Rockwell strength?? Broadheads?

[KSdan]

Can anyone explain this "Rockwell" rating?  I have been posting and interacting here on TG lately about broadheads. As I study different heads I note various descriptions including Rockwell this and that. . .  I am not sure how to compare apples to apples.  

For example- the STOS is an interesting design with the ferule going the length of the head plus it is more than one thickness at the tip.  Now- the Tusker does not "look" as strong, however- maybe the Rockwell rating is stronger?  How would you know?

Dan in KS

[grouseshooter002]

Dan,
The Rockwell scale is a means of measuring the hardness of an object that has been heat treated. To test a broadhead or any other object you will need a tester with a diamond point or go to a good machine shop and ask if they have a Rockwell tester that will check using the C scale. For us DIY types you can use a file and guesstamate the hardness by how much pressure it takes to scratch the surface or get shavings off the broadhead.

Regards,
Grouse

[KSdan]

Thanks Grouse.  I think what I a asking is how to compare the many different "Rockwell" listings on various broadheads.  How do I compare apples to apples?

For example:  Tusker = 50-52 Rockwell
Magnus Snuffer = 44c  Zwicky Eskimo = heat treated (?)

What is the difference??

[motorhead7963]

Put it on an arrow and stick an animal see what happens, if it's steel it will probably go through flesh.
Simple in my mind,
Unless you are going after some very large Dangerous animals it really wont matter, don't over think it.

[ChuckC]

Rockwell is (I think) an arbitrary series of numbers derived from pressing or scratching a piece of metal.  The amount of effort it takes to scratch it gives a number.  The more effort, the higher the number.

From what I see here and elsewhere, the number 50 is a good round number to look for, maybe a tad higher, for broadheads.  You want them hard enough to take and hold a good edge, but not so hard that they are difficult to sharpen or will snap on impact.

Older Bear heads were softer steel (lower Rockwell) and although easy to get nice and sharp, were dulled more easily and bent a bit easier.

Some heads I have seen are much harder, are harder to sharpen, don't bend as easily and hold an edge better.  

I am certain those that really know this stuff will chime in with actual numbers for more accurate information.
ChuckC

[SuperK]

As a general rule, a higher Rockwell listing is normally more durable than a lower one.  The higher one may also be harder to sharpen.  After re-reading Ashbey's studies, single bevels needs a higher "R" rating due to the twisting forces caused by a single bevel.  This can cause the edge to roll.  Like already stated, most good double bevel broadheads are hard enough to do the job.

[Charlie Lamb]

44 rockwell is softer than 50

[JamesKerr]

I will chime in with what little I have found with rockwell differences in different heads. An original woodsman has a rockwell hardness of 44. Zwickeys are around 50, and so are VPA's. The only one I have really bent to the point of it being unusable is the original woodsman. My consensus is that broadhead design plays as much if not a more important part of a broadheads strength.

[Charlie Lamb]

When you get up around 50 rockwell, knives and broadheads get difficult to sharpen with a file. It will skip off and not bite in. The harder the steel the more prone to breakage on hard impacts. The softer is more prone to bending.

Usually a happy medium works best.

[motorhead7963]

do not be put off by what was said about the Bear Razorhead they have claimed MANY world records.

[Uncle Buck]

as Charlie said Rockwell is only a measure of hardness.There are other factors to consider such as brittleness. proper heat treating is an art. Broad heads have to be fairly thin. A thin edge with a high Rockwell # would stay sharp longer but might shatter on impact with bone, where a softer head would drive through. I used to see this a lot with stainless steel replaceable blade heads. high Rockwell #, very hard steel, but they would chip and shatter on anything.

[Bladepeek]

A good steel can be VERY hard and not be brittle. A good knife blade will be up in the RC 58 to RC 62 range and still not be brittle. Problem is, such a knife will cost you $50 to $500. How many people would be willing to pay for good tool steel, properly heat treated in a broadhead they might lose? And how many would be willing to spend the time necessary to sharpen it? Like Charlie said, you could forget about sharpening them with a file.

Another point to remember is that a knife is expected to cut, and cut, and then cut some more. A broadhead only needs to cut once - in one side and out the other.

[ChuckC]

Way I UNderstand, A Knife Is A Different Critter.  You Can Differentially Harden A Knife, To Have A Very Hard Edge And Softer Back To Make It "Best Of Both Worlds".  Either Way, Make It Too Hard And It Is More Difficult To Sharpen.
chuckc

[KSdan]

Great input guys.  Thanks. .   I have been at this for 40 years of hunting, 30 with trad. Blessed to have hunted a number of species and taken a number of mature/PY whitetails. . . I shoot 55#, 190fps, 31" draw, 550-600 gr arrows.  But, I have had a couple of mishaps like 2" penetration last year on a 5 yd. shot at a 140"+ whitetail.  I see a Tusker vid with the guy blowing though water buffalo shoulders. . .  Ashby talks about blowing through bone.  And no need for commentary on placement, sharp head, yada. . . I know.  But I hunt a real world where shots and things do not always work out.  I just want the marginal shot to do the job.  Thus- my inquiry. . .  Thanks again.

[ron w]

If you can cut it or sharpen it with a file it is something less than 50 RC. As was mentioned harder does not mean stronger.

[motorhead7963]

Alright... KSdan you opened up a can, now you got to elaborate on the 2" of penetration, first off how do you know it was only 2"s did you recover the deer? where did the shot go, etc. etc.
come on now tell the story.

[Stumpkiller]

Broadheads are not knives.  A Rockwell of 44 to 48 is great for broadheads as they are easy to sharpen.  Durability of the edge is not so critical as it only has to cut 12" to 20" of meat to do its work.

I hunt with Stos - great heads.  I have a sample of the Davies and Tusker heads and would use them as well.  They seem rugged and well designed.

If you look at the Stos the design incorporates a VERY smooth ferrule transition.  That was the key feature.  Long and narrow with a smooth ferrule for penetration and to split ribs.  This they do - I have taken deer with a rib hit on either side and the head still was outside the far side of the deer.        

One I am still carrying in my quiver went through a deer and buried itself flush in a root.  The deer shapped it off with its hind leg when it spun and ran off.  Had to saw the root apart to get the head back.  A few passes with a file (and a new arrow behind it) and we're back in business.

[KSdan]

Oh my. . .  hate to relive it!  

Waited for this textbook scenario to unfold in this exact spot. . .

6 does came through,. . . 20 minutes later this 3 yr old 140+ comes running.  Should I take him?  Stops 5-6 yards below my cedar tree on up hill side-making it a mere 8' below me. Quartering away just off the fringe edge of cedar twigs. Wind in my favor. Seconds to decide. . ??  Ok. Shoot now or wait until he walks out and up the hill making it eye level, 12 yard "fish in barrel?" "One in the hand" mind racing. .  "Can't miss, just center it in his chest." Take 5 yd shot. The Magnus 4 blade is released, arrow hits and does not penetrate.  Deer bounds up the hill 25 yards and stops for a minute or so.  Entire arrow is hanging out.  As he runs off the shaft breaks off on a tree.  I wait for a short time just disgusted. I go up to where he was standing at  25y. The arrow is laying with the broadhead thread broke off at the insert.  A couple of drops of blood on ground and a just a smudge on the insert itself.  I go ahead and track with nothing but foot prints.  Find a couple drops out to 80 yds from shot.  Obviously broadhead in the shoulder blade.  My one chance at near mature deer for the year.    

This is the 3rd such incident in the past 17 years. I know for a fact 2 of those 3 lived-seeing them in following weeks/years.  I hit one other deer in this manner/same head 13 years ago- the head made it just through the blade severing the spine-  173" buck down on the spot.  5 yd shot. (was a 700gr set up)

Stay away from blade I know. . .  but things happen occasionally.

So-  I have other success with same broadheads, but revisiting here with help of TG, etc.          

Dan in KS

[motorhead7963]

Sounds like the insert pretty much broke upon impact, that's gotta suck.

[KSdan]

The insert broke off as the shaft struck a tree when the deer bounded away after it stood there for a minute.  Every scenario on this type of mishap has been close encounters.  Close happens often to me.  I still would like to think that at 5 yds an arrow would penetrate the shoulder blade though.  Just re-read my bow set up.  Pretty good for trad.