Hydraulic press questions | KnifeDogs.com Forums

All of the things that Billy said with the following exceptions:

-Minimum 6" dia cylinder (the larger the diameter the lower pressure required on the hydraulic lines)

-Build in an adjustable "by-pass" valve, that is pressure adjustable...meaning that you can adjust the valve to by-pass when a specific line pressure is reached.

- For a hydraulic forging press, build the thing 2X more beefed up than you think it needs to be....and then build it some more!

When I built my last press, I used a 12" "I" beam with 1/2" flanges and a 5/8" thick web....and I still had to add 3/8" gusset plates between the flanges to keep it from flexing during use. (Mine is a "C" frame design....I just like them better, and they have a small footprint than an "H" frame press)

One thing that scares the daylights out of me is when I go into someone's shop and they are running a small diameter cylinder on a press (5" or less), and are running line pressures 3,000psi +! If one of those lines gets even a pin hole in it at that pressure....it will cut you in half like a laser! (Most hydraulic lines are only rated for UP TO 3,000psi, unless you get hoses special made, and those are out of this world expensive.) Have a look at Don Fogg's page and don't miss the 5 or 6 other pages with links at the bottom of the page.
http://www.dfoggknives.com/hydralic.htm

There is a booklet he sells there too which runs through specs and designs by an actual engineer.
-the Baston book

A pre made shop press is usually unsuitable because it achieves its high power with a large cylinder at a very slow stroke speed

A forging press is usually recommended to have at least 1 or 2 inches per second stroke speed so you can move metal while it is still hot.

If you start doing calculations you will see that it is easy to get a high tonnage, but at a slow stroke speed because of the volume of fluid required.
This takes a large pump and motor.
You may have to reach some sort of comprise on a slightly smaller 5" cylinder instead of 6".
It starts costing real $ to up your pump volume, motor HP and wiring size above 5 hp

Is 50 tons twice as good as 25 ? probably not as good as a fast 25

The larger size will allow you to run larger dies and keep the same PSI at the die level...but there must be a practical limit..

in the numbers Billy gave he is running psi is 21.5 tons

Buy the book , look at what others have done and do the calculations with what you can buy locally.
I would tend to stay with 5 or 6 inch cylinder, go larger on the pump volume and keep the pressure down to keep the stroke speed up so you can get more squeezes per heat in.
When the steel is hot, you wont' need huge pressures to move the steel and are better served by gradual reductions to preserve your patterns.
the difference between the pump volume at 5" and at 6" is significant.

Don Fogg's specs
10 hp dual pump hydraulic station pushing
16 gallons a minute at psi.
5" double acting hydraulic cylinder with an 8" throw.
Works out to 14.7 Tons

Indian George
SUPPLIER PART# DESCRIPTION COMMENTS
NORTHERN -C161 BARNES 2 STAGE PUMP -11GPM
-C161 PRINCE STANDARD 4-WAY CONTROL VALVE
-C161 7 GALLONS HYDRAULIC OIL TANK MUST CLEAN THE INSIDE WELL
-C161 RETURN LINE FILTER
-C161 SUCTION STRAINER THIS GOES INTO THE TANK
FITTINGS AND HOSES YOU WILL NEED 3 HI- PRESSURE HOSES AND LOW PRESSURE HOSE FOR THE RETURN.
-C161 GLYCERIN FILLED GAUGE 0-PSI
SURPLUS CENTER 10- ELECTRIC MOTOR I USE A 3 HP AT RPMS
09 HYDRAULIC CYLINDER I USE A 4 1/2" BORE X 8" STROKE WITH THE PUMP AND MOTOR SHOULD GENERATE 24 TONS

"If I ever build another one it would be a H press with a minimum 5" cylinder."
__________________


Eric Fleming
WIP with automated stroke timing
http://www.bladeforums.com/forums/showthread.php?t=&highlight=press

Material list
http://www.bladeforums.com/forums/attachment.php?attachmentid=&d=

Motor – 7.5 HP
Pump – Single stage 5.2 GPM (Single stage is necessary to get repeatable timing for an automated stroke)
Cylinder – 5” X 8” Stroke

calculations.
http://www.bladeforums.com/forums/attachment.php?attachmentid=&d=


**************


220V motors are practical in these sizes

Thanks for all the input from everyone. I notice most of you are using large horsepower motors. Is there a reason to use a large motor or would a 110v motor putting out pressure be enough? Maybe if we get enough information and pictures we can make this a show us your presses thread.

I would say that a 5hp motor is about minimum required. I started out with a 5hp rpm and then switched to a 5hp rpm. The quality of the motor also makes a huge difference. An elcheapo air compressor will over heat from the constant cycling. Spend the extra $ and get a good TEFC Leeson or Baldor motor.

I am running a 5" cylinder on my press. But would prefer to have a 6".

Also, as Ed said, A bypass or pressure relief valve is a must for safety reasons. A pin hole leak in a hose at psi will drill a hole through you...

Attachments

• steve kelly 043-1.jpg
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Thanks for all the input from everyone. I notice most of you are using large horsepower motors. Is there a reason to use a large motor or would a 110v motor putting out pressure be enough? Maybe if we get enough information and pictures we can make this a show us your presses thread.

"would a 110v motor putting out pressure be enough?"
Are you looking at premade hydraulic power pack units?
They are no good for forging, as I mentioined earlier, pre-made shop presses may generate enough force, but the ram speeds are too slow.
If they would work well, then everyone would use one and no one would be building presses.
Some people rebuild log splitters, but if you don't already have one to start with, skip that it's cheaper to start with parts.


Horsepower required is part of the calculations on Eric Flemings Excel Spreadsheet
http://www.bladeforums.com/forums/attachment.php?attachmentid=&d=

and I suspect that they are based on the specs in Bastons book
Horsepower =PSI X GPM X Efficiency Rate(100% used) /

Sure you could use less, but then you would have to get your RPM and GPM specs down and then you may not be happy with it.


On Baldor's website for example a 5 hp motor is not available in 110v, it's not practical.
(you may have a 110V air compressor that is listed as 5 or 7 hp or something crazy like that
but those are total BS numbers that they should have stopped using after the lawsuits.)
http://www.wisedan.com/aircomp.html

220v vs 110v
If you go down to a 3 HP motor, you can get a dual voltage motor that could be wired 110 or 220,
but at 110 it would draw 30 amps and need 35 amp breaker and wiring,
it is actually cheaper to go 220v

rpm motor will give you the most pumping volume as pumps are listed as displacement per revolution.

Why are you thinking 110 over 220?

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