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Phil F

Forge Press Design Help

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All - I am new to this forum and looking for some help/direction. I've been knife forging for over a year now and I'm addicted. My father and I meet at least once a week to forge, smoke cigars and drink Jack. I've built (2) 2x72" grinders that turn 90deg. Watching UTube and reading forums like this one helped me figure out what to do and not to do. So I am on my next project, building a forge press. I've tried to buy Jim Batsons book but no one carries it in stock (any help finding a book even to borrow would be great). I have done excessive research on the piston and the hydraulic system but I need some advice from experienced blacksmiths so I don't make costly mistakes. I see many guys convert log splitters into forges. I like the idea but I want to build it from scatch. I have found the piston which is a Parsons 2H 3.25 bore 1.25" ram with a 11" stroke 3000 PSI max which is purchased so I cannot change this in the design. This has a bottom mount plate on the ram end so I do not have to hang the piston. In doing the calculations, I'm lost with the proper equipment for the hydraulic system. I want to run a 3hp 1ph 1725rpm motor or 5hp if I can afford it. In research it notes you get more power and life out of the 1725rpm ILO the 3450rpm motors. All design calculaters figure gas engines so I've used the 2.5 ratio. With the size motor I was thinking on a 16gpm 2-stage pump. However, I assume it will spin the hydraulic pump half speed since most pumps are rated at 3000 rpm +/-. So if the pump is rated at a 16gpm I will only get about 8gpm. Should I oversize the pump to a 28 gpm pump? Will that work properly? Also, I know you should have an oversized storage tank so I am looking at either a 7 or 10 gallon unit. Keep in mind I know this will only be between 12-16 ton press when I am done. I dont need a 20 or 30 ton press for now...maybe the next build. Any help with some calculations would be greatly appreciated. Thanks in advance!

2H Parker.jpg

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I can’t help on those questions, I’m sorry.

However, you definitely are looking at a 12.5 ton press with that cylinder, I do a lot of (or did) pneumatic and air oil systems. The physics and rules are the same. Max pressure allowance of the lowest rated part in your system (you only have your hydraulic cylinder) times the surface area of the top of your piston. There will be frictional and mechanical losses so actual tonnage will be slightly less. There is NO way your current cylinder gets you safely above that, the 16 tons quoted is out of the question

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I'm not sure I agree with using the slower motor, but yes the output of the pump would be about half the rated flow rate.  Were I putting an electric motor on mine, I would opt for a 3450rpm motor.

I have a 16hp engine driving a 22gpm pump on my press, and only have a 10 gallon tank.  It seems to be doing well.  Hydraulic system estimators will recommend a much larger reservoir to allow the fluid time to cool, but I rarely run my press for more than an hour, and 90% of that time is idle time so I don't think I am building up much heat. 

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47 minutes ago, Marten Sitic said:

I can’t help on those questions, I’m sorry.

However, you definitely are looking at a 12.5 ton press with that cylinder, I do a lot of (or did) pneumatic and air oil systems. The physics and rules are the same. Max pressure allowance of the lowest rated part in your system (you only have your hydraulic cylinder) times the surface area of the top of your piston. There will be frictional and mechanical losses so actual tonnage will be slightly less. There is NO way your current cylinder gets you safely above that, the 16 tons quoted is out of the question

I appreciate the info. Is there anyway you can give me the formula you used to calculate this information? And does a 16gpm pump seem correct? And what size motor did you calculate 3hp or 5hp?.

Thanks again.

31 minutes ago, Brian Dougherty said:

I'm not sure I agree with using the slower motor, but yes the output of the pump would be about half the rated flow rate.  Were I putting an electric motor on mine, I would opt for a 3450rpm motor.

I have a 16hp engine driving a 22gpm pump on my press, and only have a 10 gallon tank.  It seems to be doing well.  Hydraulic system estimators will recommend a much larger reservoir to allow the fluid time to cool, but I rarely run my press for more than an hour, and 90% of that time is idle time so I don't think I am building up much heat. 

Ok. is your 16hp engine gas or electric?

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What Geoff posted is a great resource.

I won’t go into GPM an piston speed, etc, I’m tired!

Ok, let’s talk force. Force ( not velocity, etc) from a hydraulic system is ultimately determined/limited  by two things: pressure produced by your pump (highest pressure and max gpm then determines motor size/speed required, again that’s for later) and the bore diameter of your cylinder. 

Ok, the pressurized oil enters the cylinder and “pushes” on top of the piston head. The flat surface of the piston head is circular, so you need to determine its surface area the pressurized oil will “push” agagainst (we will then multiply that area in “square inches” by incoming oil pressure in pounds per “square inch”. The formula for that is Pi (3.141) multiplied times the radius of the piston squared. In your situation your piston diameter is same as the bore diameter, so 3.25”.    3.141x (1.625x1.625)=8.294 square inches, now multiply that by the cylinder’s maximum rated inlet pressure, yours is 3000 psi.   3000psi*8.294 inches squared=24,882 pounds of force exerted to push the piston. 24,882 divided by 2000 (US ton)= 12.441 tons. That is theoretical max, there is oil shear and friction which drop it slightly, then small losses in any friction from your ram guides etc.

If your cylinder needs to do work while retracting, you need to determine the cross sectional area of the piston rod and subtract that from the pistons surface area (where the rod connects to the piston the pressurized oil can’t apply pressure to push it forward).

 

 

Edited by Marten Sitic

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1 hour ago, Geoff Keyes said:

I found these calculators handy when I was building my press  https://www.surpluscenter.com/Tech-Help/Hydraulics/Calculators/Cylinder-Force-Speed/

 

g

Geoff - Awesome link. Thanks again. I will post my progress.  

28 minutes ago, Marten Sitic said:

What Geoff posted is a great resource.

I won’t go into GPM an piston speed, etc, I’m tired!

Ok, let’s talk force. Force ( not velocity, etc) from a hydraulic system is ultimately determined/limited  by two things: pressure produced by your pump (highest pressure and max gpm then determines motor size/speed required, again that’s for later) and the bore diameter of your cylinder. 

Ok, the pressurized oil enters the cylinder and “pushes” on top of the piston head. The flat surface of the piston head is circular, so you need to determine its surface area the pressurized oil will “push” agagainst (we will then multiply that area in “square inches” by incoming oil pressure in pounds per “square inch”. The formula for that is Pi (3.141) multiplied times the radius of the piston squared. In your situation your piston diameter is same as the bore diameter, so 3.25”.    3.141x (1.625x1.625)=8.294 square inches, now multiply that by the cylinder’s maximum rated inlet pressure, yours is 3000 psi.   3000psi*8.294 inches squared=24,882 pounds of force exerted to push the piston. 24,882 divided by 2000 (US ton)= 12.441 tons. That is theoretical max, there is oil shear and friction which drop it slightly, then small losses in any friction from your ram guides etc.

If your cylinder needs to do work while retracting, you need to determine the cross sectional area of the piston rod and subtract that from the pistons surface area (where the rod connects to the piston the pressurized oil can’t apply pressure to push it forward).

 

 

Marten - Thanks for this info. I think I did this calculation once with some online research but this confirms what I did. You do not need to to reply today but any thoughts on motor size (3, 5 or 7.5 hp), RPM of motor and GPM for hydro pump based on my cylinder size? You seem to have extensive background on hydraulics. Hopefully one day I can return the favor to you.

Thanks in advance.

 

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Phil,

you’re welcome.

Geoffs link also has a GPM/bore size calculator for travel speed, I could walk you through the volumetric measurements and ratios but it’s really not necessary at this point. Plug in your variables and move to next step.

Geoff, Brian and others that have built for this exact application will be your huckleberries, just because I have general hydraulics experience I haven’t built a forging press specifically.

Keep these things in mind though, in general. The bigger the volume and speed of your pump, the faster your ram moves and more work you can do. Larger reservoirs prevent over heating (pressure creates heat, too much breaks down oil and parts), use filter through out, use the biggest motor reasonable that your electrical source can power, and use the recommended motor speed for a given pump- don’t assume that a half speed motor WILL do half the work, may or may not depending on how it works. Make sure whatever you do as proper pressure regulation and every part can handle the pressure it will be exposed to. Keep hoses protected from incidental contact with work pieces or slag that could damage them, and sheet metal shields are not a bad idea, pressurized oil can cut off body parts, and when it doesn’t it still can kill you via trauma and poisoning you. That last parts no joke, if you aren’t careful/competent/knowledgeable/skilled enough to set this up, move on. I don’t mean that meanly, it’s truly a word of kindness, be brutally honest with yourself.

Best

Steve Miller, aka Marten Sitic

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1 hour ago, Marten Sitic said:

Phil,

you’re welcome.

Geoffs link also has a GPM/bore size calculator for travel speed, I could walk you through the volumetric measurements and ratios but it’s really not necessary at this point. Plug in your variables and move to next step.

Geoff, Brian and others that have built for this exact application will be your huckleberries, just because I have general hydraulics experience I haven’t built a forging press specifically.

Keep these things in mind though, in general. The bigger the volume and speed of your pump, the faster your ram moves and more work you can do. Larger reservoirs prevent over heating (pressure creates heat, too much breaks down oil and parts), use filter through out, use the biggest motor reasonable that your electrical source can power, and use the recommended motor speed for a given pump- don’t assume that a half speed motor WILL do half the work, may or may not depending on how it works. Make sure whatever you do as proper pressure regulation and every part can handle the pressure it will be exposed to. Keep hoses protected from incidental contact with work pieces or slag that could damage them, and sheet metal shields are not a bad idea, pressurized oil can cut off body parts, and when it doesn’t it still can kill you via trauma and poisoning you. That last parts no joke, if you aren’t careful/competent/knowledgeable/skilled enough to set this up, move on. I don’t mean that meanly, it’s truly a word of kindness, be brutally honest with yourself.

Best

Steve Miller, aka Marten Sitic

Steve - Thanks for the safety concern. Believe me I am not running into this blind. I am taking as many precautions for safety design as I can. I own two companies and safety is always first. When I built my 2-buner forge, I built all the components even the burners. I used double shut-off protection and quick connects to remove the gas lines when not in use. My press design should keep the hydro lines clear from any forge scale and I will install deflector plates. I also plan on getting the slip on fire rated shields for the hydro lines. I know they are expensive but I'm over cautious. As of making sure all the components work together properly, I am doing as much research as I can and not rushing into buying components without doing the proper research. Hence all the design questions.

I appreciate everyones helps and I will keep you all posted on my progress. Great Forum!

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It sounds like you are making good design choices, hydraulics have a scary amount of energy contained in small areas.  When you get that far, we can start talking about the pros/cons of various designs and some of the less obvious small issues.

When I built my press (about 30 tons) I ended up going with a 3ph motor and a phase converter.  You might check into a VFD driven system and the cost of a VFD big enough to drive what you want.  In my case, 3ph let me go with a much bigger motor than I was planning on (15HP as opposed to 10hp) which make my setup very fast, about 3 inches a second on a single stage pump.  Speed means more squishes per heat (somehow they don't have a rating for Sq per He, it's important to us) since a press robs heat from the work piece very quickly.

Geoff

BTW, I have both a press and a mechanical hammer.  I use them for different things, so if you have space and the fab skills, that is something else to look at.

 

g

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14 minutes ago, Geoff Keyes said:

BTW, I have both a press and a mechanical hammer.  I use them for different things, so if you have space and the fab skills, that is something else to look at.

 

This is true. A hammer is good for thinner stock that the press will suck the heat from. A press is good for squishing thick stock down to the point the hammer takes over.

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I have explored the 3-phase option. The motors are actually less expensive but the rotary phase converters aren’t cheap. I am trying to keep the project under $1000 if possible. But I can build my press frame for now and figure out the heart of the system later and take my time on the equipment. A power hammer is on my list!

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I think that $1000 is not very much when it comes to presses.  I was able to build mine for about that, but the frame was free, built by my BIL out of the scrap pile at his work place, on his breaks.  I'll be interested to see where you end up.

g

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I think I built mine for about $1300. (It's been a couple of years, so I could be deluding myself)  That was will all new components (including the engine), and I paid a local fab shop to machine the heavy pieces of steel.  There is a WIP on it here somewhere.

To answer the earlier question, I used a 16hp gas engine.  The electric motor required to do the same job would be much smaller.

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So far I have $210 for my cylinder including shipping, $60 for a press frame I picked up at a steel yard and $100 in misc steel for frame reinforcing and (10) 5” x 5” x 1/2” plates for my dies. $370 into the project and I don’t have the hydraulic system. Most of the used complete hydro systems in my area are $400 to $800 but are all 3-phase. I would need a rotary phase converter..$$$!  Used log splitters run about the same but I would still need to swap the motor. Or I did have an idea to buy a larger log splitter and install quick connects so I can swap between my press and splitter. I won’t be using either every day. More of a weekend warrior. That way I don’t destroy a perfectly good piece of equipment. My shop is my garage so locating the gas engine outside the door isn’t an issue. However I’m inclined to buy all new parts to make my own hydro system. My guess is about $1000 - $1200 for everything. I think the log splitter is my fastest and most economical option. I’m going to work on the frame for now and keep looking at options for the system. I’ve started laying out my design. It needs some work. I posted some initial photos. Any comments or ideas would be helpful. Talk soon. 

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Started welding the press. The weld are not pretty but they will hold. 

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Keep in mind that all of the force of your press will have to be held by the welds that hold the I beam to the 4 vertical posts that hold your cylinder up.  I don't know all of the construction details, but it looks like those welds will be loaded in shear, and I would be concerned that they won't hold.

They way you have that heavy I beam on end under the area where the die will go makes it look like you think the load will get transferred through that beam to the ground.  That isn't true for a press.  All of the load will be born on the components between the the two dies. 

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Those welds look better than the 12 ton shop press I bought from harbor freight!

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Btw that cylinder looks WAY bigger on the frame than it does in the picture above. At first I was concerned about the size of the cylinder but now it looks good. 

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Thanks guys for your input. I know I still have a serious amount of structural work to do. I want to get the vertical guides in for the ram before I do anymore steel work. I just found the 1” - 14 fine thread bolt I needed for the end of the ram. So I can design the press plates. However I realized I need be able to run the cylinder to test my design. I’ve looked at all the options and for the investment I think the log splitter is my best option. I’ve located a new 22 ton unit for $750 w/ a 6.5 hp engine. I’m going to leave the gas engine and just install longer hoses and quick connects to flip between equipment as needed. So I am running a bit over budget but I will have two toys for the price or one.

I’m only getting a day week to work on this so I’ll post progress pics in a few days. Thanks again. 

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Well I’ve made some progress. I bought a 27 ton Dirty Hands splitter for $750. I do not like the auto return detent so I’m going to buy a second “spring center” detent. My plan is to install quick connects only on the supply and return to the splitter comtroller so I can just connect my new controller mounted on my press frame. I’ve reinforced the frame. Again some welds are pretty but I feel they will hold. Once I can run the ram I will add more supporting. I have my ram designed with a series of 1/2” thick square stock that I will weld to the ram bolt. The pic only shows 3 but there is a 4th that just fits over the bolt shaft. They all gets welded to one large ram. The large angle will guide the ram up and down basically to keep the rod from turning. If I did my math right I’ll have about a 7” overall opening between my press plates. I figured the largest jig I will make would be 2” round stock for fullering. So I should have 3” of travel. Being a blade is only 1/2” thick that should be fine. For making damaskis I should have about 5.5” opening. I wouldn’t be welding a billet larger than 3” as I don’t think my forge could heat anything larger. Let me know what you guys think so far. 

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I’m trying to envision where you’re going with this but I’m lost on your ram guide.

Also, you welded a frame and already had a cylinder, but you bought a complete logsplitter with a gas engine to complete your build. If I understand correctly you then will only be using some valves, and the pump. That seems a tough and expensive way to source them. Although for a complete 27 ton logsplitter, if it’s new, that’s a great price.

Sorry if I’m misunderstanding you,

Steve

Edited by Steve O

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Ok I reread and had misread one of your posts, you will share the hydraulics between the two machines, use longer hoses, and you have decided to keep the gas engine now, sorry. 

Make sure the max fluidic pressure is the same or lower for the splitter as for your press cylinder. I saw for some of that companies splitters they ran at 3300psi pump output, but I didn’t see a spec for the model you bought.

But I still don’t understand how you are guiding the ram.

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Steve - Good Point! The specs do read 3500 psi on the detent for the splitter. However I am going to run a separate detent for my press that will be adjustable up to 3000 psi. So it shouldn’t exceed the max rating of my cylinder which is 3000 psi. Let me know if I’m wrong in my thinking. 

It is hard to see from the pics on how this will run but I’ll try to explain. The ram will slide over the bolt and welding in place. Once I can test run the ram up and down I will tack on the large angle to the bottom of the ram that spans the full width of my press frame. The angle is 1/8” smaller that the 4 vertical supports (width). So they should guided the angle as it travels up and down. I will weld on additional side guides so there is no play at all. Since cylinder is attached at the bottom with an integrated wide face plate I will not get side to side movement like a converted log splitter that hangs from the top of the ram. First reason why I chose this type of cylinder. From all the research I’ve done you don’t want any movement other than up and down. Not sure if that makes more sense. I’ll probably get the ram attached to the piston Thursday. 

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Hey Phil, I gotta ask what you're welding with. Something's not quite right. If you have any questions about your machine or process, let me know if I can help. 

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