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Home made Bearing/Bush press


Maverik
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Good start, question for you and or the hydraulic experts - if you calibrate the lift at say 1 tonne and read the resulting pressure, is it a linear relationship ? i.e. twice pressure = twice effort ?

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Yeah the gauge "should" be linear for the pressure shown on the scale, I.e. for this one 900 psi = 500kg, 1800psi = 1000kg had a wee test calibration and it appears to be working as it should, the gauge cost about 5 pound so wouldn't be surprised if it was a bit unlinear closer to full scale deflection...

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I found the gauge on my press packed up the second time something went with a bang don't know if there's a way of adding some sort of buffer to reduce the shock wave.

Mike

Well that sent me off on an hours googling pressure gauge design ;-) a couple of manufacturers seem to imply that the shock wave damages the needle transmission ( simple gear setup from what I can see) with direct acting units being more likely to survive.

The one I have is an oil filled thing from an old machine that was too good to throw away so it will either work or I suppose a blank can replace it when it fails.

I have a press that I bought with her brother, its sealey 20t economy thing which is OK but the return springs are too weak to lift the heavy jack. I also have a lot of box section and some hydraulic fixings so I have it in mind to make one.

Interesting to see how this build progresses.

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After a good bit of research I looked at all sorts of hydraulic presses and nothing really fitted the bill of what I was looking for, the one I came down to wanting was about 400 pounds, even buying a chepo one would set me back the best part of 100, with an every increasing pile of scrap metal I thought I'd have a crack at making something myself that actually did what I wanted...

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...I have a press that I bought with her brother, its sealey 20t economy thing which is OK but the return springs are too weak to lift the heavy jack. I also have a lot of box section and some hydraulic fixings so I have it in mind to make one.

When I built mine, using a heavy air / hydraulic pillar jack, I used a pair of gas struts, as I felt these were easier to get than extension springs. Specification was empirical; I went for struts from the lightest tailgate I found in the scrapyard. This might have been a Fiat or a Citroen, I don't recall (collect the mounting ball joints as well as the strut). You need to be a bit canny picking the strut length, because their extension sets a limit on the press travel.

There has been one unforeseen side effect, more 'interesting' than annoying. To ensure the jack returned to the fully compressed position I arranged the strut mountings so the struts weren't quite fully extended when the jack was closed. Over several years the continual upward pressure on the ends of the jack support beam has given the beam a noticeable upward curve.

Yes, you could say I didn't get the empirical design of the beam quite right :-)

Fortunately the design of the beams (and uprights) that take the stress of the press when in action have proved to be adequate, although I haven't included any sort of pressure indicator in the design.

HTH

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A hydraulic flow limiter might help prevent the gauge being damaged, the pressure would still register but it would stop the oil moving quickly to or from the gauge. I'm sure it wouldn't stop it registering pressure when your jacking as that's relatively slow. You can get ones with a screw adjuster for the flow so just wind it right in then out just enough to work at the rate that you pump and see what happens. Just check that it limits flow both ways as some are only one way.

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That's a bit of a mutts nuts contraption, mine unfortunately wont be quite so elaborate, in the middle of an internal debate as to whether or not I should mount the jack right way up, or upside down, both have plus's and minuses... I was debating on put an external oil reservoir on it, but then that's a little over the top for a 20 squid bottle jack... got to keep things in perspective!...

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Not having a dig at your welding Mav but have you noticed how nearly all presses are bolted together?

Hehe, yup, but I dunna have a drill big enough for bolted connections. I thought about it a fairly long time, and came to the conclusion its more of a production thing than anything else. you can make much bigger (post-able) presses from bolted sections, than you can from welded.

With welded joints I guess there could be a fatigue issue, but thought of that already and got a few more structural gussets and such like to go in, and will also finish off the key stress welds with a nice ground finish... and then I just got to keep an eye out for any cracking - just like a ship really... :)

I managed to insert a piece of roll cage spec tube into the top box section to give some local strength to the spot where the jack top will be hitting, as well as a doubler plate on the outside.

I'm trying to over engineer it a bit with the potential to go up a size in jack if I ever need too...

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A bolted 20T press will move around a lot when you're using it, so I'd be a bit wary of a welded connection unless it's absolutely spot on square. Not that I don't trust your welding, but having a weld burst apart while using the press could result in some very dangerous projectiles.

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I'm not overly concerned with any bursting. I'm not using any high tensile material so wont be expecting any brittle failures, so there shouldn't be anything flying around. The energy contained in the press system if used correctly shouldn't be having any explosive capability, you'd be surprised at the strength of even a "bad" weld...

Nothing like a bit of design and some thinking to verify a design.

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You can use masonry bits to drill steel... :)

omg noise and heat come to mind :) - its more the fact my hand drill would definitely not be up for drilling multiple holes through 5mm thick steel... let alone my wrist... I can't understand why people are so scared of welds.

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I'm not overly concerned with any bursting. I'm not using any high tensile material so wont be expecting any brittle failures, so there shouldn't be anything flying around. The energy contained in the press system if used correctly shouldn't be having any explosive capability, you'd be surprised at the strength of even a "bad" weld...

Nothing like a bit of design and some thinking to verify a design.

Fair enough, I've used a bolted together 20T press quite a bit and did some stupid stuff on it, so I have developed a healthy fear and respect for it :P

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omg noise and heat come to mind :) - its more the fact my hand drill would definitely not be up for drilling multiple holes through 5mm thick steel... let alone my wrist... I can't understand why people are so scared of welds.

A cordless drill won't turn fast enough nor will you be able to press hard enough to do anything meaningful with masonry drills in steel. A drill press or radial arm drill is where it's at :)

On the bolt versus weld topic, I reckon the reason you see a lot of bolted home made presses is that everyone has the capability to drill holes, most people havnt got a welding plant capable of adequately joining the thickness of steel necessary

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Yup, need a drill press really :)

And yes... the screeching is quite loud, but only had to do it a couple of times, and wore ear protection. IIRC Simonr said he has successfully drilled an LT230 input gear for the extra oiling holes this way!

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