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Tube forging.
Will Jones -
Monday, March 15, 2010 - 3:41pm
In response to Stephen's request - I did take a few pictures the other day as I was making these buds from 1 1/2" tube (it's actually 37.6mm tube or something...) Nothing very spectacular...but it always gives me a kick forging tube as there's always a little voice in my head saying "this shouldn't work - it'll collapse!" I think it'd be much quicker to do on a conventional pneumatic power hammer giving a couple of hundred hits a minute - my KA75 just gives one whack each time I press the footswitch - and it takes some concentration not to hit too hard and squash'em. Should mention to anyone who fancies trying forging tube for the first time, make sure you pinch together or plug the end of the tube you're not working (and the one you are if possible). Fumes from the forge will heat the tube up VERY quickly if allowed to travel up it, and possibly form a bit of a toxic/explosive risk in the workshop eventually.
 tapered tube...
Stephen Fitz-Gerald -
Monday, March 15, 2010 - 8:28pm
Stephen Fitz-Gerald  Stephen, like blacksmithing,
Will Jones -
Tuesday, March 16, 2010 - 3:22am
Stephen, "enable rich text"
Stephen Fitz-Gerald -
Thursday, March 18, 2010 - 1:41am
Stephen Fitz-Gerald As usual, you've poured out
visitor -
Tuesday, March 16, 2010 - 3:12am
As usual, you've poured out a whole lot of interesting stuff there Rich! I forgot to mention about quenching. Don't do it folks!For this job, one end is sealed up by the forging process as I go along, and ive pinched together and welded the other end, but if a bit of water gets in there, next time it gets hot high pressure steam is searching out every pin hole and you're holding a kettle!Welding a bit of solid bar ito the end for a handle is sound advice. As far as the KA goes, it has it's limitations but I think during the course of this job two good things have happened 1) I'm really getting to grips with the control of it. Had it maybe a couple of years, but never worked it as intensely as this. As far as I know it's still the only one in the U.K. In my little workshop, a hammer with a sixteen inch footprint is a godsend though. Will  Will, Those KA's are great
Rich Waugh -
Tuesday, March 16, 2010 - 8:38am
Will, Those KA's are great little hammers and can do an incredible amount of work. My buddy Nathan Robertson is a full-time maker of custom forging hammers and uses a KA very successfully. He's made literally thousands of hammers on one. According to Nathan, the KA needs to be worked hard until it loosens up, which takes a number of hours actual forging time, and it needs to be so thoroughly lubricated that it's dripping oil all over everywhere. That may be a little bit of an exaggeration, but not much - I've seen Nathan's hammer and it was certainly drooling oil all over itself. But boy, can he make that thing fly! If you have the regular flat dies in the hammer you can make V-block, tapered V block, and taper dies that simply drop over the lower die, or you can make a "clamp cage" that will hold the dies and also hold spring swages or other tooling with hardy-type shanks. The clamp cage is nothing more than a band of flat bar that goes around the bottom die and has a set screw to lock it in place. It is made so that it is a bit over half an inch longer than the lower die so you can drop a die over it that has a piece of 1/2" x 2" bar for a leg. That leg gets clamped in place when you tighten the set screw and the whole works is secured in place. You can weld on a piece of square tube to the side of it to hold hardy-shanked tooling such as spring swages, fullers, etc. Hope this gives you some useful ideas of things you can do with your KA. It's a great hammer. Rich  Great pictures and cometary.
R L Sidebottom -
Monday, March 15, 2010 - 8:45pm
Great pictures and cometary. I have tried forging pipe for cattails, and you are right, the end will heat right up burning all the oil and such. It also happens to hit you right in the face. Rick Sidebottom  great pics
warren -
Monday, March 15, 2010 - 8:51pm
Will, thanks for taking the time of the posting the pictures. You sure do come up with some weird shapes. www Metalrecipes -- heat and beat to the desired shape, repeat as necessary. |
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ArtMetal
Will, Good pictures, thanks!
Will,
Good pictures, thanks! That should be helpful to a lot of folks.
I forge a fair bit of tube myself and I've discovered a few things that really help me. Probably the same things you already have figured out, but I'll post them here for others who may not already know.
For forging down tube, an angle block or V-swage is almost mandatory so as not to collapse the tube. The best swage block I've used is one that has an included angle of 116 degrees. 120 degrees works almost as well, and a regular 90 degree block works, but not nearly as well. It also helps not to have the tube too hot - I like a high orange, but not a full yellow. Final planishing at a medium to low red.
Yes, a pneumatic hammer that will give rapid, light blows works better than one that delivers heavy blows. Light blows don't penetrate the work so deeply, as you can see forging bar stock, so they actually are a benefit on tubing or pipe.
Plugging the end of the tube isn't just a good idea, it is mandatory! I have a really handsome scar on the top of my right foot where I didn't notice that my plug had come out and when I quenched the tube it horked up a big bolus of super-heated water that landed on my instep and produced an instant third degree burn the size of a silver dollar (half crown?). That burn took weeks to heal and hurt like hell. Ever since, I've made it a rule to tack weld a plug in the tong end of the pipe, or flatten it and fold it over. No more soft plugs!
When I have a number of pieces to forge from pipe, I make handles for the pipe from round bar and simply weld them to the end of the pipe. That acts as my plug and tongs all in one and is easier to rotate smoothly under the power hammer, too. Quite a bit handier than tongs, I've found.
If you have to take several heats on the pipe, you can develop a lot scale if you're using a gas forge, as I do. To minimize this, I sometimes put a short stick of wood inside the pipe. When it gets hot it burns, consuming any oxygen in the pipe, reducing scaling quite a bit I've found.
For swaging down pipe quickly, I've made a few sets of spring swages that get the job done very quickly and smoothly. You might try something similar for use under your KickAss - I think it would speed up your work. I make one side of the spring swage as a 116 degree V-block and the other as slightly radiused flat that is sized so it will fit into the V deep enough to almost close that size of pipe. Ease all sharp corners very heavily and "ramp" the openings of the V so it doesn't leave marks on the pipe.
Another tool I find really handy is a taper die for my power hammer. This is nothing more than a wedge-shaped piece of steel that sits on top of the lower die in my power hammer and allows me to taper pipe really nicely. I have them in various tapers from 2 degrees to about fifteen degrees. Steeper than fifteen degrees and you run a serious risk of the hammer kicking the work back out at you dangerously. Even with the 10 degree block you need to be sure the work is hot and you hold it firmly. I also have tapered V-block dies for the power hammer, which are just what they sound like - a shallow "V" (116 degree) that is angled at about 7 degrees for tapering pipe under the hammer. It works a treat, I can tell you!
How long have you had the K-75, Will? I've used new ones and it's difficult to get quick blows, but once they're really broken in and are properly lubed (dripping with oil all over), I can get one to go as fast as I can tap my foot - around 120 bpm, I'd guess. Fast, light blows take a bit of practice, I'm told by a friend who uses one for making hammers - I can't do it well at all, since I've only used a KA a couple of times.
Rich