EDL

I understand that closing up a billet doesn't require "pushing" stuff out, that is precisely the point. Who's arguing? I'm sorry we don't see eye to eye concerning theory and science. I think you are incorrectly judging me in this respect. I'm just trying to discuss, but you seem to be intimating that theory of solid state welding is wrong, or that certain procedures in its pursuit are wrong and all I've asked for is clarification, but whatever. I won't be "doing it" until spring, so I guess I should I just shut up, avoid those evil "theories" and not ask questions here or try to learn by discussion until then. Got it.

Before I would even consider a hammer though, I have to measure how thick the slab is where I would put it. My house and the original rectangle barn were built in 1900. The main barn is 2-story with wood floor above dirt (and the dang ground hogs love tunneling under it). The floor boards are nice wide, old timber, around 14" to 20" wide and about 3" thick. To the right side is a narrow room with some stalls that appear to have been used for milking cattle. The next room over, which was added at some point, is a large tack room which then opens out to 9 horse stalls (the previous owners owned and raised some kind of special Spanish show horses). At some point (in the 1950's I was told) a slab was poured almost the full width of the back and on the left side, like a big "L" shape and the entire barn added on to. There is a 2-bedroom apartment up in the back. Under the apartment, and to the far right of the slab, is an open area that has the hook ups for a washer and dryer and a small bathroom. To the left of that room is a 1-car garage that currently houses some shelving and my utility trailer. Moving left again is another room that is currently my woodworking room with a heavy bench I built along one wall and I'm putting up a french cleat wall on the other side. My tool boxes and woodworking tools reside there. And, off to the left of that is yet another room that is designated to become the "metal room." It's around 22 feet wide and about 25 feet long (about half the slab on the left side of the barn). Toward the front of the barn and in front of that room the slab is raised about a foot and a half (the entire barn sits kind of on the edge of a small hill). This room has wide bi-fold doors and is where I store my tractor and race boat on its trailer. The slab along the back side and to the far right is about 12" thick. I suspect it is thinner in the room I am using for the metal working stuff because of the slight grade, but I need to confirm that. I can't use the room to the far right since it is under part of the apartment upstairs, the ceiling height is too low for machines like a hammer or press. I really wanted to remove the horse stalls, since we don't have horses (and no plans for any), and use that area with its nice hard pack dirt floor, but the wife said "No!." If I am to get or make a hammer, I'm not going for a big heavy one (I don't want to have to do the isolation block thing). I need to see if a light hammer would be ok on say, some heavy timbers, like railroad ties or similar, without damaging the slab. Anyway, check out this guy's video and see his hammer. It looks pretty light, I don't know the hammer weight, but I could ask, he's responded to some questions in the past. Anyway, something along this line and even what he uses it for is what I'd be interested in. Jump to about 7:40 into the video to see it in use:

Yeah, I'm not too crazy about his set up of having to step on the pedal for each blow. I'll have a look at the pettingell hammers.

Personally, I see nothing wrong with theory if it helps to understand the process. I've never been one to simply accept "do it this way because it works", I like to understand the reasons behind it as well. Your comment "... when the layers in the billets are cambered properly..." is interesting to me because I've never witnessed, nor heard, that billet layers need to be or should be cambered. Every example I've ever seen where a billet is stacked and tacked, the billet is clamped tightly in a vice. I've also seen examples where thin material is welded to the edges to prevent oxygen from getting between the layers to prevent oxidation and scale.

I'm just thinking from the lighter end of things for planishing and smoothing. I'd probably love a heavy hitting hammer, but as I've learned from reading other sections, that gets into all sorts of modifications to concrete slabs to create thick isolation blocks and then there's the consideration of motor HP needed to power them. I am limited in that sense and have no desire to start cutting into concrete and building an isolation block. Since I have no intention of becoming a business, I think a converted log splitter for a press and a light hammer (at some point a couple years down the road maybe, definitely not right away) might be the way to go. To get going, my main focus is building a forge, finding a suitable chunk of steel to use as an anvil, a pair or two of tongs and a hammer or two and then practice and learn the basics. "Power" tools for forging won't even be considered until I am ready for them, but since I won't be building the forge until spring, I have time now to just sit, read, and delve into other subjects as well. Looking into all these kinds of tools is strictly a mental exercise at this point. It appears from his video he can control the power of the hit, but it seems sketchy at best, very fiddly or touchy as he tries to feather the pedal. Heck, for what "I" would want a power hammer for, a treadle hammer might be plenty good enough, certainly simpler and cheaper to make.

Well, as someone who doesn't even have a forge yet, I can't make any claims one way or the other, but that doesn't stop me from learning the science behind it. The term "diffusion bonding" or "diffusion welding" seems to be terms used throughout many industries, and all seem to agree that "fusion" welding is the term to describe melting of the metals in order for them to fuse. Diffusion welding (diffusion bonding and solid state welding) may or may not include heat and if heat is used, is done at temperatures lower than the melting point of the metals involved. The term is found in many, many sources, even including some encyclopedias and such, so I have no reason to think it is any sort of misnomer or that applying heat or not disqualifies the process as "forge welding" is specifically defined as using heat for the process and that it is considered a "solid state" welding process. However, I have seen videos of a smith heating mild steel to the point the surface is, in fact, liquid and can clearly be seen flowing on the surface of the piece. He then takes the two pieces and sticks them together. Without any hammer blows the pieces bond, even if weakly, due to the liquid surface melt. I am not suggesting that this is the "proper" way to forge weld, just that I have seen that. Perhaps in forge welds in the shop sometimes a "liquidus" form of steel is there if heated enough, but by all apparent definitions and process descriptions that I can find, forge welding is supposed to be a "solid state" weld. And Steve, while your referenced definition of the term "diffusion" is technically correct, it is not the only definition. Dictionary.com's definition includes: 3. Physics: a. Also called "migration." An intermingling of molecules, ions, etc., resulting from random thermal agitation, as in the dispersion of a vapor in air. I think "diffusion" is an apt description of "solid state" welding as the molecules or ions of the metals migrate into each other.

What about for planishing type work, say after beating out a PW billet? Making the final billet "smooth" and even, or maybe flattening after drilling it for rain drop pattern?

So, if I understand correctly, setting the weld on a PW billet with a press, you do it in sections, not the entire billet under a die that is larger than the entire billet? I understand not mashing too far so as splay open the end, easy does it. I like the toothpaste tube analogy, that makes sense. Did some reading and found there are two basic categories of weld, fusion and diffusion. Fusion welding is when the metals are melted at the weld area, such as with common welding machines like stick, TIG, MIG, etc. Diffusion welding is a "solid state" process. The metals are heated to a temperature lower than the melting point and then pressed together forming the weld. A couple other forms of solid state or diffusion welding, besides forge welding, is cold welding and explosion welding. Many metals can be forge welded, with the most common being both high and low-carbon steels. Iron and even some hypoeutectic cast-irons can be forge welded. Some aluminum alloys can also be forge welded. Metals such as copper, bronze and brass do not forge weld readily. Although it is possible to forge weld copper-based alloys, it is often with great difficulty due to copper's tendency to absorb oxygen during the heating. Copper and its alloys are usually better joined with cold welding, explosion welding, or other pressure-welding techniques. With iron or steel, the presence of even small amounts of copper severely reduces the alloy's ability to forge weld. Titanium alloys are commonly forge welded. Because of titanium's tendency to absorb oxygen when molten, the solid-state, diffusion bond of a forge weld is often stronger than a fusion weld in which the metal is liquefied. This certainly explains why titanium is so hard to work with in industry (thinking of the issues Lockheed had back when they were first using titanium on the SR-71). Forge welding between similar materials is caused by solid-state diffusion. This results in a weld that consists of only the welded materials without any fillers or bridging materials. Forge welding between dissimilar materials is caused by the formation of a lower melting temperature eutectic between the materials. Due to this the weld is often stronger than the individual metals. Interesting that the forge welds can be stronger than the base metals themselves. All in all, very cool.

Right, I get that, but I was wondering how using a press affects evacuating the flux like light hammer taps do. In my mind I picture it kinda of like keeping air bubbles out from under a decal when applying it. If you press it on in small sections at a time (similar to a hammer tapping on the billet) you get less trapped air and bubbles than trying to pres the entire decal on all at once (like using a press) and end up with bubbles all over it. Does that make sense?

Much reading and video watching on PW billet making leaves a question.... I've read and heard in videos that to set a pattern welded billet (when using borax flux and a hand hammer) to always give firm taps on the first heat and not to go all out pounding as this serves to squeeze out the flux so it carries impurities and scale with it. However, I've also seen plenty of smiths take their heavily fluxed billets and stick them in a press and just smash them down. Wouldn't just mashing a billet in a press like that have the potential to trap flux between the layers and create blisters or bad welds? Is one method really the best to go, or does it really matter?

Yeah, I thought that was strange. I know there are devices that will auto cycle it, but I guess he likes it. Very compact, but I don't know, I can see that air cylinder failing in pretty quick order.

Saw this on YT. Interesting, but I don't think that air cylinder is going to last long.

Aha, Oil Valley Blacksmiths Association. Found them in an article of the Titusvile Herald. Titusville is only about 30 mins north of me. It seems they go up there to do demonstrations once a month during spring/summer. All three of the towns you mention above are within 30 minutes to maybe a little over an hour from me. They don't have a website though. Hmm, I'm an IT guy by profession and I've done plenty of web work. Maybe they might want one!

Steve, the ones I looked at are designed specifically for the beginner or someone that has never forged previously...or so they say. It sounded good, but as I think about it, a day or two is an awfully short time frame to produce a knife, especially for someone that has never done it before. I'll pass on it for now. I'm just going to have to be patient and wait for spring unless I manage to get with a group in my local area over the winter.

Good points. I didn't think of any associations, so I did find the PABA website. I may just contact them and perhaps a smith locally might be willing to spend some time with me.