Drilling out rock drilling rod

[H Wally]

Hi guys, back with another self caused problem:

I want to bore out a chunk of hexagonal 1 inch diameter drill rod - the kind with the hollow core for lubricating the bit.

I spent the last couple days by pulling any possible temper out of the rod by laying it in a long hot fire, bringing it up to orange heat and soaking it at that temperature, then covering the whole fire and allowing it to burn down and slowly cool over several days. Last night I unearthed it and it was luke warm.

Here's the thing.... it still dulls saws and drill bits. I can use a cutoff wheel to cut the ends flush, but I need a better drill bit to bore the center out of the rod. Right now I'm using your basic canadian tire titanium coated drill bits.... clearly I need something better. What would you recommend for drilling out the rod? I don't mind spending money on good tools, but I like to hear some reviews on them before I spend the money.

So, what kind, brand, and where would you recommend buying some very high quality power bits?

P.S. Please don't derail over discussing how I'm boring the rod, I've done that successfully on other rod, just haven't needed higher quality bits to do it before.

 

[burnt_servo]

i've used concrete drill bits more than a few times . they have a carbide cutting bit on a soft steel shaft .

the bits are dull and need to be sharpened when new . they also shatter very very easily .

would it be possible to take a regular drill bit and make it harder than the drill rod your using ?

 

[IMagius]

"a chunk" ... are we talking a few inches? or a foot or more? My first thought was if it's a short piece, why not have a local machine shop spin it in a lathe for you?

I don't have the name of the maker, but the local Snap-On truck (might have been Matco or ...... whichever it was, was one of the regular tool trucks at the local garage) was selling some very nice Drill Bit sets a few years ago ... and they were Guaranteed not to dull or break (for any over 1/4 inch) ... if they did, you returned that bit and got a new one. Co-Worker had the set and loved them - drilled through welds, hardened bolts, etc without any issues. I'll be damned if I can remember the name of them now though ... that was 4 years ago

 

[H Wally]

i've used concrete drill bits more than a few times . they have a carbide cutting bit on a soft steel shaft .

the bits are dull and need to be sharpened when new . they also shatter very very easily .

would it be possible to take a regular drill bit and make it harder than the drill rod your using ?

That's a good suggestion on the concrete bits. What were you specifically using them for when you were drilling with them?

I personally don't have the confidence reliably temper a bit that would properly cut and not break off 14 inches inside the drill rod and screw the project. Plus I doubt the quality of my bits, so trying to temper them harder means they probably wouldn't harden, or would expose some flaws if they did. In the end I need a proper drill set, so I'm happy to spend the money.

"a chunk" ... are we talking a few inches? or a foot or more? My first thought was if it's a short piece, why not have a local machine shop spin it in a lathe for you?

I don't have the name of the maker, but the local Snap-On truck (might have been Matco or ...... whichever it was, was one of the regular tool trucks at the local garage) was selling some very nice Drill Bit sets a few years ago ... and they were Guaranteed not to dull or break (for any over 1/4 inch) ... if they did, you returned that bit and got a new one. Co-Worker had the set and loved them - drilled through welds, hardened bolts, etc without any issues. I'll be damned if I can remember the name of them now though ... that was 4 years ago

I was going to cut in half to be between 30 and 35 inches, depending how much I trim the ends in the process, so it'll need to be bored rather than run through a lathe.

If you happen to remember who was selling the bits I'd be interested in knowing.

 

[rgbai]

cobalt drill bits are all i use now you can drill through metal almost as fast as drilling wood.

 

[guntech]

I spent the last couple days by pulling any possible temper out of the rod by laying it in a long hot fire, bringing it up to orange heat and soaking it at that temperature, then covering the whole fire and allowing it to burn down and slowly cool over several days.

Unless you know the composition of the steel you may not have softened it up enough to drill/bore the center of it...

Titanium coated bits are a sales gimmick... it's just a coating... you do need a high quality bit. You also have to turn the bit or the work at the correct speed and feed so you don't burn up the bit.

 

[david doyle]

a 14 inch deep hole is gonna need a bunch of liquid flowing to clear chips and keep things progressing. Like guntech said RPMs are everything.

If you want to get the skinny on boreing out drill rod call a shop up north that rebuilds drilling equipment those guys would be able to tell you what you are up against. They might also just bore and send you the piece you need for less money then you will burn up in bits doing it yourself.


Most lathes have pass through head stocks so your length is not an issue. If you can turn a 30 inch bit square by any other means great but it will be easier with a lathe.

 

[mwjones]

A 14 inch hole is going to be impossible to bore with any kind of accuracy without a gun drill or jig boring machine, lots of oil, and carbide drills. And by accurate i mean concentric.

Drilling this hole on a lathe, you'll have to bore it with a boring bar and ream afterwards, THEN set up between centers and turn the outside diameter down. That's pretty much the only way to make sure the bor is concentric with the OD.

Sounds like you want to try to make a barrel?


Solid carbide drills are pricy and breakable. The cobalt bits you can get at hardware stores are generally crap. In fact, most drill bits you get at the hardware store are just plain garbage. ESPECIALLY the TiN coated ones. A solid carbide jobber length drill bit will cost you abotu $100 to $300 at 1/2" depending where you get it from, and that's for 3" flute 5" overall length. Indexable carbide drills that are going to be long enough to drill a 14" hole might be cheaper......well...start savign your pennies/car payments.

Might be better to just buy a piece of seamless tubing.

 

[trevj]

Unless you know the specific alloy of the rod to begin with, random heating like that could have made it worse, not better, or had no effect on it at all.

Got a machine tool supplier local to you? Be sitting, when you have to pay for a quality drill, it's gonna be a shock.

For a one-time hack use, carbide tipped masonry drills can be sharpened up using a diamond grit disk and a dremel tool. Then they can be resharpend, when they inevitably chip. Not an ideal solution, but a solution that might work.

You are looking at prices that make buying a barrel look cheap, if you want to buy a couple decent carbide or carbide tipped drills.

If you are holding onto a rod of something funky in the way of steels, it's a crapshoot. Life is easier, cutting known materials.

Cheers
Trev

 

[coyote]

I've annealed a lot of different steels in my wood stove and sometimes get one that will not anneal ,so I bring up the temperature with the torch to almost white hot and put it back in the stove.

If this doesn't work it may be a ph steel and could be tricky.
What some of the guys have said try some cobalt hss and make sure you have the correct speed and feed otherwise the steel might work harden on you and you may have to anneal again.

 

[maynard]

Plain old drill rod is usually made out of O-1 or W-1 material and is usually easy to machine unless you harden it first. You might also get into higher grades made from A2, D2, M2, M2/M7, S-7.
Very important to know what material you have before throwing heat to it.
As mentioned above, ou might be better off sending it out to a machine shop that has a gundrill if you want an accurate, smooth hole.

 

[H Wally]

cobalt drill bits are all i use now you can drill through metal almost as fast as drilling wood.

I've been considering those for a while, good to hear other positive reviews of them.

Unless you know the composition of the steel you may not have softened it up enough to drill/bore the center of it...

Titanium coated bits are a sales gimmick... it's just a coating... you do need a high quality bit. You also have to turn the bit or the work at the correct speed and feed so you don't burn up the bit.

Haha - yah, I know they're a gimmick, that's just what I have here. I've bored shorter pieces and generally flood the hole with oil then run the drill in short passes.

a 14 inch deep hole is gonna need a bunch of liquid flowing to clear chips and keep things progressing. Like guntech said RPMs are everything.

If you want to get the skinny on boreing out drill rod call a shop up north that rebuilds drilling equipment those guys would be able to tell you what you are up against. They might also just bore and send you the piece you need for less money then you will burn up in bits doing it yourself.

That's something I hadn't thought of. It would definitely make my life easier if they were able to do that... then again, depending on the price I could just buy a barrel

Most lathes have pass through head stocks so your length is not an issue. If you can turn a 30 inch bit square by any other means great but it will be easier with a lathe.

Unless you know the specific alloy of the rod to begin with, random heating like that could have made it worse, not better, or had no effect on it at all.

Got a machine tool supplier local to you? Be sitting, when you have to pay for a quality drill, it's gonna be a shock.

For a one-time hack use, carbide tipped masonry drills can be sharpened up using a diamond grit disk and a dremel tool. Then they can be resharpend, when they inevitably chip. Not an ideal solution, but a solution that might work.

I had kindof planned a hack job - it's meant to keep me busy and occupied while I wait on standby for the next two months. Figured instead of drinking or watching tv I would try to learn something.

You are looking at prices that make buying a barrel look cheap, if you want to buy a couple decent carbide or carbide tipped drills.

If you are holding onto a rod of something funky in the way of steels, it's a crapshoot. Life is easier, cutting known materials.

Cheers
Trev

I've annealed a lot of different steels in my wood stove and sometimes get one that will not anneal ,so I bring up the temperature with the torch to almost white hot and put it back in the stove.

If this doesn't work it may be a ph steel and could be tricky.
What some of the guys have said try some cobalt hss and make sure you have the correct speed and feed otherwise the steel might work harden on you and you may have to anneal again.

Definitely agree on the work hardening - for my test projects I ran slower speed and short passes with lots of oil. Seemed to work pretty well overall.

 

[BCRider]

What you did is basically right. But if it didn't anneal then it suggests that you didn't get it up past the critical temperature needed for the particular alloy the rod is made from.

Also for a heavy bar such as 1 inch you may need to hold it above the critical temperature for longer to ensure that it's up over critical all the way in to the core. Steel is actually a pretty bad conductor of heat. You may need to hold a 1 inch bar for a good 15 to 20 minutes to ensure that the entire rod exceeds the critical temperature all the way through.

 

[Anfoman76]

Hey man, is it round or hex? If your talking about rock drilling not sampling (hollow) which I'm pretty sure you are. I was a rock driller, and have used this steel before, round was called t40 and hex was t35. Extremely hard steel, your gonna need some serious heat because rock drilling will make them so hot that you have to wear to pairs o gloves to handle it (experience ) it will turn the couplers used to join them blue!!

 

[JerryJeffWalker]

What you did is basically right. But if it didn't anneal then it suggests that you didn't get it up past the critical temperature needed for the particular alloy the rod is made from.

Also for a heavy bar such as 1 inch you may need to hold it above the critical temperature for longer to ensure that it's up over critical all the way in to the core. Steel is actually a pretty bad conductor of heat. You may need to hold a 1 inch bar for a good 15 to 20 minutes to ensure that the entire rod exceeds the critical temperature all the way through.

I beleive this is correct. You need to reach critical temp in the core so it needs to be very hot for a long time. 1 inch is pretty big steel for heating and can be bright orange/yellow on the out side and black in the center. A propane or coal forge is needed and the whole thing needs to be at heat when you anneal. Then for better annealing get a few buckets of vermiculite to cool it in.

 

[burnt_servo]

here is a thought , if your using a wood fire to heat up a piece of metal to aneal it ..... wouldn't the metal pick up carbon from the burning charcoal wood and possibly end up not as soft as it should be ?

 

[trevj]

here is a thought , if your using a wood fire to heat up a piece of metal to aneal it ..... wouldn't the metal pick up carbon from the burning charcoal wood and possibly end up not as soft as it should be ?

Not normally. It'll scale off faster than the carbon can penetrate. It'd be great if it would work that way though. We'd be thousands of years ahead in metallurgy if it was that easy to add carbon to steel.

The other thing is, to make carbon steel hard, you have to get it above it's critical temperature, then lock in that crystal structure by cooling the part rapidly quenching).

Cheers
Trev

 

[H Wally]

What you did is basically right. But if it didn't anneal then it suggests that you didn't get it up past the critical temperature needed for the particular alloy the rod is made from.

Also for a heavy bar such as 1 inch you may need to hold it above the critical temperature for longer to ensure that it's up over critical all the way in to the core. Steel is actually a pretty bad conductor of heat. You may need to hold a 1 inch bar for a good 15 to 20 minutes to ensure that the entire rod exceeds the critical temperature all the way through.

I had it up at anywhere between a cherry red and orange heat for close to an hour. The bed of coals I put it on was deep enough that as it burned down it didn't lose significant heat when more wood was added to top it up. Temperature varied over the length to some degree, but the whole bar was at minimum at a medium red the whole time until the fire was covered to cool slowly.

Hey man, is it round or hex? If your talking about rock drilling not sampling (hollow) which I'm pretty sure you are. I was a rock driller, and have used this steel before, round was called t40 and hex was t35. Extremely hard steel, your gonna need some serious heat because rock drilling will make them so hot that you have to wear to pairs o gloves to handle it (experience ) it will turn the couplers used to join them blue!!

It's hex - has the fine hole, approx .2 of an inch, running through the center.

I beleive this is correct. You need to reach critical temp in the core so it needs to be very hot for a long time. 1 inch is pretty big steel for heating and can be bright orange/yellow on the out side and black in the center. A propane or coal forge is needed and the whole thing needs to be at heat when you anneal. Then for better annealing get a few buckets of vermiculite to cool it in.

I was getting decent enough temps with the wood fire, unless orange heat for just over 45 mins isn't enough. In my experience there aren't many metals that won't anneal at that temp once they've heated all the way through. Then again, I've never worked with drill rod like this.

The rod was cooled by leaving it burried in the fire, about 8 inches of coals on all sides give or take including the top, and then covered in fine sand and the moist clay that we've got. It baked up pretty solidly over the top and was still holding some heat 2 days after.

 

[guntech]

I want to bore out a chunk of hexagonal 1 inch diameter drill rod - the kind with the hollow core for lubricating the bit.

You refer to it as drill rod... is that reference a classification of the steel manufacturer? or is that reference to what this piece of steel was used for before you got it? (As in a manufactured drilling tool)

Why I am asking is because 'drill rod' is/was a classification of a tool steel and I believe it was either oil nor water quenched to harden it and your annealing process should have made it 'soft' to drill. If it was a manufactured tool that you are trying to work with, you don't know the correct process to anneal it. Some steels are simply air hardened after heating red hot.

Either that or your speeds and feeds or cheap drills are the problem.

 

[Markus]

You need to get it to non-magnetic temperature. Once it is no longer magnetic then you hold it at that temperature for several minutes and cool it slowly to fully remove the temper. If you don't reach non-magnetic you are not removing much temper. Around that temperature it will be a very bright orange colour and you may be able to see sort of a shadow moving around in the steel. When you see that you are close.

In my experience O-1 and 1095's carbon steels are still pretty hard to drill through even when they are only 1/8" thick I have still destroyed more than a few drill bits.