straightening out a blade

It's hard to determine the right amount of pressure. It's pretty much hit and miss until you get it right. I don't know what kind of a tempering oven you have but what I do more now is to clamp the blade to a length of angle iron and put it back into the oven at the temperature I used to temper at. I clamp the blade with two C clamps with a small coin under it to cause a slight counter bend.

Keep safe over there with all the demonstrations.

Doug
 
Thanks Doug

And thanks again :)

I dont heat treat myself, send knives to a shop. So all i can do so far is use the vice. Trial and error i guess :)
 
I've used a torch. Put the blade on a flat steel bench with the curve towards the bench. Slowly heat the blade and continuously moving the torch until the heat draws the blade towards the heat. I've done this on three different knives and it worked each time. Every knife I have straightened this way was stainless. I dont know how it works on carbon steel.
 
Shokr,
I do almost all of my grinding after HT. This alleviates for the most part any warpage problems.

I have Water jet cut or profile my own blades then drill out any holes & break the edge of the blade at about 30 degrees then finish to 220 grit and its off to HT. I prefer the way steel grinds after HT. You get a crisp grind instead of a smear of soft steel. Try it! you will like it! Just dunk & wipe often and never let it get hotter than you can hold.

Laurence

www.rhinoknives.com
 
Thanks guys

But i have no torch or HT oven, nothing :)
I'll see if i can arrange for the HTer tp straighten blades for me

Laurence i am not really a fan of doing that, takes me forever to grind (the remaining) after HT (maybe because my grinder isnt very powerful) mostly after HT i use 80g belt because i dont have good control yet, but still.

I dont even know how but i tried grinding a kirdashi/scalple looking blade completely after HT, i got tired before even removing 1/4 of the steel, and that was a really small part even!

What i do is i remove steel, leave edde at 1-2mm thick depending on size of knife, then after HT go bit higher to reach desired bevel height and get edge thinner.

I cant wait to use water jet really! (but why not use it for holes as well?)
 
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I use almost the same set up with the vise but I use round stock with little pins through the tops so that they dangle inside the vise. I have also found that the metal still has to be hot for me to straiten anything after HT.
 
SHOKR said:
Thanks guys

But i have no torch or HT oven, nothing :)
I'll see if i can arrange for the HTer tp straighten blades for me

Laurence i am not really a fan of doing that, takes me forever to grind (the remaining) after HT (maybe because my grinder isnt very powerful) mostly after HT i use 80g belt because i dont have good control yet, but still.

I dont even know how but i tried grinding a kirdashi/scalple looking blade completely after HT, i got tired before even removing 1/4 of the steel, and that was a really small part even!

What i do is i remove steel, leave edde at 1-2mm thick depending on size of knife, then after HT go bit higher to reach desired bevel height and get edge thinner.

I cant wait to use water jet really! (but why not use it for holes as well?)
Click to expand...

A true knife heat treater in the USA will straighten out the blades that have warped.

I don't know who you would be using? If knives are just a side line to them?

Leave them thicker and finish to 220 grit before HT.

As far as you getting tired so easy? I still don't know what we are going to do with you??:les:

Laurence

www.rhinoknives.com
 
SHOKR said:
But i have no torch or HT oven, nothing :)
Click to expand...

I use my kitchen oven:biggrin:

I use the same method that Doug stated above, clamps and shims to reverse the warp and run for a temper cycle in the oven. I then quench with water. I've had great succes doing this with carbon steel. I no longer attempt to straighten blades post-HT without heat . . . I learned my lesson the hard way. Before HT, nothing is off the table (I recently used my truck for some 5/16" 1075!)

I've had blades return warped from the best heat treaters in the USA . . . it happens, it's part and parcel with what we do.
 
Weatherman, i remember seeing that setup somewhere, really loved it, would save me the effort of trying to keep everything in place at once till i tighten jaw (so far i used double sided tape)
you just drill holes in round bars and insert smaller ones in the holes?

Laurence, i sometimes grind for 6 hours standing (record was 7 not including 2 30 mins breaks), but for the past while something is not right, i honestly don't know, i get tired easy doing anything, can't sleep right, don't eat well (probably explains the exhaustion), cant focus and take double the time i used to do some work on a blade.
from what i understand the knives i send to the HTer are new to them, they don't HT hand knives, and i doubt anybody around here actually does, local workshops just do it by feel, they dont deal in steel codes, just check sparks or trial and error and quench in water or oil accordingly, thats it! i am working through some things gradually with the HTer but i don't have enough experience to actually guide him or tell him how to do certain things
also i do finish the blades to old 120g belt before HT and leave edge between 1.2-2mm depending on size

last time i sent him few large knives, so he told me we better just HT the edge (entire edge but not tang), ironically the worst warp is at the part where he stopped the quench

Thanks Shawn, i accept that, just need to know how to fix it :D
 
SHOKR said:
Laurence, i sometimes grind for 6 hours standing (record was 7 not including 2 30 mins breaks), but for the past while something is not right, i honestly don't know, i get tired easy doing anything, can't sleep right, don't eat well (probably explains the exhaustion), cant focus and take double the time i used to do some work on a blade.
from what i understand the knives i send to the HTer are new to them, they don't HT hand knives, and i doubt anybody around here actually does, local workshops just do it by feel, they dont deal in steel codes, just check sparks or trial and error and quench in water or oil accordingly, thats it! i am working through some things gradually with the HTer but i don't have enough experience to actually guide him or tell him how to do certain things
also i do finish the blades to old 120g belt before HT and leave edge between 1.2-2mm depending on size

last time i sent him few large knives, so he told me we better just HT the edge (entire edge but not tang), ironically the worst warp is at the part where he stopped the quench
:D
Click to expand...

Shokr,
First concerning your tiredness I bet you aren't wearing a good respirator while grinding the Micarta and steel?
The Micarta release's Formaldehyde when ground and that will make you very tired and mess up your central nervous system in time.

Go to a Ladies hair Salon and see the older ladies that have been doing hair perms for years.
They move slower, talk slower and think slower than other women their age because of long term exposure to the formaldehyde & dyes.

Laurence

www.rhinoknives.com
 
Doug Lester said:
I don't know what kind of a tempering oven you have but what I do more now is to clamp the blade to a length of angle iron and put it back into the oven at the temperature I used to temper at. I clamp the blade with two C clamps with a small coin under it to cause a slight counter bend.
Click to expand...
I just wanted to second this method, it works quite well... sometimes it takes a few tries, though. It sure beats sticking it in a vise and bending it the opposite way, I have more than a few broken blades lying around from doing that.
 
Laurence, i wear a good one (i am under such impression at least) with dust/natural gases filter
 
thanks George, i will try to duplicate it using regular oven and see

Shawn, what steps/technique do use when using the kitchen oven?

thanks
 
SHOKR said:
Laurence, i wear a good one (i am under such impression at least) with dust/natural gases filter
Click to expand...

I mean a real face mask respirator with filters from 3M or my favorite MSA brand. Not those paper disposable things.
Also these chemicals can seep in through your skin and if you give your shop a great cleaning and stop cutting Micarta for a couple of months. I bet these affects will dissipate.

That was what happened to me, I had to closed my shop for months and pay someone else to clean it from top to bottom and then I finally had energy again and was able to resume knife making.

I don't/Won't use Micarta, G-10 or anything that has Phenolic resin in it anymore and I've been back to my old happy, Knife grinding self ever since!

From your symptoms? It sounds like you are slowly poisoning yourself in the shop or somewhere else?

Laurence

www.rhinoknives.com
 
Laurence, thanks for the concern and i am glad you got over that

i wear a respirator with filters, one like 3M (spanish made tho) with 2 cartridge filters, can show you pic sometime
i work in the balcony and cover my entire body, except hands and what remains of the face (and a growing bold spot :p)

as for the poison from somewhere else, well, its Cairo!! i mean a hazardous outbreak would kill half the planet and would probably just make us stronger lol

seriously tho, it can be many things, i am stressed (in more than one area of life), and don't eat well, also could be change of season (it started getting really cold (for me) about a week ago), anyway i will get over it soon God willing

thanks a lot for the concern :)
 
SHOKR said:
Laurence, thanks for the concern and i am glad you got over that

i wear a respirator with filters, one like 3M (spanish made tho) with 2 cartridge filters, can show you pic sometime
i work in the balcony and cover my entire body, except hands and what remains of the face (and a growing bold spot :p)

as for the poison from somewhere else, well, its Cairo!! i mean a hazardous outbreak would kill half the planet and would probably just make us stronger lol

seriously tho, it can be many things, i am stressed (in more than one area of life), and don't eat well, also could be change of season (it started getting really cold (for me) about a week ago), anyway i will get over it soon God willing

thanks a lot for the concern :)
Click to expand...

It can always be many things, Some of us are more sensitive than others to formaldehyde. With all of the good Halal & Kosher food you have access to you should be in great shape!:biggrin: Some Matzo soup will fix you right up!!

Also if all this HTer is doing is edge quenching you can learn how to do that with a Butane hand torch, a magnet, a fire brick or two and a pan with some oil. You can ever use old Falafel oil.

This may pain you because it does involve a book & reading. :sad:

Get Wayne Goddard's book, $50.00 knife shop. It's up to more like $100.00 these days but you can do all of this HTing on your balcony by yourself with some practice and if there is warping you can watch it happen and learn to adjust.

I can't help you with the bald spot.:s12137:

Laurence

www.rhinoknives.com
 
SHOKR,

It appears that you are trying to bend the blades at room temperature? If so, I would stop pressing your luck! I just broke at A2 Tool steel blade that way, trying to remove a very small warp. Spring steels may tend to fair just a little bit better, depending on how they were tempered and how bad the warp is, but my recommendading would be to clamp it to a straight edge as previously suggested, and bake it in your kitchen oven for 45 minutes to an hour. It may take some "over correcting", but with a little trial and error, you should see results.

I actually purchased a small convection toaster oven for tempering my blades; costs around 40 to 50 USD for a decent one that I feel comfortable with. Make sure you put a seperate oven thermometer inside though, as the dial is rarely accurate.

I've used the vise/torch method before as well, with success, but I hesitate on narrower/smaller blades due to how easy it is to over heat the edges and the tips. Make sure you clean the scale off the blade as best as you can when using this method, so you can better see your colors as the blade heats up.
 
SHOKR said:
Weatherman, i remember seeing that setup somewhere, really loved it, would save me the effort of trying to keep everything in place at once till i tighten jaw (so far i used double sided tape)
you just drill holes in round bars and insert smaller ones in the holes?
Click to expand...

Yep all you do is drill the holes and then add smaller bars.
 
SHOKR said:
Shawn, what steps/technique do use when using the kitchen oven?
Click to expand...

Rick Marchand has a great tutorial on another forum, but I'm not sure if other forum links are allowed here. I'll PM you the link and if somebody gives me the OK, I can post it here, too.
 
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