Saturday, April 2, 2011

Using the Hydraulic Forging Press


As each successive year nibbles away at my strength and endurance I am alert for opportunities to make work easier. One side of the equation involves accepting less strenuous work and the other side involves using more powerful tools.

While I attended the BAM conference last May in Sedalia, Missouri, Don Nichols invited me to his stop to see him operate the hydraulic forging press he constructed. I had considered making one for some time and his demonstration convinced me this was the right time.

I don't have formal engineering training and had never used hydraulic equipment other than a Bobcat skid loader so I started with a lot of reading. I downloaded several articles from the internet and I consulted friends at the farm and ranch store about components. The whole project stretched over a couple of months with the planning phase about six weeks and the building phase about two weeks.

The first major decision was frame style. I chose to make an "H" frame design rather than Don's "C" frame style. Now I see how I could have made a hybrid version where one limb of the "H" could be removable when more clearance was needed. It could be bolted to close the "H" again when working smaller stock.

The second decision was to place the hydraulic actuator cylinder below the ram rather that above. This has the advantage of lowering the overall height and weight of the machine but I was somewhat concerned that it might feel awkward like working backwards when forging. In practice it doesn't seem noticeable to me.

The series of subsequent mechanical decisions progressed with each selection somewhat forcing the next. The force required and ram speed required influences the cylinder size and pump size. Operation cycle influences reservoir design for cooling the hydraulic fluid.

Other decisions involved safety. Keep the center of gravity low. Minimize possibility of damaging the hoses. Keep fire scale away from the components. Provide both hand and foot control. For smooth operation I made the ram glide on greased 1/4" x 4" brass plates.

I'd say I'm still very much climbing the learning curve in testing and discovering it's potential and limitations. The first thing I would emphasize is, like most other aspects of blacksmithing and metalworking in general, there is inherent danger. This is a very powerful machine. I am happy with the closing and opening speed and my ability to control the pressing operation precisely. I suspect that happy result may be largely the result of good luck.

I have used the machine mostly for die making and pressing hot blanks into dies. The operation appears mechanically pretty safe as long as the work pieces are at a high forging heat but the die quickly sucks that heat away and the end of the ram travel will stop when the workpiece temperature falls below forging heat so the ram direction should be reversed before that point.

Cold bending/straightening is done easily but, again, this is cold work and I do it very cautiously. Cutting stock to length cold has worked well but I have been conservative in what I will attempt. I don't plan to do this with stock more hefty than 1/4" x 1". In my experimenting I quickly learned that to sever stock the "scissor" edges should not be very sharp and should be designed so that the stock doesn't completely separate but a 1/32" bridge remains so it can be snapped off by hand rather than severing and shooting off somewhere.

I will not use the press for cutting or veining with handled tools. A single test with a squat S-7 treadle hammer chisel bent the blade as the tool was pressed through the work piece and the cutting saddle before I could stop it. There now. That's enough for me.

This was also a good illustration of the tradeoff between ram speed fast enough to avoid loss of forging heat and slow enough for fine control.

I built an "H" frame type but after some experience I can see there are times when the "C" frame design would be useful but, overall for the work I do, the "H" is probably the more useful.

With practice I am able to decide which of my custom dies will work best with a power hammer and which with the HFP (hydraulic forging press).

There are lots of possibilities for making the top and bottom dies. I had two Little Giant flat dies so that is what I used. I fabricated sleeves which fit over them and have set screws to lock them in place. They have faces which are essentially disposable and protect the nice die faces. I have found this essential with cold work but advisable most of the time.

Probably my machine is overbuilt for what I need and I can see how I would change the design for "the next one" but that just won't happen any time soon. This dog will hunt and that's good enough.

6 comments:

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I don't often check for blog comments, so the best way to contact me is directly: at ottercreeksmith@gmail.com or djedwards@cableone.net