Gary,

I personally dont hot cut. I saw and grind and restack.

I leave the individual pieces as thick as I can and still get the billet in the forge door. This requires longer and very thorough soaks, but that's ok to me. Gives me time to think. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />

One very important thing to do is to get the bar a uniform thickness and width down it's entire length. I also lightly etch the ends of the individual pieces and orient them in the stack to keep the layering balanced. The time it takes to saw and restack allows me to check the innards of the billet and make any adjustments as I go.

The reason I started doing this was because my power hammer dies were not exactly set parallel and this would twist the pattern within the billet. I have since corrected that problem, but it taught me that that just because the outside is straight and flat dont mean the inside runs square with the world.

|quoted:

Gary,

I personally dont hot cut. I saw and grind and restack.

I leave the individual pieces as thick as I can and still get the billet in the forge door. This requires longer and very thorough soaks, but that's ok to me. Gives me time to think. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />

One very important thing to do is to get the bar a uniform thickness and width down it's entire length. I also lightly etch the ends of the individual pieces and orient them in the stack to keep the layering balanced. The time it takes to saw and restack allows me to check the innards of the billet and make any adjustments as I go.

The reason I started doing this was because my power hammer dies were not exactly set parallel and this would twist the pattern within the billet. I have since corrected that problem, but it taught me that that just because the outside is straight and flat dont mean the inside runs square with the world.

Thanks, Lin. I appreciate the input.

Gary

Gary I do the same as Lin with the cut and stack. One reason is that I can add things to the stack such as more 15N20 or a different layer count piece, sort of like a san mai. I have also had some bad weld issues with folding.

I am somewaht limited with a smaller power hammer on size of billets, but I usually get mine down to about 3/8" thick and then grind, cut, and stack. Then usually four pieces stacked. The length is around twelve to fifteen inches with a drawn out billet.

Brion

Thanks Brion,

I guess that I hot cut & fold mainly to be able to continue working the billet without the waiting time but I can see the advantages of cut & stack. I seem to have eliminated most failures since I started grinding down to clean steel each time rather than just brushing off the scale.

Gary

G'day All

I also cut and grind, I have found it helps eliminate lots of problems. Also with many mosaic patterns you will be working with square bare and reorienting so hot cutting is not really an option.

If I am just building up a layer count, say for random or ladder patterns, I will work hot the whole time. Final pass is big flat dies in the press, turn it on edge and give it a light squeeze, this helps pop scale off the surface you will grind. You can do the same with light passes on a hammer. Then into the vice and a 9 inch angle grinder, hot scale seems to come off easier. I then go to a 7 inch and use a 120 grit flap disc to smooth the surface. You can very clearly see the heavy grind marks and I make sure they are all gone. I also make sure the billet is ever so slightly convex. With these billets I only fold in half. I have found it is faster for me to do an extra weld or two than to draw out a long billet, clean both sides, make 3 or 4 cuts and re-stack. I cut with a chop saw and a good quality thin cutting disc. I cut and fold opposite side each weld. Tack both ends with the welder and back in. The billet is probably 6 or 7 hundred degrees when it goes back in the forge. And since you should never assume anything, I am NOT kerosene welding with a hot billet, this is old school borax welding which is why I mentioned a convex billet.

With mosaic patterns that is a different story. I am often working square bars, lots of reorientation, shims, and different pattern combinations. You really have to let everything cool, grind all mating surfaces, and then etch the bars to make sure it is all going the right way.(and then you can still shank it)

Cheers

Shawn

Gary,

I too, do a kerosene weld on the initial stack of steels and then cut, grind and stack the billet pieces. After the initial weld with kerosene, I usually put a little borax on the billet and do another welding pass. I do this just in case the layers didn't completely weld at the edges. In doing the restacks, I mig weld the edges of the billet pieces for a dry weld. I started doing this as a bit of insurance that the welds would be clean of any slag inclusions. Although, I have to admit that I seldom had a problem with slag inclusions when I did hot folds.

I like to make all welds in the trip-hammer. I feel that I can get the welds closed up quicker with the hammer and not risk losing welding heat; vs. using the hydraulic press. I always make the first welding pass by inserting the billet into the hammer dies lengthwise first, (long ways to the dies)hammering in the center of the billet and then moving sideways across the width of the billet. This first close of the welds I do with as much impact as can be applied without moving a lot of the billet material. I'll then reheat the billet and do another welding pass through the hammer dies with the billet inserted width wise through the dies. Again, starting in the center of the billet and then working end to end of the billet.

I have a set of fairly "strong" drawing dies for the hammer that I use for damascus welding and drawing out. I ground this set of dies especially for making W-pattern damascus. I don't like to have the W-pattern billets widen too much during drawing out. If you have to hammer a W-pattern billet on the edges to narrow it, it tends to straighten the layers back up and reduces the bow in the layers that create the pattern.

As Lin mentioned, when doing restacked billets, you want the pieces to be as flat and uniform as possible. After drawing the billet out in the hammer to about the thickness that I want to billet to wind up, I go to the hydraulic press. With drawing dies in the press (again to minimize making the billet wider) I place shims between the dies to stop the press at the thickness that I want the billet to be. I'll press the billet its full length with the drawing dies, then switch to flat dies and the same shims to press the billet flat. I then straighten the billet on the anvil to minimize material loss when grinding and restacking.

Going back to your original question about how long to draw the billet out to before folding, or restacking; I always try to keep the amount of area to be welded to a minimum. The limiting factor to this is the size of your forge doors, or what your hammer can handle efficiently. If I am going to restack the billet, I usually plan to draw the billet out so that the pieces will wind up roughly square when cut.

My forge doors are five inches tall, so I could insert a very tall billet into it, but I prefer to keep the billet no taller than 2 1/2 to 3 inches. If making a large billet of damascus, I will often draw the billet out to 3/4" thick. 3/4" pieces in a four stack make 3 inches. I tend to be a bit lazy about adjusting the height of my hammer dies, so often my hammer does the Little Giant Hoola until I get the billet pounded down to a height that the hammer can run properly. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />

Thanks, Steve. I appreciate the insight. I am about to make some drawing dies for my press and would appreciate any thoughts on design.

Thanks,

Gary

I've got one of Uncle Al's presses. I used pieces of 1 inch thick by 2 inch wide mild steel for the dies. I cut the pieces of steel 5 inches long. Then just rolled off the front and back edges on the belt grinder. The dies are only radiused about 3/16". I left a flat area about 1 1/4" wide on each end of the drawing dies so I could place shims there to control how close the dies closed. So, the area that is radiused for drawing is only about 2 1/2" wide. I would consider using longer pieces of steel for the next set of dies that I make. Sometimes, they are almost too narrow in the drawing area for the size of billet I am making. I'll try to take a photo of my dies and post it up here.

I'm in full agreement with everyone else about grinding/cutting/stacking versus hot cut/folding.

In my early years, I did a lot of hot cut/folding, and the results were about a 50% success rate (without cold shuts/inclusion/delaminations). As I gained more experience, and got tired of all the failures, I switched to grinding, cutting, stacking. Just by doing that it increased my success rate to around 90+%. Since then one "trick" that I have found is when grinding (I use and angle grinder) grind in such a way that the scratch pattern from the grinder goes across the bar (edge to edge) and on the last pass or two with the angle grinder, "scarf" the edges of the billet/bar. This gives flux and crud an escape path, and since learning/doing that, my success rate has been near 100%.

My "drawing" dies are also made of flat bar stock....mine are 1 1/2" wide X 3/4" thick. Remember that with a press, the more square inches of die surface making contact with the work piece, the less force you exert. One of the biggest mistakes that most folks make with a press is trying to do too much at a time....take "little bites". It might take an extra heat or two to get the job done, but you're not "chasing" a billet all over the place, trying to straighten it out. Normally, I try not to take more than about 1/4"-1/2" "bites" when using the press. The finer/closer to finish, the less depth of "bite".

Thanks for the tips, Ed. It's threads like this that certainly shorten the learning curve. It sounds like you use borax and not kerosine. When you cut & stack, do you anneal the billet after each weld or do you grind & cut shortly after welding?

Gary

When I'm "gett'in after it" I just let the billet cool enough that I can handle it with welding gloves on.....then grind, cut, and restack......then go to welding again. Most of the time I do use anhydrous borax, but also do use kerosene or diesel if the situation dictates/allows. Most often I do not anneal until after all the welds are completed.

|quoted:

When I'm "gett'in after it" I just let the billet cool enough that I can handle it with welding gloves on.....then grind, cut, and restack......then go to welding again. Most of the time I do use anhydrous borax, but also do use kerosene or diesel if the situation dictates/allows. Most often I do not anneal until after all the welds are completed.

Thanks, Ed.

Gary

I don’t anneal before cutting and restacking either. I’ve never had a problem cutting the billet.

I agree with Ed on the hydraulic press advice. A little at a time. I usually don’t reduce the thickness of the billet more than 1/8 “. And small “bites”; as Ed said.

Gary,

Though it seems like "no one hot cuts", when I first got interested in O1/L6 damascus the interest came from following Kevin Cashen around on the knife forums. In amongst his metallurgy discussions he talked about hot cutting for this metal combination because it, in part, alleviates the air hardening problems easier than the things a person needs to do to let it come to room temp. I don't recall Kevin pointing out a prohibition on billet length... not that he doesn't have a way of dealing with it... but I feel he would have said something if he had found downsides to "too long" or "too short".

So you've heard it, Joel Davis makes some very intricate damascus and he hot grinds/cuts/welds as much as he can... uses a coarse grinding cup, rips the scale off, and slams it back together. Like everything, it's in how and what a person does that makes it or breaks it.

Mike