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Twisting a Damascus Billet for Knife Making?


AidenCC

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        Recently I created my first two pattern welded billets and everything went smoothly, until I tried twisting them to develop patterns in them. For the first billet I started with 3 pieces of 1"x 0.125" x 6" of 1095 alternating with 2 pieces of 15n20 of the same size and for the second billet I used 3 pieces of each steel. I folded the first billet twice and then twisted it about 720˚ before pounding it flat and shaping a blade out of it. I folded the second billet five times and, then broke the corners (one tip I could find online) and twisted it somewhere around 1080˚.

 

      Immediately after beating the bars back to square I couldn't see any cold shuts, but after forming them into blades cracks started opening up in them that I couldn't close by welding and the final knives have ugly, heart-wrenching, inclusions. Since I couldn't find much detail or in depth explanation about making a twist pattern, I was wondering if anyone here knows what I did wrong or could offer advice about twisting pattern welded billets. I did all the work with a coke forge and fluxed the billet/worked at welding heat while beating it back to square (but not while twisting) if that matters.

 

     Also, as a side note, I was planning on making my next billet a random pattern, to keep it simpler and make a functional blade, and was wondering if 394 layers would be enough for an interesting pattern.

 

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I ground the mill scale off the starting pieces for both, but only ground between folds for the first billet. I did the first 2-3 heats after each weld at welding temp only and with flux, but while drawing out I worked them below welding temp. Every few folds I ground off part of the sides of the billets and checked for bad welds but didn't see any until after twisting.

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Does something happen to the layers when you twist them too cold? The inclusions seemed like they came from cold shuts between the high-points made by twisting because they were relatively shallow but couldn't be ground out because they spiraled around the finished pieces.

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Posted Today, 04:02 AM

"Did you cut each billet and grind all the sides that would mate to be welded? or did you fold and let junk stay inside,,/llike scale? Did you do every thing on the billets at welding heat with  flux?"

 

I learrned long ago that there aer no short cuts on this process......And after a while yoiu may indeed find a way that works well for you. But in the first answer I posted to youir question I gave you the  tips that work...Then you asked if youi should.  work billet at welding heat.....

Stteve and I have also put a lot of effort into the knfe making lessons on this site and in the advanced lessons we speak about billets...and remember billets are advanced forging..not to get on your case but the information is here if you wish to use  And the shop lets you work through the speed bumps along the way.

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I'll take a look at the knife making lessons and do some experiments to see what part of the process is causing the inclusions (whether they were there before the twist and I couldn't see them, or if the twist caused them). And I'll make sure to use plenty of flux and to grind all the surfaces between folds.

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a twist operation will not add material into a good weld, if you have an inclusion, it was there because you let crud get in there when you welded it up.  a shear can happen, if it was not welded well in the first place, or if the metals have different expansion coefficients. Or if you are too cold. or........

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a twist operation will not add material into a good weld, if you have an inclusion, it was there because you let crud get in there when you welded it up.  a shear can happen, if it was not welded well in the first place, or if the metals have different expansion coefficients. Or if you are too cold. or........

 

From what I can tell, the inclusion happened when I was flattening the twisted billet and several of the ridges got pushed together instead of straight down creating a seam filled with scale which didn't open again until I worked the billet more aggressively while forming the shape of the blade. If I try twists again in the future I'll check for bad welds from the folding before twisting as well to make sure that's not what's happening. I'll also etch and take a closer look at the blades to see if the it looks like any welds sheared while i was twisting. 

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So basically you were pounding a cold shut into it just like regular run of the mill smithing.

 

Really rounding the billet can help prevent this as there are no ridges. Twisting and then grinding smooth can help this as there are no ridges to be pounded into cold shuts.

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So basically you were pounding a cold shut into it just like regular run of the mill smithing.

 

Really rounding the billet can help prevent this as there are no ridges. Twisting and then grinding smooth can help this as there are no ridges to be pounded into cold shuts.

I'll try rounding the billet more instead of just breaking the corners and grinding it smooth after the twist next time. Thanks.

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Some of the suggestions you read above I took a while back and have had great success with twists. Lots of heat and flux for me. If one of those high spots decides to roll over on itself there will be flux in there and it will weld when you flatten it out.....do it cold or without flux and you will have failures. I treat every operation of a twist just like a weld and have good luck! Cheers and have fun!

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One thing to add is to stop when the billet drops below welding heat.If you start twisting at welding heat and keep twisting until you are too cold, the the billet will still fail. It usually takes many heats to twist a billet unless you have a twisting machine. I know you are using coal but in my propane forge, I clamp the billet to the edge of the forge and pass it though to back hole. When at temp I keep it in the forge, attach a wrench and twist while it is still in the forge.  This only works for long billets though. 

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One thing to add is to stop when the billet drops below welding heat.If you start twisting at welding heat and keep twisting until you are too cold, the the billet will still fail. It usually takes many heats to twist a billet unless you have a twisting machine. I know you are using coal but in my propane forge, I clamp the billet to the edge of the forge and pass it though to back hole. When at temp I keep it in the forge, attach a wrench and twist while it is still in the forge.  This only works for long billets though. 

 

 

just for comparison, for a normal billet I get will only  about 1 1/2 twists per heat, and I have been doing this a little while. What is the rush? I have been here this long pounding the billet,  why hurry now and ruin it.

I'll make sure to add taking my time to the list of things to keep in mind while twisting. Is there any benefit to pre-heating the jaws of the vice like you would a die/anvil, or would it be a waste of time?

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Twist  fast is fine, but do not move it  after getting below the welding heat. Also many tool steels have a gap between the range for welding heat and range for forging,  like L6 and O1 if you hit them in the danger zone,  you will mess up the steel.

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