Overarm jammed on horizontal mill

[19brendan81]

OK, so I got the vertical screw fixed on my old horizontal mill, now I need to sort out the other issue that needs attention. This being the overarm is completely stuck. No matter how hard I try to turn the handle thats designed to move it, it will not budge...not even a millimeter. I have loosened off the two gib screws, but this didnt work. I sprayed as much WD40 as I could in the join but still she wont budge.

Im pretty sure the problem lies in the ways that the overarm rides in as the handle indicated in the picture below actually moves a little bit, indicating that its not seized in its shaft.

Any suggestions?

[Vernonv]

I don't know anything about these machines, but is there a locking handle/lever or bolt that allows the overarm to be locked in position?

[19brendan81]

It feels as if something is locking it in place, thats for sure. All i can find though is the gibs locking bolts, one is visible in the picture below, the other is obscured by the wheel.

The ways/dovetails dont appear visibly rusty...im surprised at its refusal to budge. I would expect it to be stiff, but this is way past that.

Would some gentle taps on the end of the gib be a bad idea?

[Dave J]

Does it have screws in each end or one end of the gib? If so it's a tapered gib and will only come out one way.
A few firm taps with a brass or aluminum rod wouldn't hurt it.

Dave

[19brendan81]

Hi Dave, Im unsure about the screws you mention...i'll have a look when I get home.

Brendan

[19brendan81]

OK, I have freed up the overarm somewhat. I found that the gib was held in place by a screw at each end so I pulled them out and tapped the gib out a little with a piece of aluminium, it moved easily. I then pulled out the gib tightening nuts entirely and tried turning the handle again, but still no good.

So then I turned to my old friend Mr Stillson. I grabbed onto the round stub of the handle and levered gently, lo and behold she moved. I continued this way until I had moved the overarm about a foot. Looking up underneath I can see a heap of rust and crap there. Seems the previous owner gave her a clean before sale and this is what has caused it to bind. Im going to have to take the overarm all the way off to sort it out, which is going to be fun as the rack and pinion will not move the overarm enough to come off. Its designed so you "slide" it off the rest of the way. This sliding part will be fun given how stiff it is.

[Stustoys]

19brendan81 Did you remove the gib? It should slide all the way out. If you didn't you may have hit it the wrong way. They have a very shallow taper on them so you may have unstuck it with the hammer and then tightened the gib by driving it deeper. Try hitting it the other way.

Stuart

[19brendan81]

The jib came out with the overarm, so its hanging out about a foot...but isnt all the way out yet. I plan on getting it out completely tonight. I loaded the whole thing up with WD40 before hitting the hay last night in an effort to free things up a touch.

[Stustoys]

If its doing that I would guess you have hit it the wrong way. It "should" come loose, then you "should" be able to slide the gib out by hand. Of course sometimes things dont do as they should.
Good luck
Stuart

[19brendan81]

I think its like you mentioned in the other post, most of the grease on this thing has set like concrete. Ive been cleaning up all the contact surfaces since I bought it to try make things a bit smoother. The seller told me on the way out that he gave it a steam clean before he sold it...I didnt ask for details but new it was probably not the best idea. The steam is no doubt whats caused this overarm to bind. It took a while to free up the x and y travels too, although they werent too bad from the onset.

[19brendan81]

I got the overarm off last night. It took a fair bit of effort and a bit of creativity but its out. The Gib is indeed tapered (why do they do that?) by an absolute poofteenth, I think the difference accross the 450mm gib was about .3mm or so.

I cleaned the gib up last night and will move onto the other contact surfaces on the weekend. They have a fair bit of visible rust and whatnot in them, I hope thats what was causing the problems. Now the overarm is off I can definately confirm that the wheel thats meant to move the overarm back and forth is spinning freely in its shaft.

The best news is though, that after I got the overarm off I was able to identify the third and final problem with the mill, which was its refusal to go into low range (bottom 8 speeds betwwn 25 and 103 rpm). I was worried something was broken but it turns it out that the problem is a patch of rust on the shaft the gear slides on. I should be able to clean it up without difficulty.

The other thing I noticed is that there is a sight glass on the right side of the mill which I assume is where you fill the oil up to. However when looking down from above, i can tell that if I filled the mill cavity with oil up to there it would require a vast amount of oil, id estimate between 50 and 100 litres. I can see oil in it, but its only probably 10 or 15 cms deep....filling it to the sight window would require adding oil until it was 60 or 70cms deep. Does that sound right?

Brendan

[Stustoys]

Glad its off Brendan
Gibs are tapered because that's how they are adjusted, screw it one way to tighten things up, screw it the other way you loosen things off. That's why I was saying to try hitting it the other way.(this is for gibs that have adjustment screws at ends, there is another style that the adjustment screws act directly on the back of the gib)
As far as the oil goes. Is there a oil pump in there somewhere? On some machines I have seen sight glasses where you can see oil running over the inside of the glass so you know the pump is pumping.
Stuart

[19brendan81]

Yep, it has an oil pump. Up the top I can see where the oil is meant to be pumped onto the rear and front spindle bearings. Im not sure whether the oil pump works though, i dropped a wire brush down into the sump last night and want to fish it out before I fire it up.

The oil is filthy in the damn thing, im going to change it. Its all rusty coloured. fair dinkum, who steam cleans a mill?

[Stustoys]

fair dinkum, who steam cleans a mill?

Well I guess it depends how dirty it was, steam cleaning might not be so bad "just before you pulled it down", but to steam clean it and leave it does seem a little silly. I wonder how careful they were of the electrics? Still I doubt there is much electrics on it.
Can you see a way for the oil to flow past that glass on its way back to the tank?
Stuart

[19brendan81]

Its a bit obscured, ill have a look and let you know. I do know however that I cleaned the window when I first ran the mill, then afterwards it was oily again. So thats a good sign I spose.