steel arriving bent...err maybe just not straight

[N.N]

The past few months' steel orders have all arrived....let's just say less than straight. Not bad, but enough that I want to straighten them before the initial bevel grinds. It doesn't matter where I order from. Is this common? As I've not been doing this long, it seems as though the first orders I made and up until just recently there hasn't been a problem, but that's changed.

I've tried hammering the bar stock with mixed results (if anyone knows a better method than laying in a work bench and beating it with a rubber mallet, I'm all ears). I've tried waiting until HT and using the "shim it with a file while tempering" technique with mixed results. Nothing seems to work real well.

I'm asking this with hopes that someone has some easier way or technique. I just heat treated a blade and thought I had most of the bend out (hold on, it wasn't the quench that bent it I'm fairly sure). But the tip right about the spot where the drop point is to the tip curves to one side a little. I didn't notice because it's hard to see while looking down the spine because of the drop point.

anywhoo....how do you guys deal with this? How do you straighten your steel bar stock if it arrives bent or warped?

 

[Self Made Knives]

I'm new at this, but I recently asked the same question about some 14c28n stainless I received. I bought a 24" long stick and it was bowed about a 1/8" or more from end to end. It was even cupped from side to side from being sheared off. The pros on here told me that it is pretty normal to receive stock that way, so I straightened it mostly with a shop press. I blocked up the ends and pushed down on the middle, repeatedly, until it finally sprung back mostly flat. After I got a blank profiled, I used a 12" disc sander to flatten it. What you and I really need is a surface grinder, and I want one, bad!!!

 

[Frank Niro]

Even on 1/8" stock I use the flat surface on a ball pien hammer. If it's a long piece I will often put one end in the vice and just pull on the other. I will move the bar in and continue to do the same if I "see" that is what is needed. On small pieces I will just lay them on the counter with believe it or not a tooth pick under and give them a hit with that same hammer. The rubber mallet hasn't worked for me. If you can't "site" down the bar and tell if you have it straight or not, lay a straight edge, even the edge of a steel ruler on it to see. Hope this helps some. Yes, it is not an uncommon thing. I NEVER figure any metal coming into the shop is either straight or the same thickness throughout. Frank

 

[N.N]

Yeah, i've been laying them flat on a large file to see the straightness but haven't tried the ball pien hammer yet. I can get them to move with the rubber mallet, it's just hard to get them to get straight. It seems i get the middle flat but now the ends are curved a little. I work on the ends and the middle isn't flat anymore.

 

[J. Doyle]

I've found steel even 3/16" thick can be bent in a vise. Even in blade sized lengths. I will pull it and tweak it in the vise by hand until I get it as flat as I can. Then when I scribe my lines for my rough ground edge and tapered tang, I will grind away any that remains that I couldn't get out by hand. Hope that makes sense.

If it's so bad that I can't pull it by hand, I'll use the three point pin method in my arbor press to tweak it.

 

[KenH]

Since I'm a cheapskate and haven't purchased "precision ground" steel..... yet {g}, I'm sure some of the steel in long sections have been bent a tad. If the bend is an even curve from one end to other, then it's "usually" fairly easy to clamp one end in vise, and pull on other until it's straight. Then lay the blade length up to flat platen and grind on each side "usually" takes care of any warps left in steel.

So far, the 14C28N I've purchased from Alpha in 12" to 13" lengths have been pretty straight. A bow in the width wise of blade would be a tad harder to get straight for sure.

Ken H>

 

[rhinoknives]

Ken,
I too am a cheap skate at times and only buy Coarse ground because it really costs me less. Its shear cut and about 80 grit ground which saves me time and belts that I would use up getting the bark & scale off of the billet.

Try it! You will like it! :biggrin: . It also helps eliminate the wobble in the billet most of the way. After I profile I lay the blank on a 6 x 48 flat sander if there is any bend in it?

I purchased a large batch, a full sheet ATS-34 cut into 2" billets in about 2002 that had such a hard bark & scale on it, "It must of been in the mid-high 60's RC" that I wasted a few Blaze ceramic belts cleaning up the scale & wobble. Also the scale stunk so bad that I threw out my t-shirt and jeans after afterwards!:w00t:

So generally I have seen three grades.
1) With the bark and scale and maybe wobble.
2) Coarse ground shear cut. What I buy mostly. Very flat, clean and maybe the slighest amount of wobble.
3) Precision ground that is saw cut. Flat & true!

I've been buying the coarse ground since 2002 and it has saved me money on belts with less aggravation too!

Have fun!

 

[Knifemaker.ca]

So, from a suppliers point of view, most of the steel we get is mill finish - anything but precision. Thickness varies as done bow and cup. Surface grinding is not the panacea many expect. Much like a wood planer, the material will be (more or less) uniformly thick and parallel, but can still be bowed to whatever extent the magnet sucked it down and it might spring back when off the magnet. Of course, surface grinding ups the price of the steel a lot. Lastly is the shipping. FWIW, short pieces are more likely to evade shipping bends than long pieces and some sort of backing wood seems to provide some protection.

If suppliers were to start putting bars in a three point vice, you wouldn't like the price at all. I think straightening steel is part of being a knife maker, but if you guys can think of any reasonable way we can improve the condition that steel arrives at your door, let us know. We all aim to please.

Rob!

 

[J. Doyle]

I think straightening steel is part of being a knife maker.

Rob!

Excellent point. And I agree 100%. We can get the steel perfectly straight and flat and do plenty to it in the process of making a knife that makes it come out of the quench not flat and straight anymore. In which case, we STILL will need to know ways and methods to straighten it. So in a way, and meant nicely.............if your steel arrives warped or bent, your better off finding ways to deal with it. Gonna have to sooner or later anyway.

 

[KenH]

Coarse ground shear cut

I like the sound of that, and some of that scale can be a real bugger. The stainless I've purchased hasn't had much in the way of scale, nothing like the scale that can form on high carbon steel when forging or HT'ing, especially in a forge.

Laurence, where do you find your steel course ground? Is this for SS or high carbon steels? Would your source have any Sandvik 14C28N? Since Calvin referenced that steel to me, it's been my only SS to use.

Ken H>

 

[Frank Niro]

To get rid of the scale soak in a weak solution of ferric chloride, some vinegar, or a very weak solution of muriatic acid which is HCL (hydrochloric) Better to do this outside. Frank

 

[rhinoknives]

I like the sound of that, and some of that scale can be a real bugger. The stainless I've purchased hasn't had much in the way of scale, nothing like the scale that can form on high carbon steel when forging or HT'ing, especially in a forge.

Laurence, where do you find your steel course ground? Is this for SS or high carbon steels? Would your source have any Sandvik 14C28N? Since Calvin referenced that steel to me, it's been my only SS to use.

Ken H>

Ken, I like and use the CPM metals from their CPM-D2, CPM-154 CPM-S30V and CPM 35VN this is about 90% plus what I use except for the occasional billet of Damascus I buy from Devin Thomas, Randy Haas and family and a few others.

Coarse ground Shear cut is how I order it all from NSM http://www.nsm-ny.com/index.cfm

Franks tip of using acid to get the bark off does work quite well. I just like to use as little heavy chemicals as possible. I use plain apple Vinegar to itch my carbon steel Damascus blades. It takes longer, but I can do it with any fear of the fumes and just dump it down the drain without any alarm for the pretty Ocean I live by or my health from any long term exposer to these kinds of chemicals.

I knew I fellow maker that left the top off of a vat of hydrochloric acid that he used to etch his Damascus steels. He closed up his shop and went away on a trip for a few hot summer days. The acid fumes etched & ruined and or made a ton of work to clean up about $300.00 of different steels he had in his shop. LOL. Its funny now! It wasn't when he told me about it.

He was way ahead of the curve with the new acid etched stainless steel knives you see these days! LOL

 

[KenH]

Thanks for the info Laurence - I remember looking at that site before but felt the prices were a tad on the expensive side. I can get 14C28N for less than he's selling the 440C for, and I think we all agree the 14C28N is the better knife steel for kitchen knives.

I've used vinegar for removing scale from blades before, sure is easier than grinding.

Ken H>

 

[rhinoknives]

Thanks for the info Laurence - I remember looking at that site before but felt the prices were a tad on the expensive side. I can get 14C28N for less than he's selling the 440C for, and I think we all agree the 14C28N is the better knife steel for kitchen knives.

I've used vinegar for removing scale from blades before, sure is easier than grinding.

Ken H>

Ken,
I use to look at steel pricing the same way. Its more than just the bark/scale you need to remove. I've I only made one knife out of 14C8N so far and it hasn't been HTed yet, 440C is the KING of culinary steels. I've heard only good things about the 14C8N, but don't underestimate properly HTed 440C for most any culinary knife.

All I can say is when you see how much less time and belts coarse ground & shear cut steels will save you I think you will agree.