[TheForge] Hydraulic Press
Andrew Vida
osan at netlabs.net
Sun Mar 20 08:59:18 EDT 2011
I was not going to get into all that at this point. Over-complicating a
discussion in its earliest stages can become a problem - but all your
points are well taken.
My main issue with the square tubing stems from my knowledge of
blacksmith behavior - the tendency to scrounge in favor of spending
money when one is well to so do. Not all 1/2 or 3/4" walled tubes are
made equal as you imply below. Screwing around with materials, possibly
junk, in pursuit of saving a few hundred $$ or satisfying one's sense of
adventure or curiosity (look what I can do Ma!) is not always well
considered, as this discussion has illustrated in some abundance.
Because of this and the general dearth of actual engineering experience
I lean toward gross over-design in the interests of keeping everyone
alive and in possession of all body parts in proper functioning order.
I am educated as a mechanical engineer, but have not worked as one, so
even I do not have some of the crucial practical experience required to
make me competent to execute thin-margin designs of such contraptions.
These sorts of beasts can be very dangerous is improperly designed,
constructed, or operated. I like "safe".
One other thing I would add regarding design: in a double- or otherwise
multi-frame layout, I would design for cascading failures. In machine
tool design, the cutting inserts go first, then tool holders, and so
forth - mainly to avoid damage to costly equipment and secondarily as a
safety measure for personnel. I would give some serious thought to this
in press design with operator safety as the primary concern. Using
tubing, 6x6 on one side and either 6x8 or 8x8 on the other side so that
the 6x6 is most definitely the weaker side and will fail long before the
other side does in the event that your hydraulics manage to exceed the
limits of the structure. Similarly, you could build both sides with
the same sized tubing but gusset-up one side more heavily than the other
with the same goal in mind. I am also in favor of shielding certain
critical areas - those most likely to throw parts when they experience
failure - to contain or redirect the shrapnel. 1/8" sheet bolted around
such areas should be enough for a human-sized press, though do not quote
me on this without doing some calculations. This allows for easy
maintenance.
G. Watts wrote:
> Andy,
> Not sure that your basic assumptions here are correct regarding the
> properties of square tubing...I assume that Mark was referring to HSS
> (Hollow Structural Sections) square tubing 6x6x1/2, don't know what the
> "bridge beam" that you mentioned refers to, but I'd assume that you
> meant a Wide Flange Structural Shape. The 18"-24" designation you used
> only tells part of the story, since that refers only to the flange to
> flange outside dimension and doesn't cover the thicknesses of the
> flanges or web. Beam sizes are given thusly: w18x35 or w24x146. the
> "w" designates that it's a wide flange beam shape, the "16" or "24"
> designates beam height, measured flange to flange (outside dimension)
> and the final number designates the weight in pounds per linear foot.
> The thickness of the flanges and web may be inferred from the beam size
> and weight using a chart of industry standard properties.
> Mark would need to make sure that he knew what grade steel he was
> designing for- HSS would generally be grade ASTM A-500, wide-flange
> beams usually A36- then determine the tensile strength of the grade,
> then determine the cross-section of the shape, then...do the math, being
> sure to add a reasonable safety factor. Point being that regardless of
> shape, it's the cross-section and grade that matter most...although I
> believe that HSS square compares favorably with the wide flange and H
> forms, which is why the Japanese have been building most of their modern
> high-rises using square columns instead of H forms (like we do).
> I'd also recommend using a complete penetration weld from the
> verticals to the base and top plates (grind bevels on the ends of the
> verticals before welding), not just put fillet welds around them.
> Welding ought to be done by a certified structural welder, not somebody
> who just welds trailers and furniture and such.
> Here are a couple of references for your perusal:
>
> http://www.engineersedge.com/structural_shapes_menu.shtml
> http://www.cim.mcgill.ca/~paul/HollowStruct.pdf
>
> George.
>
> PS-I'm not a structural engineer, but I do work with them frequently.
> PPS-Not trying to rag on ya, Andy...but the generalization re: square vs
> beam kinda ticked me off.
>
>
>
>
> On 3/18/2011 9:06 PM, Andrew Vida wrote:
>> No doc. You don't do this with square tubing. You get yourself a
>> length of 18"-24" bridge beam and go from there. Trust me on this one.
>> 100 tons of energy sprung up in a structure like that is a lot. If it
>> lets loose, anything in the way of the flying debris is going to meet an
>> unpleasant fate. Start with good materials - over-engineer the deal,
>> ESPECIALLY if you are not an engineer capable of calculating the
>> stresses to a reasonable degree of accuracy. Better to have an entirely
>> over-built press that is safe to operate and a PITA to move than to die
>> or be maimed in an accident.
>>
>> Mark A. Pesetsky wrote:
>>> Hello All,
>>>
>>> Haven't been here in quite a while but I have a question that I am hoping one of the experts here can answer. I am embarking on building a hydraulic press. I have a 100 Ton cylinder and I need to know which square tubing would handle this load. I did an exhaustive internet search but found nothing. My partner and I are thinking 1/2" wall thickness 4X4 or 6X6 should do the trick. Any suggestions, charts, or general help would be greatly appreciated.
>>>
>>> Thanks Guys
>>> Mark
>>>
>>> ________________________________________
>>> From: theforge-bounces at mailman.qth.net [theforge-bounces at mailman.qth.net] on behalf of Andrew Vida [osan at netlabs.net]
>>> Sent: Friday, March 18, 2011 9:18 PM
>>> To: Blacksmithing List Sponsored by ABANA
>>> Subject: Re: [TheForge] now Japanese nuke plants OT: POL:
>>>
>>> peter fels wrote:
>>>> On Mar 18, 2011, at 8:08 AM, Andrew Vida wrote:
>>>>
>>>>> James Binnion wrote:
>>>>>> On Mar 17, 2011, at 11:47 AM, peter fels wrote:
>>>>>>
>>>>>>> That's changing, both in the cost and efficiency of solar cells
>>>>>>> etc,
>>>>>> Alternative energy sources aren't even close by orders of magnitude
>>>>>> yet, yes they are getting better but they still cannot compete in
>>>>>> scale or cost with petro or nuke.
>>>> Petro is a diminishing resource and a serious balance of payments problem.
>>>> If you count construction cost, waste disposal ,decommissioning, risk and cleanup in the nuke cost..
>>>> ...it doesn't look so good.
>>>>> A truth the nuts and twigs crowd flatly refuse to acknowledge. If they
>>>>> want to return to the stone age, I support them fully so long as they
>>>>> leave the rest of us to live as we see fit. Unfortunately, the
>>>>> watermelon marxists seem ill-contented to leave us alone.
>>>> Does the name calling make you feel better Andy?
>>> Much. :)
>>>
>>>> What's a watermelon Marksist BTW?
>>> Green on the outside, red on the inside. :)^2
>>>
>>>> The idea is, we have a serious problem and we need
>>>> to start working on it real hard now,
>>>> while we still have the margin to do so.
>>> Don't hold your breath. The problem is manifold. First, those in
>>> power want to stay there, whether in the corporate or governmental
>>> worlds... increasingly in both as we are a defacto quasi-fascist state
>>> now :(
>>>
>>> This being the case, government sets market regulation such that
>>> barriers to entry in a given industry become nearly impossibly high and
>>> the establishment of new industries that might cannibalize the extant
>>> ones are prohibited by regulation. For example, were I to brilliantly
>>> develop a high temperature superconducting material good to well over
>>> the boiling point of water by spilling red wine on iron (this has been
>>> recently claimed by Japanese researchers), one of three things would
>>> befall me to prevent my capitalizing on this invention that would change
>>> the face of life on the planet in ways most people cannot imagine: I
>>> would be simply shut out by regulation, I would be bought out by the
>>> competition or, refusing to submit, I would be executed. The great
>>> blessing of "regulation" has a purpose: to maintain seats of economic
>>> and political power. There is no other purpose, all grotesquely
>>> distorted proclamations to the contrary notwithstanding.
>>>
>>> This being the case, those at the top have no interest in changing the
>>> game until such time as they extract the maximum market value from the
>>> existing investments. The collateral benefit is that conditions in the
>>> world go so far to hell that those in power now use that as the pretext
>>> for further arrogation of power to which they are in no way entitled.
>>> Whether "the people" grant such expansion of authority is irrelevant to
>>> the question of legitimacy because the grant would be made under
>>> fraudulent circumstances. History provides us with examples of this old
>>> trick in such abundance as to herniate the mind before assuming 5% of
>>> them in one's thoughts.
>>>
>>>>> And it is not "green", so what's the point - at least until the oil
>>>>> spigots run dead-dry?
>>>> It's somewhat cleaner and we have a lot of it so we don't have to go further into debt to the Arabs.
>>>> The nat gas can act as a transitional fuel.
>>>> Burning fossil fuels when we are going to need them as feedstocks is awful shortsighted.
>>> I was being a bit facetious about the "green" thing, which is pure
>>> idiocy and provably non-viable on the whole. When a unit of energy a
>>> consumer uses requires more than a unit of energy to produce, you can
>>> rest easy in the knowledge that you do not have a viable system at hand.
>>>
>>> That all said, I must declare that good old fashioned home made ginger
>>> tea is one of life's fair and simple pleasures.
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>
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