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.