Don't force yer way during plate quench !

R

rashid11

Joined
Dec 8, 2005
Messages
707
:mad:
$%#%&U#$(%*&#$(*&%(* !!!!

Was heat treating my D2 integral shute. The blade wuz all looking
real pretty, ground & stuff, integral bolsters and butt. Milled the whole
thing out of 3/8" D2. Took the blade area down to .200, tang to about
125. Did it all on my mini mill, using carbide end mill (this steel work-hardens
in NO time I discovered, but it ain't no problem for carbide).

Made a nice tight SS envelope (no PBC this time, wanted to be 100%),
double creased & everything.

Fired up the oven, hit 1875, 20 min hold. Next to oven, I had 2 Al blocks
for plate quench. Fired up the tempering oven. 450F.

Got the blade out, in the envelope, put it onto one block and then laid another one on top. And this is where disaster stuck :eek: - for some crazy
@$$ reason I decided to step on the top block. Of course, lost the balance,
upper plate moved and I knew right then and there I'd bent the blade !

When it cooled down some more , I cut the envelope oven and there it wuz,
bent real bad ! I tested it with a file - it was glass hard, file wouldn't even touch it.

It is tempering now. I figure I will try saving it, but it didn't look too good :(
Will keep it as a reminder in the shop, no better way to remind you about DONTS of the trade :)


Real dumb and stupid, what can I say :(

The plate quench is real effective w/o one forcing the affair. Heck, it will
quench as fine in still air ...
 
I beleive you can soften it enough to bend it back. Don't give up. If its not perfect.... Gift it to a soldier, It can still stab somebody or cut rope.

pakagesfromhome
 
I'm sorry for ya... I am not a fan of plate quenching you know. So no advice, sorry.
But try to reheat it to hardening temp and check if it straitend by itself. Give it a good soack and quench as usual. I do not know if D2 is brittle after tempering, but you migt starighten it with small sharp hummer. Call me if you want I'll tell you how.
 
Sadly, you'll probably have to anneal it and try again; there's really no way to straighten it (with sufficient control) now that it's fully hardened. The steel is flexible while it's cooling until about 400ºF (give or take, depending on the alloy) but then Martensite begins to form and by the time it gets to 150º, you've got a hardened blade. Even if you temper it really hot, you'll just make it nice and springy, not formable.

Plus, you may have bent that blade mechanically, but I'll bet a lot of it is also stress from uneven cooling when you moved one of the plates.

Plate quenching works great, but it still has to be done carefully. But you already knew that.
 
Hinge the quench plates. Make it so they can open up, and when closed, will be able to move a little vertically, so it will accommodate different thicknesses, but won't slide or rotate.
Soften it up, straighten it, reharden.
Good luck salvaging it.
 
I am one of the biggest fans of plate quenching, but I'd never considered the problems posed by an integral. Seems like it would only have point contact in a couple of places. At least with air quench, it would be out of the envelope. Am I missing something?

Just curious. :confused:

Rob!
 
Re heat the blade to full heat 1820-1850. Take out of the envelope, and straighten. forced air cool. Temper as normal. i don't like plate quench. Here's why. first, you can control warp-age of the spine, but not the edge. You need to be able to see the edge while it is cooling. More importantly, you want the edge to cool faster than the spine. This works great at positive air pressure. The plate pulls heat out of the flats, and spine quickly, but insulates the edge in hot air. Exactly the opposite of what I'm after. Mike
 
guys - thanx a bunch for the advise and stuff. I won't try fixing it, not
worth the time. It is bent way outta whack - the tip is off by more than 1/8. Will make me another one.

With integrals one starts hitting limits of mini-mills ability as you need to remove quite a bit of material. And it fairly nasty too, as you need to side-mill here and there. And doing it in smallish increments (10 thou or so per run) produces these tiny and really nasty needle-like splinters. Flood coolant will wash them away, but when dry-milling these will fly all over the shop.

With X3 or Bport I'd use a corncob rougher and hog away in no time, mini, of course, has no power for it :)


But still I must have an integral in me collection :)
 
Hey rashid11, could you pm me, I was wondering how you milled the whole blade out on a mini mill?
 
Mike: You absolutely can straighten your blades when press quenching. After the blade is cooled below 800-900F, the Martensite formation is guaranteed and you can remove the blade from the packet and do whatever you want to it. I have straightened many blades using this technique.

As for the spine cooling faster and the edge not cooling fast enough, well, that's just not true. The spine acts as a heat sink, and does indeed draw heat from the edge. Yes, the edges will still be warm when the spine is cool, but, the cooling rate is far in excess of that of still air. You're not going to get any type of differential hardening regardless of how you quench-the whole blade will be the same hardness. And, you can always hit the edges with some compressed air while the blade is still in the foil if you're worried about the edges.

Rashid11: You can always put some standoffs on your lower plate that will prevent the upper plate from tipping if you stand on it. I always stand on the upper plate.

RJ Martin
 
The key to milling an integral on yer mini mill is modesty. Don't try to hog away metal, do it in max of 40 thou per pass, with 1/2 carbide end mill.
Keep that bar square till the last second - this is how you can chuck it up
with min hassle.

Use cutting oil every now and then.

With a "typical" machinist vise : 4" wide jaws, you mill in two passes:

- first the handle area. Get trusty parallels out, right height, so that metal sticks out may 5 thou more than what you intend to remove. You want to grab that bar securely. Do one side of tang/handle, flip over, do the other

- now chuck up the blade area. Reduce to whateve thickness, same way, flipping over when necessary.

- here's a bit of know-how: use the finger-guard protrusion to yer advantage. For the width of that protrusion,
DONT mill out in the blade area. It will be later cut off anyway, so you don't have to mill it. But MOST importantly,
if you leave a 1/4" wide strip of flat metal there, you can use it as reference plane later on, when you need to chuck up
the OTHER side of the blade area AND it will leave more metal for the chuck to hold on to.

Ideally, if money is not an issue, I'd mill an integral out of bar that is wide enough to leave such 1/4 - 1/8 wide
strip on both sides. But that would mean you'd have to pay $15-20 extra for the metal that ends up in trash later
on. Your call. 1 1/2" wide is all you need for 9" chute integral.



- while it is still square, mill the strap hole in the buttstock. Chain drill with
whatever undersize drill bit and then mill out.

- while it is still square, I'd drill the handle holes. You can always do it later.

Now it is BS time. Handle will have the thicker material so it will be tougher to cut. When cutting the blade area, use a piece of scrap metal/plastic, of right thickness, to keep it level.

With integral, you only have one chance to get it right, so back off the 60 grit
hogging and go with a hand file shaping bolsters and buttstock.

Special attention to the blade right by bolster area. I recommend hand file
and sandpaper. DONT use the belt there, it is real ez to taper or divot there
and then you'd be in the world of pain. :eek:
 
Thanks RJ. Interesting, and makes sense. You arn't supposed to quench in still air, but rather forced air. What is the advantage to quenching with the plate, as opposed to t fiorced air? Mike
 
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