frozen bearings & paper gripper, SP-15

I am refurbishing a SP-15, which had been sitting in parts in a basement for 20 years (and when I say parts, I mean that the bed was removed from the legs). I am having troubling loosing up a few parts. None of these parts have much apparent rust… they are just not moving.

Problem 1: The grippers will not move from the gripper bar. I have removed all the knobs, rings and spring. The bar with grippers has been soaking first in mineral spirits and then in Evapo-rust over the last three days. I have also tried liquid wrench. I have tried lightly tapping the bottom of the grippers with a rubber mallet. Any suggestions?

Problem 2: All the bearings, except one, are frozen. I have tried similar soaking procedures with these, and after 3 days they are bubbling when immersed in Evapo-rust, but are still not moving. A car mechanic suggesting I try boiling them… any other suggestions?

Thank you for any advice,

Jessica Peterson

Paper Souvenir

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Eric Holub
Editor
14 years ago

The only wooden bearings would be the ink drum bearings. They are inaccessible for lubrication, so a durable tropical hardwood was used on some models, and I think that includes the SPs.
If the other bearings have freed up, perhaps the grease inside just needed to be worked and loosened up.

Eric Holub
Editor
14 years ago

Good point Alex. I hadn’t really thought about the bearings. I assume now we are talking about the impression bearings. If they are sealed ball bearing rollers, and they are not free-turning, they would probably need to be replaced, whether or not any treatments have penetrated the seals. They may well be standard bearings and available as stock items. There are other ball bearing rollers that can be repacked with bearing grease, but again, if they are not already free-turning, there may be corrosion and damaged surfaces also requiring replacement. Simple bearings without balls or pin-rollers just need to be cleaned and polished on the working surfaces.
If we are talking about the cylinder eccentric bearings, they would need disassembly and cleaning and lubrication. Last year I had to take a side piece off a SP-15 cylinder carriage because of a stuck cylinder bearing, and it was just a matter of removing a residue like dried root beer (lubricate, and use the right lubricant!), polishing the surfaces with crocus cloth, and lubricating. And by the way, it turns out that even a clean cylinder eccentric will freeze if you over-tighten the setcrews on the cover plate. There needs to be clearance between the cover plate and the side-frame so the assembly can turn.
The ink drum bearings are wood aren’t they? Crud could interfere with its movement, and moisture could dmage the bearing itself, so inspection would be a good idea if you are already taking things apart.
Any other bearings to consider?

Alex Brooks
14 years ago

There are chemicals that dissolve alum oxide, but the liquid can’t get to the center of the pin – so it’s not a viable solution – this happens with vintage bicycles all the time – with aluminum seatposts and stems which slowly oxidize over the years. Literally no amount of physical force can break the bond – the aluminum would break first. So they’re usually cut out – destroyed – so the frame can be saved.

If I were you, I would put it in the oven and heat it up, take it out and let it cool, repeat a few times – then while it’s hot i would tap the pins with a brass hammer. If this won’t work I’d take it to a machinist and let them try an arbor press. But if the pins are oxidized in place, even if you do remove the pins, the gripper bar may be permanently damaged, galled, and might not ever work right afterwards.

I find that heat is usually a better cure than miracle liquids – especially evaporust – it’s good for certain things but as soon as you remove the item it starts flash-rusting, so your bearings might already have rust inside them. bearing depend on packed grease to work properly, so I would just bite the bullet and buy some new ones – they were only supposed to last a ‘lifetime’ of ten or twenty years anyway…

Alex Brooks
14 years ago

Jessica-
There’s nothing that could be holding the pins in except old grease, dirt, rust, or aluminum oxide. The pins are steel and could rust, but your penetrating oil can’t get into the center of the pin – but you should still be able, with a brass hammer, to get the pins out by using some arm muscle. But the gripper bar is aluminum and aluminum doesn’t like water. Aluminum oxide is the equivalent of rust except it can expand 300-400%. Has the gripper bar been wet or damp for a long time? If it’s oxidized inside, there’s a physical bond that is super strong. You might be able to push the pins out with an arbor press, but it might also damage the aluminum bar.

if you think this is frustrating, hold on – the gripper bar is one of the easiest part to recondition… BTW, Eric – won’t penetrating oil or the water based evaporust ruin the grease in the bearings?

Eric Holub
Editor
14 years ago

You did loosen the Allen setscrews, right?

Eric Holub
Editor
14 years ago

I would tap the bottom of the grippers with a pin punch (the largest that will fit) and hammer.
No point using Evapo-Rust if rust isn’t there, but penetrating oil is needed. Slightly better than Liquid Wrench is Kroil from Kano Labs. Acetone mixed 50-50 with automatic taransmisson fluid is supposed to be the best, but one person I suggested that to could not get the two to mix properly.
Such penetrating oils will be needed on the frozen bearings too, but disassembly will be needed in any case. All the de-rusted bearing surfaces will need to be smoothed with scrapers, synthetic steel wool, fine grit abrasive, crocus cloth, etc.

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