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14th Mar 2018, 09:37 PM #31Most Valued Member
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I am going with your idea Graham I should be picking up a little bit of 150mm c channel not the perlin stuff but the actual heavy duty structural stuff tomorrow I will look into the flat 100×12mm sides it would be easy to obtain flat bar, I should really only need around 20-25 ton but if the crank is stubborn the 50 ton will come in handy
That's a good idea about the pins I was looking at pre made ones on ebay I don't know what a machine shop would charge to spin a few pieces on the lathe
Shop do u think that press u had could have been strengthened in certain locations to stop it from twisting?
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14th Mar 2018, 10:35 PM #32Most Valued Member
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gazza it didn't twist, the channel would flex, when pressing something the top c channel's would bend up and the table c channel's would bend down.
There was also a length of flat welded inside the channel's to strengthen them but this was not enough, I reckon at 35 ton there would have been at least 30 mm flex between the top and bottom c channels.
The press would make a hell of a bang when pushing a tapered shaft out of a flange. I think that you should go and have a good look at some presses before embarking on this project, take a few pictures and have a good think about it.
shed
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14th Mar 2018, 11:52 PM #33
It is not so much the twisting but the deflection and possible slippage which can cause the load to move off axis and the result can be that the job shoots out sideways at a great speed.
Certainly that press in question could have been plated across the bed.Typically it is what you can expect from Chinese equipment -Rated at 50 ton it deflected at 35 ton. I would also suspect the quality of the chinese steel, but thats just my opinion.
Perhaps some kind soul adjacent to you in Sydney might use their lathe to spin up some pins. Volunteers anyone?
If not what about long Ht Bolts-if you can find them that long at 22mm . Mine are Grd 8 and were 16m but only had to span 150mm.
Grahame
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15th Mar 2018, 02:07 PM #34Most Valued Member
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That 50 ton press looks like a shell it looks to me like it is relying on 6 to 8 bolts for the entire force it would have a lot of torsional twisting i'd imagine
Mine will have a full solid structure I plan on running two sides of c channel, the top will have c channel back and front, the press plate will have 65x65x5mm she steel one on the front one on the back, I haven't worked out the feet yet
I just picked up 3.7 meters of 150mm channel that thing is bloody heavy! But it's a good thing
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15th Mar 2018, 03:48 PM #35
gazza2009,
I am not sure what you mean. I am no engineer for sure, but I can't see where a torsional force is imposed by the action of pressure from the jack being applied centrally.
Taking for granted that the press is constructed asymmetrically and pressure is applied to the jack it pushes centrally against the top cross member and the press bed, why would the frame twist?
Granted, there is some slack to be taken up by the bolt holes clearances but the amount is minimal.
I have operated powered and manual hydraulic presses for near 50 years and have yet to see this. Perhaps it is just a matter of semantics?
What really puts the wind up me is pressing where the press tool is not applied squarely and positively.I have seen lots of near misses and some minor injuries but believe me, as the pressure used gets higher the more dangerous the work becomes.
Work or unsecured press tooling can fly out sideways.
I thoroughly recommend a mesh screen or shield to pull up the "slips"
Grahame
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15th Mar 2018, 04:35 PM #36Most Valued Member
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I made one of those threaded rod presses and mine twist ever so slightly under 4 tons of pressure I tried pressing out a car wheel bearing with the one I made lucky the jack maxed out before the press did, it would only need the ever so slightly off on one side to create tor sion forces, I tried to get mine level with the base but maybe mine twisted due to the threads stretching I only used it once and left it it just seemed like a skethy press
The press that was liked in here I personally think and that's just my assumption under 35-50 tons of pressure that is an incredible amount of pressure on such a flimsy looking press, I reckon the steel is stretching under such forces it may be very minor stretch but I reckon that old mates 50 ton press bending at 35 ton was under engineered, when I said it looked like a shell there is not much structure to it there is a reason things these days break vs the old days, the old days everything was built solid and robust these days it's all engineered to use the lease materials
I know my press will be solid and I'm looking at adding a pressure gauge so I know the limits of the machine
The safe mesh guard is a really good addition safety is the most important thing after all if I lose 2 eyes I won't need a press and we are talking a serious bit of machinery at 50 tons of pressure it's not kids play
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15th Mar 2018, 05:01 PM #37Most Valued Member
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Here is the c channel measures 3.7 meters and is bloody heavy, I picked it up off gumtree it came from a demo site where a new house were built it must have been excess to needs it was free but I paid for it
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15th Mar 2018, 06:01 PM #38Most Valued Member
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the exxon valdez
gazza this is a 40 ton press that my father built, you can get 15 ton off the car power steering pump and it has a foot pedal to get it up to 40 ton.
The frame is 75x 10 flat and the top of the frame is built as a truss and the cylinder is bolted in and is the centre post (or web) of the truss, this is a very strong arrangement and is a low cost for strength way of building.
The pins for the table are about 22 mm dia and most likely 4140, you only need unturned bar for these and l am pretty sure that the 50 ton chinko press had 25 mm dia pins, good idea to use 4140.
As you can see the old boy was concerned about anything flexing, the table is fabricated out of 25 mm plate.
I got it off my brother and that is why l got rid of the other press, pity he didn't fix all the oil leaks before he gave it to me
cheers shed
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15th Mar 2018, 06:10 PM #39Most Valued Member
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Looks much more sturdy than the Chinese press on ebay hard to believe the old timers used the plate steel for construction of a machine capible of 40 tons I thought using plate steel in those sizes mentioned in this thread would handle such loads, that's a nice old press look at that bed!!!! Can hold an elephant and more haha
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16th Mar 2018, 08:19 PM #40Most Valued Member
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What is the fastest way of drilling this thick steel? the back of the channel is 6mm the top and bottom are 10mm i was using a Lenox 19mm hole saw recently to drill thru 5mm steel it took around 15mins to drill each hole, my drill is only able to go down to 600rpm my whole saw requires 400-450rpm
should i look at getting a arbor or a normal drill bit instead?
sorry to push other guy's threads down
just got a clean up happening i need to clear out my gym room than the shed i have crap everywhere than i can start on the press, looking at tack welding the A frame of the press and squaring it up before drilling
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16th Mar 2018, 08:38 PM #41Most Valued Member
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Annular cutter.
Nev.
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16th Mar 2018, 11:52 PM #42Most Valued Member
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Found the 22mm annular cutter but finding it hard to find the attachment that goes into the chuck, the only one I could find was like $60-$70
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17th Mar 2018, 01:23 AM #43
How about a "Blacksmith's Drill" Half inch shank on them. Mine go up to 1" inch in 1/8ths from 1/2" and I've seen a couple that are 1"/1/8" and 1"/1/4" diameter.
Best Regards:
Baron J.
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17th Mar 2018, 10:27 AM #44
Maybe it is just me, but is using a 22mm hole for 22mm pins the best way forward?.
To my way of thinking, size for size invites a lock up the first time the press is subjected to a bit of grunt.
What do the rest of you, think?
Also, the layout of those holes will be pretty important as well. Talk about twisting, that is where the problems will come from if just one of the holes is not in alignment with its opposing neighbour. A good lead taper on the pin ends would not go astray either. My H frame press holes were marked out with the equivalent of a storey rod from the same datum point so any marking out descrepencies would all be aligned. I agree with tacking the uprights together and then marking from a common datum line.
Can a magnetic drill with the annular cutter be hired?
It seems to me, by the time you buy an annular cutter and the adapter you are getting close to the cost of hiring a magnetic drill for the day.Surely engineering hire items like that are available in the big smoke.
Grahame
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17th Mar 2018, 12:17 PM #45Diamond Member
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It seems as though all the high end presses are made from flat bar for some reason, just what I have noticed anyway. Probably a good reason for it.
With the holes I would be using a magnetic drill. You can get adapters to suit morse taper drills but it might make things a bit more awkward. A second hand magnetic drill can be had for $200-$300 or try your luck with chinese. https://www.ebay.com.au/itm/Variable...4AAOxyVaBStpTn
I would also do all your holes before you start putting it together. Have you considered bolting rather than welding?
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