Looks like a punch press similar to this http://tinyurl.com/f5yj4 is
following my son home tomorrow afternoon. I know little about these units.
Where do I go for beginner info on what all I can punch and what dies etc. I
need. How do capabilities compare to an iron worker, shear, press brake??

I got the unit for scrap weight value or less, I'm just hoping its not a
boat anchor for the shop. I've got enough of those already.


Karl

"Karl Townsend" remove .NOT wrote in
message .net...
Looks like a punch press similar to this http://tinyurl.com/f5yj4 is
following my son home tomorrow afternoon. I know little about these units.
Where do I go for beginner info on what all I can punch and what dies etc.
I need. How do capabilities compare to an iron worker, shear, press
brake??

I got the unit for scrap weight value or less, I'm just hoping its not a
boat anchor for the shop. I've got enough of those already.


Karl


Oh boy! Nice press! What do you want to know...specifically? It's not any
of those other tools but it is only limited by your imagination. First,
check the safety systems; then the bush in the flywheel and the crank
bearings. Make a die that punches out saleable parts and sell the parts for
a profit. Count fingers constantly!

Karl Townsend wrote:

Looks like a punch press similar to this http://tinyurl.com/f5yj4 is
following my son home tomorrow afternoon. I know little about these units.
Where do I go for beginner info on what all I can punch and what dies etc. I
need. How do capabilities compare to an iron worker, shear, press brake??

I got the unit for scrap weight value or less, I'm just hoping its not a
boat anchor for the shop. I've got enough of those already.


Karl




The press is fine, the dies will kill you on cost.

Suggest checking out used book stores for punch and die books although
there are probably also some new ones on Amazon. Not much use for 1-off
type things although you could probably scab together a bar shear or
something. You might be able to angle shear also but again, the die
block starts getting expensive. It also has some potential to flatten
things without much investment in dies. Best to look into something
that you can sell 100,000 of on e-bay and invest in the die.

Koz

Karl Townsend wrote:
Looks like a punch press similar to this http://tinyurl.com/f5yj4 is
following my son home tomorrow afternoon. I know little about these units.
Where do I go for beginner info on what all I can punch and what dies etc. I
need. How do capabilities compare to an iron worker, shear, press brake??

Oh that's way cool. One suggestion, at least semi-serious: make a simple
post and top pad and you have a really bad-a**ed planishing hammer.
Sneer at people with their wussy English wheels. Get all carried away
and make shrinking/expanding dies, start making ashtrays out of 1/4"
plate. Well, maybe not that last one.

--
Fred R
"It doesn't really take all kinds; there just *are* all kinds".
Drop TROU to email.

Oh, I forgot...I use one of my 60 ton to make schnitzel really, really fast!

--There's a monthly trade pub called "American Tool, Die & Stamping
News", probably from Taunton Press or someone like them. It's free and has
some good articles on how to use a press.

--
"Steamboat Ed" Haas : Concave, convex, con
Hacking the Trailing Edge! : carne: all is Zen..
www.nmpproducts.com
---Decks a-wash in a sea of words---

Oh, I forgot...I use one of my 60 ton to make schnitzel really, really
fast!

We haven't got another Kraut in the group? (My grandparents didn't speak
English till the end of '41)

FWIW, I think I'll pass on this unit. The scrap guy gets it. Just don't have
room for another big tool I won't use.

Karl

Dont make it into a planishing hammer, or try to forge with it- unlike
planishing hammers or power hammers, punch presses are not meant to hit
things and bounce back- they break, and pieces fly thru the air. Not
healthy.

Punch presses are designed for high production stamping and punching
with dedicated dies. As mentioned the dies are the big money item.

You can buy some premade die sets that are blank- you add your own
punch, or forming tooling- like this one from
MSC-http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=1178&PMT4NO=6454694&PMT4TP=*ITPD&PMI TEM=03225083

This company also makes a lot of cool tooling that you could buy, if
you have lots of money, or copy if you have a good machine
shop-http://www.vogeltool.com/

It is not an ironworker, a shear or a press brake. It hits once, hard.
Always the same hardness- so it isnt good for fussy bending. You could
make a bending die, but it would need to be sized for the exact
thickness of material you are bending, and the right angle.
Same with shearing- it will shear, within its capacity, but its tricky
to do freehand work on it without losing your free hand.

As far as books- there arent too many- but the best place to look is
probably abebooks.com- thats the national database of used bookstores.
A few books I have that cover the use of punch presses, but are pretty
technical-
If you can find it, the Bliss Power Press Handbook has some info.
And Practical Design of Manufacturing Tools, by the American Society of
Tool Engineers, Mcgraw Hill, has some info.
But punch presses were never designed for the home user, so there isnt
much in basic books- there are some technical books on die design, but
use of the machines was usually taught on the job.

Dont make it into a planishing hammer, or try to forge with it- unlike
planishing hammers or power hammers, punch presses are not meant to hit
things and bounce back- they break, and pieces fly thru the air. Not
healthy.

Punch presses are designed for high production stamping and punching
with dedicated dies. As mentioned the dies are the big money item.

You can buy some premade die sets that are blank- you add your own
punch, or forming tooling- like this one from
MSC-http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=1178&PMT4NO=6454694&PMT4TP=*ITPD&PMI TEM=03225083

This company also makes a lot of cool tooling that you could buy, if
you have lots of money, or copy if you have a good machine
shop-http://www.vogeltool.com/

It is not an ironworker, a shear or a press brake. It hits once, hard.
Always the same hardness- so it isnt good for fussy bending. You could
make a bending die, but it would need to be sized for the exact
thickness of material you are bending, and the right angle.
Same with shearing- it will shear, within its capacity, but its tricky
to do freehand work on it without losing your free hand.

As far as books- there arent too many- but the best place to look is
probably abebooks.com- thats the national database of used bookstores.
A few books I have that cover the use of punch presses, but are pretty
technical-
If you can find it, the Bliss Power Press Handbook has some info.
And Practical Design of Manufacturing Tools, by the American Society of
Tool Engineers, Mcgraw Hill, has some info.
But punch presses were never designed for the home user, so there isnt
much in basic books- there are some technical books on die design, but
use of the machines was usually taught on the job.

Dont make it into a planishing hammer, or try to forge with it- unlike
planishing hammers or power hammers, punch presses are not meant to hit
things and bounce back- they break, and pieces fly thru the air. Not
healthy.

Punch presses are designed for high production stamping and punching
with dedicated dies. As mentioned the dies are the big money item.

You can buy some premade die sets that are blank- you add your own
punch, or forming tooling- like this one from
MSC-http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=1178&PMT4NO=6454694&PMT4TP=*ITPD&PMI TEM=03225083

This company also makes a lot of cool tooling that you could buy, if
you have lots of money, or copy if you have a good machine
shop-http://www.vogeltool.com/

It is not an ironworker, a shear or a press brake. It hits once, hard.
Always the same hardness- so it isnt good for fussy bending. You could
make a bending die, but it would need to be sized for the exact
thickness of material you are bending, and the right angle.
Same with shearing- it will shear, within its capacity, but its tricky
to do freehand work on it without losing your free hand.

As far as books- there arent too many- but the best place to look is
probably abebooks.com- thats the national database of used bookstores.
A few books I have that cover the use of punch presses, but are pretty
technical-
If you can find it, the Bliss Power Press Handbook has some info.
And Practical Design of Manufacturing Tools, by the American Society of
Tool Engineers, Mcgraw Hill, has some info.
But punch presses were never designed for the home user, so there isnt
much in basic books- there are some technical books on die design, but
use of the machines was usually taught on the job.

As others mentioned, dies are the expensive part. Don't even THINK about
using it for hammering or planishing, you will bend the crank on the
first hit. You unit will likely have a 3" stroke, the force varies with
the cosine of the crank angle, max force is at the bottom of the stroke
(not in the middle!) The tonage listed is the max the unit will
withstand without bending or breaking.

Comparing to an iron worker is apples and oranges. A punch press is high
volume with fixed tooling, an iron worker is low volume and universal.
A punch press will run something like 70 strokes per minute, crunching
out smaller parts, one per hit. You can also get notching and piercing
dies that do good work on tubing.
http://www.vogeltool.com/piercing.html

While it is not required, it is very good practice to mount all your
dies in die sets. IIRC, you are near Minneapolis. I have seen stacks of
used dies and die sets at one of the suplus dealers, forget which one.
Sample:
http://www.enomotousa.com/guidemax/stamping_die.html

Warning: a punch press is a SERIOUS tool that has a disasterous safety
record. Proper guards, double palm buttons, light curtains, etc are
MANDATORY!!!!!! A 10 ton unit like you showed will move 3" in the 400
milliseconds after it is tripped. Your hands are either clear of the
machine or they are gone.

Karl Townsend wrote:
Looks like a punch press similar to this http://tinyurl.com/f5yj4 is
following my son home tomorrow afternoon. I know little about these units.
Where do I go for beginner info on what all I can punch and what dies etc. I
need. How do capabilities compare to an iron worker, shear, press brake??

I got the unit for scrap weight value or less, I'm just hoping its not a
boat anchor for the shop. I've got enough of those already.


Karl

Oops! The picture you showed was a 35 ton, not a 10 ton like I assumed.
2-1/2" stroke, but it runs UP TO 110 strokes per minute. That is FAST.
Notice the double palm buttons for safety. Sorta.

RoyJ wrote:

As others mentioned, dies are the expensive part. Don't even THINK about
using it for hammering or planishing, you will bend the crank on the
first hit. You unit will likely have a 3" stroke, the force varies with
the cosine of the crank angle, max force is at the bottom of the stroke
(not in the middle!) The tonage listed is the max the unit will
withstand without bending or breaking.

Comparing to an iron worker is apples and oranges. A punch press is high
volume with fixed tooling, an iron worker is low volume and universal.
A punch press will run something like 70 strokes per minute, crunching
out smaller parts, one per hit. You can also get notching and piercing
dies that do good work on tubing.
http://www.vogeltool.com/piercing.html

While it is not required, it is very good practice to mount all your
dies in die sets. IIRC, you are near Minneapolis. I have seen stacks of
used dies and die sets at one of the suplus dealers, forget which one.
Sample:
http://www.enomotousa.com/guidemax/stamping_die.html

Warning: a punch press is a SERIOUS tool that has a disasterous safety
record. Proper guards, double palm buttons, light curtains, etc are
MANDATORY!!!!!! A 10 ton unit like you showed will move 3" in the 400
milliseconds after it is tripped. Your hands are either clear of the
machine or they are gone.

Karl Townsend wrote:

Looks like a punch press similar to this http://tinyurl.com/f5yj4 is
following my son home tomorrow afternoon. I know little about these
units. Where do I go for beginner info on what all I can punch and
what dies etc. I need. How do capabilities compare to an iron worker,
shear, press brake??

I got the unit for scrap weight value or less, I'm just hoping its not
a boat anchor for the shop. I've got enough of those already.


Karl

"Karl Townsend" remove .NOT wrote in
message .net...

I got the unit for scrap weight value or less, I'm just hoping its not a
boat anchor for the shop. I've got enough of those already.

To add to what others have said, you can set the shut height of a press too
big as many times as you want. You can set the shut height of a press too
low ONCE.

The flywheel in a mechanical press has between 10 and 20 times the press's
rated capacity in total stored energy. Setting the shut height too low on a
40 ton press could subject the tooling and the press to some 800 tons of
force. Worst I've heard is the flywheel broke off a 1,000+ ton press when it
was setup below the die shut height. The flywheel crushed the operator (it
fell from about two stories up).

Regards,

Robin

Interesting discussion.

I have a small 2 ton punch press like this...

http://cgi.ebay.com/ALVA-F-ALLEN-B2-...QQcmdZViewItem

that I have yet to get around to use. If one wanted to build small dies
for this press, any suggestions as to how to?

Thanks

TMT

"Too_Many_Tools" wrote in message
oups.com...
Interesting discussion.

I have a small 2 ton punch press like this...

http://cgi.ebay.com/ALVA-F-ALLEN-B2-...QQcmdZViewItem

that I have yet to get around to use. If one wanted to build small dies
for this press, any suggestions as to how to?

Do you know what you want to make with the press? Round piercing dies (scrap
slug is punched out of blank part/strip material) and round blanking dies
(piece part is punched out of strip material) are the easiest to make, but
dies make only specific parts.

You'll at least need a die set. You can use one die set to run various
operations if you do it right (a "universal" die set). While someone
mentioned you don't need a die set, I would be *very* hesitant to not use
one. In industry this is basically unheard of. Press ram's are virtually
never as tight as they need to be for stamping anything under 1/8" thick and
a crash could prove fatal to the operator (even using a 1 ton press).

After the die set, you need to give us an idea of what you want to make.
Punch presses are capable of doing many different types of operations from
simple cutting to forming, drawing and even tapping.

There are a number of different books on die making. They usually stay
pretty simple if you've got a mind for the work. Unfortunately tool and die
apprenticeships are 4 years for a good reason. I've built half a dozen small
dies but there's a big difference between where I am versus being able to
take a part drawing and producing a die that makes a good part.

Regards,

Robin

"RoyJ" wrote in message
nk.net...
As others mentioned, dies are the expensive part. Don't even THINK about
using it for hammering or planishing, you will bend the crank on the first
hit. You unit will likely have a 3" stroke, the force varies with the
cosine of the crank angle, max force is at the bottom of the stroke (not
in the middle!) The tonage listed is the max the unit will withstand
without bending or breaking.

Dies are cheap if you have a lathe.
It won't bend the crank on a 35 ton, it'll lock the press...been
there...lots!

Well the press I have does not have any tooling with it.

Where would one find a die set for this type of press?

As for what it would be used for, I can see it being set up to form
different sheet metal pieces that would be needed in quantity. As you
said, the dies would for the most part be specific to the product and
so the reason for the acquisition of press tooling to be low priority
yet...I haven't needed larger quantity of parts yet.

I understand the need for safety around these machines...I intend to be
able to count to ten for a long time to come.

TMT

Dies are cheap if you have an EDM. Lathe only helps for round holes,
might as well get an iron worker.

You will only lock the press if get the stroke a few thousandths more
than the shunt height. Anything more and it breaks the crank. Either one
does not do the press any good.

Tom Gardner wrote:
"RoyJ" wrote in message
nk.net...

As others mentioned, dies are the expensive part. Don't even THINK about
using it for hammering or planishing, you will bend the crank on the first
hit. You unit will likely have a 3" stroke, the force varies with the
cosine of the crank angle, max force is at the bottom of the stroke (not
in the middle!) The tonage listed is the max the unit will withstand
without bending or breaking.


Dies are cheap if you have a lathe.
It won't bend the crank on a 35 ton, it'll lock the press...been
there...lots!

Old die sets are pretty common in the scrap yards. Usually they have
been reused several times and have more mounting holes than a piece of
swiss cheese. For your little 2 ton press, you will need the smallest
ones you can find.

The rule of thumb for punching round holes in sheet/plate is "80 tons
per inch per inch" ie a 1" hole in 1" plate takes 80 tons of press.
Yours is barely enough to do a 1/2" hole in 18 ga steel sheet. More than
likely it was set up to crimp wire terminals, bend tabs, or something
similar.

Too_Many_Tools wrote:

Well the press I have does not have any tooling with it.

Where would one find a die set for this type of press?

As for what it would be used for, I can see it being set up to form
different sheet metal pieces that would be needed in quantity. As you
said, the dies would for the most part be specific to the product and
so the reason for the acquisition of press tooling to be low priority
yet...I haven't needed larger quantity of parts yet.

I understand the need for safety around these machines...I intend to be
able to count to ten for a long time to come.

TMT

Thanks RoyJ...I wondering how useful it was.

The type of work I would want it for would be for 18ga and
thinner...small holes, tabs, slots, etc. in sheet metal.

I haven't seen any small die sets around...they have all been for
larger punch presses.

Any suggestions for what tools to have to make the dies? Or is it
better to get some punch tooling from a manual press and adapt it?

Thanks

TMT

"Too_Many_Tools" wrote in message
oups.com...
Well the press I have does not have any tooling with it.

Where would one find a die set for this type of press?

You can build a die set with a mill and lathe pretty easily. You'll probably
want a surface grinder but it's not absolutely necessary.

The shoes would be CRS. Ideally ground top and bottom. The pins can be dowel
pins. Something like 3/8" should be just fine. You'll need to turn brass
bushings that fit into the upper die shoe, and over the pins (which are in
the lower shoe).

It is ciritical that all the fits are correct:

Upper shoe and bushing - You have some options here. Either a wring fit
which means you can slide the bushings into the bored/reamed hole in the
shoe, but it's very nearly an interferrence fit (clearance would be less
than .0005" total). You will have to make a shoulder on the bushings and
retain the bushings with small clamps. The other option is to have a light
press fit but you run the risk of pressing the bushing into the shoe out of
square, and/or collapsing the bushing to the extent that the dowel will no
longer slide through.

Bushing to pin - This is a very important fit. The pin must slide through
the bushing with no binding. If you're good at reaming you can do it with a
reamer, but boring is more reliable. If there is preceivable play between
the bushing and the pin, it's probably too lose.

Pin to shoe - this should be a slight but solid press fit. We put our pins
in the lunchroom freezer for 30min before knocking them into the shoe. Use a
precise v-block to make sure the pin enters squarely. Make sure to use oil.
The pin should not bind as you wack it in. If it feels like you're hitting a
solid piece of metal at some point, you're doing something wrong. If the
pins don't go in squarely, you will have issues closing your die correctly.

The shoes should be bored on the mill in the same setup. The upper shoe
should go on the top, then a spacer (thin ground parallels at the four
corners) and then the bottom shoe. This is because the holes for the
bushings in the upper shoe are larger than the holes for the pins in the
lower shoe. Clamp from the top, not in a milling vice. If either shoe moves,
your die won't close.

Once assembled, the lower shoe should slide into the upper shoe without any
perceivable play, and you should be able to do this by hand (without a
hammer or manual press). Being able to assemble a die set correctly is
something of a skill, and you'll have to do it a number of times for each
die build. If you don't do it correctly, you're liable to jam it so badly
that you might bend the pins when you (forcably) seperate the two shoes.
Think about making something like this to seperate your dies if req'd:

http://www.danly.com/webapp/commerce...idanly&mrn=181


As for what it would be used for, I can see it being set up to form
different sheet metal pieces that would be needed in quantity. As you
said, the dies would for the most part be specific to the product and
so the reason for the acquisition of press tooling to be low priority
yet...I haven't needed larger quantity of parts yet.

I understand the need for safety around these machines...I intend to be
able to count to ten for a long time to come.

When it comes time to actually design the die and run it as well, tell us
about what you're doing so we can make recommendations. Safe die design
isn't new so there's no point in you experimenting.

Regards,

Robin

"RoyJ" wrote in message
nk.net...
Dies are cheap if you have an EDM. Lathe only helps for round holes, might
as well get an iron worker.

You will only lock the press if get the stroke a few thousandths more than
the shunt height. Anything more and it breaks the crank. Either one does
not do the press any good.


While this is good advice, it's not technically accurate.

On our flange and restrike dies at work, we set the shut height of the
mechanical presses below that of the die, sometimes by millimetres (shut
heights for our dies ranges between one and two meters) to get the tonnage
up such that the part is properly hit. These are straight-sided presses in
the 800 - 1,500 ton range. We'll get the tonnage meter to read about 600
tons before hitting a part. The bolster actually gives (down) to accommodate
the jamming condition. None of this is required for dies which perform only
cutting operations.

When someone goes too low (very rare) we typically have to torch cut the
four bottom blocks to unlock the ram.

As far as the little dies are concerned, however, I don't think anything
more than a thou or two is acceptable. OBI presses are not of very solid
design anyway and will eventually fatigue open if they are run too hard.
Assuming you can read the actual tonnage being applied by the press, running
at maximum 80% of capacity is a good idea for press life.

Regards,

Robin

"RoyJ" wrote in message
nk.net...
Dies are cheap if you have an EDM. Lathe only helps for round holes, might
as well get an iron worker.

Oh, as you can imagine I make wire wheel parts, EVERYTHING (almost) is
round. I have a limited perspective. I have 10 presses in the 20 to 60 ton
range, mostly 30's. I haven't bent or broken a crank yet...thank GOD! But,
we've jamed them all up at one time or another to the point of dissassembly
of the crank. Round dies ARE easier in every way, even on a shoe or die
set.


You will only lock the press if get the stroke a few thousandths more than
the shunt height. Anything more and it breaks the crank. Either one does
not do the press any good.

You can make some short run (100's to 1000's of parts) dies with a wire
EDM. Take a suitable piece of 4140 or S7 plate, use the wire EDM to cut
the outline of the hole you need with a precise and carefully calulated
draft, heat treat to harden it. Mount one piece in the top of the die
set, the other in the lower. The draft is just enough to give proper
clearance as well as good slug ejection. You can get some fairly complex
shapes for very low tooling costs. Don't try to run it fully automatic
with a feeder though.

As for crunching things picture a 150 ton hydraulic press with a 18"x42"
die set in place (used for pierce and forming 1/4" material). Operator
cycles the press, on one side the leader pins gall and grab on the way
back up, cocks the upper part of the die set at an angle. Not good.
Operator didn't know what to do so he cycled the press again with the
upper not in alignment with the lower. REALLY not good. A LOT of yelling
went on shortly thereafter.

My local machine repair place had some 5" diameter x 14' main posts from
a 600(??) ton 4 post press in for rework. Seems that someone had plucked
the threaded ends off the shafts.

Tom Gardner wrote:
"RoyJ" wrote in message
nk.net...

Dies are cheap if you have an EDM. Lathe only helps for round holes, might
as well get an iron worker.


Oh, as you can imagine I make wire wheel parts, EVERYTHING (almost) is
round. I have a limited perspective. I have 10 presses in the 20 to 60 ton
range, mostly 30's. I haven't bent or broken a crank yet...thank GOD! But,
we've jamed them all up at one time or another to the point of dissassembly
of the crank. Round dies ARE easier in every way, even on a shoe or die
set.


You will only lock the press if get the stroke a few thousandths more than
the shunt height. Anything more and it breaks the crank. Either one does
not do the press any good.

RoyJ wrote:


My local machine repair place had some 5" diameter x 14' main posts from
a 600(??) ton 4 post press in for rework.


Where are you these days? Things have been absolutely crazy here. I
guess you know where we will be going.

Where in the world are you ? So I would like details please.

mk5000


"being good in business is the most fascinating kind of art"--andy
warhol

Robin S. wrote:
"RoyJ" wrote in message
nk.net...
Dies are cheap if you have an EDM. Lathe only helps for round holes, might
as well get an iron worker.

You will only lock the press if get the stroke a few thousandths more than
the shunt height. Anything more and it breaks the crank. Either one does
not do the press any good.


While this is good advice, it's not technically accurate.

On our flange and restrike dies at work, we set the shut height of the
mechanical presses below that of the die, sometimes by millimetres (shut
heights for our dies ranges between one and two meters) to get the tonnage
up such that the part is properly hit. These are straight-sided presses in
the 800 - 1,500 ton range. We'll get the tonnage meter to read about 600
tons before hitting a part. The bolster actually gives (down) to accommodate
the jamming condition. None of this is required for dies which perform only
cutting operations.

When someone goes too low (very rare) we typically have to torch cut the
four bottom blocks to unlock the ram.

As far as the little dies are concerned, however, I don't think anything
more than a thou or two is acceptable. OBI presses are not of very solid
design anyway and will eventually fatigue open if they are run too hard.
Assuming you can read the actual tonnage being applied by the press, running
at maximum 80% of capacity is a good idea for press life.

Regards,

Robin

However all presses do not have a cushion such as your description:

The bolster actually gives (down) to accommodate
the jamming condition.

In fact I don't believe I've ever seen a small press such as this with
a cushion. Too long a stroke in relation to the shut height (without a
cushion) will definitly damage the press.

dennis
in nca

"rigger" wrote in message
ups.com...

However all presses do not have a cushion such as your description:

I'm pretty sure it's just the press giving. In all the courses I've taken,
I've never heard of a cushion of this type. If the press is capable of 100
tons and you're below shut height but only using 50 tons, it stands to
reason that you're not jamming the press.


The bolster actually gives (down) to accommodate
the jamming condition.

In fact I don't believe I've ever seen a small press such as this with
a cushion. Too long a stroke in relation to the shut height (without a
cushion) will definitly damage the press.

Without question. Great care must be taken, especially when you don't have a
tonnage meter. Indeed trying to run a die which requires more tonnage than
the press can deliver will yield similar results.

Regards,

Robin

"RoyJ" wrote in message
ink.net...

My local machine repair place had some 5" diameter x 14' main posts from a
600(??) ton 4 post press in for rework. Seems that someone had plucked the
threaded ends off the shafts.

On the large hydroform press at work (6,000 tons) the tie rods have
hydraulic nuts for preload. I believe the rods are heated before the nuts
are tightened to increase the preload as well. They had to cut a hole in the
3-story roof to get the rods into the press using a crane.

It's interesting that a jam could cause the posts to fail. I wonder where
the rod-ends ended up (in another time zone perhaps.)

Regards,

Robin

I got the impression that the failure was fatigue related and that the
first clue was alignment. Half of the press had a different level than
the other half. All 4 did not go.

This was an interesting shop. 4 guys, probably 150 years of experinece
among them. They do only machine repair: posts, gibs, press cranks,
tables, etc. Ancient equipment but the big lathe will do a press
crankshaft journal without walking across the floor.

Robin S. wrote:

"RoyJ" wrote in message
ink.net...

My local machine repair place had some 5" diameter x 14' main posts from a
600(??) ton 4 post press in for rework. Seems that someone had plucked the
threaded ends off the shafts.


On the large hydroform press at work (6,000 tons) the tie rods have
hydraulic nuts for preload. I believe the rods are heated before the nuts
are tightened to increase the preload as well. They had to cut a hole in the
3-story roof to get the rods into the press using a crane.

It's interesting that a jam could cause the posts to fail. I wonder where
the rod-ends ended up (in another time zone perhaps.)

Regards,

Robin

Robin S. wrote:
"rigger" wrote in message
ups.com...

However all presses do not have a cushion such as your description:

I'm pretty sure it's just the press giving. In all the courses I've taken,
I've never heard of a cushion of this type. If the press is capable of 100
tons and you're below shut height but only using 50 tons, it stands to
reason that you're not jamming the press.


The bolster actually gives (down) to accommodate
the jamming condition.

In fact I don't believe I've ever seen a small press such as this with
a cushion. Too long a stroke in relation to the shut height (without a
cushion) will definitly damage the press.

Without question. Great care must be taken, especially when you don't have a
tonnage meter. Indeed trying to run a die which requires more tonnage than
the press can deliver will yield similar results.

Regards,

Robin


If the press is capable of 100
tons and you're below shut height but only using 50 tons, it stands to
reason that you're not jamming the press.

Pardon my ignorance Robin, but are you describing the operation of a
hydraulic press? If not I have a little learning to do. You did
notice the image shown at the start of the thread was a mechanical
press, right?

dennis
in nca

Robin S. wrote:

"RoyJ" wrote in message
ink.net...

My local machine repair place had some 5" diameter x 14' main posts from a
600(??) ton 4 post press in for rework. Seems that someone had plucked the
threaded ends off the shafts.


On the large hydroform press at work (6,000 tons) the tie rods have
hydraulic nuts for preload. I believe the rods are heated before the nuts
are tightened to increase the preload as well. They had to cut a hole in the
3-story roof to get the rods into the press using a crane.

It's interesting that a jam could cause the posts to fail. I wonder where
the rod-ends ended up (in another time zone perhaps.)

Regards,

Robin


The total preload on the rods must be at least the total tonnage of the
press. The preload for each rod is calculated by using diameter of the
rods and how much the must be streched to get the preload in the rod.
The nut on the rod is tightened. By using the pitch of the threads the
amount of strech is calulated to give an answer in degrees of rotation
of the nut. The rod is then heated and the nut is advanced to that
position. The rod cools and the preload is in the rod. It works
backwards for removing the rods. Heat them up and back off the nuts.


If you didnt have more preload on the rods than the press tonnage, the
press would come apart. At any amount of tonnage the pressure would
strech the rods and a gap would form every time the press cycled,
beating the press to death. With the rods preloaded, the force is just
transfered from the uprights to the crank with no movement of the rods.


John

"rigger" wrote in message
oups.com...


Pardon my ignorance Robin, but are you describing the operation of a
hydraulic press? If not I have a little learning to do. You did
notice the image shown at the start of the thread was a mechanical
press, right?

I am referring to a mechanical press. I can see where you're coming from,
however.

As I said, we run our does below bottom. We have to in order to get a good
hit.

Does anyone have an OBI press which has a tonnage meter? I'd be interested
in seeing whether a "below bottom" hit causes the force of the ram to exceed
the rating of the press. Everything is flexible, including the frame of the
press, the crankshaft and the die being run. When I say "below bottom," that
could mean .001" or perhaps slightly more, not a hundred thou or anything
like that.

Interesting discussion though. I've done very little small press work so I'm
sure things are a bit different on that end of the spectrum.

Regards,

Robin

"john" wrote in message
...

If you didnt have more preload on the rods than the press tonnage, the
press would come apart.

I'm not sure I understand this figure. It seems that if the preload was
equal to the press's capability, then the rods would be loaded up to double
the press's capability during normal production (higher during crashes).

Is this a "law of physics" figure or a rule of thumb? I'm not questioning
you, I'm just interested (we don't get to build or fix the presses - just
break them)

Regards,

Robin

I use my press to bend pins for yarn racks(creels)... I made a V-block
for the ram and then put a block of 3" thick by 12" sq. rubber for my
table... It was a new chunk of forklift tire rubber (very strong)...
I never need to worry about a crash... It work very well... I hold the
pin with my hand while it bends it... I've made thousands of pins with
no problem... The metal I work with is 3/8" to 1/2" round...35 ton
Bliss press...

wrote in message
ups.com...
I hold the
pin with my hand while it bends it...

No light-beam guards eh? ;-)

Regards,

Robin

"Robin S." wrote:

"john" wrote in message
...

If you didnt have more preload on the rods than the press tonnage, the
press would come apart.

I'm not sure I understand this figure. It seems that if the preload was
equal to the press's capability, then the rods would be loaded up to double
the press's capability during normal production (higher during crashes).

Is this a "law of physics" figure or a rule of thumb? I'm not questioning
you, I'm just interested (we don't get to build or fix the presses - just
break them)

Regards,

Robin

Think of it this way. Your are pulling on a strong spring at 100 lbs.
Along comes someone to help you hold the spring in tension. He applies
75 lbs of force to the spring and leaves you holding 25 lbs. The
spring displacement doesnt change but the force is transferred to the
other person. You being the press frame. and the other guy is the crank
and everything above it.

hth

John

John wrote:

"Robin S." wrote:

"john" wrote in message
...

If you didnt have more preload on the rods than the press tonnage, the
press would come apart.

I'm not sure I understand this figure. It seems that if the preload was
equal to the press's capability, then the rods would be loaded up to double
the press's capability during normal production (higher during crashes).

Is this a "law of physics" figure or a rule of thumb? I'm not questioning
you, I'm just interested (we don't get to build or fix the presses - just
break them)

Regards,

Robin

Think of it this way. Your are pulling on a strong spring at 100 lbs.
Along comes someone to help you hold the spring in tension. He applies
75 lbs of force to the spring and leaves you holding 25 lbs. The
spring displacement doesnt change but the force is transferred to the
other person. You being the press frame. and the other guy is the crank
and everything above it.

hth

John

I left out, the 100 lbs is the preload. As long as the preload is more
than the force transferred, the press frame is held in place. Once the
force exceedes the preload the frame below the bearings of the crank are
no longer in compression and they move around.


John

Robin added:

I hold the
pin with my hand while it bends it...


No light-beam guards eh? ;-)

Reminds me of one of the set-up guys at my first industrial type job
back around '58.

Yep, good old Lefty.

dennis
in nca

"John" wrote in message
...
I left out, the 100 lbs is the preload. As long as the preload is more
than the force transferred, the press frame is held in place. Once the
force exceedes the preload the frame below the bearings of the crank are
no longer in compression and they move around.

John,

That makes perfect sense. Thank you.

Regards,

Robin

Robin S. noted:

Yep, good old Lefty.

Oh, the stories...

And now the REST of the story....

This company had about 6 presses and none had even air clutches, only
mechanical foot pedals. I'd asked someone why the small press was
running with only a chunk of steel on the foot pedal and that's how I
learned about Lefty.
Man, he was handy with that hook (actually a little more sophisticated
than just a plain hook). He could roll a cigarette as fast as anyone.

dennis
in nca