Lets get something straight

[tomsm44]

I have several 1084 blades cut out, ground, and ready to heat treat once I drill the pin holes.  The problem is that every one is warped.  I cut them out on a band saw and ground them on my belt sander.  I'm not sure when the warping happened, but that's not my concern right now.  I need some help straightening them.  I think I recall seeing a method on here that involved clamping the blade straight during the tempering cycle, but I don't remember what thread it was on or all the details.  I would appreciate any help you guys can give.  Also, how can I prevent warping in the future?  

Thanks,
Matt Toms

[D.Ellis]

Matt, not sure if it was my thread you saw it in, but I did post it here  http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=110;t=004464;p=3
As to preventing it, you need even grinds, normalize well and usually a stress relief heat cycle, and then when you quench, make sure you go into the oil straight with no side to side movement. Oh, and a little luck never hurts either      :D
Darcy

[bculberson]

If the blades are warped pre-heat treat you should staighten them before proceeding with the normalizing and heat treating.  If the 1084 is Aldos annealed 1/8" stock you can bend them by hand.
If the blades are warped post heat treat then staighten them using the "clamp during temper" method.

[Lin Rhea]

Just to add to what has been said, If they come out of the quench warped and you want to straighten them, Do one cycle of draw back before you clamp them straight. If you attempt to clamp them fully hardened, you might break them when you tighten the clamps. Clamp them and draw them back on the second cycle.

I use a much thicker bar that is pre bent to pull the blade over to it. The thick bar also holds heat much longer after the oven is off. This residual heat will provide the expansion needed on the "short side" while the "long side" is cooling and contracting at a faster rate.

[Kevin Evans]

What these other guys said works

Plus if they come out of the quench warped and you have a vice handy very loosly clamp and straighten with your hand.
You have a few seconds and nothing bad happens
 lets say you have under one minute

to see if its warped I hold up in sky light as I do while forging, its pretty easy after a while

[tomsm44]

Thanks guys.  Darcy, That is where I saw it.  Thanks.  It is Aldo annealed 1/8" stock, so I will se if I can straighten it by hand before I heat treat it.  I'm still not sure what happened.  I cut the blade profile out with a band saw and then ground the final profile.  After I noticed that the first couple were warped after finishing the flat grind, I checked the others and they were all already warped before the flat grind.  I wouldn't have thought I would have built enough heat with the saw or the small amount of profile grinding I had to do, but apparently something happened.  Maybe I'll figure out what is causing it and be able to avoid it in the future.  I'll watch it more closely on the next ones I do.  Anyway, it shouldn't be a problem to fix, I just didn't want to mess up what I had done so far by fixing it the wrong way.  I'm building 9 matching knives for a friend/colleague of mine to use as Christmas gifts next year, so it'll be a while before I finish them, but I'll get some pictures up once I do.  

For the record, batch work sucks.  I'm going to flat out refuse to do more than a couple of matching knives at one time in the future.  

Thanks again,
Matt

[tomsm44]

Darcy, I have another question.  You mentioned normalizing.  I am using stock removal and am going slow enough with the grinding that I am keeping the steel pretty cool, making sure to not let it get hot enough to turn blue.  I have mainly seen normalizing mentioned in reference to forged blades.  Is there any benefit to normalizing or to a stress relief heat cycle for a blade made using this method?  I know I've read a lot of how tos where these steps are not done on stock removal blades and so apparently aren't required, but I was just curious if there would be enough benefit to be worth the time it would take.

[gables]

It is possible you warped them with drilling or grinding. Thin annealed stock will bow if drilling between two support blocks if spaced far enough apart. If you are pressing hard with the handle part of knife while grinding you could be bending blade at ricasso area. Fully support material while drilling and use a push stick against blade while grinding if either are possible causes.

[D.Ellis]

Originally posted by tomsm44:
Darcy, I have another question.  You mentioned normalizing.  I am using stock removal and am going slow enough with the grinding that I am keeping the steel pretty cool, making sure to not let it get hot enough to turn blue.  I have mainly seen normalizing mentioned in reference to forged blades.  Is there any benefit to normalizing or to a stress relief heat cycle for a blade made using this method?  I know I've read a lot of how tos where these steps are not done on stock removal blades and so apparently aren't required, but I was just curious if there would be enough benefit to be worth the time it would take.

Matt,
I would always normalize a blade of 1084, just because you do not know for sure what the grain structure is like and I want to refine the grain size before HT. It doesn't hurt, but could make all the difference in the world performance wise. To go with the steel as supplied would always leave me unsure of the finished product..........my personal opinion.
Also, you can still cause stress in the steel with stock removal,less so than with forging, but still can be a problem. A couple normalizing heats takes very little time and effort for the peace of mind they provide.
My <.02    
Darcy

[tomsm44]

Thanks Darcy.  That makes a lot of sense now that I think about it.  I'm always interested in anything that'll improve the quality of my work.