Making parts from drill rod

Michael Moore · Sep 23, 2006

Drill rod appears to come in lots of useful fractional sizes and to have a nice surface finish. This makes it look attractive for use in spindles (for example motorcycle axles) where all you want to do is just put a thread on each end for a nut, or maybe a thread on one end and a welded boss on the other, and then slide it into a standard bearing.

I've looked in the tool steel section of Machinerys Handbook but that appears to be largely concerned with the property of the steels after hardening, and doesn't make it clear to me how appropriate it might be to use the steel in "as supplied" un-hardened condition. I also seem to run into a "too much information" situation where I don't have the background to evaluate all of what I'm being told.

Is it safe to use something like O1 oil-hardening drill rod as a structural part? If you weld something to one end of the oil-hardening steel and let it slowly air cool will it get harder/more brittle and prone to fracturing, or is that not going to be an issue if you avoid the air-hardening steels?

Or should I just be looking at turning things out of annealed or pre-hard 4140 instead which I'm pretty sure is suitable for the parts I'd be interested in making? The 4140 doesn't seem to be as readily available in all the handy fractional sizes though.

cheers,
Michael

SND · Sep 23, 2006

I'm not sure about the normal properties of O1 to be used as is for shafts and such. It's probably fairly good though.

When it comes to welding, it can crack at the weld. Usualy a stainless filler is used to reduce the chances of that happening. The stresses on the part would have to be examined for proper welding procedure and destructive testing of a sample may be a good thing to do.

There's quite a few kinds and sizes of Precision Ground Shafting. Some of which is case hardened and some that isn't. It's not something I deal with very often but I'm sure other members will have more info and perhaps some suppliers names.

Michael Moore · Sep 23, 2006

I used some Thomson "Quick Shaft" for the pivot shaft in my shaper, but that is just a plain shaft - no threading or holes in it. That does look like a good product for running inside bronze bushings.

It may prove that the drill rod isn't sized to slip through bearings. I have a vague recollection of trying some metric drill rod and finding that it was a pretty tight fit, and having to hammer axles in and out isn't an ideal situation.

If buying a length of drill rod that was nominally the right diameter (but was going to need a skoosh taken off to let it actually fit) is the case then I suppose I'd probably be better off to just go with the 4140/4340 and turn it to size I need.

cheers,
Michael

jburstein · Sep 23, 2006

Typically drill rod isn't precisely sized enough to use it for a bearing fit. Actually, in my experience it frequently isn't terribly round either.

-Justin

Carl Darnell · Sep 23, 2006

I think you would be better off with the 4000 series steels but if you weld them they harden and can crack also. You can anneal it by heating it and stuffing it in sand and letting it cool. Check the machinist handbook for the temp. or color to anneal.

Michael Moore · Sep 23, 2006

Hi Justin,

I haven't seen enough of it to know.

cheers,
Michael

precisionworks · Sep 23, 2006

I keep an assortment of W1 drill rod. For many applications, it's hard enough (20HRc) as supplied. If you need greater hardness, it is by far the easiest material to torch heat treat - bring it to red heat & plunge into cold water. W1 also costs less than O1, A2 or D2.

Drill rod, like many items, is available in a wide variey of grades & prices. If you need close tolerance material, be sure to specify centerless ground. Up to 1/2", the tolerance is +/- .0005, from 1/2" to 2" it's +/- .001. Here's one of many suppliers:
http://www.diehlsteel.com/drillrod.aspx

Google 'centerless ground drill rod' for dozens more.

---------------------
Barry Milton

johnoder · Sep 23, 2006

As noted above, centerless ground stock can be out of round. Has to do with how well it is done. It is entirely possible to centerless grind and end up with the "tri-lobed" geometry that checks good with ordinary OD mic, but is nowhere near round.

John

Peter Neill · Sep 23, 2006

I like the Stubs Silver Steel (same as drill rod) that we get over here, and use it quite a lot.

To be honest it's more accurately sized and with a better finish than I can turn a shaft to, never had a problem with roundness, and it works very nicely for that half thou' fit in a plain bearing.
And it's harder than the mild steel shafts it replaces.

Peter

matt_isserstedt · Sep 23, 2006

I also have a good collection of W1 drill rod.

I view it is a nice-machining general-purpose high-carbon steel without ever doing any heat treatment at all, in fact I don't ever recall trying to harden a piece of W1. It will typically machine to a nicer finish than the garden variety CRS too.

Usually I reserve the O1 for anything I want to be homebrew heat-treated (to a hardened Q&T state).

JRouche · Sep 24, 2006

If you weld "SOMETHING" to one end of the oil-hardening steel and let it slowly air cool will it get harder/more brittle and prone to fracturing, or is that not going to be an issue if you avoid the air-hardening steels?

Welding? No, I would not weld it to another material unless it was the same material and then TIG weld it.

Treat it as any other high carbon steel including cast iron.

When you weld a high carbon steel to a lower carbon steel the carbon likes to migrate from one material to the other to "normalize" it's content creating a high concentration of carbon at the joint. The high carbon joint will be brittle or "hard" unless its treated with heat properly.

But, I'm not a weldor so its all just conjecture on my part, Haa

JRouche

ulav8r · Sep 24, 2006

As for "lobing" of centerless ground rod, it can have 9 lobes or more. We once had a problem with 9 lobes on a shaft, when used with a ball bearing that had 8 balls it created quite a bit of bearing noise.

If there is lobing from the centerless grinder it will be in multiples of three because of the three contact points, the grinding wheel, the regulating wheel, and the workblade.

tnmgcarbide · Sep 24, 2006

I also have a good collection of W1 drill rod.

I view it is a nice-machining general-purpose high-carbon steel without ever doing any heat treatment at all, in fact I don't ever recall trying to harden a piece of W1. It will typically machine to a nicer finish than the garden variety CRS too."

yes, matt has the right idea.

w-1 ,or 1095...blahblahhbaaa, is pretty tough on its own + spec'd for as-is condition for dowel
pins and low rpm shafting.. and such, in factories
and mills..

hi-carb , no alloy...cheapest toolsteel you can get.

JST · Sep 24, 2006

Interesting.... I have found drill rod to be somewhat obnoxious to machine, with many of the same oddities as low carbon.

Tearing, rough finish, a tendency to re-weld chips onto the surface, etc.

I don't know if that is JUST W-1 or both O-1 and W-1. I have some of both, and seem to recall both being about the same.

I think the 4140 PH was much better for machining than either low carbon or drill rod. It cut nicely, even if it is tough and hard. Much less or no issues with re-welding etc.

The D-R does harden nicely for the off cutting tool or the like, which I suppose it ought to, after all it is "drill rod".......

Does having problems with it suggest poor technique in some way?

matt_isserstedt · Sep 24, 2006

As far as welding, I've welded O-1 square-broached socket to a CRS shaft before when making a special crank handle for a shaper.

Welding was Mig, the O-1 was in the soft, "as-machined" state.

Once the welding was complete, I did my homebrew quench and temper process on the O-1 socket.

All is well, part is in use and working well under occasional useage, no adverse affects or durability problems to report.

Michael Moore · Sep 24, 2006

Thanks for all the advice. I think I'll probably reserve the drill rod for less critical and non-welded parts and not put it in important areas on my race bikes.

Peter, I'd seen that "silver steel" mentioned a lot, but could never figure out what it was. Thanks for clarifying that.

cheers,
Michael

adama · Sep 24, 2006

can highly recomend stubbs silver steel (drill rod is us name for same stuff i think). have had no issues with lobing problems on name brands such as stubbs. very usfull for all sorts of things due to the range of sizes ( 1mm step from 1mm to 50mm stocked by most good tool shops).

shawnspeed · Sep 24, 2006

Michael, when I was building /reparing dirt track race bikes , I had a customer come in for me to repair his swing arm/ frame after an axel failure from an axel made from drill rod with a nut Miged on one end...needless to say the repair included a 1020 MS axel...4140 was out of his budget, still in use as far as I know....Good luck Shawn.

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