Dave Propst's H Frame Hydraulic Press

[Mayhem]

Now this is how you build a shop press:

http://davepropst.com/Article/Art6/Article6.htm

[EdK]

That thing is a work of art. Very nice, but it must have cost a fortune to build.

Thanks for posting the link.

Ed

[oldgoaly]

Check out his other things too like the sand blast cabinet. I haven't chatted with Dave in a few years. Everything he builds is well thought out and very adaptable to many jobs.

[aametalmaster]

Its nice but impractical for me anyways. If you did a certain job which you would never move the table that's fine but sometimes i move up or down to suit the job...Bob

[awemawson]

That's why I like my Epco 60 ton press. It has four huge acme threaded screws to lift and lower the 'platen' - these are linked on top by a chain and sprockets driven by a 1 HP motor. The screws run on thrust bearings when lifting / lowering but the bearings are on enormous springs that bottom out when the press is used so the force is transmitted by the bearing housing and not the bearing. A neat design that baffled me when I re-built it. It had been fire damaged and the heat of the fire softened the springs so the bearings were never in contact, and the chain drive thus wouldn't function. I had to have new springs made at vast expense - they are about five turns of 8 mm spring 'wire' but the rating has to be bang on to function correctly.

[TomG]

I definitely added that site to my links. Love the trolley arrangement on the cylinder.

Tom

[stevec]

(10-29-2013, 07:17 PM)aametalmaster Wrote: Its nice but impractical for me anyways. If you did a certain job which you would never move the table that's fine but sometimes i move up or down to suit the job...Bob

Bob, the number of precisely spaced holes up and down the columns indicates that the table can be moved.
How that could quickly and easily be done escapes me.
So it's impractical for me too.

[awemawson]

On one design I've seen, the ram is fixed to the table by an extension, then the pegs removed and the ram extended, then the pegs re-inserted. It means having a set of extension pieces for the ram nose though.

[Mayhem]

It is difficult to believe that he spent that much time and effort in the design and build that an easy means of adjusting the table hight was overlooked.

[dallen]

in this part of the article that I copied explains why the table is not easy to adjust for height

Quoted from his article.

For the uses this press sees, the above two characteristics are of much more value than any of the advantages a slip-fit pin connection provides. But in fact this adjustability with rigidity and strength does come at a price. Changing the lower cross-beam height to new positions it is not performed as rapidly as is the case with a slip-fit pin design. However, when a cross-beam height change is needed, a portable hydraulic lift table actually does the lifting and repositioning. This lift table is used instead of an integral cable winch system because that would interfere with end-load access and ram trolley motion. All that is required of the operator is to run the lift table up to the cross-beams, remove nuts from one end of each of the four shafts and pull the shafts, change the lift table height, then replace the shafts. The heavy work plate and even any workpieces, etc are left in place on the crossbeams The operation can be done by one person in five minutes versus about one minute or slightly less for changing beam height of a well-designed pinned frame with integral cable winch.

To suggest this particular press should have 'rattle-fit' pin connections and be fitted with a cable winch is to misunderstand its intended usage. It is to misunderstand the forces involved at the connections given the open-ended design. It is to be unaware of the other elaborate equipment in the shop and the type of work done with it as presented at the rest of this website. It is to attempt to find a solution to a problem that simply does not exist. This press design causes no disadvantage in our shop since this is not the only press available. This press is not a 'stand-alone' piece of equipment. Rather it is only one tool among many in a commercial fabrication operation. Therefore, when a job is more appropriately performed by a traditional, rapidly adjustable, pinned-frame press, that job is done in just such a press! On those very rare occasions when the job is more appropriately done in a large, high-tonnage press, that job is taken to just such a press at a nearby heavy fabrication shop. This press is not meant to be a one-size fits all, be-all, end-all device. No claim is made to that effect. On the contrary, this press was designed to very efficiently perform tasks that are specific to custom car fabrication as explained at Shop Overview . This press is but one small part of a larger group of tools that work togeth


DA