rebuilding a hydraulic press

A while back, I got a hydraulic press "kit" at a garage sale. Hydraulic components (pump, hose, pressure head, gauge) all
still in their original packaging, unused. All of the steel parts in like-new condition, never unassembled, with two exceptions: no table, and the head cross-piece looked like it had been used for target practice with a BFH.
Built a new head assembly and a table, and put everything together. Looks nice, but I discovered another problem: the holes in the uprights aren't aligned properly. Found this out when my nice flat table wobbled on the pins. Turns out the hole on one side of an upright may be 1/32" or so above or below the corresponding hole on the other side, so at any position I checked, I may need 1/16" or more of shims to get the table to stop wobbling. But while it's now steady, it's not square vs the uprights and may be off by 1/8" in 12" or so in either or both of left-right and front-back vertical.
I don't have a die grinder (no compressor, either), so looks to me like I clean the holes up with a big rat-tail file.
Or is there a better way to fix things?
Tove
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Tove Momerathsson wrote:

There are lots of things you could do, many of which may be too much work. Let's see. You could put a backing bar behind the holes and plug weld them solid and then start over and bore them true. Or you could remove the table, feet & crossbar (leaving you two vertical columns) and set each up on the mill and bore each hole to a larger size, boring right through so they'll be aligned (check your mill head is trammed). Or you could add braze to the bottom of a hole bored too low, and then file the hole true.
Or you could remake the columns. Which is exactly what I'd do.
Grant
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An electric die grinder or even a drill with a good bur (rotary file) will be a lot faster but a good big file is not a bad idea. You may find that the table or frame is flexible enough to sit okay with any normal pressure.
Don Young
Don Young
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First question I ask is what will you use the press for? If it's like mine, I use it to push bearings in and out etc. A misalignment as small as you describe isn't a problem for me.
Is the error the sam all the way up the adjustment? If so, simply shim the supports to set them level and wobble free and weld the shims in place.
If the error varies through the adjustment, you've got a bigger problem. You either re-shim the table everytime you move it, change or make new uprights. I certainly wouldn't want to file mine. They're about 5/8 thick with a lot of 1" clearance holes.
If you can live with it, do so.
John
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John wrote:

It'll be used mostly for building tools and small live-steam locos, for press-fitting wheels onto axles, broaching keyways, probably some bearings, straightening a few feedscrews in old machines. That's what comes to mind.
The error seems to vary from level to level, though I didn't check many. Mostly because when I discovered the problem I said "Oh $#!%" and quit for the night.
Something I considered was making four eccentrics, 1" pieces of 1.25" dia crs with pin-sized holes drilled 1/8" off-center. There'd be one under each corner of the table and you just turn them until the table is lined up squarely. The drawback would be that the area of contact between an eccentric and the table wouldn't be much and I'm not sure what would happen under pressure. May just try it and find out...
Tove
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I come back to the question of do you need a high level of accuracy? The operations you've listed don't need it. They should all self align. Indeed to try to force them into alignment in the press is wrong. You mentioned an error of 1/8" in 12". That shouldn't be an issue for these jobs. I admire you wanting to get things spot on right but is it worth it? I would say not.
John
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John wrote:

I see your point, but now I'm puzzled. Possibly because I think of a press as a BFH with a lot of finesse.
What type of work would _need_ a high level of accuracy?
Tove
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Tove Momerathsson wrote:

A hydraulic press like this is just like the BH you describe but can position things accurately in the vertical axis. It can push to a measured point and stop where a BH stop is governed by the resistance it meets. That makes it very useful for straightening shafts, positioning bearings, etc. What it doesn't do is locate well in either horizontal axis. Here you want the assembly to float and find its own centre. For example, if you are pressing in a bearing and the housing is strapped to the press table and the bearing is rigid to the press ram, if the two aren't perfectly aligned you get a fight and someting has to give. You can't push a bearing into a housing a few thou off centre. much better to let everything find it's own location. The only work that need a high degree of lateral accuracy is punch or die work. These presses are generally not best suited to this being too slow. If you must do it, a purpose made jig is a better sloution. When pressing in bearings, etc, I always use a short floating shaft under the ram. However, DO make sure it's well located. I was using a 5/8 cap head for this once and had about 5 tonnes on it when it kicked out. Fortunately, it went away from me. When I found the remains, it was bent though 45deg and the end had blued as it slid off the ram. I've also had bearings shatter and castings break sending shrapnell around the workshop. I now wear safety specs as a minimum. These things are dangerous. Treat them with respect. Once you see what one can do it makes a 14lb hammer look like a toy.
John
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might not be level.
A frame can shift by that much - shim up one foot to match the other. It might adjust then or under strain - and then you have it.
Like a lathe - four feet - one not touching the ground...
Martin
Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Life; NRA LOH & Endowment Member, Golden Eagle, Patriot"s Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member. http://lufkinced.com /
Tove Momerathsson wrote:

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