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


JHCC

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On 7/8/2020 at 8:44 AM, JHCC said:

it seems like most of the filters out there (at least at first glance) have much lower operating pressures (~150-200 psi)

Having looked at the filter mechanism, I've realized that this is the minimum operating pressure, not the maximum. There's a spring loaded valve that closes the inlet, and I'm guessing that it only opens to allow the fluid into the filter once the pressure differential between the inlet and the outlet reaches that minimum. This presumably keeps any filtered contaminants from floating back into the system when the pump is not running.

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The kind of overkill folks unsure of what they're doing, make. I looked at the rows of log splitters at Home Depot Saturday and not one has a reservoir close to gallon size and those get hours of heavy use. By heavy use that's sometimes 15 seconds of shoving a wedge through a block of wood on the second stage that makes a 10hp+ Honda engine WORK. Before the accident a helper and I could put up 7+ cord of firewood in a not long day without killing ourselves. 

You'd have to tie the handle down and go have lunch to generate enough heat to need a 5 gallon reservoir. You could probably wrap it in insulation.

Frosty The Lucky.

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Well, in that case, I'll just clean off the flaking paint, take the copper off the line to the valve, and stop worrying. Thanks.

In any event, I'm rather pleased that the excessively long ends of the threaded rods and those extra nuts finally are getting put to good use. I'm going to pretend that I planned it that way all along.

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If it gets to hot to touch it's time to think about cooling. It doesn't hurt to think about and play with potential problems and solutions. Sand that reservoir off and paint it flat black, that's not overkill A'tall A'tall.

Just because you explore alternatives doesn't mean you did you didn't plan it that way all along. Being inflexible isn't planning, it's fantasizing. 

Frosty The Lucky.

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Question: can I do the connections on the low pressure side (that is, valve to filter to reservoir to pump) with regular Schedule 40 black pipe and fittings?

I think I can cobble together at least some of the connections from my bin of extra hydraulic fittings, but it would sure make things easier and more affordable.

 

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If you're going to use steel pipe make sure it's rated for the max PSI of the pump. Just because it's on the return circuit doesn't mean it can't receive max pump pressure. If, for instance something blocks the filter or a fitting completely everything plumbed in will be pressurized at pump pressure until the motor stalls, the operator shuts it off or a circuit breaker kills the power. 

Pressure relief valves are just like circuit breakers in an electrical system with the SAME caveat. A 20amp breaker does NOT mean the current is limited to 20 amps it means it will open the circuit if it's exceeded. Until it opens the circuit full line amperage is available. If you are shorting the circuit YOU get whatever amperage is available on the power pole until a breaker throws.

Use hydraulic pipe and fittings rated to take max pump pressure. 

Frosty The Lucky.

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Glenn sent me a link to the pressure ratings for Schedule 40 pipe, and while the bursting pressure for the relevant sizes is well in excess of what I'll need, the working pressure was much too low. That answers that question.

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I know I should just keep out of this but.....What's the Max operating pressure for your filter assembly? I'm pretty sure that's going to end up being less then the working pressure of sch 40 pipe.....manufactured reservoir tanks have a breather (no pressure) and suction line is rated for what, 250 PSI? Most filter assemblies are Max 250 PSI?.....I'm just saying.....There are calculation to figure your return pressure depending on pipe sizing and flow rates.....My return is 3000 PSI hose (it came on it), and my filter assembly is only rated 250 PSI max......but I don't know what I'm talking about with hydraulics.....

Edit - In looking at your earlier post, you answered my question. The 15 PSI BYPASS means anything under that pressure does not go through the filter, the 250 PSI is the MAX rated pressure......unless I'm misunderstanding what you said.

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A filter assembly is designed to be nearly full flowing at return pressures..  Where the difficulty comes in is when the filter starts to get choked out..   I used a filter on a return line that was open centered (control valve) (which means fluid moves through the valve all the time except when moved forwards or backwards out of detent, nearly at 0 psi (some slight resistance to passing through the filter).. 

There are open center and closed center control valves..  With open center the pressure is less until the pressure is needed and it built up when the spool moves into the up or down position.  With this setup the fluid moves like water with very little pressure basically straight through the valve and such.. In other words the fluid is constantly circulating. 

With a closed center the pressure on the pump is there all the time  on the upstream side of the valve.. Once on the other side of the valve it just moves to very little pressure with more pressure the more the back pressure from the filter/outlet etc, etc.  (to small a line for a given volume can also increase back pressure).. 

the filters have a bypass valve and good ones also have a pressure gauge so you know the pressure at the filter and amount of plugging up. 

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Test fit of valve > filter > tank connections (showing location of filler cap):

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And tank > pump connection:

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I am happy with this. Next step is to drill holes, weld in flanges, clean and paint tank, and hook everything up. Then I need to get a 5 gallon pail of hydraulic fluid.

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Side note: when I went to the local ag implement dealer yesterday for hydraulic parts, it came to light that one of the women in the back office forges small-scale decorative items and also does farrier work on miniature horses. We had a great chat. 

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Working on it!

Big steps forward on the tank today. Cleaned off the old chipped paint, down to the original finish:

F5B51AF6-8B4D-4DB1-A752-BF09ABF0DF09.jpeg

Drilled the holes for the fittings. Didn't have the right size hole saw, so I used my step drill to get as close as possible, and then finished the work with a rotary file in the die grinder.

Naturally, the fittings didn't fit flat against the curved surfaces. Here's the inlet:

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The outlet:

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And the strainer for the filler/breather cap:

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However, some careful hammering and a bit of filing, and they fit much better. In the same order:

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The welds on the flanges came out pretty well:

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After all that, there was a fair amount of crud that had fallen inside the tank. I poured in a few handfuls of sand and swished it around to catch the filings and drill swarf. I poured that out, and then rinsed the tank thoroughly with water. It's currently drying, and I'll paint it and install the filler cap tomorrow.

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The good news is that I got the tank painted and installed, all the connections hooked up and leak-free, the tank filled, and the motor running smoothly.

 The bad news is that I’m having exactly the same problem as before, with the ram moving at 0.66”/sec and bypassing at either end of the cycle. Here's a video:

What the Dickens is going on here?!?

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