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View Full Version : Blacksmithing Meets Machining: Resurfacing Power Hammer Dies



lazlo
09-23-2010, 01:07 PM
In the companion thread, Forging a blacksmith's hammer (http://bbs.homeshopmachinist.net/showthread.php?t=43748) I showed Will Bastas, a well-known blacksmith, using a Sahinler (http://www.sahinlermetal.com/eng_5-sahmerdan.html) power hammer. These are massive (2600 lb) machines, with a 75 lb ram.

The dies are large: 4.75" x 2.375" x 3.5", and weigh around 11 lbs each. The dovetailed blocks above and below the hot metal:

http://i164.photobucket.com/albums/u15/rtgeorge_album/Power%20Hammer%20Dies/SahinlerDies1.png

They're through-hardened S-7, but as you can imagine, they eventually become wallowed from pounding 2500 metal:

http://i164.photobucket.com/albums/u15/rtgeorge_album/Power%20Hammer%20Dies/IMG_3783.jpg

Deja Vu
09-23-2010, 01:14 PM
I don't see any machining...yet?
more pictures? Maybe a video?

Is it ground? Is that what I see?
Will the surface be flat (one plane) when operations are complete?

lazlo
09-23-2010, 01:18 PM
Will gave me a set of the Sahinler die blocks, and asked if I could resurface them. They're $400/set, so I was a bit nervous...

http://powerhammers.com/pages/hammerhead_dies.cgi?mrchcatid=2&mrchid=5

It's hard to tell from the initial photo, but there's ~ 1/8", highly asymmetric depression in the middle of the die blocks. I measured the surface hardness before I started, and they had a work hardened skin that was well above 60 Rockwell. :eek:

The skin followed the wallow, and was wildly asymmetric: there's a V-shaped trough that starts on one side of the die block and both depens and widens toward the other edge. Along the long axis, there were two humps about an inch in from the ends, with a deep valley in the center.

I was originally planning to mill the dies with an APKT facemill my Excello and then touch it up with the surface grinder, but I would have gone through at least one set of inserts. 5 APKT inserts @ $7 each...

So I ended up doing the whole job on my surface Grinder (a Harig 6x18 manual).

http://i164.photobucket.com/albums/u15/rtgeorge_album/Power%20Hammer%20Dies/IMG_3785.jpg

...and this is what the first pass was looking like:

http://i164.photobucket.com/albums/u15/rtgeorge_album/Power%20Hammer%20Dies/IMG_3787.jpg
http://i164.photobucket.com/albums/u15/rtgeorge_album/Power%20Hammer%20Dies/IMG_3788.jpg

Boucher
09-23-2010, 01:24 PM
The cable tool type drilling rigs used in the oil patch and water well construction used forged sharpened bits. On site this was done with sledge hammers and a small forge. The forming of the original bits was done with large power forges. It makes one wonder what happened to this equipment when it was no longer needed.

Deja Vu
09-23-2010, 01:24 PM
So far your grinder is up to the task. How's the wheel wear?

Nice magnetic vice/table!

lazlo
09-23-2010, 01:24 PM
After I got past the work-hardened skin (about 2 thou), I measured the core die at 50 Rockwell, which matches the manufacturer's specs (good! :) ):

http://powerhammers.com/pages/hammerhead_dies.cgi

Grinding off this much of the surface generated a tremendous amount of heat, so I did both dies in parallel, swapping them out ever 10 minutes or so to let them cool off.

This is the second (upper) die. Notice the wallow is different. I had to change the feed almost every pass to account for the different amounts of material I was removing. Much more material removed at one edge than the center, the least amount of material removed at the far edge.

http://i164.photobucket.com/albums/u15/rtgeorge_album/Power%20Hammer%20Dies/IMG_3790.jpg
http://i164.photobucket.com/albums/u15/rtgeorge_album/Power%20Hammer%20Dies/IMG_3791.jpg
http://i164.photobucket.com/albums/u15/rtgeorge_album/Power%20Hammer%20Dies/IMG_3792.jpg

lazlo
09-23-2010, 01:51 PM
So far your grinder is up to the task.

It's a Harig 6x18 manual. 1 HP motor. Probably would have been faster with coolant, but the machine had no problems.

http://i164.photobucket.com/albums/u15/rtgeorge_album/Power%20Hammer%20Dies/Harig6x18.png


How's the wheel wear?

It was a lot of grinding -- I went through most of an 32A46-I (open, coarse) wheel.

So after some serious rough grinding to remove the wallow on the upper and lower die blocks, I went over the surface with a single finishing pass with a 60-grit wheel. There's some optical waviness on one edge (with the deepest grind) from the previous rough grinding that I could have removed with another pass or two, but it's a power hammer die -- no point.

I chamfered the edges on the belt grinder, and here's the final product. I don't know why the picture is showing that hazy border on the bottom corner of the die in the foreground (flash effect?) -- the die is perfectly smooth. Will was really happy with it :)

http://i164.photobucket.com/albums/u15/rtgeorge_album/Power%20Hammer%20Dies/IMG_3798.jpg

Ries
09-23-2010, 02:14 PM
Interesting.
My Anyang power hammer dies must be a lot softer- because I just throw em on the bridgeport, and take ten thousands off with a crappy 3/4" end mill from Grizzly.
I do this once a year or so, and I have never had any trouble getting a plain old Tin coated endmill to cut the stuff.

I forge a LOT of stainless, and also do a lot of spring swage work, both of which tend to wear the dies more than just mild steel forging would- and I still can sometimes go 18 months without resurfacing, so I dont think my dies are THAT soft, but I have no way of checking rockwell hardness, so I just use em, and, once in while, mill em flat again.

I dont have a surface grinder, so I have never tried that.

lazlo
09-23-2010, 02:29 PM
Interesting.
My Anyang power hammer dies must be a lot softer- because I just throw em on the bridgeport, and take ten thousands off with a crappy 3/4" end mill from Grizzly.

We have an Anyang -- that's a neat little Chinese power hammer: 33 lb ram (much smaller machine than the Sahinler). Yes, the dies are soft. In fact, I'm probably going to receive a set of the Anyang dies tomorrow for the same treatment. I plan to facemill those...

Ries
09-23-2010, 04:40 PM
Mine is a two piece 88lb machine- which is beefier than a one piece 88lb er.

It has an 1100 pound anvil, that sits underneath and is shimmed and wedged in place.
little guy hits hard, I like it better than the sheet metal machines like the Sahliner.

The dies are hard enough, though. I was forging with it today, and it does the job.

lazlo
09-23-2010, 04:52 PM
Mine is a two piece 88lb machine- which is beefier than a one piece 88lb er.

What's the one-piece/two piece refer to? This is the Anyang 33 we have, which I thought Will said was a 33 lb ram? Ours has a pyramid base that's 1/4" plate filled with concrete. This picture shows a square base:

http://www.anyangusa.net/images/hammers/anyang33sm.jpg

It's definitely a lot more controllable for little stuff, but it takes awhile for the air compressor to warm up, and it leaks a lot of oil :) It obviously doesn't hit anywhere nearly as hard as the Sahinler.

We have a Sayha that's Will's favorite (110 lb ram), but he won't let us run it until we take the power hammer class, which is always full :(

Ries
09-23-2010, 06:03 PM
A two piece hammer has a separate anvil, which is installed first, then the hammer is dropped over the anvil and bolted down.
It allows the anvil to conduct the blows to the ground, rather than thru the frame of the hammer.
Usually two piece hammers are 150lbs and above, but a few two piece 88lb hammers were imported by Stryker, even though they were Anyangs.

Bigger hammers are sometimes 3 piece- I had a friend (well, several friends, actually, the hammer was sold a few times) who had a 750 lb chambersburg. The anvil was a bit over 10,000lbs, as I remember, and the hammer itself another 15,000lbs plus, and the hammer came apart into two pieces for shipping- BIG BOLTS.

Here is the chinese anyang website-

2 piece hammers-
http://www.chinesehammers.com/pneumatic-forging-hammer.html#2

and 1 piece hammers-
http://www.chinesehammers.com/pneumatic-forging-hammer.html#1

notice how the 1 piece hammers are shorter, and flat on the bottom, while on a 2 piece hammer, the anvil sticks down below the base plate of the hammer. On a bigger hammer, this means a pretty involved footing, with a step. This is why many smiths buy 1 piece machines. But for a given ram weight, the 2 piece hammer will hit harder and do more work.

Mine is set up on a steel box I built, so the base of the hammer is 18" or so above the floor, and the anvil itself sits on the floor. Actually just about right height for forging.

Mcgyver
09-24-2010, 12:34 AM
that's a lot of grinding....when i saw the size of indentation and how much you had to take off.....made me think of creep grinding; you know, the whole 1/4 in one slow pass. I wonder with coolant if that would be feasible on a grinder like tha. May hang a weight of a pulley for the feed. (mines a similar/size weight, but I'd feel more comfortable if you to tried it first :D )

wierdscience
09-24-2010, 01:36 AM
Look good Robert,I used to do some for the local fence builder,I just used a nasty looking old 3" flycutter in the mill running 300rpm .010" DOC and about .008"/rev no coolant.I could make 4 or 5 passes,stop the spindle and touch up the point with a diamond hone then run again.

I have also built them up with Blue Demon hard facing wire and ground them down too,that stuff is gawd awhful tough thou :eek:

Black_Moons
09-24-2010, 04:15 AM
Id be tempted to do it with an angle grinder.. You cringe, but come on guys, it a hammer face, and a 7" angle grinder can get things pertty flat with proper technique and measurement.

sconisbee
09-24-2010, 06:08 AM
Id be tempted to do it with an angle grinder.. You cringe, but come on guys, it a hammer face, and a 7" angle grinder can get things pertty flat with proper technique and measurement.

If I had a surface grinder then i would probably do a combination of both, use a 9" angle grinder to rough it "flat" and then dust of the last with the surface grinder.... well depending on how lazy i was feeling that day:rolleyes: