Tension wrenchs brake all the time

[alyks]

Hi, I followed pyro's video on making picks and tried to make a tension wrench following his instructions. I found some carbon steel blades, heated until white hot with propane, and bent under the flame and rapidly cooled in water. The problem is that when I go to use them, they bend when I apply tension with them. Making them ineffective, and then they brake after enough use. What am I doing wrong?

[Gordon Airporte]

What am I doing wrong?

I'm going to say using hacksaw blade for wrenches. Try windshield wiper strips first. You can bend those without messing with the properties of the metal. Keep the hacksaw for picks.
If you want to keep at it with hacksaw blade, check out this page which explains what happens with various kinds of heat treatment.
http://jchemed.chem.wisc.edu/JCESoft/CC ... /CD2R1.HTM

[alyks]

Thanks

[undeadspacehippie]

If you find that your wiper blades are twisting a bit, put some small twists in them. I wish I had a cam to post some pics of what I am talking about. What type of hacksaw blades are being used? - Try bimetal blades - you may be able to make a tension bar out of them. I use wiper blades solely for my tension bars now.

[undeadspacehippie]

If you find that your wiper blades are twisting a bit, put some small twists in them. I wish I had a cam to post some pics of what I am talking about. What type of hacksaw blades are being used? - Try bimetal blades - you may be able to make a tension bar out of them. I use wiper blades solely for my tension bars now.

[alyks]

I'm making them out of carbon steel, but I also made one with bi-metal. They both bend. I'm going to go pick up some wiper blades tommorow.

[darrel.h]

You should "quench" the heated wrench into cooling oil instead of water because it adds more carbon into the steel.

[unbreakable]

heated until white hot with propane

I don't think You're suppossed to heat them to be white hot, only to red. Anyone here who can back me up on this?

Personally, I prefer wiper blades, but getting tem can be an issue.


Unbreakble

[darrel.h]

Yes, Unbreakable is right. You should only heat them tilll they turn cherry red. If you heat them till they are white hot, it will destroy the metal's properties. Also, how did you get it white hot? I don't think propane torches get that hot. Correct me if I am wrong but it would have been an odd 2000 degrees to turn steel white hot.

[anders]

Hello,
If you use sawblades, you can let them cool a bit before quenching them in water/oil/whatever you are quenching in.
That will make the material less brittle, I suspect it depends on what kind of blades you use how much you need to let them cool

/Anders

[skedone]

wiper blades mate its easy just go to your local car breakers/scrap yard and ask them if it okay to grab some, they will all say its okay the have no value to them thats what i do i pick up a good 100plus inserts at a time

[horsefeathers]

just gotta ask........how the hell do you break a tension wrench?

Just how much tension are you putting on the lock for it to break? I have never even come close to breaking one, not even bending out of shape. Whether homemade or professionally manufactured ones, they should deal with the amount of tension required to open most locks (comnined with correct picking techinque of course). I suggest you are using way too much tension to be successful.

just IMO

regards

[Shrub]

You should "quench" the heated wrench into cooling oil instead of water because it adds more carbon into the steel.

No it doesnt,

You cant heat your steel to white hot the material will not allow it to get that hot,



I have written this many many times in both long and shrt versions but heres a quick short one,

If you want to use hacksaw blades as wrench's you need to anneal them afterwards, this takes the brittleness out of them and any stress youve put into them,

Shape your blade to the size and shape you want, dont worry about getting it to hot in this case,

Take your blade and rub it down until its shiney,

Heat it up until its as brighter red as you can but dont use acetalene use propane,

Bend to your required shape,

Quench asap in cold cleen water,

Dry the blade then polish back to shiney,

Gently and careully reheat the blade under low heat until it goes a straw colour (dark yellow at most),

Quench in cold clean water asap,

Polish your wrench and your away,

[TAMUmpower]

Hardened allen wrenches are indestructable. I have a friend who works at Toys R Us in the assembly dept. Every bike and swingset comes with a new allen wrench set. Over the course of a week he collected about 500 and gave them to me.

If you go up to one of their stores Im sure you could pick up a bunch for free.

[Varjeal]

I agree with others on the amount of tension as well. If your busting a lot of tension wrenches you are using wayyyyyy too much tension regardless of the temperature your heating the tools to. I would suggest purchasing a few mfg'd ones to see how they compare to your homemade ones. If you find the durability is about the same, then its your picking technique that needs to be adjusted more than your pick-making technique.

Good points all about tempering though.