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Converting an inverted hydraulic press into a light-duty forging press


JHCC

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Yes, I do, and I did. Having the nuts holding the top cap on meant that I didn’t have to worry about the cylinder coming apart during disassembly or having to assemble the cylinder and the top at the same time. All I have to do is remove the nuts on top of the table, extend the ram enough to allow the cylinder to drop down far enough for the bolts to be below the underside of the table, disconnect the hydraulics, and unscrew the cylinder. 

If I want to remove the saddle and die holder, that’s just held on with the one 1/4” bolt. 

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Looks like you are just about there John, congratulations.  In my earlier comment I didn't mean that I thought the all thread would fail, just that it would be weaker than the equivalent grade bolt with only a final inch of thread.  Your fine thread selection looks plenty good to my eye.

I don't know too much about hydraulics, but will there be any way to speed up the stroke?  Even at a loss of squeezing pressure I think you will be happier with a slightly faster machine.

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I’m pretty new to all this myself, but my understanding is that both speed and force are governed by the pump. Speed is a function of gallons-per-minute, and force is a function of pressure times cylinder area. All of this is backed up by the power of the motor behind the pump and its ability to move fluid through the system. I have a 1-1/2 horsepower motor, a 3/4 gpm pump that generates 3,000-4,000 psi, and a 4” diameter cylinder. 

I can’t increase the speed and keep the same force without increasing the power of the motor, because this one won’t have the oomph to move more fluid through the system at the existing pressure. I could get a stronger motor, a bigger pump, and a larger fluid reservoir, but that’s an extra investment I don’t have the cash to make at the moment. Keep in mind that I’m still only about $175 into this project, which includes the original press, steel for the upper frame, welding wire, threaded rod and nuts, and some ATF (but not my time or Fowllife’s substantial gift of time, expertise, and welding rod).

That said, I am keeping an eye on the website for the industrial surplus place where I got this, to see if any candidates for  pump replacement present themselves.

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A little construction detail: After bolting the cylinder in place, I measured the position of the ram relative to the bottom guide at both top and bottom of its stroke and noticed that it was moving on an angle very slightly forward of the frame. Two little shims made from soda can, and the problem is fixed.

DA8F2C5F-554F-46E7-8CA5-E0B230DDA259.jpeg

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I see what you're saying; just thinking out loud. I still need to get hot metal into this as it stands, and then see if that tradeoff is necessary or worthwhile. I'll keep you posted, and thanks.

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Latticino: That's a hard trade to make with this unit. Motor with higher RPM or higher volume pump unless a person wanted to rig a transmission. Say a pully jack shaft to increase pump rpm. Doable but . . . ? RPM makes speed, Torque makes PSI, you can adjust with a jack shaft. You can get better speed by plumbing everything possible with steel pipe and the largest fittings possible. Judging by the sound of this unit I don't think the gain would be worth the expense and trouble.

My solution to speed in this situation is to use a control valve that does NOT return the ram it just stops when you release it. Only leave enough space to fit the work on the next heat. If it only has to move say 1/2" little heat will be lost.

Smaller area dies increase the effects of lower power rams as well. Not enough psi from the ram, reduce the number of sq/in you're asking it to effect.

This is basic physics and you don't need the math, not really. You can do the calculations using the same arithmetic as figuring levers or sprockets. Once you get a handle on hydraulics it's really pretty simple.

Frosty The Lucky.

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I did just spot a small hydraulic pump at the industrial surplus place that (according to the manufacturer's website) does 2 gpm at 1,200 rpm and 2.5 gmp at 1,500 rpm; I deduce that it does about 3.6 at my motor's 1725 rmp, which is well within its maximum speed of 4,500 rpm. The maximum psi is 2,500, which would give about 15.7 tons of force. If it's still around when I get a few more bucks together, I might buy it and hang onto it until I can also afford the larger tank that I presume I'll need for that larger volume of fluid.

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It might be worth it to have on the shelf but I'll take force over speed any day. The fluid recirculates you wouldn't need a larger reservoir unless you're pushing through longer lines, a larger cylinder or it starts overheating. 

Over heating is easy, point a fan at the tank, hoses don't conduct heat well but the tank well. If it needs more drape a piece of burlap  over it and wet it so the fan can evaporate it. Watch it and when the burlap starts moving in the breeze toss another splash of water on it. 

If you MUST, rig the radiator on the return line before it gets to the tank. It's low pressure and unlikely to cause problems.

Frosty The Lucky.

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Made a set of flat dies:

5E938748-0F54-45E3-B10A-4D39786D62A8.jpeg

So we’re basically done!

6D0E3E7A-AF89-4D9A-BE55-85CDF1977900.jpeg

Still need to make some bits to keep the dies in place and a foot pedal, but it will squish!

 

(The bottom die is removed in this video, since I had just a hair too little daylight to fit in the can.)

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14 hours ago, JHCC said:

I did just spot a small hydraulic pump at the industrial surplus place that (according to the manufacturer's website) does 2 gpm at 1,200 rpm and 2.5 gmp at 1,500 rpm; I deduce that it does about 3.6 at my motor's 1725 rmp, which is well within its maximum speed of 4,500 rpm. The maximum psi is 2,500, which would give about 15.7 tons of force.

If we us the formula HP = flow x pressure / 1714 that pump would take a 5 HP motor (3.6x2500/1714=5.25hp). If you run the numbers backwards I think the best you could do with your 1.5 hp motor would be 1gpm @ 2500 psi.....Going to a 1gpm pump would speed up your stroke by about 30% but would reduce your force to about 15tn going to 2500 psi.....if my numbers are right. 

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Well, I actually got hot metal between the dies for the first time, with mixed results. 

On the positive side, nothing blew up, and I did actually move some steel. This is a bit of 1/2” x 1” with one end worked down to about 1/2” square with the flat dies:

B07695C6-781C-4D98-9E2B-72167CD99A56.jpeg

On the other hand, it was very slow going, and I could easily have done it faster by hand. The dies were definitely sucking the heat out of the workpiece faster than it was deforming. Seemed to go a bit faster as the dies warmed up, and I’d like to see how things are with round dies. 

And then I ran out of propane, so that put an end to the evening’s experimentation. 

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Added an extension to the valve handle to rotate the action 90 degrees without having to change the mounting:

F5E73D58-4CE4-40DC-824C-A461A9E8885D.jpeg

I also think I may have identified at least part of the squeezing problem: one of the dies was in backwards, throwing the alignment off. When I turned it back around, everything lined up nicely, and (on the end of a board, at least) it was squeezing more evenly. We’ll see how it does with hot metal. 

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A good learning session today. Played around with my earlier test piece, which did much better with properly aligned dies. Learned a couple of good lessons: get your workpiece really hot, take little bites to minimize contact with the dies, and have another project going simultaneously to fill the time between heats.

I jury-rigged a foot loop out of heavy election sign wire. This acts as foot pedal that closes the dies when I push down and opens them when I pull up. Not perfect, but much easier than a hand control. I'll see about making something more permanent (and less flexible) from some flat bar.

C72C09B1-11EF-4C05-9923-EDE14A7A4369.jpeg

 I also made some fullering dies with some 1-1/2” round and 1/2” plate from my steel supplier, reinforced with some of the 3/8” round that used to hold up the rubber shield when The Pressciouss was still a bearing puller.

531E7750-FE58-4ADE-8EE5-B285DC06CA73.jpeg

Here's a test squish with a chunk of pallet wood. Looking forward to trying it with metal.

 

Still needs a bit of cleanup on the edges, but I've got a good feeling about them.

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Made a small rounding hammer almost entirely on The Pressciouss. Most of the drifting was by hand, and I set the touchmark with the treadle hammer, it everything else was with hydraulics. Slow going, but a good learning experience. 

1BA54819-00CB-4FE1-BD09-FF8300013C98.jpeg

Had some problems with dies shifting, so I need to make some latches to keep them in place. 

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On 7/1/2019 at 3:52 PM, JHCC said:

I did just spot a small hydraulic pump at the industrial surplus place that (according to the manufacturer's website) does 2 gpm at 1,200 rpm

Further reading of the manufacturer's data sheets tells me that the 2 gpm at 1200 rpm was for generating 100 psi with an input of 0.3 hp; the performance data (highlighted in the photo below) says that if you input 1.75 hp at 1,200 rpm, you'll move 1.8 gpm and get 1,000 psi, and if you input 3 hp at 1,200 rpm, you'll move 1.7 gpm and get 2,000 psi. 

Where I get confused is that this doesn't seem to work with the formula mentioned earlier:

On 7/2/2019 at 6:52 AM, Fowllife said:

If we us the formula HP = flow x pressure / 1714

That is, pressure = hp x 1714 / flow. By that reckoning, 2 gpm and 0.3 hp should generate 257.1 psi, not 100; 1.8 gpm and 1.75 hp should generate 1,666.39 psi, not 1,000; and 1.7 gpm and 3 hp should generate 2,938.29 psi, not 2,000. What am I missing?

On 7/1/2019 at 3:41 PM, Frosty said:

Motor with higher RPM or higher volume pump unless a person wanted to rig a transmission. Say a pully jack shaft to increase pump rpm. Doable but . . . ? RPM makes speed, Torque makes PSI, you can adjust with a jack shaft.

This gets me thinking: if I change the drive from the motor to the pump from direct to pulley and the pulleys have a 2:3 ratio (motor:pump), my understanding is that that will decrease the speed at the pump by a third and increase the torque by half. With my 1.5 hp motor running 1,725 rpm, such a reduction would put the rpm at the pump at 1,150 and the effective horsepower at 2.25. Eyeballing the performance data sheet, I'm going to guess that I would get about 1.75 gpm. Plugging that into Fowllife's formula, that would give me 2,200 psi, which would give about 14 tons, but the higher gpm would roughly double the ram speed. Does that make sense? Would it work?

F071C7BD-B27F-431C-9972-7C7CDB289373.jpeg

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