"carl mciver" wrote in message
nk.net...
"Ned Simmons" wrote in message
...
| It was about time I did that!
| They are http://metalworking.com/DropBox/PressDsn.jpg and
| http://metalworking.com/DropBox/PressDsn.txt
| The text didn't come out as well as I would have liked, but
it's the
| idea that's most important.
|
|
| I was wondering at first why you weren't just using the
| jack's ram directly, but I can see a few advantages to your
| design, the most obvious being flexibility in mounting
| tooling.

That's the plan. This can do the job of a much smaller press,
even an
arbor press, as well as something much heavier duty, all with the
same tool.
I like the versatility and real estate saved in my garage. Being
able to
change the press tonnage from nothing to incredible easily appeals
to me as
well. I can use a one ton jack just as well as I can a twenty ton,
and they
just sit in same place since they're all roughly the same height.

| The first thing I would suggest is to replace the single
| tube with gusset that you're using as the column with a
| pair of tubes spaced apart under the horizontal sleeve.
| This'll make a huge difference in the stiffness and
| strength of the column. (I hesitate to call it a column
| because columns are normally thought of as carrying
| compressive loads, while this member, even though vertical,
| is subject to bending loads that more resemble a beam.) To
| really stiffen it up you could add a web (or triangulation)
| between the two tubes, at which point you've got something
| that resembles an I-beam with tubular flanges (or a bar
| truss, in the case of triangulation.)

Ah, excellent idea. Would the same be gained by just welding
two tubes
to each other? The inner tube would be in tension under load, while
the
outer tube would be in compression. I just had the notion that I
could fill
the outside, "unused" tube with concrete, which resists compresssion
(and
buckling the walls of the tube,) but I'll have to cap the ends off,
of
course. Then again, one or two small I beams or channel between
them sounds
pretty strong too, with the outer tube full of concrete would be
good.
Resists twisting really well, too. Whaddya think?
Gusseting the horizontal tube would get interesting, of course,
but most
of that load just passes around it, rather than the whole thing
being a
cantilever beam. There's a hard to read note about the column
"wrapping
around" that tube, which passes the load around it nicely.

When I first starting thinking about this, before I was aware of
the PM
design, I had a much simpler design using an I beam as the column,
but I was
concerned about it twisting, so was kinda stuck. You've helped me
work that
out.

| Another thing that occurs to me is the possibility of a
| lever that you can actuate manually in place of the jack.
| Sometimes the feel of a manual press is preferably to
| having lots of force available.

That's one of those details that was so easy to implement, I
just noted
it in text, and the text pretty much washed out in the scan. With a
double
tube lever, I'd just weld on a couple pieces of tubes to the side of
the top
one and slip in a piece of pipe to suit. This way it's just as easy
to use
the press in manual mode or when necessary, just reach over and
start
pumping the jack, since the jack isn't attached to the upper lever.
There's
many times I suspect that the jack's job is over, and the rest of
the
operation requires less pressure, so all you have to do is just
reach up and
pull.

|
| Ned Simmons

Thanks for sticking with me this far through it! Your input has
been
invaluable.

One problem I see is the jack might have to be on pivots if the ram is
going to move any appreciable distance. The pivoting arm isn't going
to stay parallel with the pad the jack is sitting on, and the contact
point along the pivoting arm will change too. I suspect the ram may
tend to bind in the socket, too.

I'd be tempted to make a wood or cardboard model of the linkage first