Tips for drilling metal

[Sugarfryz]

At work I somewhat regularly have to drill out bolts that are rounded off, usually on a very rusty car.

I seem to have no idea what I'm doing, I have 3 snap on sets that (one for quick change, one that came with my extractor set, and a huge set of hss bits).

Only the hss bits seem to work honestly. When I'm drilling out a rusted bolt the other two sets have either broken, immediately become dull, the first time I've used them. I'm quite pissed actually. I bought these sets assuming high quality.

I'm not sure if the bits are junk, the has bits are actually good quality and do work well the first couple times but some have gone dull for sure. Very frustrating when one snaps, or is dulled out halfway through a bolt.

I try going slow and spray penetrating oil, half the time they don't even seem to be cutting even when brand new. So I put some force on it, cuts for a little bit then snaps. All the first time of use. My co worker has matco ones that he has no complaints with. I have a strong feeling this is user error, and if so I'd like some advice. Is the metal just to hard to drill in to? It's not a problem with my drill I know that.

 

[mrobins297aaa]

I was going to say cutting oil also but jr beat me to it.
get a set of transfer punches, there a bunch of punches that have the same outside diameter as the bolt, that way when you punch the rusted bolt you'll be more likely to get the punch mark on center of the bolt

 

[Sugarfryz]

Use an actual cutting oil
Always center punch
Drill an 1/8" pilot hole
You have to push pretty hard or the drill doesn't really cut and it dulls quickly
Get a cobalt HSS (M42) set if you're drilling harder steel such as 8/10.9 fasteners

I do have an hss set from snap on, they seems to be the only ones that work. I guess i assumed all of snap one would work. Maybe some are just not meant for it. The bits I got with my extractor broke the first time I used them

 

[Sugarfryz]

I never used a center punch as I don't have one. Just hoped for the best. I bet it has no where to start and just gets real hot trying to start a hole. Is that possible?

 

[Sugarfryz]

Also it would help for being centered for obvious reasons

 

[wagon]

Slow your drill down. If you drill at high speeds, you'll weaken your drill bit, and you'll work harden the material. If your chips are purple or blue then you're going WAY too hot.

Go slow, and keep it wet, as they said.

Viking / Norseman 135deg drill bits are beastly, even on stainless. They're not too expensive for an index, either. If yours burn up, invest in a set. Union Made in USA to boot.

 

[PugetDude]

Good sharp HSS drill, slow speed (cordless drill) steady pressure, don't push too hard, let the drill do the work. If you're drilling upside down sideways, or overhead, the best lube I've found is chainsaw bar oil. It's really sticky and doesn't run away from the hole.

 

[mlum6969]

cobalt drill bits, slower speed. center punch and pilot hole is also a great idea.

 

[WittHay]

Use an actual cutting oil
Always center punch
Drill an 1/8" pilot hole
You have to push pretty hard or the drill doesn't really cut and it dulls quickly
Get a cobalt HSS (M42) set if you're drilling harder steel such as 8/10.9 fasteners

This is good advice, drilled out a broken grade 8 bolt on a machine yesterday. I just used ordinary HSS drill bits. The other trick is to use a 12V cordless drill set at the slow speed. You have more control with the small drill.

 

[d.mcfarland]

The pilot hole is the only real game changer I can think of here.

 

[Mike W.]

Good advice here, if I had anything to add it would be left hand drill bits and even more important carbide. Carbide chips easily but should cut through grade 8 easily. I would use it after the pilot hole as the "to size" bit.

 

[Dingleburry]

Use an actual cutting oil
Always center punch
Drill an 1/8" pilot hole
You have to push pretty hard or the drill doesn't really cut and it dulls quickly
Get a cobalt HSS (M42) set if you're drilling harder steel such as 8/10.9 fasteners

This.
This.
This.

1/8th pilot hole use second gear. Drill fast.
Push hard. Push as hard as you can.
Use cutting oil.
Peck drill to help clear chips and keep drill cooler.
If your bit aint cutting its heating up and dulling.
When i see people drill, more times then not they arent putting enough pressure on the drill.
You want 2 long swirly cuts coming off the bit.
If youre only getting 1, then your drill is only cutting on one side
That tells you your getting a good cut.
If you getting small little chips youre not cutting properly.
Oh and lots of pressure!! Untill youre about to break through, then let up on the pressure. Youll be able to tell when your about to break through, itll start getting easier to drill.
Imo a center punch isnt "necessary" but it helps. Maybe helps alot more on chisel points, but all my drills are split point.
Ave does a good drilling video on the youtubes.

 

[mbshop]

Many tries with all sorts of bits. Best success with cobalt bits and cutting oil. Some oils or sprays will actually harden the bolt and then immediately dull the bit. Medium speed eith firm pressure should do it. And like the rest of us, practice practice practice.

 

[6PTsocket]

Use an actual cutting oil
Always center punch
Drill an 1/8" pilot hole
You have to push pretty hard or the drill doesn't really cut and it dulls quickly
Get a cobalt HSS (M42) set if you're drilling harder steel such as 8/10.9 fasteners

Cobalt will drill hardened steel and hold an edge better but the tradeoff is that it is more brittle than HSS and snaps really easily. You have to be very careful not to snag the bit.

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[sberry]

I am going to see if I can find a drill out I did the other day, I rarely use oil, I pilot bit also and use battery drills. I drill 1000's of holes very rarely lube. Keeping wet without enough pressure just allows it to slide.

 

[d.mcfarland]

Wait. OP never said if drill bits he had were sharp.

 

[dogdog]

There OP, I had just viewed this video yesterday.... some actually makes sense from him.

 

[ez-duzit]

Use a center drill, first, to drill a pilot hole.

 

[CoyoteKyle]

You aren't suppose to drill a pilot hole. That actually wears the drill out unevenly stresses out the cutting edge. Drill bits are used to drill holes not expand existing holes.

 

[HanShotFirst]

Slow speed, cutting oil, cobalt drill bits. If it's a hardened part, sometimes you'll have to get a carbide drill bit. Those are typically only sold at places that sell machinist tooling.

 

[TReel98]

Coming from working in a machine shop there are a few things you can do that will greatly help. First off get yourself some tap magic this stuff works amazing its meant for tapping holes but I love using it to drill its a great lubricant in general. No. 2 get a good center punch and make a good indent on the head of the bolt. No. 3 either start with a smaller drill like 3/16 to make a pilot hole or use a center drill to start out. No. 4 The smaller the bit the faster you need to turn it. No. 5 put a fair amount of pressure on the drill but not enough that the chips come off and are blue HSS isn't meant to cut that hot. and lastly when the bit gets dull don't throw it away get a drill sharpening gauge and learn how to resharpen your drills. Its easy as long as you have a good bench grinder.

 

[COO USA]

What everyone else said, also, I'm just going to throw it out there and I doubt it is the case, but are the bits that came with your extractors left hand? The nice snap on extractor set has left hand bits. Wouldn't be the first time I saw people running them in forward and not cutting at all! Just burns the tip.

 

[sberry]

I agree with tap magic. I get a handfull of the small Minnisota bits from a guy at a flea every other year or so. 1/8 and 9/32 for a bit more strength, they are really good. A few bigger ones too, a couple new 1/4 or so. Tsmall ones will bunch 1/2 and 3/4 plate in 20 seconds drill time for pilots.

 

[EOC_Jason]

You might want to invest in a drill bit sharpener in the future too. I've used my drill doctor so much it makes night & day difference with a dull bit. Sure it's not as good as having a professional sharpen it, but when you are in the middle of a job and your bit is getting dull you can spend a few minutes to touch it up and make life so much easier...

 

[theoldwizard1]

Use a center drill, first, to drill a pilot hole.

YES !! But you really need to center punch it first !

 

[crguy]

You aren't suppose to drill a pilot hole. That actually wears the drill out unevenly stresses out the cutting edge. Drill bits are used to drill holes not expand existing holes.

You don't drill much, do you?

 

[pstemari]

YES !! But you really need to center punch it first !

Better to use a spotting drill. Wide angle (120 or 140) for tough materials, 90 for mild steel and softer stuff.

Center drills are for drilling centers for running material on a lathe.

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[jimmy-ray]

I like tap magic also, it doesnt seem to help much unless im on a drill press though, all i ever seem to drill is grade 8 fasteners though. All my drills are too fast, i think thats the problem. We went though the whole shop the other day trying to find the slowest drill, it ended up being my 1/2 inch older snap on and its still to fast.

All the cordless and corded we have are to fast even on slow. Everyones snap on 3/8 is way too fast.

Im also starting to think you only get 1 or 2 uses out of a bit before it snaps or dulls and thats with really good technique. I basically have to get lucky to not mess it up because i dont do it often enough.

Ive had every kind of snap on bits and i think they all **** to be honest. Ive given up and only buy cheapos now. I have had a little luck with sharpeners but then you have to sharpen every time.

We have been struggling with this in the shop lately. I had some hardened rounded off t27's-3/16 yesterday. Usually i can hammer a crappy t30 in there, get it fully seated and presto. However, whoever tightened these ones really didnt want them coming out, ever. They wernt dry or rusted either, just really over torqued. Anyway the t30 just rounded it worse, i really got it in there deep and tight too. So i tried a snap on extractor, lol yeah right, the bits created a nice metal dust, thats it. All my bits did the same or not even dust.

So my coworker suggested we try to chisel them out, pff that never works, not once in my entire life has this ever worked. They did bite really nice and after a couple of cracks the damn bolt actually moved. First time in 20 years it actually worked for me and thats not including all the times before my professional career... and we didnt even screw up and accidentally chisel the area surrounding the fastener. Im going to find out what the chisels are and get some.

 

[Sugarfryz]

I like tap magic also, it doesnt seem to help much unless im on a drill press though, all i ever seem to drill is grade 8 fasteners though. All my drills are too fast, i think thats the problem. We went though the whole shop the other day trying to find the slowest drill, it ended up being my 1/2 inch older snap on and its still to fast.

All the cordless and corded we have are to fast even on slow. Everyones snap on 3/8 is way too fast.

Im also starting to think you only get 1 or 2 uses out of a bit before it snaps or dulls and thats with really good technique. I basically have to get lucky to not mess it up because i dont do it often enough.

Ive had every kind of snap on bits and i think they all **** to be honest. Ive given up and only buy cheapos now. I have had a little luck with sharpeners but then you have to sharpen every time.

We have been struggling with this in the shop lately. I had some hardened rounded off t27's-3/16 yesterday. Usually i can hammer a crappy t30 in there, get it fully seated and presto. However, whoever tightened these ones really didnt want them coming out, ever. They wernt dry or rusted either, just really over torqued. Anyway the t30 just rounded it worse, i really got it in there deep and tight too. So i tried a snap on extractor, lol yeah right, the bits created a nice metal dust, thats it. All my bits did the same or not even dust.

So my coworker suggested we try to chisel them out, pff that never works, not once in my entire life has this ever worked. They did bite really nice and after a couple of cracks the damn bolt actually moved. First time in 20 years it actually worked for me and thats not including all the times before my professional career... and we didnt even screw up and accidentally chisel the area surrounding the fastener. Im going to find out what the chisels are and get some.

This has been mostly my luck. They dull out soooo quickly. I figured it has to be a technique issue. Thank you for all the replies. I also assumed applying pressure would cause the drill bit to break!!

 

[ez-duzit]

Originally Posted by ez-duzit View Post
Use a center drill, first, to drill a pilot hole.

YES !! But you really need to center punch it first !

Of course you center punch.

The advantage of the center drill for creating the pilot hole is that it is extremely rigid, for the size of the pilot hole, unlike an equivalent diameter drill bit, and so is highly unlikely to snap under pressure.

 

[Dingleburry]

I like tap magic also, it doesnt seem to help much unless im on a drill press though, all i ever seem to drill is grade 8 fasteners though. All my drills are too fast, i think thats the problem. We went though the whole shop the other day trying to find the slowest drill, it ended up being my 1/2 inch older snap on and its still to fast.

All the cordless and corded we have are to fast even on slow. Everyones snap on 3/8 is way too fast.

Im also starting to think you only get 1 or 2 uses out of a bit before it snaps or dulls and thats with really good technique. I basically have to get lucky to not mess it up because i dont do it often enough.

Ive had every kind of snap on bits and i think they all **** to be honest. Ive given up and only buy cheapos now. I have had a little luck with sharpeners but then you have to sharpen every time.

We have been struggling with this in the shop lately. I had some hardened rounded off t27's-3/16 yesterday. Usually i can hammer a crappy t30 in there, get it fully seated and presto. However, whoever tightened these ones really didnt want them coming out, ever. They wernt dry or rusted either, just really over torqued. Anyway the t30 just rounded it worse, i really got it in there deep and tight too. So i tried a snap on extractor, lol yeah right, the bits created a nice metal dust, thats it. All my bits did the same or not even dust.

So my coworker suggested we try to chisel them out, pff that never works, not once in my entire life has this ever worked. They did bite really nice and after a couple of cracks the damn bolt actually moved. First time in 20 years it actually worked for me and thats not including all the times before my professional career... and we didnt even screw up and accidentally chisel the area surrounding the fastener. Im going to find out what the chisels are and get some.

How was every drill too fast?
Ive had the same drill bit index at work for 3 years. Very rarely do i need to sharpen my bits.
I mostly drill mild steel from 1/8th to 5/8 thick, but also gr8 bolts, stainless.
I get many many many uses from one bit.
Ill try multiple gr8 bolts though see what happens! Im curious

This has been mostly my luck. They dull out soooo quickly. I figured it has to be a technique issue. Thank you for all the replies. I also assumed applying pressure would cause the drill bit to break!!

If using a cordless basically apply as much pressure as you can.
Your breaking the bit by not applying pressure. Just dont use a 6ft snipe on a drill press

 

[sberry]

It took me a long time for the feel to become second nature. I see people struggle and it's difficult to explain.

 

[sberry]

As I said I am looking for a piece that kicked around for a while. I can drill straight and quick.I punched a 1/2 stud 3/4 long straight thru with 1/8 the other day.

 

[pstemari]

I've drilled hundreds of holes on one bit:
https://goo.gl/photos/BaHRqjeFbfVGbdJ56

You should be able to, as well.

You do need pressure to keep the drill engaged. The center part of the drill doesn't cut—it pushes the metal out of the way. That's why pilot holes help so much—a pilot hole that's about the size of the chisel point/web thickness of the main drill allows it to cut without extruding the metal.

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[sberry]

I lost my drilpress in a fire 30 yrs ago and never really replaced it. I never use one, pretty much hand drill it all especially once we went to battery drills. I cut holes with a plasma too when it structural and practical.

 

[66354dream]

Don't mean to hijack but I use new motor oil when drilling, is it really necessary to use cutting oil?

 

[GirchyGirchy]

A slow heavy duty drill will help. I have a Makita 6302H that's awesome...0-550 rpm with tons of torque.

 

[dutchgray]

That above, a big heavy corded drill helps as long as your drilling downwards and not in a tight space, I use our dry diamond core drill when drilling 5mm or so holes in steel work so we can screw wood to them, has about the right speed, the clutch will activate when the drill catches so you don't end up breaking a load of bits.

 

[nes999]

A slow heavy duty drill will help. I have a Makita 6302H that's awesome...0-550 rpm with tons of torque.

I set a Bosh on fire last week that was similer sized and I kept over heating my Milwaukee 1660 on some 16 inch walnut joists.


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[pstemari]

Don't mean to hijack but I use new motor oil when drilling, is it really necessary to use cutting oil?

Not really. Unless you're doing something exotic (stainless, Inconel, titanium, etc) almost anything is better than nothing and any oil of reasonable viscosity will be fine.

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