Castor wheels for the mill

Discussion on all milling machines vertical & horizontal, including but not limited to Bridgeports, Hardinge, South Bend, Clausing, Van Norman, including imports.

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liveaboard
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Re: Castor wheels for the mill

Post by liveaboard »

My idea is to build the pump from scratch.
Bottle jacks run at around 600 bar (8500 psi), so their pumps have tiny volume.

Since my design pressure is just 5% of that, a bigger volume pump will work better, and all it needs is a hole with an Oring groove, a rod on a pivoting stick, and a couple of check valves that are easily made with a steel ball in a hole.
I might need a bit of brass in the bottom to get a seal (drill a small hole then tap a larger hard steel ball against it to create a seat).
Pressure relief valve is an interesting problem; it could be built from scratch in a similar way, or maybe I'll find one from a car engine.

Anyway, other problems have raised their heads here so I'm afraid this fine idea will have to be placed on the back burner for a while.
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Bill Shields
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Re: Castor wheels for the mill

Post by Bill Shields »

Why not a grease gun?

Who says it has to be oil?
Too many things going on to bother listing them.
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liveaboard
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Re: Castor wheels for the mill

Post by liveaboard »

Yeah, I thought of that.
They're CHEAP!
But think about the tiny piston, it would take an hour to pump it up.
And release would be difficult if it was grease.

You can put oil in a grease gun, I have one with way oil in it for pushing into the fittings on my mill.
But volume problem remains; and no PRV, no release to let the oil out of the pistons either.

So, thanks for the thought,
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Re: Castor wheels for the mill

Post by Inspector »

Air cylinders with the shop air compressor? Leaks are easier to clean up. :lol:

Pete
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Bill Shields
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Re: Castor wheels for the mill

Post by Bill Shields »

i saw a $70 hydrotest pump on amazon the other day....
Too many things going on to bother listing them.
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Re: Castor wheels for the mill

Post by pete »

The air cylinders only seem like a good idea Pete until you run the real world numbers and figure out how large the cylinders and pistons have to be with 120-150 psi of shop air to lift I'm estimating about 3,000 lbs for Mark's new mill. Call it 3 air cylinders as the minimum stable number, so 1,000 lbs on each roughly, 150 psi of shop air needs at least 6.6 square inches of piston surface area to lift that 1,000 lbs of weight plus add whatever frictional losses there might be. At least 7-8 square inches of piston surface area. So to be safe and it would work for sure, about 2.5"-3" diameter on the pistons. Not impossible, but hydraulic can be much more compact and efficient because of the higher pressures. Now if Mark just happened to have a 3k psi dive tank compressor handy, then yeah it would be the best and easiest.
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liveaboard
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Re: Castor wheels for the mill

Post by liveaboard »

My compressor is 10 bar (150lbs) and as the pistons will be made from the castor hubs, they already exist.
The pressure required to lift the mill (1.3 tons) is already calculated at around 30 bar (450 lbs).
That already figures in that the front wheels will be considerably higher loaded than the rear.

A leak would indeed be a mess. That's the risk with low budget Orings instead of using hydraulic seals.
I can make it so that I can recut the grooves and fit the expensive seals if necessary.
That would only happen after my floor gets soaked with oil.

I found an old jack bottom (I used the jack cylinder for my press). It has a needle release valve, a check valve, and a pressure release valve.
600 bar one, but I should be able to change that.

Anyway, I can't work on this at the moment.
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liveaboard
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Re: Castor wheels for the mill

Post by liveaboard »

I had to move my whole workshop, which took time as I need to run power, water, and data lines 250 yards.
I've now managed to get some work done;

I cut the castor pivot rods down to 46mm with a 50mm lip.
Made cylinders with Oring grooves and threaded caps.
hydraulic parts half done.jpg
Hydraulic cylinder closeup.jpg
I lifted the mill onto my small workbench, drilled and tapped 15 10mm bolt holes. The lower bolt holes are blind into the cast iron base plate. Upper ones penetrate the top of the cutting oil reservoir.
250-710 Ruhla on workbench.jpg

Made the mountings and welded them onto the cylinders.
Pressure tested at 40 bar, 600 psi. To my pleasant surprise, none of my home made little puck cylinders leaked at all.
pressure test 40 bar.jpg
Now waiting for the paint to get hard before assembly.
I still have to make the pump; I need the mill for that so I'll put it into the workshop first.
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Re: Castor wheels for the mill

Post by Terry - W6LMJ »

I am new to machining. The last time with a machine shop was Hughes Aircraft Company in Torrance, California. Before that Research Tool and Die, and before that high school. I just bought a Precision Matthews PM-728V-T. I installed castors/levelers on its stand and it seems to work well. It is easy to spin and move if you go slow.
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liveaboard
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Re: Castor wheels for the mill

Post by liveaboard »

It looks like you'd need to wind down each wheel by hand?

I mounted my homemade ones on the machine but I'm having trouble bleeding the air out.
I think it sucks in air around the Orings when I pull the pistons down. I'll try another method.
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Re: Castor wheels for the mill

Post by liveaboard »

I bolted the wheels to the machine.
I thought I could bleed the hydraulics by pumping the cylinders by hand with a tube in a can of oil; but air pulls in around the orings on vacuum.

So I made a pressurized reservoir to solve the problem and get everything filled so I can move the mill before I make the pump.
Just a fizz water bottle with 6 psi of air to push the oil down the tubes.
oil pressure bottle2.jpg
Filled with oil and closed with a valve, the wheels support the mill at the predicted oil pressure of 30 bar, around 450 psi.
wheel down 2.jpg
Then I hoisted it up on the tractor to take it out to the workshop;
Ruhla 250-710 on tractor 2022.jpg
Rolling it to the back of the shop container; I had to remove my saw, drill press, and bench vise.
rolling mill into workshop.jpg
After opening the valve to let the oil out, the old girl settles into position.
wheel up.jpg
I started working on the pump unit; it's going well but I had to stop until I get the orings for it.
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Re: Castor wheels for the mill

Post by Harold_V »

Nice! Well done.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
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