DIY machine jack

I am attaching a picture of the bottle jack. It seems to be very difficult to remove the cylinder from the base. It seems to have been screwed in through the hex at the top of the cylinder. I could try unscrewing it, but I am afraid that all the oil will just leak out and I wouldn't know what and how much oil to refill ...

In the picture, the edge where the hydraulic pump and the lever is located is the back side (away from the machine edge)

Much better.

Please examine this:

Notice how the saddle assembly wraps 180 degrees around the male channel welded to the bottle body. If you had X-Ray Vision, you could see a steel 'bearing block' welded opposite the 'toe'. It has a large area that bears against one surface of the male channel (welded to the bottle body).

If it should corrode, you'll be able to free it up easily because there is only one surface in contact with the channel, not the (six?) surfaces you show in your drawing. Note also that small axial angular displacements will not cause this design to bind because of racking.

Axial angular displacements will cause additional contact to the sides of the channel, instead. Neat!

I see that the object you are trying to move will rest against the frame of the jack in such a way as to develop friction. The object to be moved should only be in contact with the toe & saddle.

's a tried and true design and it works quite well.)

(...)

Please re-define 'hot air gun' to include 'propane torch' or you will get as old as I am, waiting for your base to come up to temperature.

This is where your motorized rotating table with the firebrick top will pay for itself in limiting drudgery.

:)

--Winston

Timur Aydin wrote in news:VYGdnR6Xls_PQp snipped-for-privacy@giganews.com:

Try re-reading what Bob said (but got snipped):

"The point of welding the base on is to keep the jack from tipping toward the load. So only the back has to be fastened (the front is in compression). And the back doesn't have to be welded, only held down. I probably wouldn't drill & bolt it, but your base could have hooks or a bar that the jack would fit under."

Just fab yourself a "tray base" to hold the jack in position. Put a "lip" on the tray edge to keep the jack from tipping toward the "pressure-letoff" screw while pumping on the lever.

You think too much, Timur. :)

As long as you keep the bottle aimed away from the center of the earth, you'll be fine. Have clean rags available though!

Jacks are very tolerant of fluid level errors. I normally put the jack on newspaper and fill via the hole (under the rubber plug). A few cycles of the handle with the valve open; excess air comes out of the fluid and excess fluid leaks out of the jack. I normally tip the jack so as to lose an additional ~1 cc of fluid.

Pop the seal back in and wipe down the outside. No precision required.

The first time you actually use the jack after refilling, wrap a clean rag loosely around the bottle to catch the rubber plug if you over filled. This will prevent a wild goose chase for the elusive plug.

POP! DAMHIKT

I disassembled one of those jacks so that I could replace the saddle with a thick extension rod welded to the end of the piston. The whole operation was quite fast and easy because I didn't realize that it *could* be difficult. :)

Here's a short video of that jack doing it's job All By Itself:

--Winston

These of course..and I have a number of them..work the best...

Gunner

"Aren't cats Libertarian? They just want to be left alone. I think our dog is a Democrat, as he is always looking for a handout" Unknown Usnet Poster

Heh, heh, I'm pretty sure my dog is a liberal - he has no balls. Keyton

I had read that part a few times, but having seen a number of pictures on the net where the jack bottom seemed welded to the base, I was biased towards welding. But after reading the comments posted, I understand that welding is not the way to go. As Bob suggested, I will squeeze the back edge of the bottle bottom to the base using a piece of 15 mm bar and a screw/nut. Similar to the clamps that are used on the tables of milling machines.

Yes, when you can actually insert the jack under the machine. There are similar jacks available here for around 150 dollars. I wish they would have worked for me ...

But if the machine is sitting on the floor with only an indent that is

2-3cm high, those aren't an option. Also another problem with those is that they are quite tall. So if the machine has parts that protrude beyond the foundation of the machine, you won't be able to use these jacks.

A machine jack stands very low and its toe is elevated from the ground by at most 2 cm for the weight class that I am looking at.

I think I can disassemble this jack, but I am not sure that I can put it back together so that it will lift the rated weight :)

That cart is nice. I would be able to use such a cart when cutting long pieces with my horizontal bandsaw. The other end of the piece cut could rest on the cart, after the height is adjusted to the height of the bandsaw table. Here, those carts are very expensive as well, so that is another future project for me once this machine jack is complete :)

Cheers,

Oh, wait! Your modified design:

't need the base to be fastened at all!

Originally, with just the Z-shaped hook hanging on the piston there was a side force (i.e., radial) on the piston. This created a torque on the jack which required the base to be fastened down. But the modified design, with the hook sliding in side plates takes the side force off the piston & hence the torque off the jack. The jack doesn't need to be fastened at all - its only load will be axial.

Bob

No way to simply stick a crowbar under one end and slide under a bit of wood?

True enough for the Stuff Sticking out bit..but in machine tools..its rare.

Shrug

Gunner

"Aren't cats Libertarian? They just want to be left alone. I think our dog is a Democrat, as he is always looking for a handout" Unknown Usnet Poster

Heh, heh, I'm pretty sure my dog is a liberal - he has no balls. Keyton

(...)

There you go again, thinking. :)

You are going to laugh when you do this because it is waaaay easier than you think it is. First step is to grab a clean plastic mayo jar with lid. Place the jack on a few sheets of newspaper on a drip pan. Operate the master cylinder until the piston is all the way up. Grab a wrench and spin the top nut until it is quite loose. When you spin the top nut up, it loosens spring pressure on the top seal. Remove the filler plug and open the valve on the side of the bottle; lift the piston and nut straight out of the cylinder. Pop! No piston rings, nothing complicated.

Set the piston aside on a clean, lint free cloth.

Place the jack so it's solidly supported on an inverted coffee can or a block of wood or anything similar that is somewhat taller than your mayo jar.

Beware! There is a spring and ball bearing waiting to exit as soon as you have the valve core loose enough. Arrange a plastic bag over the valve so that these parts launch themselves into the bag instead of over your shoulder, to parts unknown.

Allow the fluid to drain into the mayo jar. When it's finished, you can tilt the top of the jack to pour any remaining fluid into your jar. Screw the cap on your jar and label it 'Hydraulic Jack Oil -- Do Not Drink!'

You'll want to use solvent to clean the last of the oil out of the cylinder. Stuff a water dampened rag into the cylinder. When you weld your channel to the side of the bottle, you won't want to breathe the copious smoke produced by burning oil. Ventilation Is Key!

After cleanup, remove the rag and wipe the cylinder with solvent to displace as much water as possible. Now would be a good time to air the cylinder out in front of a hair dryer to evaporate as much water as possible. Wipe a thin layer of oil around the inside of the cylinder. Reverse the disassembly steps and you'll have it all back together.

When you have everything assembled and painted, you will want to re-fill your jack with fresh 'hydraulic jack oil'. The stuff is cheap and easy to get. Of course, if the oil in the jar is clean and free of water, you can re-use it. I consider that false economy, though.

See? Piece of cake.

--Winston

Also notice that the feet on either side of the lifting toe stick out as far or farther than the toe. This is an important feature. Without this, anything heavier than the jack will make it want to tip over, tipping the machine you are lifting, or kick out sideways from under it as it comes down, possibly suddenly, at high speed, towards you. If nothing else, please update the feet on your baseplate design... --Glenn Lyford

Ok, here are the pictures of the machine jack being built and finally in action:

Thanks to everybody for all the useful advice I have gotten.

BTW, as you can see, the quality of the welds is not so good ...

I first tried 3,2mm 6013 rod at 160 Amps. But this almost caused a burn through even though the pieces are 15 mm thick. So I reduced the current to 110 Amps and finished the welds using this current. Would it be better if I had used 4 mm rod with 160 Amps?

I tried to look at your pictures a couple of times, but it timed out.

I think the rule of thumb is to multiply the rod diameter in mm by 40 to get amps. So the 3.2 mm rod would be at about 130 amps.

This is a posting by Ernie a couple of years back.

The amperage rule is applied differently to stick welding than TIG welding. It is applied to the electrode diameter, not the base metal thickness.

1/8" welding electrode =3D 1/8" wire =3D 0.125" =3D 125 amps midrange. You can go from 20 amps colder to 20 amps hotter, or 105 amps to 145 amps.

3/32" =3D 0.094" =3D 94 amps, or 74 amps to 114 amps.

You rarely run electrodes in the higher range, but you can if you must.

The most practical range for a 3/32" electrode is 75 to 95, and for

1/8" electrode, 105 to 125.

Dan

Me too.

Me three.

--Winston

Please try again. There was a temporary problem with my web server.

Timur

Got it.

It's Alive! Well done, Timur.

I'm not trying to rain on your project, but I have a couple comments:

1) It needs feet! Eventually, someone is going to pick up something really heavy. The top of the jack will tip into the load and dump it forthwith. This just ain't safe.

2) You see where paint transferred to your uprights in

Someone might have mentioned that this would be a point of friction.. :)

3) The shoulder around your jack screw might mush in use. If the jack isn't fully seated in the frame, you will increase the mush factor.

--Winston