Hydraulic press

I've asked others before but haven't got a satisfactory (to me) answer to my question so I'll try again.
Recently I have been interested in making a press. I have seen an Air/hydraulic jack that is air actuated for what I consider to be a very reasonable price.

Has anyone tried making a press out of one of these things? I already have a compressor, so it would be just a matter of building a frame and spendimg $90 to $150 for the jack. No motor, pump etc to deal with.

Does anyone see a reason it wouldn't work?

For $90 I can get a 8 ton (kinda small?) with a long stroke or for about $150 I can pick up a 20 ton unit.

Would 8 ton be enough for blade work? Or should I go for a bigger one?

I have most of the stuff for a regular press (BIG!) but it would be sooo much easier with the air/hydraulic unit.

Any advice?

Moldy