DIY machine jack

Timur Aydin wrote:
(...)


Yes definitely. You don't want to cause the piston to bend or stick in the cylinder due to side loading. The coupling between the top of the piston and your hook should allow a few thousanths of 'flex' because you want the side force to travel through the frame, not through the piston and cylinder.

I expect you could put a wet rag in the cylinder to keep it relatively cool. It is critical that the welding be done with the piston completely separated from the body of the jack. You don't want to convert the jack into a steam boiler!
There are experts here that can help.
--Winston
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Winston wrote:

Ok, I can see now how the side force can cause the hook to dislodge. I have revised the design so that it includes the rails as well. For completeness, I am including it here as well:
http://www.taydin.org/web/jack/diy_machine_jack_rev2.pdf

I think I will try heating the cast base of the bottle jack to 100 degrees celsius using a hot air gun and then I will put small tacks around the base and let it cool in between. Let's see how it works out ...
--
Timur

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Timur Aydin wrote: ...

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.
My ideas are always better when I have the objects in hand, so this suggestion-from-a-distance may not be all that great <G>.
Bob
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Bob Engelhardt wrote:

Winston wrote:

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 ...
http://www.taydin.org/web/jack/img_1771.jpg
In the picture, the edge where the hydraulic pump and the lever is located is the back side (away from the machine edge)
--
Timur

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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.
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RAM wrote:

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.
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Timur Aydin wrote:

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: http://mysite.verizon.net/reswoead/sitebuildercontent/sitebuilderfiles/fencecart.mov
--Winston
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Winston wrote:

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 :)

http://mysite.verizon.net/reswoead/sitebuildercontent/sitebuilderfiles/fencecart.mov
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,
--
Timur

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Timur Aydin wrote:
(...)

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
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Bob Engelhardt wrote:

Oh, wait! Your modified design: http://www.taydin.org/web/jack/diy_machine_jack_rev2.pdf doesn'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
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Timur Aydin wrote:

Much better.
Please examine this:
http://www.mcmaster.com/catalog/115/gfx/large/8799tp1l.gif
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.
http://www.mcmaster.com/catalog/115/gfx/large/8799tp1l.gif
(It'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
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wrote:

These of course..and I have a number of them..work the best...
http://www.tksimplex.com/html/product_detail.php?pid &catname=Mechnical%20Equipment&scatname=Ratchet%20Jacks
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
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Gunner Asch wrote:

http://www.tksimplex.com/html/product_detail.php?pid &catname=Mechnical%20Equipment&scatname=Ratchet%20Jacks
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.
--
Timur

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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
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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
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Glenn Lyford wrote:

I see what you mean. But if the toe does not protrude beyond the feet, it won't go into the notch ...
Using the following procedure improves the situation somewhat:
- First lift the machine enough so that the jack feet will fit underneath it and then put wooden blocks under the machine.
- Second, release the jack and push the jack forward so that both feet are under the machine. Then continue to lift the machine.
This procedure would also eliminate the friction between the rails of the jack and the machine edge after the feet are under the machine. But before that, there will still be friction.
--
Timur

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http://www.taydin.org/web/jack/finished/img_1784.jpg
In this photo, notice that only the front edge of the base plate is on the ground. It would not take much (someone leaning on the machine, whatever) to get the line of force that's going through that corner to move even closer to the machine. At that point, the only thing keeping the jack under the machine is the friction on that itty bitty lifting toe to resist maybe a ton acting off center. Feel lucky? Luck is about all you have going for you at that point, and is a very bad way to routinely deal with heavy, expensive, and precise machines.
It looks like this machine was flat across at the point where you were lifting, and the existingf feet left a huge gap for you to place the jack under. A 1" wide foot on either side of your toe of the same thickness would not have mattered, and would have taken luck and friction out of the risk equation. With the feet, I bet that the bottom plate would have been flat on the ground all the way to the back.
If you do have a situation where you have enough room for only you lifting toe, then perhaps the correct solution is to use a prybar at that location to create a gap adjacent to it large enough for the lifting toe AND proper stabilizing feet.
I'm glad it worked and you got done everything you needed to do without injury, but just looking at that gadget makes my fingers and toes hurt. --Glenn Lyford
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Glenn Lyford wrote:

After reading your explanation about the safety aspects involved, my fingers and toes started to hurt as well :)
When Winston talked about the need to have feet, I wasn't clear what he meant. But now I understand it... I will weld pieces to the left and right side of the toe.
Because of the existing rubber pads, I won't have a problem on the lathe. But the milling machine is next and it also has a flat cast iron base and just two openings for the forklift rods to go in. I hope the new jack with the feet will be narrow enough so that it fits in to the forklift opening...
But in any case, I have to exercise utmost care when working with this jack. I will never, ever, put any finger under the machine or the feet :O
--
Timur

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Glenn Lyford wrote:

After reading your explanation about the safety aspects involved, my fingers and toes started to hurt as well :)
When Winston talked about the need to have feet, I wasn't clear what he meant. But now I understand it... I will weld pieces to the left and right side of the toe.
Because of the existing rubber pads, I won't have a problem on the lathe. But the milling machine is next and it also has a flat cast iron base and just two openings for the forklift rods to go in. I hope the new jack with the feet will be narrow enough so that it fits in to the forklift opening...
But in any case, I have to exercise utmost care when working with this jack. I will never, ever, put any finger under the machine or the feet :O
--
Timur


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Timur Aydin wrote:

Please see Glenn's third paragraph and closing remark.
I discovered this thing called a 'Slate Bar'. http://s7d2.scene7.com/is/image/WMHToolGroup/2604_main?hei `0&wid`0
They cost about U$30 at the local Home Depot and are worth every penny.

What keeps the jack from tipping?
This is *really* risky, Timur. What would happen if there were almost no friction in the system? Your jack would slip out from under the load and rocket towards something valuable and mushy, like your body or worse, someone else's.
Add feet, please. They will keep you safer.

Doesn't sound plausible to me. The jack would just tip into the load.
--Winston
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