I have wanted one of these things for a LONG LONG time but it's never been important. The other day a certain awesome forum member asked if I had a press...
So I had a look around on the usual sites for NZ and found China presses with hydraulic jacks in the top and typical frame shapes in the 200 to 400 NZD range. OK.
Decided the 12t presses looked a bit flimsy jack wise. Went looking and found 20t jacks on special at half price: 50 bucks NZ. Bought one.
Went to pick it up today and found this 12t 270nzd China press: https://twitter.com/FredCookeNZ/status/ ... 2113260544
Complete crap. Small weak jack. Flimsy frame. Poor alignment. Small work area. Short overall frame height. Low position for placing items. All the things that would make it shit to use in general. Quite shit.
Then I found my 20t jack on a shelf marked 100, so it was a genuine sale. It's China quality, passable, but not fantastic. Not too bad. Plenty beefy, though, and plenty cheap:https://twitter.com/FredCookeNZ/status/ ... 7399586820
Next step, find some used/scrap steel suitable for building uprights, movable cross beam, top plate, and sliding press beam.
I want the uprights to be stout enough to not flex pretty much at all when under asymmetric stress from pressing something.
I want the top plate to be stiff enough to not flex pretty much at all at full 20t pressure. Ditto the lower movable cross beam.
I want the sliding press beam to have long close tolerance greased sliders on the uprights so that it's maximally stable in use.
I'd like the jack to be upside down, but I'll live without that luxury in exchange for not having to modify it. :-p
Weak reference (video about upside down jacks): https://www.youtube.com/watch?v=0nlSp21KZJ8
Boring video with good construction: https://www.youtube.com/watch?v=9W-IXL7USHM
Old man talking about his press, some good ideas: https://www.youtube.com/watch?v=LOqbC_K7caU
1) winch setup to raise/lower the cross beam
2) external tank for the old jap jack he used (I like this better than the mods in the weak video above)
3) height enough for things like entire diffs, ensure my setup can fit a diff and fit in the garage
4) possibility of sliding the jack across from side to side at the top
5) everything is on wheels. I had already thought about this, see below.
But in his design it'd be important to centre it otherwise things could skew.
I see no drawback to 5 aside from excess height with reduced range and possibly movement when using it, if not using locking wheels.
100-150 thick uprights, probably taper channel steel
600-1000 gap between uprights for max utility value
1800 max overall height for this garage space
1600 usable work height if using 100x50 channel
50x5 galv angle for base pieces, so no rust on carpet, angle cut ends to avoid injuries
So, for example:
100x50 taper channel steel:
6m length piece
1.5m height uprights
750mm x 4 wide minus 100 =
650 usable width
Reducing the width by 50 gives us 100 extra height. so it could be 600 usable and 1.6m high. But really it requires more than 6m of steel to build to a good size.
My new jack as pictured above is: https://twitter.com/FredCookeNZ/status/ ... 8250887168
and https://twitter.com/FredCookeNZ/status/ ... 9558515712
So from total height we'll lose at least:
100 + 100 + 242 in working height, plus thickness of cross bars/plates, plus possibly the feet height, depending on how it's attached/built. Let's call that 80mm or 100mm
So if it's 1500 high, we'll likely lose 550 from that and end up with just 950 max working space for things.
Ducking downstairs I find that my two diffs are 1550 (Volvo) and 1600 (van/ute) long. But perhaps that doesn't matter?
If I build it 1800 high to fit this garage space, then I'll lose 550 and get 1250 of working space. However I could build it taller and fit it between the beams, up to 2100, 2080 in the store room.
So if I give it a little clearance, say 50mm, and build it to 2050 or 2000 with lots of clearance, and I want to work on the diff, I'm still out of luck because I'd only have 1450 or 1500 irrespectively.
Thus I should build it to fit something around 100 to 200 and have it at optimum eye level bench height, or lower, which from the workbench thread is 1100 to 1200.
From bottom to top this gives us 1150 + 50 + 200 + 250 + 100 = 1750 + 50 or - 100
Going back to our steel quota we get 700 overall, 600 working, 1600 total height, minus 350 = 1250 max object height, minus 200 = 1050 base height, minus 50 for plates = 1000 top of cross beams, minus 100 = 900 bottom of cross beams in a typical working position? Seems OK. Could be better a bit wider or a bit taller, though.
Let's say 1200 is too wide, 700 is minimum width, 900 with 800 usable might be nice? And 1800 high. Total steel needed to do that is: 900x4 + 1800x2 = 7200 plus 8 cuts of 5mm = 40mm.
Checking the steel site: "Standard stock lengths available are 6, 9, 12, and 15 metres"
All of the above works similarly well for 50x50x6 box, too, except that it's cheaper, less stiff, and less gap on the work surface for pushing bigger things through.
And, of course, the return springs will be volvo bonnet springs! :-)
Any and all thoughts welcome! Especially from the likes of Sim!