Why isn’t this a great idea for a hobbyist?

Bühlmann

Well-Known Member
I'm considering a press. I'm considering whether or not I want to mess around with fabricating my own. But that's not the topic of this thread. In my excursion down the rabbit hole that is forging presses, I came across this and was impressed at the ingenuity and efficiency of design:


Has anyone else seen this before? Built one? I'd like some good opinions on if this might be a wonderful (or not so wonderful) small shop/hobbiest solution. Why or why not?
 
I have not seen a press/power hammer combo before. I did see a press/roller mill combo at Blade show a couple of years ago but I have not seen it since. I like the idea and admittingly I did not watch the entire video, I just watched the machine work. Great idea (space saving) but there is a lot of movement in both sides of the machine. Its better than I could build for sure though.
 
I have not seen a press/power hammer combo before. I did see a press/roller mill combo at Blade show a couple of years ago but I have not seen it since. I like the idea and admittingly I did not watch the entire video, I just watched the machine work. Great idea (space saving) but there is a lot of movement in both sides of the machine. Its better than I could build for sure though.

Agreed on the movement. I think it would benefit from being anchored to the floor. I also think maybe some additional cross-bracing at the top of the press may aid in overall stiffness. I just bought the plans, so I'm gonna spec stuff out & see what the overall costs will be. There's no magic in a press, but the pneumatic side interests me a lot to see how that could be a possibly cost effective option for a small-timer like myself with some welding & fab capabilities.
 
Agreed on the movement. I think it would benefit from being anchored to the floor. I also think maybe some additional cross-bracing at the top of the press may aid in overall stiffness. I just bought the plans, so I'm gonna spec stuff out & see what the overall costs will be. There's no magic in a press, but the pneumatic side interests me a lot to see how that could be a possibly cost effective option for a small-timer like myself with some welding & fab capabilities.
I think @KenH is pretty good with hydro's maybe he will weigh in on that. Its a great concept for sure.
 
I've watched this thread on this site and the other site, and watched the video. The 10 ton press in the video is a bit more than Coal Iron's "12" ton press which is only 9 ton (3" cylinder at 2550 psi) so the 10 ton will work pretty well.

There is a small bit of space and material saving by using the press column for both press and hammer. One thing to consider, a power hammer normally has a thick concrete base to sit on, not just a normal shop concrete floor. I'm not real impressed with the idea - not sure the hammer will have the power to really do good work. I'm thinking a good 12 to 16 ton press might be more useful. This is somebody speaking who does NOT own a power hammer, and only used a power hammer one afternoon.

I think he said a 29 KG hammer, that's over a 60 lb hammer which is a good size. Should work good.

Now I've written a lot of verbiage, I'm still not sure what I think of the combo. Of course a good 25 ton press and a separate 50 lb hammer would be best, but that's not always possible.
 
How big (besides "bigger is better") of an air compressor would be required to run that air piston? It's an 80mm bore X 200mm stroke in the plans.
 
In the video, a 300 litre receiver is mentioned (around 80 Gallon).

80mm bore x 200 stroke is as near as dammit one litre. In round figures, there are 30 litres to a Cubic Foot.

If we feed at 100 PSI(g), we'll need about 7.5 litres of free air per working stroke, or 1/4 Cubic Foot.

It'll need a little less for the return stroke. How much less will depend on the diameter of the rod and this is not given. Worst case would be an infinitely thin rod and the same air volume again for the return stroke: half a Cubic Foot per full stroke cycle.

Blows-per-minute is obviously the big variable. On a small power hammer, full speed is likely to be 200 bpm or a little more. That would suggest 100 CFM as potential air usage.

My guess is that the power hammer is only ever going to be run in short enough bursts that the compressor size is largely irrelevant and the receiver capacity alone determines how much air you are going to get.

Size-wise, it seems broadly comparable to the BigBlu 65 Max. That seems to have a 2.5" x 7.5" cylinder (the website says "2" (63.5 mm) bore cylinder with double wear bands." and "7.5" Adjustable Stroke" Since 2" is 50.8mm and 2.5" is 63.5mm, it seems likely the 2" is an error and should read 2 1/2"). The BigBlu claims a maximum of 220 bpm, "runs effectively at 90 psi" and "Average air consumption during hot forging is 14-16CFM-Normally paired with a 3.5HP to 5HP compressor with an 80 gallon tank".

14-16 CFM at 90 PSI is around 98-112 CFM FAD, so, assuming the BigBlu numbers are realistic, it looks like things are probably in the right ballpark.

It is worth noting that an 80 x 200mm cylinder has 66% greater displacement than a 2.5" x 7.5" cylinder, so it's probably fair to say a compressor of 5hp or more would be appropriate for the unit in the video. Bigger, as noted, would be better.

Another way of looking at things is that, if the 300l receiver is initially charged to 10 bar(g) (150 PSI) and the supply to the hammer is regulated to 6 bar(g) (90 PSI), there will be 1200 bar litres of free air available without running the compressor. At 15 litres/cycle, that would give around 80 blows before pressure to the hammer starts to drop.

It is worth noting that 2-stage compressors seem to be much less common in Europe than in the US and that 6 bar is usually considered "normal" supply pressure over here. With a 2-stage compressor charging to 200 PSI (13.5 bar), a 300l receiver would provide 1950 bar-litres of available free air and allow 130 blows.
 
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