DIY 20 tonne press

[Gazzar]

I'm going to build a 20 tonne press, using bits I've accumulated over the last few years.

I'm looking for tips and pictures.

I've also got a question:

I've been looking at commercial and diy designs using a bottle jack, and they all have the jack at the top, and springs to pull the lot back together after the pressing is done.

Why?

Why does the jack have to be at the top?

If it was underneath then the weight of the lower jaw in the the press would push the jack down it's self, saving on a component. And functually, how would it effect the use of the press to have the jack at the bottom?

Any other tips and pictures would be most welcome, as I'm suffering from a lack of thinking power at the moment!!

G.

[M&S]

Jack at the top your using all of the force for pressing (and overcoming the springs I suppose) and gravity will help the released component drop away.

Jack at the bottom your using some of the force to lift the component and what you're pressing will be pressed up and out, so would be left to possibly topple away rather than drop down.

Also your components will be sat on the table, and the jack pressing onto them. Nice and safe. I wouldn't fancy balancing components on the jack and lifting them up to something (clamping them).

[kkk2]

Hi Gary, in my experience with the bottlejack on top press it means if you have a big component to press something out of, there is room to do this. I'm not sure how it would work with the jack on the bottom, My biggest concern using the press is if something slipped and flew off the press, so I have made a wire mesh to protect the user somewhat

K

[zardos]

My thoughts on why the jack is at the top.

I think it's mainly down the jack being smaller than the base plate.

With the press being lower than your eyes it is easier to see around the item being pressed.

It is also easier to balance the component on the base plate than the small jack end.

But if you attached the base plate to the jack and had static attachments to the top frame you then you would have better visibility.

But then you would have a large base plate to guide up and down would be more difficult and as the base plate on some commercial press are actually bars with a movable base plate with holes/cut outs in to allow things to be pressed through.

Making this strong enough and movable would be a challenge.

But if you look at some of the cheap commercial pipe benders, these have the jack at the bottom and have return springs.

This suggests that the weight of the bend form and the pipe with gravity is not enough to return the cylinder.

The return spring will probably apply more force than gravity.

[nickwilliams]

The jack is at the top for a simple reason - so that you can load the press with the workpiece and it then does not have to move before the force is applied to it. If you have the jack underneath the work then the workpiece has to move up with the end of the jack until the press is closed before any force can be applied to it. It basically makes the difference between being able to use the press with only two hands or needing three.

I've recently made a press frame to enable me to press the suspension bushes out for my 90 re-build. I'm using an ex-RAF rescue kit as the basis of the hydraulics, but a Machine Mart body straightening kit would do the job.

I'll try to post some pictures later, after I've finished stripping down the LT230, which is this afternoon's job.

Nick.

[Gazzar]

The jack is at the top for a simple reason - so that you can load the press with the workpiece and it then does not have to move before the force is applied to it. If you have the jack underneath the work then the workpiece has to move up with the end of the jack until the press is closed before any force can be applied to it. It basically makes the difference between being able to use the press with only two hands or needing three.

I've recently made a press frame to enable me to press the suspension bushes out for my 90 re-build. I'm using an ex-RAF rescue kit as the basis of the hydraulics, but a Machine Mart body straightening kit would do the job.

I'll try to post some pictures later, after I've finished stripping down the LT230, which is this afternoon's job.

Nick.

Now, That makes sense. Thanks all!

Do post up pictures, I'll do the same if and when I do this!! Depends on how wet it is next week, the wetter, the more shed time i'll have.

KKK2, the cage sounds like a cunning plan, you didn't have that the time I was there, did you?

G.

[lrfarmer]

Hi Gary, in my experience with the bottlejack on top press it means if you have a big component to press something out of, there is room to do this. I'm not sure how it would work with the jack on the bottom, My biggest concern using the press is if something slipped and flew off the press, so I have made a wire mesh to protect the user somewhat

K

dont get it wrong a friend broke his arm and took half his ear off when something slipped.

[Les Henson]

You'll probably find that a normal bottle jack won't work upside down. I think you can buy just the ram part from the likes of MachineMart, and make the frame up yourself. Make sure your welding is up to scratch or things will go bang

Les.

[Gazzar]

You'll probably find that a normal bottle jack won't work upside down. I think you can buy just the ram part from the likes of MachineMart, and make the frame up yourself. Make sure your welding is up to scratch or things will go bang

Les.

Thanks Les, most of the bottle jack variety press have the jack right side up, so I was just going to copy that.

The welding will be strong, I've been going a lot recently, and my depth penetration, and general quality has improved to a standard I'm happy with. Not pro, but tidy enough. High amps and lower wirespeed should do the trick.

The bit that I'm concerned about now is the die and former tooling, and how that fits into/onto the lower Jaw. I'm sure I'll figure it, though.

G.

[nickwilliams]

Here's one wot I made earlier...

The sides are 6mm x 100mm channel, the top and bottom are welded up from 12mm thick plate. The strengtheners in the base (top is the same) are probably overkill for a 10t ram, but that's the way I like it, and I have access to a 50t ram as well if I ever want to use it.

The design is such that none of the welds are actually load bearing. I decided to bolt it together rather than weld it, partly so I could dismantle and store it to take up less space, but also because 4 x M16 8.8 bolts are quite likely stronger than any welds I could easily achieve, and having decided to make the top cross piece movable, it made sense to bolt the bottom one in place as well.

The holes for the bolts were drilled with a mag base drill, and the only thing I would do differently if I made another one is that rather than mark out and drill all the holes in the side channel independently of the ones in the cross-pieces, next time I would drill the cross pieces first and then drill the holes in the channel through the cross pieces. As it is, I had to re-drill some of the holes since the precision with which the mag drill can locate the holes is not high enough for them to all exactly line up. I'm sure that the resulting oval holes don't significantly alter the strength of the frame, but the fact that they are not round irritates my tidy mind!

Nick.

[Gazzar]

Heavy construction Indeed!

g.

[Gazzar]

The hole drilling is a concern of mine, mainly as it could be quite time consuming.

I was wondering if I could cut slots into the "c" Channel instead. This I could do with the angle grinder.

If I cut a slot, at an angle, into the "c" channel side, such that the pin on the crossbar causes the frame to tighten (a bit) under pressure, then I can't see it being weaker than a hole.

I think I'll do a picture, as I'm somewhat inarticulate with words.

G.

[FridgeFreezer]

We've got a "wrong way up" one that a normal 20T jack sits in the bottom of, works fine.

[Gazzar]

We've got a "wrong way up" one that a normal 20T jack sits in the bottom of, works fine.

It might come to that!

Anyway, I've made some progress, I've collected up the various bits of steel. The C channel is fine, but the rectangular box I was going to make the jaw from is too light, it's only 2.5mm wall.

So, I'm going to use a RSJ instead, bit heavy, but I hope the springs will cope. Failing that it is going to be "wrong way up".

Picture:

Nothing welded yet.

The top is going to have the box welded into the C of the channel as sides,and a strip of 10 mm steel with a piece of angle welded along the back as the top, with this UNDER the box so that, under pressure, the top pushes into the side.

G.

[Gazzar]

Well, it's not finished, but it has been pressed into service (sorry).

Some pictures:

It works well, however, I don't think that normal springs will bring the ram back up.

I've chanced upon some old two way rams, and a hand crank for them, and may incorporate them into the plan.

G.

[Vit rich]

Iv built two of them now, one for the workshop at home and one for my bigger workshop where i keep my truck. I only have photos of the home workshop one, but il try and get the others tomorrow.

Rich

[Ex Member]

None of that steel is strong enough for that jack.

[Gazzar]

I've no doubt you are right, but as long as it's stronger than what I'm working on then it will suffice, also it is a LOT thicker than the commercial offerings I've seen.

The channel is 6mm, the top press beam is two pieces of 6mmish box welded along the centre - so that the main force is along the centre.

The pins are too thin, series shock mountings, but will do until I obtain some stronger thicker stuff - like shackle pins.

The upper assembly is strong enough, a piece of 10mm strap braced triangular with some 5mm angle. It isn't going to bend.

I will monitor the joints and brace as appropriate.

Any advice would be welcome.

Oh. and that press by RIch is great.

G.