DIY Lifting Cart using 4 bottle jacks!

[damae]

I want to build a steel cart with four hydraulic bottle jacks attached to it that can move my Bridgeport mill. The idea is to avoid the safey hazzards and hassle associated with using an engine hoist or pallet jack. I want to be able to move my mills around the garage on a whim, and without needing a second person.

Recently, I started a thread asking if a pallet jack could be used to move a Bridgeport sized mill. The answer is yes, but not very safely.

http://www.cnczone.com/forums/showthread.php?t=19435

So here's my first attempt at mocking up the idea. Just a bunch of 4" square steel tubes. The dolly can adjust to differnt size pedestals for a range between a series I mill and a Series II mill. The size can be adjusted by sliding the red tubes through the corner brackets. I'll pin the tubes in place, sort of like my adjustable shop crane from Harbor freight.

The small orange cylinders are cheap 4ton hydraulic bottle jacks. I picked up 4 of them today from Harbor Freight for about $45 total.

The yellow parts are intended to sit on top of rollers. So to lift and move a mill, I would assemble the pieces around the mill's pedestal base, adjust to size, and start jacking the mill up. Once it clears the ground, I should be able to start moving right away.

One problem is weight. I think I overdid it, with 3/8" wall thickness. My CAD software predicts a weight of almost 1000lbs for just the dolly! Any ideas? I don't have a good feel for how thin to make the walls, or what size tube to use. I want this thing to be able to handle moving up to a 4 ton mill.

This is still the pie-in-the-sky design stage, so I welcome any criticism, pointers, ideas, or questions!

[Ken_Shea]

Damae,
If you are intending to move it very frequently that may be a good idea.

What I did was simply use 4 HD caster wheels, tilted the front up, remove the leveling pads, insert the dual wheel HD casters, let it down, same for the back, roll into place then reinstall the leveling pads.

Same on my lathe, works real easy if you have reasonably smooth floor.

Ken

[Zumba]

4", 3/8" wall tubing in that configuration is beyond overkill. That's the type of metal you would use to lift about 40 tons, not 4 tons. Besides, that stuff costs what... $30 a foot?

Note that a typical 2-ton engine hoist uses 2.5", 1/8" wall tubing (or rather its metric equivalent) telescoping inside 3" 1/8" wall tubing, and it is just a single tube supported on one end. You have two tubes supported on both ends.

In any case, I don't think a pallet jack is necessarily unsafe for a BP mill. It's just that a BP isn't set up to be lifted by one without a pallet in place, and unfortunately, used BPs rarely come with pallets. (In contrast, some machines like my 1800 lb woodworking jointer is set on top of two 4x4 blocks. I can move it around with a pallet jack, even though it has no pallet. w0w)

I bought a 9x42 Jet not too long ago. It had a decently sturdy pallet. He problem was that it was not designed for a pallet jack. Fork lift only with the forks spread farther apart than usual. My machine is therefore sitting on the ground right now. If I find the need to make it mobile, I will probably use wood to build a new pallet. The plan would be to get some redwood 4x4s, plane them down to about 2.75 x 3.5", screw a couple 2x6s on top, and that's it. $40 solution. I would probably chamfer the edges and paint it Jet black with automotive paint to make it look "stealthy".

[unterhaus]

one issue with moving something as heavy as a bridgeport is that you have to get it stopped once you get it moving. Since from your picture, you weigh somewhat less than 2000 lbs, there could be a problem.

At work, they moved the bridgeports on a 2 wheeled dolly. Then there was a third piece like a Johnson bar on the front. When they wanted to stop, they let down the Jobar, and it stopped. They didn't use jacks at all -- they lifted it using the knee.

I've moved some incredibly heavy things on a pallet jack, but none were that tall. Bridgeports are top heavy.

[martinw]

[QUOTE=damae]I want to build a steel cart with four hydraulic bottle jacks QUOTE]

Dear damae,

One thing you have to look out for with some bottle jacks is they specify a maximum "lift" of a certain number of inches, but what really happens is that they sink back maybe 3/4" before actually holding. In other words, the max lift is not the one that they can maintain (without you continuously pumping!)

I got caught out by this once.

Best wishes

Martin

[damae]

Originally Posted by Ken_Shea ... What I did was simply use 4 HD caster wheels, tilted the front up, remove the leveling pads, insert the dual wheel HD casters, let it down, same for the back, roll into place then reinstall the leveling pads.....

Ken, what are HD casters? Are these solid steel wheels? Do you know of a good source for such wheels?

Originally Posted by Zumba 4", 3/8" wall tubing in that configuration is beyond overkill. That's the type of metal you would use to lift about 40 tons, not 4 tons. Besides, that stuff costs what... $30 a foot? .....

I hadn't priced it yet, but I was hoping to find the steel I need at a local scrapyard for $.025/lb. Which is still expensive with it weighing so much! I'll try reducing the tubes to 3" and a thinner wall. That should save a lot of weight. I also had a 1" thick steel plate as part of the footing. That can probably be a lot thinner. The steel base on the jack itself is only 0.25" thick. Your point about wall thicknesses on an engine hoist is a good one.

Originally Posted by Zumba ...In any case, I don't think a pallet jack is necessarily unsafe for a BP mill. It's just that a BP isn't set up to be lifted by one without a pallet in place, and unfortunately, used BPs rarely come with pallets. (In contrast, some machines like my 1800 lb woodworking jointer is set on top of two 4x4 blocks. I can move it around with a pallet jack, even though it has no pallet. w0w) .....

Another good point. Do you think this is still true for a 3ton Series II mill? I have limited celiing height, but there should be enough room to fit a permanent pallet under my Series I mills. My new Shizuoka is Series II size and I don't yet know if a pallet will fit.

Originally Posted by unterhaus one issue with moving something as heavy as a bridgeport is that you have to get it stopped once you get it moving. Since from your picture, you weigh somewhat less than 2000 lbs, there could be a problem......

Haha. Yes, I do weigh just under 2000lbs; about 1800 pounds short! I have a flat floor. Then again, it's probably got a little slope. What exactly is a Johnson bar? I haven't heard of it before.

Originally Posted by unterhaus I've moved some incredibly heavy things on a pallet jack, but none were that tall. Bridgeports are top heavy.

This is the fundamental problem with bridgeport mills -- they're top heavy. No matter if you're lifting with a pallet jack, shop crane (aka. engine hoist), or some custom dolly, the lifting device is always a small fraction of the mill's mass. So no matter how you lift, you don't change the center of mass very much, unless you add mass to the system. That's why a forklift work so well =)

[QUOTE=martinw...One thing you have to look out for with some bottle jacks is they specify a maximum "lift" of a certain number of inches, but what really happens is that they sink back maybe 3/4" before actually holding. In other words, the max lift is not the one that they can maintain (without you continuously pumping!)....[/QUOTE]

Wow, thanks for the heads-up! I didn't know about this limitation! For my application, I only need to lift 2" to get it off the floor. Do I need to lift it to 3" and let it settle first? Perhaps they need to be bled to remove air from the system? The manual that came with mine had instructions for bleeding the air out.

[damae]

Ok, second try. I reduced the weight from ~1000lbs to 520lbs. Changed to 3" tubes, with a maximum of 1/4" wall. I think I can go thinner yet.

Does anyone have a link to standard box steel shapes and wall thicknesses? What is a standard wall thickness between 1/8" and 1/4"?

Also, I don't yet own a set of Hilman rollers ("Skates") and am interested in finding an alternative. Some large diameter steel wheels would be great, if anyone can point me in the direction of a source.

Thanks for all the great feedback and ideas so far. Keep the ideas and comments coming!

[martinw]

Originally Posted by damae I didn't know about this limitation! For my application, I only need to lift 2" to get it off the floor. Do I need to lift it to 3" and let it settle first? Perhaps they need to be bled to remove air from the system? The manual that came with mine had instructions for bleeding the air out.

Dear damae,

The jacks I used didn't have an air bleed facility, and I do not know if the "fall back" was just because mine were really cheapies. If you can, my advice would be to buy one jack and load it up to whatever you will be using it at. See how much it sinks under load, bleed air, and repeat. Then you have all the information to make the decision about whether to buy another three of the same type. The important thing is to see how much it sinks under load, beause it will not sink when really lightly loaded.

Hope this helps.

Best wishes

Martin

[Geof]

Your first design was indeed serious overkill which I am all in favor of; BSH engineering (Built like a Brick S**t House)

One thing you might not find are tubes in the 3" square region that slide together nicely and a sliding fit is an integral part of your design. You can get square tube that is around 0.20" wall thickness that will take 2" square inside; it is used for the receiver on trailer hitches. I think 2" square 1/4" wall tube would probably be large enough for your frame for moving bridgeports but whther it would take your 4 ton goal I do not know.

Regarding the fall back on your jacks you should have pin holes in the vertical tubes that the legs slide in. Jack it up and put in a locking pin.

[damae]

Jack, good idea about testing the bottle jack under load. I already bought 4 of them, but could always return them. Now, to find something that weighs a [literal] ton and figure how to keep it on top of the jack. Oh... I can jack up 1/2 of my mitsubishi.. it weighs about 4000lbs.

Geof, excellent idea about the vertical locking pin! That would also help coordinate the heights on all 4 sides, by counting how many holes up the locking pin is.

Anyone know where I can find large steel wheels?

[Geof]

Originally Posted by damae Anyone know where I can find large steel wheels?

Steel wheels? Use rubber wheels.

[martinw]

Originally Posted by Geof Regarding the fall back on your jacks you should have pin holes in the vertical tubes that the legs slide in. Jack it up and put in a locking pin.

Dear Geof,

I absolutely agree, but the problem is that you have four jacks to attend to and they "sink" almost instantly. You cannot attend to four jacks at the same time unless you have four hands. A squid might manage, but humans will not.

Best wishes

Martin