D-bits

[lampy]

I found a few threads about how to make D-bits and would like to try my hand at it, I have a newbee question about the making of D-bits. Will a HSS cut drill rod? If not what do I need? I don't foresee a surface grinder being added to my shop in the near future so I am limited to using my HF mini mill and Craftsman lathe. Should I get oil hardening or water hardening drill rod?

 

[chucketn]

HSS will cut drill rod nicely. I have made several tools from it on my X2 mill and 7x14 lathe, d bits, threading tools, and countersinks.
As to oil hardening or water or even air, it's up to you. I think either type would work for you. I use oil hardening because I change the oil in my vehicles and lawn mower, so I always have old oil on hand.

Chuck

 

[lampy]

Thanks for the quick reply Chuck. I am going to order some drill rod from Enco and they offer two different types of drill rod, water hardening or oil hardening. I am unsure if one is better than the other for making d-bits or other tooling.

 

[chucketn]

Before you buy, do some more research on the differences between them. I did, and chose oil, but I honestly can't remember why. Maybe because I had old oil on hand. I don't think there is much difference in how hard they get. You also must temper the tool bit to draw back the hardness. If you just harden the tool is glass brittle, and can break/shatter. Tempering is a way of putting back a Little flexibility but not softening back to the machinable state.
If you need to adjust the shape after hardening/tempering, you can anneal the metal back to machinability by heating again and letting it cool slowly. Yes, it is an art, but no more than machining the bit in the first place. Goggle is your friend, search for hardening and tempering drill rod (or silver steel as it's called in Europe). It's a common topic on lots of forums.

Chuck

 

[lampy]

I just got done with a google search and found people who swear by oil hardening rod and just as many who swear by water hardening rod..... My guess is either will work. I could be wrong but from the description in the enco catalog water hardening rod could be used without heat treating, but does that mean it's going to be harder to machine? Oil hardening is going to be easier to machine but will require hardening.... Please correct me if I'm wrong.

 

[Tin Falcon]

Lampy just buy a couple pieces mark it so you know what it is and make some bits learn what works for you.

water hardens faster than oil oil you need to do outside. you can buy w-1 rod and quench in oil and not have to temper. there are lots of ways to manipulate results.
Tin

 

[lampy]

Thanks Tin. Kind of funny I didn't of trying both oh:

 

[Tin Falcon]

No problem I think when we start out we want to do everything right. It is ok to try different things within reason and use what is on hand sometimes relax and enjoy the journey. It makes getting to the destination more enjoyable and rewarding.
Tin

 

[chucketn]

Lampy,
What are you going to use the D bit for? I have lots of notes on making/using them.

Chuck

 

[lampy]

I don't have a specific job that I need one for yet. I just got done building an air motor and could have used a reamer to make a better fitting hole. I started looking at reamers but don't want to spend the money on a set of reamers yet, my research on reamers led to a thread about d-bits and how they can be used to bore a clean, close fitting hole along with making custom profile end mills and lathe bits. I think this would be a useful skill/tool so I want to get set up to be able to make what I need when the need arises ;D I thought I'd start with 1/4", 3/8" and 1/2" to match my collets.

 

[maverick]

Lampy,
You're right on the money wanting to learn to harden and temper drill rod as well as make D bits. Sorting these things out before
you need them is the way to go. Anyone who's done this has there own preferences and methods, here are mine.
Water (W-1 or oil hardening (O-1)?
Both machine well in the annealed state with W-1 having a slight edge, it seems to be finer grained. When hardening, O-1 is a little more
forgiving about temps without "burning" the edge and as the quench is less abrupt, there is less tendency to warp. O-1 is also a better
choice if the part has thick and thin sections and complex forms, heating the quench oil to 100 degrees F will aid quenching this type of part.
Oil quenching tools of any size is best done outside as there is a lot of smoke. Using a brine quench with W-1 will make it less abrupt
with less chance of warpage, the brine can be saved and reused. When tempering using colors, be sure to polish and degrease the tool
to more accurately see the colors. Once tempered, both types perform well and you should see no difference
in normal home shop use. This is based on my experience and will most likley vary with equipment and application.

Best Regards,
Mike

 

[lampy]

Thanks for the info Mike, I'm going to start with W-1 and see how that goes. ;D

 

[Swede]

Good luck with it. Hardening and tempering carbon steels is an art that every HS guy should go for at some point. Remember that as the cross-sectional size increases, maximum hardness requires holding the tool at or above the transformation temperature for a period of time... but in doing so, it becomes more likely to potentially ruin the steel with excess heat, so you've got to go carefully.

Tempering is where the tool is truly made, IMO. Too high a heat, you've got a soft tool. Too low, and your tool will break due to brittleness.

If this becomes something you find you enjoy, it is tough to beat a little bench furnace. It is easy to convert a very cheap bench muffle into a computerized job with a $99 PID temperature controller off of eBay, and once you're set up with an accurate system, you can (with confidence) tackle air-hardening steels, even exotic steels, and know it'll come out well. I've even used mine to solution-treat and artificially age aluminum, turning raw castings that machine like hard bubble gum into a delight.

 

[kwoodhands]

HSS will cut drill rod nicely. I have made several tools from it on my X2 mill and 7x14 lathe, d bits, threading tools, and countersinks.
As to oil hardening or water or even air, it's up to you. I think either type would work for you. I use oil hardening because I change the oil in my vehicles and lawn mower, so I always have old oil on hand.

Chuck

Chuck,why isn't air hardening tool steel used more frequently?This is what I have used for D bits and several taps I made. I only have air hardening stock on hand, if water or oil hardening is that much better I'll order some.
mike

 

[PerryRT]

lampy, I've used both, and mostly I use W-1....but that's because I'm a bit parsa...parse....parsta....cheap, and from the suppliers I use, W-1 is typically about 15-20% cheaper. Other than that, I haven't noticed much difference in hardness, but to be honest, generally I work with aluminum and brass, so take that for what it's worth.

 

[Blogwitch]

In the UK, invariably when we purchase silver steel (drill rod) you are sent water hardening, and that is what 99% of model engineers use.

Only the very minority stipulate air or oil quenching, maybe because of a stipulation on a blueprint or a special request. In fact you have to search it out, it just isn't available normally from general model engineering suppliers, you ask for silver steel and you get water hardening.

I have hundreds of pieces of silver steel in my stock, and every one is water hardening, and I have never yet had to resort to anything else, and in my time, I must have made many hundreds of tool bits, most doing a perfect job, with any failures being because I was asking too much of it.

So why complicate matters?


John

 

[Swede]

I love air hardening steels. Being able to wrap in stainless foil (no scale that way) and avoid messy quenches is nice. One thing A2 and similar air-hardening steels also have going for them is better hardness at higher temperatures. The tempering temperatures for a given Rockwell C hardness is very much higher than O1 or W1, meaning if used for a cutting tool, they can be pushed a bit harder and hotter without losing their edge.

The D series of tool steels is also supposed to be good steels, with a higher chromium content. I'm thinking D would be good for engine parts subject to corrosion.

Wikipedia has a decent article on tool steels and their composition... http://en.wikipedia.org/wiki/Tool_steel

 

[lampy]

Thanks for all the replies and pointers everyone. My Enco order should be here in time for me to try making a couple D-bits this weekend.

 

[smfr]

What would happen if you were to try water quenching with an oil-hardening steel? I guess the quenching speed and temperature might be different, but would it make that much of a difference?

I ask because I have a bunch of oil-hardening drill rod around, and don't have a pot of oil to dunk things in (and would prefer to avoid the smoke etc).

 

[tel]

You would be better using oil for oil hardening - there is very little smoke involved, just a quick puff as the workpiece enters the quench.

I do use water hardening for preference, but one bloke I get stuff off only carries the oil stuff and is a bit cheaper than the usual suspects, so when needs must .....