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I Forge Iron

Keep bending my slitter

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This is frustrating!

I made a slitter to slit a 1/4" hole, with the idea to drift the hole to 1/4" so i can hot fit the 1/4"" square stock for this project im planning to build.

But the darn slitter keeps bending on me. 

Im cutting into 3/8ths square stock. I get the steel plenty hot to do the cuts with, but every attempt just leaves me with a slitter that i need to redress. 

I made the slitter out of an old chisel, and the chisel is 1/4". I hardened and tempered it, yet with every attempt i try in learning how to slit and drift, the slitter bends. 

In the picture you can see my new start, and after the second strike the slitter bent.

Is the slitter to small for this idea of a project?


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Small tooling heats up and softens *fast* when being punched into orange+ hot steel.  I would advise using one of the high alloy tool steels that has a tempering temperature in the glowing range---like H-13 or S-7; much harder to work in making the tool; but well made tools don't have the issues you are seeing.

Other wise: take one hit-quench, one hit-quench....  Work fast and clean and minimize the amount of time the tool and work piece are touching.

Note you don't quench the high alloy steel tools in use, let them air cool after you are done.

I've generally gotten my high alloy steels for tooling at Quad-State where folks who have run across a supply as scrap/drops have sold it on cheap!

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Are you cutting straight onto your anvil face? If so, it may help to have a mild steel cutting block under your piece so the tip isn't getting pushed onto hardened steel. It may also protect the face of your anvil if your slitter is still pretty hard when it makes its way through.

That being said, just looking at the temper colors in the tip, it was definitely pretty hot and needs to be cooled much more often like TP said. If you're using spring steel for your tools, just make sure the tip isn't red hot (it happens) when you quench it to avoid potential cracking (...it happens :ph34r:).

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Good point about making sure it's not above critical when quenching to cool!   Blacksmithing is very much a "hurry up and wait" set of processes and when you are starting out it's particularly hard to get the "hurry" working right. 

If you watch some Pro's you will sometimes see that the hot workpiece doesn't even touch the anvil until the hammer is already on it's way down to hit it.  The first hit when the workpiece is hottest you also get the most bang for your buck to a tentative "tap" wastes that golden moment. 

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