Ted Ewert

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About Ted Ewert

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    Senior Member

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  • Location
    Mill Valley, CA
  • Interests
    Building stuff

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  1. I'm actually building a design by Joshua De Lisle. It's a very simple hammer, but just what I want. https://www.youtube.com/watch?v=hfJFDZTZTqc I'm in the process of collecting materials. There is a construction site close to my work with a large dumpster marked "metal only". I talked to the foreman and he told me to take all I want. Golden words! It may take a while, but as soon as I get all the pieces I'll stat a new build thread.
  2. I thought about it, maybe if a few people are interested I will. I just get tired of the negative comments here when I don't build things the conventional way. I'd love to if I ever get up your way. Thanks
  3. Thanks KS, glad you like it. I didn't know anything about power hammers before I built it either. My method of learning is to build one, and by the end I know exactly how they work. I have a pneumatic build just starting. Mechanical hammers move plenty of metal, but air hammers have so much more control. I think a VFD is a waste of money. A decent clutch will do the same job, for a lot less money.
  4. When you turn your air flow down you'll start to get burnback through your burner. This is because your flame front exceeds the velocity of the gas exiting the hole. I have found that most ribbon burners have way too many holes for efficient operation. I run mine on six holes and it gets as hot as I want with no problems whatsoever. Plug up about a third of your holes with Kaowool and see if the problem goes away.
  5. It will only backfire if the rate of burn (flame front) exceeds the exit velocity of the gas. An easy fix is to plug up a few of your burner outlets with some wool. That should increase the gas velocity through the other ports.
  6. "So it only has one speed?" No, it has two speeds: on and off. If I wanted to vary the speed I'd have to get a VFD or a pneumatic drive system. It's simply a proof of concept for a possible alternative to a clutch. "I'm not see much snap to it either." If you watch the drive rollers in the video, you'll notice that they only extend about half way up the lever. I wasn't running it full tilt. I was running it at the amount of impact I wanted at that time, which is the whole point of the mechanism. I can now feather the drive so I get a nice point on a taper instead of a squished mess, or I can run it hard to move a lot of metal. I have a whole lot more control than with that lousy clutch I had. I consider it an improvement.
  7. In an effort to get some more control of the hammer, I decided to try something a little different. A V belt is not made to slip, and makes a lousy clutch. A flat belt would work better, but it's still a clutch. I figured that varying the distance of the drive linkage to the fulcrum might be an option since that will change the distance that the hammer travels. I tried a number of configurations that didn't work well, but finally got something to work pretty good. It aint perfect, but it does vary the amount of impact on the work. I built a sliding roller which pulls the linkage in towards the fulcrum to increase the travel of the hammer. This works against a spring which returns the linkage (upon the release of the foot lever) to a spot out on the lever where the hammer oscillates without making contact with the anvil. This is the "neutral" position This is the engaged position The roller is screwed into a piece of 1 X 1 solid bar stock, which slides through the 1 1/4" tubing. Steel cable is attached to the end of it and run down to the foot pedal. I got rid of the spring rocker and used a solid piece of 1/2" X 2.5" steel instead. I built a spring into the hammer to take any excessive shock load off the drive train. And because I know someone would want to see a video, I made one of those too...
  8. I'm only a couple of miles from the ocean, which provides natural air conditioning for most of the summer. It also chases the magic winter dust away. The down side is that none of my kids can afford to live where they grew up.
  9. I've heard of that stuff. I see it in pictures along with Santa Clause. Must be left over from Christmas.
  10. Nice hammers! That's a big ol' piece of steel you have there. My back hurts just thinking about trying to move it. What's all that white stuff on the ground?
  11. I'd like to see your hammer, and that block of steel. You must have some heavy equipment, or a hoist, to move that stuff around. All I have is a hand truck a three strong sons (if I can rope one in) to help me move my equipment. I also need more space. I had to shoehorn this hammer into a small area close to the forge, which makes it hard to work on. I'll be retiring in a couple of years and would like to buy a property with a separate shop, or the room to build one. I need a place that I can make some noise without the neighbors or the wife complaining about it. All theory aside, the hammer I built is more than adequate for the stuff I make. It's a great time saver for drawing out tapers or flattening thick stock. It's a decent hobby hammer. A lot of guys are in the same boat I'm in; limited space and limited access to heavy materials and the machinery to work it. I'm hoping this thread gives those guys some ideas on how they can also build a moderate hammer to fit their needs and budget.
  12. A lot of people here seem to be stuck on the idea that a large mass is the best or only way to attach an anvil. It does work just fine, but it is not the only effective way to mount an anvil. Keep in mind that the only thing a large mass does is to reduce vertical displacement of the anvil. That's it. The reduction of vertical displacement can also be accomplished in a number of other ways. Take for example using a large base area. More area on the base will reduce the PSI across the surface, thereby reducing the amount of compression on the floor. This would work well on a dirt floor. A solid column buried deep in the ground will also provide ample stiffness. The depth would depend on soil conditions. A 6 or 8 inch pipe, filled with concrete and capped with a 3/4" or 1" thick plate would make a nice stand. I pounded in nine 5/8" rods below my anvil today and stiffened it up considerably. I didn't hit the hard rock I was hoping for (which seems to be everywhere else on the property where I try to dig a hole), but I did hit some good solid earth. We'll see how it holds up over time.
  13. I wanted to clarify what the difference in power distribution is between a crank and a cam. The following wave forms roughly represent the comparative linear velocities imparted to the hammer by each device: The blue line represents a crank The black line represents a double action cam This chart represents 360 degrees of rotation. The vertical axis represents linear velocity, horizontal axis is degrees of rotation. We'll say that the 180 degree mark represents the point of impact of the hammer. As you can see, the maximum linear velocity the crank imparts occurs at 90 degrees. At that time the velocity decreases to zero at the point of impact. This slowing is also acting as a drag on the hammer. On the other hand, the cam continues to increase the velocity of the hammer up to the point of impact. This significantly increases the energy imparted to the work, and also increases the efficiency of the hammer. The cam is similar to a pneumatic hammer in this regard. The crank imparts zero linear velocity at the point of impact while the cam is at its maximum velocity. This is the key difference between the two. The cam also reflects a much smoother load on the drive train, allowing better clutch performance and reducing wear. I have heard that people are generally disappointed with the performance of their hammers when using a VFD. I would speculate that the crank is a major contributor to the lack of performance. I think a cam would work much better. The design of the whole drive train can be simplified with a cam, since it needs far less spring to store and release energy than a crank does. That could be a separate thread in itself. I hope this information has been helpful, as I have found the cam to be a major improvement over the crank.
  14. It's about 100 lbs. Buzzkill is correct as the concrete bares no load. David. I currently have a rubber mat under the anvil. The problem is that the slab acts like a trampoline. It's sitting on sand, which gives enough to allow deflection. As with your presses, I need to isolate the shock. The rock can't be more than a foot below the slab. I tried to drive a grounding rod in just outside the garage and only got down about 6 inches before it stopped cold. I'm going to try the pilings tomorrow and see what happens. If that doesn't work I'll start digging.
  15. I agree. If you're on soft dirt, a large mass above grade may be the best option. All we're really trying do here is to minimize vertical displacement. However that's accomplished is dependent on the individual circumstances and preferences. I've been toying with the idea of drilling holes in the slab below my anvil and driving steel rods down to the bedrock. I would then grind them to within an eighth of an inch of the slab, and mount the anvil on those. Maybe 6-8 "pilings" would be enough. I might try it just to see if it works.