P/H Anvil - increasing mass.

[Astro_Al]

Hi guys, I'm about to start my pneumatic power hammer build. I have found some 7" diameter steel for the anvil, but a 2 foot length gives an anvil weight of around 140kg (about 300 pounds). I'd like a little more mass to it. I have a 63mm diameter pneumatic cylinder which is a good size for a decent weight, and I'd like to take advantage of that by building it reasonably beefy.

There was a thread on here where someone was building a 'composite' anvil (BIG) with welded steel bars. Seems like a good idea to increase the anvil mass to me. I can't for the life of me find the thread now (anyone got a link?), but does anyone have any inputs on how to make a larger anvil that acts as a single mass?

Cheers, Al.

[arftist]

Hey Al, Here is my input, for what it is worth. 7 inches diameter is a goodly chunk of steel. Part of the problem though, aside from the weight, is that it is most likely too short. The obvious solution then is to set it on top of another chunk of the proper length and weld them together. Be sure to allow for the thickness of your machine base(1/2" minimum to as thick as you can drag back to your shop) and the thickness of your bottom dies. When I built my hammer, I used an extra plate 1.5" thick under my bottom die. This gives me more room on top of the 9" dia. sow block to work on odd shaped sections, and also gives me more room to install or use oversize tooling if I remove the spacer.
In conclusion, if you could find a chunk of steel larger than 7"dia., round, square or whatever, use it under your existing chunk. If it is somewhat smaller, but long enough, and all that you can find, such as 6" round or smaller square, add it to the top of your seven inch chunk. Since a proper weld preheat would involve an unbeleivable amount of b.t.u.s, weld them together as best you can, but also brace each chunk to the mast with something substancial, such as 1"x6" plate, properly beveled, and completely welded with 7018, 8018, or stronger. If you place the bar in a vertical position, the uphill welding will essentialy help preheating if you do multiple passes, which I would do.Good luck on your build, an please report back often on your progress.

[Astro_Al]

Hi, thanks for the input.

7" isn't too bad, but I'm aiming for a anvil:hammer mass ratio of greater than 10:1, and with a 63mm cylinder diameter I think I can afford a decent mass 'hammer' ('tup'?). Seems a shame to waste the capacity of the pneumatics for lack of anvil mass. I was thinking 40 to 50 pounds for the 'hammer' end, so I need to find another 100 to 200 pounds of mass for the anvil.

I'll weld it all to a thick plate, it'll be whatever I can find at the scrap yard, but not less than 1 inch.

I was thinking about 70 cm for the anvil height would be about right, given the addition of a wooden platform, base plate and the bottom die. I'll have a re-measure to make sure, but I can get the 7" bar in any length I need it, so I'm not limited to 2 foot.

Man I wish I could find that thread. Who here is slowly making a very large anvil from cylinders welded together (if I remember rightly, a large central one with others welded around it with their top ends cut off at an angle). I've been all through the power hammer section of the forum, I'm starting to think I dreamt it!?! Anyone?!?

Cheers, Al.

[arftist]

Hey Al, If you have plenty of 7", 3' would give an anvil weight of 450# plus the weight of your baseplate. I made my baseplate out of 1.5", and love it. weight down low where it belongs, and an ultra stiff frame. My nine inch diameter anvil is 3 feet high.
I think the article you are looking for on built up anvils may be in the powerhammer section of Anvilfire.

[Frosty]

You can weld several pieces of the 7" together side to side for as heavy an anvil as you want. Dave Mudge with LAMA built a 300lb kinyon style utility hammer by welding 7 sections together to make the anvil. Three lengths of your 7" welded in a triangle would make a respectable anvil for a 50lb hammer.

Frosty

[welder19]

If all you have is the one length of 7" then get an old oxygen cyl. or a piece of heavy wall pipe, cut it to length and then fill with lead, if you can melt it and pour it in that would be best, I have done this for several projects, mostly bases for different things, it works great and lead is the heavier than anything else so the weight really adds up fast.

welder19

[Astro_Al]

Frosty - you're a GENIUS!!! - There it is! BIG Hammer

Thanks, I can't describe the relief, thought I was going nuts!

I like the triple-column idea. If I welded together 3 7" diameter columns, and put a 4" length in each of the 3 grooves around the outside I'd get an anvil weight of 600 kg (1320 lb). That sounds good to me! I guess the gaps between cylinders don't matter.

Welder 19 - thanks for the idea. I have a good source of this 7" stuff so I'd like to use that if I can. Good idea on the density thing though.

Thanks guys. Just need a base plate and a million other bits now...

Cheers, Al.

[Frosty]

Well, if remembering how a buddy built a big hammer is genius . . . Dave did the deed, he deserves any credit for the thing.

The gaps won't make much difference with rounds this size if you get the bottom and top buttoned down good and you have a nice thick base. If the base flexes eventually the longitudinal welds will shear though if it's only a 50# ram on that weight of rd. it might not be a problem at all.

However, I'd weld it as solidly as I reasonably could just for GP. Be aware you can warp steel of even this weight if you lay one humongous bead down the full length of a join. I'm not saying it's "easy" to warp this stuff but it can be done. Work both sides of the bars to keep the heat and pull even and it'll come out well.

Frosty