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03-17-2017, 08:18 PM #1
Old Eclipse 18x6 mag chuck reburb
I hope this is the right forum.
I recently acquired this old chuck. It is kind-of associated with a 1928 Brown and Sharper #2 grinder I am restoring but I do not know if they are contemporary. It looks old.
Despite the handle moving freely, it is as dead as a doorknob. Barely a trace of magnetism.
It looks like it has been dis-assembled at some time - maybe to fix it, maybe that is why it is dead. :-) Who knows.
I can get it re-magged locally so I'll get it cleaned up and fix what needs to be fixed if I can. I'm not so concerned about losing magnetism by dis-assembling it because it is already dead.
I have it apart. It is full of what look like 100 year old camel poop.
I have some questions if I may:
* Notice the bolt/nut left of the eccentric. It sticks out. I can push it back in, but when I operate the eccentric it pills that plate forward but when it goes back the bolt remains out. Do these bolts undo and just push through the assembly of magnets? Will it all fall apart if I do that?
* Does the magnet assembly 'lift off' from the chuck top or is it secured somehow?
Last question: what is that camel poo??!! Grease? So, when I reassemble it all do I smear (non-drying) grease over everything?
03-18-2017, 01:59 AM #2
The bolt holds the stack together, its just a pile of magnets + spacers. The chucks work by lineing the magnets up with the poles on the chucks top for "grip" and then to "turn off" they short the magnetic flux back through thoes pole pieces by sliding the whole magnet - spacer stack so the poles short across the spaces - keep the magnetic flux in the chuck.
Rough guess the bolts snapped - damaged fix that and it may just work once more.
The eccentrics tend to wear on most magnetic chucks, this reduces the movment and they then lose there grip as they don't move far enough to turn fully on + they tend to also not turn fully off.
Camel poo is probably a mix of lube and coolant - corrosion. Every magnetic chuck i have encountered is full of some kinda lube, oils more common though, but i have never had a eclipse one apart.
03-18-2017, 02:13 AM #3
I guess that means I am good to go with dismantling further. Cool. Unless I'm told it is a stupid idea I'll dremel numbers in the magnets and spacers before disassembly to make sure it all goes back in the same way.
I gave things a good clean. Yes. The poo is grease and/or dried oil but also lots of rust. The base interior is quite pock marked with rust - I got the angle grinder and wire wheel on it.
I have read some people drill/tap for a drain plug in the base to permit refreshing the oil - sounds like the right thing to do. I guess it would not matter to this old girl if the lube was oil or grease. But if oil, then gasket sealer required when getting it back together I'd say.
03-18-2017, 02:49 AM #4
Oh, should that magnet assembly lift of the top plate? Like, it is held there magnetically and I should pry it off?
(There is still a little magnetism in the magnets)
03-18-2017, 04:41 AM #5
Well it is a magnet and top is steel.
Is magfield doing the rezap? About $130? I have an 18X6 here I got from Sydney that is weak. Previous owner pulled it apart and once Al Nico magnets get the keeper removed you have something like 3 milliseconds before it starts losing some magnetism.
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03-18-2017, 10:51 AM #6
I think it's this old Tony on YouTube but he does some stuff with cleaning up a similar eclipse chuck. I think he filled it with a heavy gear oil.
03-18-2017, 01:10 PM #7
The magnets are held to the top magneticly. Clamp the top plate to a bench. Using pipe/extending clamps, place them from a table edge to the far side of the Mag cluster, the idea is to slide the cluster off the top plate. If you can advance one side a bit more than the other, this reduces the field effect of the magnets to the pole pieces. Beware this will fight you every inch of the way, if a clamp slips off, the magnet will want to align itself, real quick, and it could bite you.
I would suggest Not disassembing the magnet stack, just replacing the broken bolt. Very important the order and polarity of each magnet.
I rebuilt a 6 x12 Ecilipse, it had fixed magnets attached to the base with glue, that had broken loose, as well as a broken link for the slide. If you have something similar, be careful not to break the glue joint, or move them.
03-18-2017, 04:48 PM #8
Thanks Tom. Good advice. I'll be back into it today.
RC, yes - Magfield Manufacturing at Tullamarine. $130.
Ianagos - I had a look through his vids and didn;t see one. But, I'll scan about. Thanks.
03-18-2017, 08:38 PM #9
I don't think this thing had much of a chance of working anymore.All three bolts broken.
I dremelled numbers into each magnet and separator and then slid them off one by one and placed them in order on the base plate.
You know, what I didn't understand about the insides of this thing was "what actually moved when the lever/eccentric was moved"? But now I see the whole darn magnet assembly moves .. it slides along underneath the top plate as a unit. I didn't really understand why all that grease was necessary but now I get it. When I got the base plate off and operated the lever to see what stuff did, just the end plate the eccentric attached to moved ... but of course, I didn't realise it was not actually attached to anything any more! I knew *something* was supposed to moved but I didn't realise it was the whole lot. Got it now.
I gather these bolts are bronze, so I'll need to get some of that to make some new ones, and while I am at it, I may make a new lever rod with the eccentric bit. It is pretty rusted and tired.
Thanks all. I'll post some pics here when that all gets underway or completed.
03-20-2017, 05:41 PM #10
Yep bolts need to be a non magnetic alloy, go carefull some bronzes are partially magnetic and it will rob the chuck of strength if they conduct magnetic flux.
Looks like that chuck uses the bottom plate as a pole piece - keeper, the chuck i pulled parat had the magnet stack clear the bottom but then had a bunch of steel shims as keepers. My case i did not remagnatize, but then i never removed the keepers or the magnets! My probelms were in both cases a worn - sloppy actuation cam. Simple rebush and job solved.
03-20-2017, 09:22 PM #11
I believe it's mixed in somewhere with his grinder rebuild sorry I can't really remember where or if he even has that much video on it.
03-21-2017, 04:48 AM #12
Adama, thanks. Brass it is then, but I'll take along a magnet anyways. I'll likelty redo the cam as well. Seems reasonable. This one is pretty worn.
Ianagos: np. I've seen those rebuild vids. Pretty cool. I'll have another look. :-)
03-21-2017, 03:31 PM #13
03-23-2017, 03:57 AM #14
I guess it means it also sticks to the bottom with only a smidgen of clearance.
Here is my chuck apart. It is of similar build except the magnets are smaller and of cheaper build then the eclipse.
I wonder how they rezap them. As I believe the poles of each magnet have to be opposites. Yet they are zapped while the magnet is assembled.
03-23-2017, 04:17 AM #15
If you want full grip you want a complete magnatism circuit, any air jumps and grip levels really fall off. Hence the magnatism goes from one magnet up through the chuck top in one pole, across through the work piece down another pole in the top to the next magnet in the stack which is the opposite way up, it then needs to be returned to the first magnet, which in my case was done with a stack of shims, in your case, the bottom of the chuck.
Remember with magnetism like repels and opposites attract, hence why the poles on a mag chuck alternate North and south.
The whole demagnetization thing is a bit of a lemon IME, a mag chuck's magnet circuit has to be able to handle a loss of the flux loop whilst remaining magnetised, other wise every part you put on the chuck that was smaller than the whole chucking surface would degrade the grip.
03-23-2017, 04:19 AM #16
To remag, you just zap em one pair of poles at a time, or you have a big enough coil setup to do it all in one. But multiple zaps is probaly the fastest + easiest.
03-23-2017, 06:11 AM #17
Be interesting to see how they do zap them. After doing much research there seems to be zero information on the internet how it is done.
Whether it is done with the top plate on the chuck or not, where the actual coil is positioned for each magnet?
03-23-2017, 09:43 AM #18
Can't tell you how, but me i would zap from pole to pole with magnet turned on and correct pole pieces on a magnetising coil to link up with em. Nothing cleaver, just have to drive it to full magnetic saturation, hence its normally just a large capacitor discharge through a big electro magnet. Don't even have to hold it just one large hard ZAP!
Magnetises i have been around there not much to see, just a loud bang as the coil energises fast that’s it. Soild state switching you probably get near silence.
03-23-2017, 04:58 PM #19
Looking at mine again with a compass shows my initial observation was wrong.
Turns out every second piece in the pack is a piece of steel and that one side (the top) is north and the bottom that goes onto the base is south.
I was under the impression the magnets were supposed to alternate north south but maybe that is only the newer builds that use ceramic or rare earth magnets.
03-24-2017, 12:51 PM #20
Take a bar magnet 3" long, one end North one end south, break magnet in half, the south end of the magnet will be north, and at the break line one will be south the other north