Diy hydraulic shop press

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When people are talking "press forces and ratings" it is easy to quote numbers without really appreciating what they mean. And if the frame is distorting then it may be strong enough not to fail, but is certainly not STIFF enough to hold its shape!

...snip...
Of course, Manufacturers have reputations, safety legislation etc. to consider when they make and rate their goods. We do not always follow those rules (do we even know the rules?) when we make stuff in the workshop, so just be careful.
K2 ;)

While I absolutely agree with what you say I wasn't kidding about the rating (8 posts back up). Here's a vid of a similar press in action. Note the die area he is squeezing with - he's not punching. Note at about 2:30 how the stiff high carbon steel heats back up to yellow with the internal molecular friction of the applied force. Like you say however this requires a massive stiff frame and a well thought out rigid design. As you allude, most weapons have a "stored energy spring" of some sort (metal, air etc) as the initiator! A weak frame could also be it's own trigger.

 
When people are talking "press forces and ratings" it is easy to quote numbers without really appreciating what they mean. And if the frame is distorting then it may be strong enough not to fail, but is certainly not STIFF enough to hold its shape!

A 1.5Tonne jack will lift one end of your family car easily and safely. This force to lift - say the front under the engine/axle - would be on maybe a 2inch piston. But not lifting 1.5 Tonnes, as the load is not the jack's safe (quoted) limit.
My Compact Suzuki is only 1.5 Tonnes when wet! - Roughly 1 Tonne front, 1/2 tonne rear axle.
A Mitsubishi Truck may be able to pull a 3.5 Tonne Horse box - including the horse. It will only weigh maybe 2.5Tonnes itself? - But is rated for braking to be able to stop the gross weight of 5 tonnes... - even though you may drive so you only use maybe 1 tonne of braking force - fully laden? (0.2g decelleration to stop the horse falling over?).
A truck for hauling a 30 Tonne trailer may be 10 Tonnes ?....
The trailer complete with all the goods on board may be up around the 30 tonne region... So a big hydraulic system from and old truck jack is what we are talking about to apply a 30 tonne lift... Just look at how much metal is used on the truck's axle members etc. to get a good idea of the forces required by seeing the metal used to manage these forces. As the 30 tonne trailer will have maybe 3 axles, each axle is managing 10 tonnes... Is the 30 tonne press built like a truck axle or stronger?
Cheap mild steel has a 20 tonne tensile strength, good stuff has a 40 tonne tensile, and "stronger steels" up to 100 tonne.... but that is the Ultimate Tensile strength derived in tons per square inch.
To make a 30 tonne jack, you need everything stressed so you have way less than the tensile strength of the material managing the forces. A 1 inch 80 tonne bolt will strip threads or snap at maybe 30 tonnes, as there isn't enough steel to withstand 80 tonnes: that is just the rating of the steel used to make the bolt. And threads have stress raisers that quadruple the stress in the material, so you can consider a 1/2 inch bolt in "80 tonne steel" to go "ping" at maybe 8 tonnes? - Depending of tensile/bending/shear loading...
The "20 Ton" press where I worked as a lad had a pressure gauge - indicating the hydraulic pressure applied on the 3 1/2" ram.... It had 2 main steel legs at least 6" diameter to take the tensile forces when in use, and retain the STIFFNESS required for any off centre loads. One day my rig slipped because it was not EXACTLY square and true to the alignment of the pressing job, and flew across the workshop and hit the steel cladding with a loud "Bang". - Nowadays we have guards in industry, but the Boss gave me a stern lesson in safety and care when doing any job after that.
Looking at the frames shown, I guess they will likely distort after little more than 1 tonne applied load? I'm OK, watching on the computer, but please be careful if trying to apply such huge loads as you are discussing. When the load is applied the frames distort and then everything is a big spring of stored energy awaiting some point where it goes out of alignment and slips, when it fires small metal bits like a catapult!
I suspect your 2 tonne jack is only applying 1/10th Tonne load to press in a bearing, or it would destroy the bearing and housing?
I have been in a small group where we used a car as a jack to press-in a small job, simply jack the car up (front-end with a screw jack), fit the bits beneath the frame and road (with bricks and wood packing) then lower car gently (easy with a screw jack) and it pushed the shaft into the next bit of the assembly. (may have been a bearing? - I can't remember!).
I removed and fitted crankshaft bearings on motorcycle crankcases using similar methods - in a stair-well between 2 walls at the apartment block where I lived. More than 2 tonnes load would have pushed the walls out!
So be careful with how you describe the strength of these flimsy frames...
Of course, Manufacturers have reputations, safety legislation etc. to consider when they make and rate their goods. We do not always follow those rules (do we even know the rules?) when we make stuff in the workshop, so just be careful.
K2 ;)
Very good post . Bottom line is check things before stressing lifting a one ton dual rear wheel truck with half ton aluminum jack is not a good idea . I now have a bigger jack LOL glad I didn’t get under that one. Also inspect jack stands I’ve now broken two they don’t like shock loads China made junk I had a big goose neck car trailer with big unknown hydraulic power tongue jack. It blew a hydraulic line while hooking up in truck bed dropping the hitch in the bed big dent. Oil sprayed everywhere . The age old rule here is don’t get under any thing you can’t lift yourself without heavy duty support .
 
Hi Daryl, Yes, that is a proper press! No visible deflection anywhere. I noted that at one point the billet was so large beneath the ram that the force required to compress the billet was at the limit of the press, so he nibbled the billet instead so as to only compress smaller areas of billet at a time.
Excellent demonstration!
K2
 
Hi Daryl, Yes, that is a proper press! No visible deflection anywhere. I noted that at one point the billet was so large beneath the ram that the force required to compress the billet was at the limit of the press, so he nibbled the billet instead so as to only compress smaller areas of billet at a time.
Excellent demonstration!
K2
Here's another danger to watch for. Oil injection caused by damaged hose. What can seem initially as a minor injury can, in the end, be fatal if not dealt with properly. Keep away from leaks! Test with a board. Always something to consider near hydraulics.



On a lighter note, showing the forces work both ways, I always remember jacking up a '75 Ford LTD (terrible for rust) to change a tire. I put the jack in the bumper slot and started jacking. After a while I noticed that, while the bumper was up nice and high, the rest of the car hadn't moved. One can only imagine the amount of my eye rolling here. After finding/using a scrounged scissor jack under the axle (BTW two studs sheared off the wheel) to finish the job and change the wheel I had to throw the huge massive bumper in the trunk to get home. That was the "throwing in the towel" last drive of the Ford LTD. ;-)
 
The old rusty ford reminds me of my former boss. He still has a mid to late 70’s 3/4 ton 4wheel drive truck with snow plow. I don’t think it’s ever been washed . Being a minnesota truck there is plenty of salt on the roads in winter plus he regularly salts his steep driveway the bed floor is long gone replaced with palette and plywood there are almost no sides left on the bed no wheel eels the remaining bed is held on with a pair of ratchet tie downs with an old rotted palet between the remaining forward part and the cab . Floor boards are just that plywood , replaced yearly the hood has several rust holes now . Recently I saw he had a couple pieces of plywood across the remaining hood. Attachment unknown I YHINK the newest thing on it is the plow pump we replaced about 10 years ago. The tires are so old I don’t know how they hold air we did put tubes in a couple times he may have filled them with the foaming insulation years ago we had lunch a couple weeks ago and I asked about the truck believe it or not it still runs we had near record snow this year . He said it struggled. Bit but by careful use of the plow he managed a winter . His shop truck is a bit newer but is pretty much gone below the belt line. I would not lift either truck with a jack.
 
The old rusty ford reminds me of my former boss. He still has a mid to late 70’s 3/4 ton 4wheel drive truck with snow plow. I don’t think it’s ever been washed . Being a minnesota truck there is plenty of salt on the roads in winter plus he regularly salts his steep driveway the bed floor is long gone replaced with palette and plywood there are almost no sides left on the bed no wheel eels the remaining bed is held on with a pair of ratchet tie downs with an old rotted palet between the remaining forward part and the cab . Floor boards are just that plywood , replaced yearly the hood has several rust holes now . Recently I saw he had a couple pieces of plywood across the remaining hood. Attachment unknown I YHINK the newest thing on it is the plow pump we replaced about 10 years ago. The tires are so old I don’t know how they hold air we did put tubes in a couple times he may have filled them with the foaming insulation years ago we had lunch a couple weeks ago and I asked about the truck believe it or not it still runs we had near record snow this year . He said it struggled. Bit but by careful use of the plow he managed a winter . His shop truck is a bit newer but is pretty much gone below the belt line. I would not lift either truck with a jack.

Well that LTD lived on a bit longer as the basis of my Stickler wood-splitter. In high school shop (1970's) I completed everything I was supposed to so I got to do "an extra". I chose a new wood-splitter design that I saw in a Harrowsmith magazine called "The Stickler". Basically an oversized wood-screw that was driven off an axle. I sized it for the LTD. I learned threading on a taper and internal threading with this. Turns out the real Sticklers were manufactured reasonably close by so I went out to see the factory (shop). The president was so impressed I was taking this on as a kid he gave me a genuine replaceable tip (they're hardened). It's held in by a spirol pin. You can see it in the pic. I found that it wasn't much faster on wood like birch but at the time Dutch Elm disease was killing big old Elm trees all over. We had lots on our farm and dead Elm is fantastic for heating, lots of heat and long burning. Elm, however, is near impossible to split with an axe. The grain is fibrous, meanders everywhere but a straight line and the fibers are clingy. The Stickler was perfect for this. You'd, chock the far drive wheel, jack up the car (scissor jack), remove the near wheel, bolt on the stickler, fire up the car and put it in drive, sit on the removed wheel and slap wood pieces at 45deg (bottom braced on the ground) against the spinning tip. It would pull them on and split them easily. For a big log you'd work around the massive 2-3ft dia splitting off pieces. Every once in a while though you'd dive in a little too deep and end up splitting the 2-3ft log in half all at once. That got a little scary as the engine would slow and the differential would start to load up and you could feel the car trying to move as the log "cracked" and "popped". Being a high school project I didn't have the fancy kill switch that the bought product came with. In the end we never needed it but there was a few times I was worried that LTD was going to drive itself off across the field with 3 wheels and an Elm log with us running after it.

Anyway, that was almost 50 years ago. My high school shop project Stickler still exists (pic), the LTD does not. This Stickler reflects the very original "Stickler" design and not the subsequent 2nd gen ones you see pictures of on the net.
 

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