a good grip. Cause it will wrap you up.

 

[SPYDERLK]

Nicely done.

Probably just how I would have done it, be it 1/4" or 5/16". I assume dewalt saying "pilot point" is just a fancy name for split point bit?

Pilot point has a small drill splitpoint profile for the 1st 1/32" or so, then blends to a very hi angle point [170*?] to make the nominal hole size. Pilot points are available down to nominal size of ~3/16".

Yould not want to use a pilot point to enlarge a hole.
larry

 

[LD1]

I see. I googled some images:thumbsup:

Not sure how I would like them. The look expensive. And forget about sharpening.

I like the bits we been getting at work. Triumph Thunderbits.

 

[SPYDERLK]

I see. I googled some images:thumbsup:

Not sure how I would like them. The look expensive. And forget about sharpening.

I like the bits we been getting at work. Triumph Thunderbits.

Pilot point, I believe, is aimed at the geterdone/contractor niche. Fast drilling, durable, and usable well into dullness - as the drill body cut angle forces the small tip. Then throw away. ... They could be resharpened to a more standard profile tho.

Not terrible on expense. I got a 16 pc set to 1/2" @ Grainger for around twice the price. ... And Grainger had to be part of that factor.
larry

 

[prs]

Heat is the enemy here, thus the need for proper speed and weight loading to cut instead of slipping or grinding and the need for a cooling cutting fluid. I had an experience yesterday in cutting an overly long PTO shaft to fit my tiller on a CUT. All I had was a framed hacksaw and a good blade. The use of Brownell's Dew Drill cutting fluid made the daunting job a lot more tolerable, cut pretty fast . The blade remained fairly cool, the chips floated away from the cut, and blade was still sharp after the four cuts (I cut a bit too long the first try). The fluid is good for heavy filing too; and, of course, drilling metal. The tools stay sharp much longer and hold their temper, thus the operator holds his temper too ;-)

prs