Drilling out rock drilling rod

Drill rod used for drilling rock can be brittle and for that reason it against WCB regulations in BC to use it as an anchor pin for a life line. This might make drill rod unsuitable for use as steel to make a barrel for a firearm. Just guessing.

Regards,
Bradford
 
I think the material is the problem. Like trevj says, unknown material can be a big headache. You can take a planer blade and heat it red hot for a long period, cool it gradually and it will still be hard. I suspect rock drilling bits would be made out of something similar.
 
I think it will be pretty impossible to get the hole you want to be accurate. Is the hole already through it from the extrusion or is it bored bar stock?

Either way, any drill you get will just wander its way down, following the hole that's already there. If i was doing it, i would probably drill it larger, to make to easier to bore after. Leave a good .075 to .100 to clean it up and make sure it's true and leave it .002-005 undersize, then ream to your desired bore size. You would need an EXTREMELY rigid setup of a very tiny, but very long boring bar, super slow feed, on a lathe. Run 5 or 6 dead passes to make sure.

This stuff might make a nice flintlock pistol barrel....
 
guntech said:
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.
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It's a reference to its use. It was in a pile of scrap from old drilling equipment.
If you'll check my earlier posts I avoided the air hardening by soaking it for 45 mins at an orange heat and then burying the whole fire under sand and clay to cool over two days.

Markus said:
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.
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As I noted earlier I held it at, or near an orange heat for 45 minutes. The only times it was below an orange heat was when the fire was stirred up or new wood caused a section to get smothered, but generally that would only be for 5 minute or so, since there was enough of a bed to get it to full heat.

powderman said:
Drill rod used for drilling rock can be brittle and for that reason it against WCB regulations in BC to use it as an anchor pin for a life line. This might make drill rod unsuitable for use as steel to make a barrel for a firearm. Just guessing.

Regards,
Bradford
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That's a fair concern. Mostly I'm doing this as a hands on learning project. I'll be proof testing it fairly rigorously, and if it explodes, I'll have learned something.


mwjones said:
I think it will be pretty impossible to get the hole you want to be accurate. Is the hole already through it from the extrusion or is it bored bar stock?

Either way, any drill you get will just wander its way down, following the hole that's already there. If i was doing it, i would probably drill it larger, to make to easier to bore after. Leave a good .075 to .100 to clean it up and make sure it's true and leave it .002-005 undersize, then ream to your desired bore size. You would need an EXTREMELY rigid setup of a very tiny, but very long boring bar, super slow feed, on a lathe. Run 5 or 6 dead passes to make sure.

This stuff might make a nice flintlock pistol barrel....
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I'm not super concerned about it being accurate :p The gun will be a smooth bore, and I'm using hand tools, and the purpose is to learn what I am capable of, so if the barrel functions safely, then it's a success. The primary reason I'm using a rock drill rod is because it has a hole that I can follow using a piloted drill bit - I sacrifice accuracy for the ability to bore a deep hole without a lathe. I'm probably going to bore only so far as it takes to remove any pitting or gouges left over from use and manufacture of the drill rod. Ideally it would end up .50, but I'll settle for smooth and not exploding when proof tested :p
 
If Anfoman's post is a hint then the rod you have may well be one of the high speed steels. I know that to anneal a high speed steel it needs to get up to a temperature that is somewhere around bright yellow and soak at that heat level long enough to ensure fully reaching that temperature to the core and then ever so slowly reduce the heat over a 24 hour period. Usually this is done in an oven. The critical times are the descent from bright yellow to white down to the bright red sort of temperature range which needs to be done over a couple of hours.

If this rod of yours shares some of this charactaristic then it may be that you didn't get it hot enough for long enough and evenly enough and that due to the nature of air currents through the fire some spots cooled too quickly and re-hardened even if they did reach annealing temperature.

For example to "quench" a 3/4 inch square rod of HSS you just need to take it from the oven and wave it around in the air.
 
Even though it will be smoothbore, you still want to make sure the hole is straight!! You won't need a piloted drill. A regular drill will follow the hole.
If you can get a long enough drill, 5/16 is .3125, and you could probably polish it out and shoot .32 round balls. I wouldn't go with a 50 with hand tools. I wouldn't trust a hand threaded breech plug to a .50, unless it was a class 3 tap and die. but that's just me. plus, if you break the carbide tap and die you'll be out 5-600 bucks :S A smaller thread will be easier to cut by hand.

Boy, will your wrists be tired after reaming 14 inches of hardened steel, and tapping by hand :)
 
BCRider said:
If Anfoman's post is a hint then the rod you have may well be one of the high speed steels. I know that to anneal a high speed steel it needs to get up to a temperature that is somewhere around bright yellow and soak at that heat level long enough to ensure fully reaching that temperature to the core and then ever so slowly reduce the heat over a 24 hour period. Usually this is done in an oven. The critical times are the descent from bright yellow to white down to the bright red sort of temperature range which needs to be done over a couple of hours.

If this rod of yours shares some of this charactaristic then it may be that you didn't get it hot enough for long enough and evenly enough and that due to the nature of air currents through the fire some spots cooled too quickly and re-hardened even if they did reach annealing temperature.

For example to "quench" a 3/4 inch square rod of HSS you just need to take it from the oven and wave it around in the air.
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Well, that would be the first I've come across that quenches at that temp. Good to know in any event. I'll cut some chunks and start testing them at different heats and cooling rates and see what happens.

mwjones said:
Even though it will be smoothbore, you still want to make sure the hole is straight!! You won't need a piloted drill. A regular drill will follow the hole.
If you can get a long enough drill, 5/16 is .3125, and you could probably polish it out and shoot .32 round balls. I wouldn't go with a 50 with hand tools. I wouldn't trust a hand threaded breech plug to a .50, unless it was a class 3 tap and die. but that's just me. plus, if you break the carbide tap and die you'll be out 5-600 bucks :S A smaller thread will be easier to cut by hand.

Boy, will your wrists be tired after reaming 14 inches of hardened steel, and tapping by hand :)
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I find on the first pass using a drill bit that has a pilot ground into it helps follow the hole (have done this on a short section of far softer steel). It seemed to produce a far smoother cut on the first pass where the hole wasn't necessarily smooth, concentric or strait to begin with.

Odds are I'll stay under 40 cal, haven't really thought that far. I'll probably go with whatever I can find that I can get an appropriately sized tap.

This is really not intended to be a 500 yard muzzle loader. All it's meant to do is give me something to do that has an interesting end result.
 
OK (donning scorn Kevlar), a completely different approach. My father had need to drill neat holes in glass when I was a kid. He used carborundum-and-water paste and a hollow brass tube of the appropriate diameter. Clamped down the sheet of glass on his drill press, put a blob of carborundum paste where he wanted the hole, chucked in the tube and weighted the feed handle (fairly lightly, as I recall). He'd go back every so often to swab out and replace the paste. It was slow, but it worked well.

If it will work on glass, I suspect it would work on even tempered steel if you cannot find another way.
 
H Wally said:
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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.
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I work with hot steel in a forge every day I go to work. I forge material up to 1x1/2 and 1 1/4x1/2 flat bar mild steel in a triple burner propane forge capable of doing nasty things to steel if left to long on full blast. These heavier sections require considerable time reach a core temperature that match the outside temp and must be run at full blast for up to 10 minutes to reach a forging heat. I realize you are only needing to reach critical temp but I doubt a large section of high quality tool steel would reach it with a constant pressure wood fire. It wont hurt to overheat the bar a bit to reach critical temp. You have a ways to go before you start burning the carbon out of it. Hardwoods were used in the past in forced air coal forges when coal or coke or charcoal were unavailable. Wood fire forging was considered second rate because the metalurgic heat capability is far surpassed by coal. If you really want to anneal the inside of this bar you will need to bring it to a heat, that when viewed on a sunny day, under a small shade like a tree, "glows" bright orange. If you know what to look for you can see the dark core of an underheated section. If you were able to use a leaf spring forge at a shop you would get better results.
 
True - as with the rest of the nature of this project, I'm making due with what I have, and a minimum of extra work... I know... avoiding work never works.

Odds are I'll have to build a proper trough forge, since the rod is too long for a conventional coal forge, and most propane forges. Since I'm away from home that means I'll need to make a proper set of tongs too, and find a suitably sized blower.... and suddenly the project grows massive again :p
 
you may want to get some softer steel to make a barrel

for black powder barrels seamless tubing can be used

you dont want some thing too hard as it will most likely shatter

even 4140 not heat treated right will shatter or split (4140 is what most moden rifle,pistol,shotgun barrels are made of)
 
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Going back to those drill bits. I have had great success with good quality Cobalt bits, and generally only buy them now (still have hss for miscellaneous work where bits might break, bind, etc). However I recently saw some bits that "appeared" to be/say cobalt, but were in fact a cheap assed knockoff that were cobalt coated or some such nonsense.
 
I doubt that you have reached a high enough temperature for long enough time.1650-1750*F for aprox 2 hrs for S1 and 1700-1750*F for S7. Then allow to cool very sllloooowwwllllyyy The steel that rock drill rods are made from is a shock resistant tool steel.(S1,S7) It is generally alloyed with Chromium,tungsten and Manganese. These components make working the metal very difficult, neigh impossible with titanium-nitride coated HSS tooling. A carbide tipped drill is the minimum requirement. All members of the shock resistant steel family exhibit; low machineability,deep hardening depth,moderate to low decarberiseation resistance, low to poor safety in hardening,with a moderately high susceptibility to heat distortion when tempering.
Long and short of it is that if you are not using a heat treat oven with precission controls and carbide drill on your 'S' steel drill rod you are making a crooked drill eating BOMB not a barrel!
Go with some 10-28 steel .500" or .625"IDx 1" or1.125"OD seamless drawn tubing. A 36" barrel should run you about $60-70 from the metal super market.
 
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camerl2009 said:
you may want to get some softer steel to make a barrel

for black powder barrels seamless tubing can be used

you dont want some thing too hard as it will most likely shatter

even 4140 not heat treated right will shatter or split (4140 is what most moden rifle,pistol,shotgun barrels are made of)
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The steel that rock drill steels(bars) are made from is specifically designed to resist shock. That being said the stress cracks that may be present from its use as a heavy duty pneumatic tool, The heating of the steel for the purpose of anealing can and most likely will cause stress cracks. As the steel alloy becomes unstable at high temperatures and through its critical range its successful manufacture is accomplished by strict adherence to precise protocols. Not a steel for a beginner metal smith.
 
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You're starting too fast. The first little tiny cut you make is the most important to how that bit will last if you're cutting a hard material. Once you burnish the very tip of the bit, it will heat soak the rest. Start VERY VERY slow.
 
H Wally said:
True - as with the rest of the nature of this project, I'm making due with what I have, and a minimum of extra work... I know... avoiding work never works.

Odds are I'll have to build a proper trough forge, since the rod is too long for a conventional coal forge, and most propane forges. Since I'm away from home that means I'll need to make a proper set of tongs too, and find a suitably sized blower.... and suddenly the project grows massive again :p
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A long forge is often unpractical to DIY unfortunately, for heat treating purposes. It's difficult to achieve an even temperature. If you think you're up to the challenge, you'll want a plenum on that blower as well.

12 hour soak and a 24 hour cool down should be fine.

Really though, I think you just need to slow your initial feed rate. You do have an oil feed on your drilling fixture as well, right?
 
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