Bridgeport knee elevation

I

ironwrx

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Hi I have a round ram Bridgeport that I picked up a few months ago. The mill did not have a head, and I was able to get a J- head and mount it. It’s far from perfect, but it works for this back woods machinist.
The machine is in my shop, which has a good roof, but certainly not climate controlled. So, when we get sticky or drippy weather, unfortunately, my machines are sometimes prone to condensation. Well, the last couple of weeks, I haven’t been able to use the mill, and keep ahead of the moisture. I usually try to keep after it with Kel protective oil spray, but a bit of surface rust came in in spots. Not really a problem that a wire brush and a little scotch bright won’t take care of.
The big problem turns out to be the knee elevating gears and handle. When I went to Jack up the knee, it was really hard to move so hard, in fact I ended up snapping off the handle, and when I used the splined end with a pipe wrench to try and get the knee up, I started to skip teeth with the bevel gears on the elevation screw.
Obviously, something has bound up and will need to be taken down and freed up, just wondering if anyone else has ever had to deal with this situation, and could give some wisdom.
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If you move the table to the far front of the machine you can remove the leadscrew cover on the carriage to gain access to the gears and screw for the knee.
Being seized it’s either in the ways,the elevation shafts or gears. Might need a long soak in some penetrant and oil.
 
Transmission oil is your friend.
Pull the gib on the knee and continue soaking.
Clean what rust you can get at on the ways for the knee...again transmission oil and scotchbrite are your dear friends.
Get a little movement one way clean oil and try to move the other direction, clean oil and repeat.
 
The absolute best penetrant is ATF+acetone mixed 50/50. I keep a 1qt pressure sprayer full of it on hand. The beauty of this mix is it gets the ATF in deep and stays unlike say WD40 or other penetrating oils.

Being close to the ocean rust is a constant problem here and I’ve tried everything and the only product I’ve found that is truly spray and forget is Fluidfilm. I also keep my lathe, mill table and bandsaw table covered when not in use.
 
C-Bag said:
The absolute best penetrant is ATF+acetone mixed 50/50. I keep a 1qt pressure sprayer full of it on hand. The beauty of this mix is it gets the ATF in deep and stays unlike say WD40 or other penetrating oils.

Being close to the ocean rust is a constant problem here and I’ve tried everything and the only product I’ve found that is truly spray and forget is Fluidfilm. I also keep my lathe, mill table and bandsaw table covered when not in use.
Click to expand...

Do you think this 50/50 mix is better than kroil or PB B’laster?


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Hopefully the knee gib isn't seized up. There are horror stories about the work needed to undo that particular mess.
Given the amount of rust in the first photo, you should probably back out the gib until the knee is quite loose before trying to move it again.

For future reference, if you come even remotely close to bending (let alone breaking) a crank, STOP! Either the axis is locked or something is bound up, and adding more force will just make it worse. Take it completely apart if needed, but don't force it.
 
ironwrx said:
Do you think this 50/50 mix is better than kroil or PB B’laster?


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Click to expand...
Yup, I’ve not touched or re purchased either since finding out about ATF/acetone here on H-M. I’ve always been amazed at ATF since I got the tip from one of my instructors in college about putting 1qt in for 500mi before changing oil on cars that seem to be using oil but not smoking. If the engine has been ignored and the oil rings have gotten sticky and especially if the valve guide seals have gotten hard. All those additives it has is great for everything. YMMV.
 
Transmission fluid is predominantly detergents, emulsifiers and friction modifiers. The oil is mainly a carrier and a means of creating hydraulic pressure. Its not surprising that it would have penetrating oil qualities.

Not much acetone won’t dissolve thats petroleum based (sludge, paint, etc), so it also makes sense that it would help penetrating old iron. Only thing about acetone is that it flashes off super fast (leave a can open overnight and it will either be empty or nearly empty the next morning) so its actual “penetrating” qualities I would question.

But, if it works, it works…,
 
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