source a press/vice screw for large-ish bookbinding pres?

[jkn]

Hi all I have a yen to (someday) build a bookbinding press. One of the mainstays of this is of course the press screw which does the pressing. I'm wondering where to get a large example of one of these from. I've seen vice screws on (eg.) the Axminster website, and I'm sure these could be turned to this purpose. They are spec'd at around

28mm diameter. If I were to decide I needed something a bit larger than this, any idea where to find one?

(Any links to plans or ideas for building such a beast also gratefully received)

Ta jon N

[Owain]

There are jolly big screws on the bottom of some acrow props for adjusting them to exact length required. If they can hold up walls they should be able to extert considerable force.

Owain

[Cicero]

================================== Most hydraulic 'bottle' jacks for cars have a screw section at the top for fine adjustment. You might be able to adapt one of these but it might be better to use the hydraulic action instead of a screw. You can see the general idea here:

here:

[nightjar]

Any decent engineering workshop should be able to run you one off. I used to make some very pretty ones in brass, with all the other fittings, for a chap who did fore-edge painting and sold presses for other people who wanted to try their hand at it.

Colin Bignell

[jkn]

[...]

I had wondered about using a bottle jack, but was concerned about the return of the table, and a few other things. FWIW I've just come across a design for a press based on one on t'web:

quite suitable for my purposes, thanks...

J^n

[Cicero]

================================== That one looks quite good, although the return springs (bungee cords) might not give a smooth return with the possibility of the top plate tilting and jamming. Nonetheless, it's a clever and simple way of doing the job - possibly a bit dangerous as those cords will need to be under considerable tension to retract the column of a bottle jack.

Cic.

[jkn]

Hi Cic,

The smoothness of the return doesn't bother me too much. When you say ... 'retract the column'... I guess you're simply referring to the bungees having to lift the combined weight of the Jack + platen? Yes, this is something I wondered about.

Is it possible to use a bottle jack upside down? if so, you could fix it to the top of the frame, pointing downwards, and the bungees would only have to lift the platen, and the bit of the bottle jack that has just been 'released' ... whatever that's called.

J

[<me9]

Why not make the top plate fixed, and use gravity to retract the lower plate? Is there anything WRT bookbinding to require the bottom plate to be fixed?

[jkn]

Hi there

Yes, this is a design idea I have been thinking about. A couple of possible points:

- it starts to make the thing a bit top-heavy, which is not so good.

- The 'moving' plane has to have a bit of float to it, and in this design that would be the part which carried the whole book, prior to it coming into contact with the fixed upper plane. I'm not sure if this is impractical for bookbinding (I'm not an expert in the art!)

More thoughts welcome - ta.

J

[Cicero]

================================== I don't think it's just a case of lifting the jack and platen. The bungee cords will have to force the jack's column back down into the housing. This requires considerable effort, which is usually applied by the weight of a vehicle or other load. I think you would have to experiment to see if the bungees were strong enough to do this or decide to do it by hand. That shouldn't be a real problem unless you go in for mass production with a time and motion programme in force.

I don't believe the average jack will work upside down. Whilst making a small press recently to remove car stub axles I came across the information that most of the common car type hydraulic jacks will only work on their side if the handle side of the jack is facing downwards. This restriction would seem to suggest that they won't work upside down but it's worth testing individual jacks - under load - to see if they will do so.

Cic.

[Andy Dingley]

[jkn]

Hi Cic.,

All fair points. You could have a separate non-elastic rise mechanism

- a cord on a cam or something - such that you release the bottle jack and then raise the platen in a separate operation. But this is starting to get over-complicated IMO.

I too strongly suspect they won't work upside down. I'm starting to think that the original plan of a decent press screw may be the best way to go ...

Jon N

[Cicero]

=================================== I think you could get over the lifting issue by using a single lever which could be strong enough to retract the jack column and raise the top platen in one movement.

I would suggest that you check the capacity of the vice screws from Axminster before you buy. The screw *thread* is actually 23mm diameter (not 28mm - just measured one I've had waiting around for some time). The

28mm referred to in the catalogue is the internal diameter of the handle part - you're supposed to supply your own 28mm cross handle to go through that. These vice screws are really not intended for applying serious pressure (I'm guessing) and would probably be damaged if you tried to apply pressure over a large area such as you're considering.

There are screw jacks and ratchet jacks on the market which you might consider which are obviously designed for heavy work, unlike the Axminster range. You might use the original press you found as a prototype and work out how to replace the bungee cords with a lever as I've suggested.

Cic.

[jkn]

True, if it could be made elegant.

Thanks - that's useful to know. They did seem a little thinner than advertised from the images I'd seen.

This guy does a slightly beefier one for about twice the price

'm not sure just how much pressure I'll need, and the other thing to bear in mind is that this depends not just on the screw; old presses often have large cast-iron plates on the back of the floating platen, to spread the load I assume. This implies that both platens should be pretty damn rigid. I've seen a few images of homemade presses and they don't seem to take this into account...

J

(using Gentoo Linux, as it happens! ;-)

[Cicero]

=================================== The rigidity is usually achieved by a 'web' of stiffeners (much like a spider's web or wheel spokes)to reduce the weight of the platen and to ensure that the edges are under the same pressure as the centre. You can see that the example you cited uses an extra thickness of timber to achieve this.

That extra thick vice screw you found *might* be the answer but of course the pressure generated actually depends on your personal strength and how well you can anchor the whole press whilst you're twisting the screw. I think you would create a better working tool by following your original idea of an hydraulic jack especially if you can work out a satisfactory lever system for releasing the pressure. Personally I would not feel safe using the bungee cords as they would sooner or later break down in use.

Cic.