Picked up some old hammer drill bits at a garage sale. Question regarding material.

[tulsavw]

I bought these 5 old hammer drill bits at a garage sale the other day.  The guy who was having the garage sale was a retired pipeliner and said that they used these to bore through rock when crossing under roads, creeks, etc.  They're ~1 1/4" across and 2-4' long.  I figured they are probably made of some tool quality steel, so I couldn't pass on them for the $5 the guy was asking.

 

Anyways, I've been doing a little searching and have been having trouble finding any information on the specific metal types used on bits like these.  Part of that problem could be the search terms that I'm using, seeing as how I'm not sure that I'm calling these bits by their proper names.

 

Could anyone offer some insight as to what type of metal would be used (for the main rod, not the carbide cutters) for tools like these?  I would imagine it would be a metal with abrasion resistant qualities.  I'm going to use these for some tooling of my own, if I can verify that these would be an appropriate material to use.  Of course, I don't expect anyone to know exactly what these are made of, but if anyone does know or suspect what we're looking at here, it would be of some benefit to me.

 

 

[Steve Sells]

try jack hammer bits

[tulsavw]

Alas, that returned some leads.  Time to do some investigating.  Thanks!

[tulsavw]

Okay, after doing some pretty heavy reading from multiple sources, it looks like the steel is most likely S5.

[Steve Sells]

keep reading... :)

[yahoo2]

>working with scrap jackhammer bits no point reinventing the wheel

 

that 32mm shank will fit an atlas copco and a few others, if it has an airhole down the shank to clear the rock chips so it can rotate it is a jackhammer bit, if its solid, it fits a breaker.

 

I reworked a breaker moil and chisel tip a few weeks ago, they both had cracks from a previous sharpening, consensus on the day was it was a cheap boron steel and the metal had been worked too cold. I snipped the cracked ends back and kept them above a dull orange and they formed up OK.

[joshua.M]

Probably something like 4140 of 1045, that coolant hole runs all the way through right? use them for monkey tools

[bigfootnampa]

Yes, Steve is right!  According to guys who ought to know those type bits are usually made of steels something like 1050 but with some added traces in the alloys to give them performance somewhat like S7 steel but at much lower cost.  Still, I have found them useful stock... they seem to do a pretty good job of approximating the performance of the more costly alloys.  I have used them for masonry chisels (the hand struck kind)... pretty well in line with their original design tasks.  They are also good for things like nail headers and forging hammers.  I haven't tried this yet, but I think they'd be good stock for trowels.  Certainly they'd be well suited for making pry bars and probably for hot punches as well.

[Frosty]

Easier than all that, just call a company that builds roads. Even if they don't run air tracks (drill rigs) they know who does, a blasting company probably. Call that company and ask who supplies their drill steels. THAT company will be able to tell you more about those than you'll want to know.

 

The longer ones have carbide bits so the steel only has to be impact resistant rather than hard. The bits themselves come off so the shafts may be different steel entirely. Air tracks typically use rope threads and don't couple to the hammer like those seem to so they could well be a jack hammer type rock drill.

 

This is a good example of the yellow pages being a faster and better search engine than the internet. You can talk to people on the phone so you can ask simple questins, they can use some judgement or just connect you.

 

Frosty The Lucky.

[knots]

My understanding is that forging these hollow drills can be dangerous.  Air can become trapped in the bore and cause the forging to rupture resulting in flying red hot debris.    Paver breakers and smaller pneumatic tools, without the bore, are common and easily obtainable.  I usually buy mine from equipment rental shops so why take a chance.

 

I like the idea of using them for monkey tools .

[Frank Turley]

Check sandvik.com. They make 4 grades of hollow drill steel.

 

Sayings and Cornpone

Master: "I'm sick of your not being able to measure correctly. For once and for all, how many thousandths in an inch?"

 

Apprentice: "I don't know, but there must be a million of 'em!"
 

[ThomasPowers]

S7 would make a great drill bit---just like Titanium would make  great car bodies---seen many Ti bodied cars?

 

In manufacturing the "best" is quite often subsumed by "the cheapest that will do"