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My first 90 degree flex test

D

DaQo'tah Forge

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Aug 26, 2002
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Hi this is Daqo'tah

I have always heard that in order to make sure my blades are true High Performance that you have to do something called a flex test.

Well, I didn't think I ever would do a flex test, I mean, the very idea of making a nice cutting blade, then just sticking the point into the jaws of a vice and bending the knife to see if it will snap? Well, I just didn't think I would ever do it.

Then this week I have been working on a new 5160 blade, when after the 3 heat treatments and 3 temperings, I noticed a flaw in the steel. There was this little spot, a pin sized dip in the surface of the steel.

I knew it would take me hours to sand the blade down to the spot, and even if I did that, there no telling if the spot goes deeper.

I was about to toss out the blade when I remembered Ed Fowlers words about the need to test my steel

So I flexed it to 90 degrees no problem, the only trick was that the pipe I put over the blade to push down on, kept slipping up the blade,,,,well that,
and the fact that I had to work around one of my cats that kept examining all the details of how the flex test was going...


I hope this link works for my photos-

http://eastof29.tripod.com/daqotahforge2/id31.html
 
Congrat's DaQo'tah! Did the edge crack? Did you try bending it the other direction to see it she'd go 180? Maybe you don't want to completely ruin her, judging by the pic's you have a great knife for cutting corners:D

Rick
 
Hi Rick, this is DaQo'tah

this was a knife blade that I had all set to start placeing the guard on, when I noticed the flaw on the blade.

I had it very, very sharp.,,,now when I flexed it, the pipe rubbed the sharpened edge over for about one inch....but there are no cracks.

as for going to 180?..
perhaps next time, I have to get a different pipe to place over the blade.

The pipe I used this first time was not actually wide enough to fit over the knife at the widest part of the blade.

also, I had some trouble keeping the pipe in one place as I pulled down on it. The pipe kept wanting to slide near the tang.

when I got it flexed to 90 I was worried that the pipe would pop off , and Im not sure if that would have hurt or not...LOL

anyway, I was pleased to see that there is no sign at all of any cracks, and that the blade did what I wanted it to to,,,,

But I must admit,,,as I placed the pipe over the steel and put my weight on it...I thought it was going to snap!

But, the 3 heat treatments and temperings did the trick....
 
Don't suppose you did any cutting tests? Could you straighten her out and see how she cuts?

Rick
 
I think that your supposed to put the blade in the vise and put the pipe on over the tang of the knife. But it worked either way, congrats. You just passed part of the ABS JS test, too bad you didn't do any cutting tests first.
 
Dag DaQo, you made a real nice looking Persian out of it (or is the cat a Persian?).

Roger
 
cutting?

oh, I never ,,,,oh well,,,I want to keep the knife all bent to show the guys at work,,,so I dont think I can still cut with it due to the curve. I dont have any of that type of rope you guys use to make cutting test yet anyway...

I have a question about how to flex the blade. I will tell you what I did, you tell me what to change next time.

I put two chunks of thin plywood in the vice.
Then I stuck the tip of the blade between them. I sank the blade down about 2 inches.
then I placed the pipe over the tang, and moved it down the blade untill it stuck about one or two inches above the vice. The wide belly of the blade is wider than the pipe is so I could not sink the pipe all the way down to the vice.

the pipe was about 4 feet long, and I slowly lowered it untill I knew I was past 90.degress

The pipe wanted to slip up the blade, I had to fight to keep the pipe down close to the vice. had to stop a few times to reset the pipe.


When I let off, the blade sprang the pipe back up..I pulled down on the pipe one more time to make sure it was a good test. This time I didnt try to push the pipe down, and I seem to have flexed more of the Tang/blade joint this time
 
DaQuoTah: Congradulations! I was hoping to see a post like this comming from you. You have taken a serious step in your quest for knives that can be counted on.
Take Care
 
DaQuoTah, Contrats, Its tests like this that gives you the confidence in your blades to make sales. Next time do some cutting tests first. The ABS test requires the blade to be at least 10" long. The knife must cut one free hanging rope that is 1" dia.with one swipe and cut a construction grade 2x4 in half 2 times by crude chopping, next shave arm hair and finally bend to 90 deg with 1/3 of the blade clamped in the vice and the pipe over the handle. Do this and you make the Journeyman Smith performance requirements. Keep it up and thanks for the post. Have you joined the ABS yet? If not start now, time flys
 
Hi this is DaQo'tah

I do etch all the blades I have made so far,,I do this because I want to know for myself that each blade I make is my best.

,but I dont do an etching well yet...I first would take the etched blade to my buffer, but I seemed to buff the etched finish right off the blade.

next the forum guys said to just use a Metal Polishing compound, so I went to the car place and got some Turtle Wax stuff

well,,,thats really has not worked out yet for me as well.

I do yet see a dim etch in my flexed blade..but nothing my printer/scanner that I use to post photos could ever pick up.

,,,the other thing is,,,,,that when I show a etched blade to my co-workers, they all ask "When will it be done?"...something about the look of my etched blades just seems "Not finished yet"

so far what I have done is that after I finish the blade, and Im happy, (more or less) with the knife, I buff the blade untill its like a mirror,,,,thats what people seem to like to see.

when I made my very first knife a few months ago, I was so happy with it, I sure thought it was darn good....now as I finish each knife, I keep noticeing more and more flaws with my early blades...


Now the next time that I end up with a blade for flex testing, I will be ready,,,I will do the cutting tests first, and take real photos of each step for my website.
 
Good job DaQo'tah,

Something that may help with your etch, I use about 4-5 to 1 water to ferric cloride(archer etchant), clean blade with soap and water and hold by the tange and while still wet with clean water submerge in the solution. I take it out after about five minits and wet sand with 1500 grit paper. I do this three or four times till I get the depth I want then go to the buffer and use a loose wheel with some pink no scracth compound to brighten everything up. I should mention that the blade was hand rubed to 600 grit, not buffed, before etch.

I like an etched finish for anougther reason, it doesnt' show pattina as well as a highly polished blade.:D
 
will52100

I have a question about buffing.

lets say I have some of that pink stuff

how do you use it?
, I have never really had a buffing lesson,,,I just ram that stuff into the spinning buffer..but I never know how much to do?..

then how do you buff with it?

do you press the blade into the buffer very hard,,?

do you go all one way?

do you use water?
 
The way I buff out the etch is to use a loose buff, and be very carefull as a loose buff will grab a blade a lot faster than a sewn buff.

I've use pink and white compound befor, the trick is to use just a little and go real light with the buff, or you'll be re-etching, like you said it dosnt' take much buffing to wipe the etch out. A trick Bruce Evans showed me is that after loading the compound on the wheel give it a spray of WD-40, this will help lub the compound and keep the black deposits down.

I usaly go every which way I can while buffing, but always buff the trailing edge,(the part of the blade faceing the direction of wheel travel) keeping the leading edge(the part of the blade faceing into the wheel travel) off the buff slightly to keep it from grabing. I just make a light pass down both sides turn the blade around and repeat, then go longways. Wipe clean with a rag and some WD-40, inspect and usally don't have to buff again. Final clean up for me is a soft nylon brush and hot water in the sink with some Dawn dish washing detergent.

You can buff till you only have a shadow of a temper line, or you can leave most of the grain flow that showes up, the look is up to you. And don't forget, practice practice practice!:D You can also hand rub to a real fine 600 grit and the harnded part of the blade will show up in the light.

Oh yea, I use an 8" buff on a 1/3 horse 1700rpm motor with a double ended pillow block bearing for my buffer set-up. I like the low horse motor because I can bog it down most times with out throuwing something. The faster your motor turns the smaller diameter the buffer wheel needs to be. An 8" is pushing the upper limit for me with a 1700 rpm., some like a real fast buff, but that's getting to dangerous for me.

Hope this helps

Will

Almost forgot, I spray the blade down with Windex after etching, to nutrolize the feric. Also while washing with soap and water after the etch I use a small hand full of bakeing soada to help nutrolize the acid also.
 
WD40! I never tried it but it sounds like a great idea! I'm gonna try it.I've picked up a couple of really good ideas here today. I use hard wheels mostly and at most a half HP motor.I get less grabbing that way.
 
Hey Will, You mentioned that you hand rub a 600 grit finish on the blade prior to etching. Do you know if a mirror polished blade would have a different look when etched than a 600 grit hand rubbed finish?

Rick
 
The only way I've been able to get a good etch with a mirror polish is to dunk for a couple of minits, rub the whole blade with 1000 grit and then etch as normal. The etch seems to work best with an open surface, I've taken blades to a mirror polish and then etched, but it tends to come out blochy if left very long. One thing I've done is to give it a mirror polish and then go back with 600 grit and lightly sand everything. I've noticed that a good etch will wipe out shallow 600 grit scratches.
 
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