Image below is the cross drive for a mini lathe. It is rusted solid. I have soaked in WD40 for a couple of days and still stuck. The arrows in green are points I can tap with hammer but dare not hit too hard in case the `lug` breaks off.
Never used heat before on rusted items but would `hot air` paint stripper gun work? I am not too bothered re the paintwork as I will be repainting the main body before I re assemble the lathe.
Any other ideas?
Hot air *might* work - but it will not tend to give the thermal shock you get from a blow torch or similar. (ideally you want bits to expand / contract bits of it at different rates to force some movement in the rusted contact surfaces)
The yanks seem to get good results with Evapo-rust leaving it soaking for a day or more.
WD40 isn't necessarily the best thing for freeing rusted joints, 'proper' penetrating oil such as Plus-Gas may do better and/or other even more specialised formulae.
From the picture (and not being wholly familiar with lathe mechanics) I'm not quite clear what's supposed to slide on what.
I *looks* as if the threaded screw is meant to rotate and move the lump of metal with a groove in it across the other U-section larger piece of metal. Given that I'm not quite clear why tapping at the green arrow points would help, especially the ones on the LHS.
The harder I look the less I'm clear about what's meant to slide! :-)
However, one thing that's worth trying (it's often worked for me) is to hit the seized joint so that you squeeze it, preferably with a heavy block or bigger hammer on the opposite side to increase the effect of the hitting.
ss used his keyboard to write :
WD40 is next to useless as a penetrating oil, try a proper penetrating oil or diesel.
Hot air gun may help a little, I would hot and cold shock, spraying penetrating oil at the thread block interface so the cold contraction helps draw the oil in.
+1. The best penetrating oil is ATF. It's 100% detergent oil. If no solvent is added it's just slower to penetrate.
Check out youtube, there are numerous ways to free up rusted parts. Evaporust is sponsoring lots of youtubers to promote their overpriced solution. Project Farm trialled some options.
NT
Plus Gas and all those kind of products are pretty useless TBH, esp if they've been on the shelf for a while. Best results come from freshly mixing isopropyl alcohol with a thin hydrocarbon oil and giving that mixture time to penetrate. A heat gun is far too puny and not worth bothering with IMO.
The threaded screw turns and moves the smaller metal part along the 2 rods. The 2 rods should just push out and locked with grub screws, so in theory tapping at the green arrows should push out the 2 metal slides. I dont want to thump too hard in case I break it.
Ah, so not only should the bit with a groove move across the other but the two rods shpuld be possible to extract.
My suggestion still stands, put something large and heavey underneath and bang the top with a hammer. No risk of breaking anything and it might do the trick.
+1 Tabs. ATF and IPA 50-50 mix. If that doesn't shift it then an oxy torch surely will.
I think I would immerse it in diesel for a week. Are the grub screws out? If so, relatively light tapping should then move the rods with much less force than it would take to break the casting.
The grub screws are out, I have hit it quite hard, I believe the part has been sitting in a shed for a few years unused.
+1 for not using WD40.
One other trick I've seen used on TV is to heat a thicker oil before immersing the item.
I wonder if some kind of reverse electrolysis is possible? The problem is though, even if you get it all to move, how much damage has been done to the surfaces and hence any kind of precision movement. Brian
That is right, wd stands for water dispersion as far as I am aware, and hence is supposed to actually stop water attacking the metal, its a bit late after the event. In my experience wd 40 also degreases as well which is not good in the long term, but might dislodge gunked up bits, though not rusty ones.
Brian
With cast stuff like that, usually surprisingly little. I have watched the like of Keith Rucker restoring some old machine where you think that a part is rusted beyond saving, and yet a good soak in evaporust seems to have it back in a surprisingly good condition.
The term you're looking for is electroplating - doing it well is not simple.
Two minutes before posting this I was watching a repeat of the "Repair Shop". As others have suggested an overnight soak in Auto (Gearbox) Transmission Fluid/Oil and an Acetone mix to remove rust and free up a mechanism.
Yes, that is one of the classic mixes, but we don't all have ATF and acetone to hand. Acetone helps by mopping up any free water, as well as by thinning the mix. Good old Plus Gas contains some anti-rust agents, I believe. Simmering it gently in engine oil is another option. When you have deep close fitting parts like the rods it takes time for capilliary action to get lubricant all the way in.
Unless it is actually urgent to get it apart I'd go low tech long time.
If you have managed to get oil in any gap don't heat it up too much to carbonise the oil. On the occasions when things were tight all it did was seize things up even more.
Does the threaded portion rotate? The prominent part seems to have a left hand thread. Is the other part a right hand thread?
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