John Larson

Grant, ya know I knew it was a 6, but somehow that 8 showed up in print. :-)

Boy are you right about unhappy customers not returning. I believe you can please people many times but only displease then once. So the Seattle ABANA event being controversial is proving hard to overcome. Even without the Seattle controversy ABANA may have seen membership decline. Personally I am forming the opinion that the crafts movement that seemed to start in the 70's is ebbing. When I look at designer magazines at the news stand I see less iron work than 2-3 years ago. Iron was hot for a long time in high end houses. Colonial Williamsburg is having a tough economic time. When I'm at hammer-ins I see smiths in the audience start to get restive at mid-morning because the stuff being shown isn't new enough--or whatever. Fifteen years ago it seemed that information was a lot harder to obtain. Now we can watch youtube, read many superb books, go to assorted smithing schools, buy new tools on the net, etc. Just seems to be enormously easier and less of an adventure nowadays even for (and maybe especially for) newbies. I still think we have to hang together and ABANA plus our local guilds are the best vehicles. Volunteerism is weird stuff, to be sure. Right now I think Rome and his crew are doing what needs to be done and we gotta give them our support. End of my sermon.

Glenn, I read the message and that is why my post yesterday was worded the way it was. You seemed to think I was doing some advertising for ABANA to avoid them paying you. Nope, not the case. Was just speaking my personal opinion with some rationale offered.

That's what I like to hear, guys. I have no connection to ABANA's marketing efforts. I just spoke as a concerned smith. Glenn edited my post perhaps because he thought otherwise. No matter. Grant, I first saw you at ABANA-Alfed, NY in '96 when the KA-75 was shown and then two years later ABANA-Ashville, NC when you showed off your "8-cylinder JY hammer."

In the past few years Rome Hutchings and the board have done far more than previous folks have, well IMHO anyway, to make ABANA useful. In 6 0r 7 months the big ABANA hammer in takes place in Memphis. Try to make that part of your vacation planning. Every effort is being made to keep your expenses low, in contrast to the Seattle vent 4 or 5 years ago. I personally know three members of the board and they are sincere, hard workers, and want the organization to be a big improvement over where it was a while back. Come and say hello and try out my machines in Memphis.

Houghton and another of my sources speak of a very interesting quenching variation. Namely, quench the steel down to the upper temperature where martensite starts to form from austentite, and then hold that temperature until the whole piece is uniformly at that temp, and then let it air cool to almost ambient before tempering as usual. This prevents the martensite shell on the surface from constricting around the hotter core and thus quench cracking. Takes a pretty hot quench, or second soaking tank of molten metal or salts or whatever to implement, but they claim it is immently practical for manufacturing shops. My stratified approach is simpler for me, but if a die had to be uniformly of a given hardness this scheme makes infinite sense.

This is good information. Thanks for sharing it. I just finished reading a somewhat simplified account of the time-temperature transformation diagram and appreciated this booklet's first few pages. Let me share an idea that sprang from some www discussion with Grant Sarver on differential hardening. I harden power hammer dies of 4340 or 4140 by using stratified heating of the dies. I formerly used through-and-through heating and sometimes had cracking. I switched to stratified heating (hottest at the die working face, coolest at the opposite dovetail face) and full immersion quenching. I believe this has stopped the cracking problem, possibly from the exterior of the cooling die not totally encapsulating a hotter die core. All other aspects of my heat treating process were kept the same.

My experience with cogged belts in my protoype self-contained hammer is that the cogs on the belt shear and/or erode easily. It is tempting to use cogged belts to achieve the small motor pulley needed to get a suitable drive ratio. Tom Clark told me that the Europeans use 50cycle current so that with 60 cycle current here in the USA the machines runm too fast, and that he also found use of no cogs on the big pulleys (the shrunk-on rims) allowed enough slippage to avoid problems. I solved my speed problems using V-belts with a 1200 rpm 3 phase motor. AND, since that long ago time, thetire hammer has come along with its version of the speed solution. The variable frequency gizmo is perhaps the most elegant method, though pricey.

Give Brian Russell a telephone call (he prefers that to e-mails) and he'll help you out. He's a real good guy. Google on Sahinler to get his tel #.

The tire hammer mimicks the construction of older mechanicals like the Little Giant. So it performs like them. Soooooo many people have had success with the tire hammers and its parents that I think that speaks louder than words. But there are differences between mechanical hammers and the two basic kinds of air hammers. Frosty did a good job of telling the story. I'd add that the mechanical hammers have a "slapping" blow whereas an air hammer has more of a "punching" blow. Each correspondingly varies in energy input and energy output. Mechanical hammer proponents suggest their relatively low power input is due to air hammer inefficiency. Ya gotta examine one type of machine's input relative to its output. Bottom line IMHO tends to be that a mechanical's hammer head weight has to be bigger than an air hammer's hammer head for a given block of hot steel. The umba's online librarian will sell you a $7 dvd of Clay Spencer showing the tire hammer at its best with all kinds of his tooling for it. Check it out.

Mike-hr, no one is really arguing the control versus raw power issue. At leeast I think that is true. And I certainly agree that this particular thread has been quite valuable even though most of the quibbles were expressed long ago by folks such as the late Tom Clark. My friend Deker, the knife guy, says why not both? For me he means keeping good control and raising power. Achieving control WITH power (while keeping hammer head weight constant) is quite difficult and I'm quite proud of learning over the years how to have control AND high power. Getting higher power is, not surprisingly, related to increasing the air flow in an air hammer. Up to a point it is easy to obtain, but control is usually just not there when a choked machine (because of small air lines) is hot rodded with bigger lines and valves. So some outfits don't run big lines and valves, preferring to sacrifice ultimate power for good control (I presume because they don't have my control secrets). The volumetric efficiency of utility hammers like Phoenix, Big Blu, and Iron Kiss is limited by what Norgren engineers refer to as the critical back pressure ratio. Once air outflow pressure is brought to less than about 53% of air inflow pressure no increase in air flow is accomplished. Pushing harder on the treadle doesn't accomplish anything. Essentially, the air flow becomes too fast through ports and valves, like an airplane trying to break the sound barrier. So bottlenecks have to be removed to reduce the air flow speed in order to increase air flow volume. That is what I was thinking about when I did a post following the 150's testing. A custom cylinder with less restriction is needed. For maanufacturwers' regular product lines, the National Fluid Power Association has dimensional rules for all the manufacturers that have been agreed upon so that brand A and brand B are interchangeable. All the catalogs are based on these agreed upon equalities across brands. To obtain better maximum power output from any of my hammers I have to remove bottlenecks that choke the machines at wide open throttle. If I didn't have to have air cushions to prevent damage to cylinders under certain conditions of reckless operator behavior, I could modify my cylinders to achieve what I want. However, I want the factory to create larger air cushion spears and orifices because they have the tooling and parts to do it. It amounts to using parts from a 6" bore cylinder in a 4" bore cylinder, the size used in Octagon 150s and 125s. When I build self-contained hammers I do all the port and passageway "hot rodding" in the master and slave cylinders. My self-contained 160 in my shop hits with such gusto that I'm dang near afraid to run it full tilt. However, for a self-contained there is no air cushioning really possible when the top-of-piston air chamber is at below-atmospheric when the hammer head is near the top of its up-stroke. Another means of cushioning has to be used, or excess stroke capability has to be designed into the (essentially longer) cylinder (the Sayha/Saymak/Kuhn solution). Or, some way of using atmospheric air pressure in the cushion has to be devised, the complicated Nazel solution to the problem. Some old steam hammers used a spring loaded pin that the piston would contact at the top of the stroke. This may be boring as can be to you and others, but to designers it is the area of refinement that separates the best from the rest. Sooooooooooo, the typical solution appears to be and to have been to build hammers so that they really don't have to run "full tilt." Avoid air flow bottlenecks and use air cushions in utility hammers, and avoid having pistons reach and hit the tops of their bores in self-containeds is how to do this. As with mechanical hammers, just keep making the hammer heads heavier to obtain the amount of "squish" that you demand. I very much prefer the elegance of utility hammers and their air cushions that prevent destruction of cylinders when running full tilt. And that is the direction I'm headed right now. Sorry to have blather-itis. :-)

Concrete provides weight and sound deadening, but it powders when impacted. Which is why people use rubber or plywood between a power hammer base plate and a concrete floor. I'd fill that box tube with lengths of cheap rod (rebar?), weld it top and bottom and grind smooth and square, and then cap with steel plate that can be drilled and tapped, for example, for attaching dies. I'd say the anvil mass-to-hammer-head ratio needs to be more than 10:1. Think about a hand hammer weight and a regular anvil weight. A 10 pound hammer on a 100 pound anvil is not very attractive to most blacksmiths. In my 13 years as a power hammer builder I have steadily increased the ratio, beginning around 8:1. My standard machines use more than 16:1 and they work pretty darn well. I've built a couple of 20:1 machines that were not discernably different in performance. Bolt or weld together the hammer frame and base plate and anvil and you can pretty much count that weight into the anvil mass just like you can count a big steel mount for a regular anvil when they're securely bolted together. In all cases however, the real sweet spot for rebound comes from the mass of steel going straight down from the bottom die just like on a regular anvil. BTW, enjoy the build process. Designing/building machines gives an immense boost to your self esteem (aka bragging rights).

Thanks, Grant. You've been darn helpful to me with info and tooling. Your video material is tremedously useful. Lemme tell ya, the blocking out of the power hammer die is inspiring. As for more on the heim joints on the tire hammer arms, Paul Garrett, the head smith at John C. Campbell, is credited with using NASCAR grade heim joints on one of the first tire hammers built. You ought to try contacting him directly via the school. A truly fine guy and he'll tell you what works.

I've used standard heim joints and found that the body of the joint can be stretched. Then the bearing fails. Use steel heims and use large size and your maileage may vary. The 3 point hitch joints are definitely a good idea.

Frank A asked me to run the test with his Iron Kiss Octagon125. The 5 blow # is .411 and the 10 blow # is .260. That is more than 50% better than the 100's and the 150's results averaged. I just looked at the original post on page 1 and I was surprised. I've reported flattening 3" at the ends of the 1x1 sticks and not the 2" called for in the test. That makes a big difference. The Iron Kiss results are therefore uniformly understated. :-)

Very nice work, Mr. Hofi.

This has been extremely informative. Thank you all. I'd like to learn more about the effect of using a V-block or half-round bottom fuller, as compared to flat dies and the SOR method. Maybe Mr. Asbury can help out.

I just found your video, Grant. Superlatives warrented. T^hansk for the show.

Can you tell me your router brand and its features? I can use such a beast. My die grinder is not hefty enough, but I have seen a machinist re-cut a Nazel 3B's sowblock dovetails with one.

Hofi told us at a hammer in that he didn't forge his tungsten drifts, but rather abrasively machined them to shape. He said the armor piercing shells can be found on the desert floor.

Keenjunk was superceded by forgemagic.com. Also farwestforge.com is similar and technically superior, though sparsely populated. Glenn made this site, probably about the same time as Keenjunk was retired. This site is much superior technically, but the style is topical rather than gossipy. More like a library and technical support center than forgemagic. Keenjunk archives are available if you want to do the effort. The plumbing scheme mentioned by JNewman is simply a way to turn the air to the roller valve on-off as the treadle is depressed.

So Ed, what did you end up doing and how has it worked out for you?

Pounding Out the Profits is extraordinarily well researched. There is so much history to power hammers it is phenomenal. Steam hammers date back to James Naismyth's invention of one to forge propeller shafts for early steam ships in Great Britain. Once you get into the web & library research you'll enjoy the enterprise regardless of how impatient you may be right now. One of the most interesting hammers I've ever seen, not shown anywhere else, is on an old Woodwright's Workshop tv program from when Roy Underhill was visiting France; a cross between something like a little giant and an air hammer. Pounding Out the Profits talks about that kind of hammer, but not this specific machine.

I finished up a 150 pound Iron Kiss and gave the test a go. The 5 blow number is .412" and the 10 blow number is .272". I used A36 1x1 just like before. Now having done the test and reflecting on it, I'm not so sure it proves a lot. Others have expressed that control trumps brute force, and I totally agree. Virtually none of my customers has ever expressed interest in the brute force aspect this test highlights. Everyone is concerned about control for jobs like tapering a table leg, punching, etc. I see in the test results an approximate segregation of self-containeds and utility hammers, at least enough to convince me that self-containeds have better air flow volumetric efficiency at full treadle. Generally speaking, the more air pumped through a hammer at full treadle, the more work done. I've built self-containeds, studied the concept intensely, and think I know why this is the case. And I pretty much know how to increase the volumetric efficiency of my utility hammers. The air cushion spears in the air cylinders have to be custom made larger so that the corresponding ports can be larger. Most of the other pieces of the air flow system can be acquired off the shelf. Whether or not that change in utility hammer volumetric efficiency would bring about test equality is uncertain. Movement in that direction is very likely, but there are other factors to consider. Watching operation of old steam hammers do single blows suggests to me that a utility hammer could be made superior to a self-contained for this kind of test. For what its worth, I set out to produce the best utility hammer on the planet. Now that this test is part of the public record I feel compelled to step up my R&D. :-)

Ed, I have had excellent luck with 3/4 plywood. I use a corral around the base to keep the hammers from twisting and I let them float. I agree with Hollis about there being no need to tighten floor anchor bolts when the hammer is heavy. Hope the machine runs well. John Larson