Magnetic chucks

Gents,

I have the possibilty to buy an Eclipse magnetic chuck for our Myford S7.

It is a second hand chuck with a Myford backplate already fitted. Are these worth having? Are they dangerous (anymore dangerous than a newbie who already has a lathe I mean)?

Can a magnetic chuck lose its magnetism?

Thanks in advance,

Mark

Yes ... If working to spec. they can be very useful

But yes ... magnetic chucks can and do lose magnetism

MichaelG.

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Edit: I presume it’s similar to this:

https://www.eclipsemagnetics.com/na/ax12c-p-circular-premier-chuck.html

Edited By Michael Gilligan on 10/01/2020 11:51:23

Hi Michael,

Thanks. It is an Eclipse AX475C magnetic chuck 40/034. I think given the fact that they degrade that I’ll give this one a miss.

Mark

Mark,

What price? I might like to experiment.

I guess it depends on cost really; there's a couple on ebay at the moment to give you a guide.
I have one on a Myford backplate and do use it occasionally, mainly for thinning or truing washers (or at least things that shape anyway).
Mine came a few years ago for £40.

I also bought a Meddings high speed drill, where the previous owner (a well respected model engineer) added a backplate to an imported one so it could be used as a table. Handy for making repeat parts, as the vice can easily be positioned and locked down with something else as a workpiece stop/locator. Say a 1-2-3 block with a threaded stud sticking out.

The genuine Eclipse one is thinner and has more holding power than the Chinese import one. I'd be very careful using the imported on on a lathe.

Bill

Edited By peak4 on 10/01/2020 12:27:42

I'd love to have one. Get it if it's any good and the price is right. Sort of thing you don't use often but when you do need it, it's invaluable. Easier than supergluing to dummy faceplates etc.

I don't think I'd ever have the nerve to try a magnetic chuck on a lathe, even surface grinders normally have a positive stop to rest the work against to prevent the wheel firing projectiles across the workshop. Grinding forces are much less then turning ones, good luck.

@KWIL, he wants €175 for it. Let me know if you are interested, I could possible haggle him down a tad.

! I think I will pass on that one, thanks for the offer to haggle.

K

There's a couple on ebay at the moment, one of which is in Hampshire, so maybe saving on the postage.

For small workpieces, I surround them with M12 thick repair washers; seem to hold well enough and with light cuts, things stay in place OK.

Bill

Very useful in some cases but do not strip it down as you will lose the magnetism and will have to go back to Eclipse for repair and're magnatising near to Meadowhall Sheffield. It may have a lubrication hole just use a slideway oil. Careful on thin or small diamiter pieces at least may need packing to stop sliding.

David

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Having discouraged you, Mark ... I felt obliged to find some supporting evidence

This is a direct quote from the Eclipse ‘Ask The Expert’ page:

Longevity of magnets – how long will a permanent magnet stay magnetic?

How long any magnet retains its magnetism for will depend upon the application and the environment that magnet is placed in.

If a permanent magnet is well looked after, not damaged, kept at room temperature, kept in a dry environment away from moisture, corrosion risks, radiation and external magnetic fields, it will in theory remain magnetic indefinitely (i.e. it could outlast the product lifecycle). As a rough guide based on well looked after magnets over 10 years the drop in performance for high permeance coefficient magnets should be very low e.g. nearing 0% for NdFeB, nearing 0% for SmCo, under 2% for ferrite and under 3% for alnico. In practice the conditions are not ideal so the long term performance could well be worse (or far worse) than stated (so please do not use the guideline values as to be expected values – you could be disappointed).

MichaelG.

Do magnetic chucks attract all the steel swarf ? Not quite so bad in a grinding situation.

Speedy,

They will hold steel swarf in a machining operation for as long as they are energized. Remove the job(s) and 'switch' the magnetic chuck off again and the swarf will fall away of it's own accord

You might then find the swarf magnetic, it depends on the material, but that is hardly of much concern

Regards Brian

Michael,

Thanks for the follow up. An interesting read. I’ll continue to keep an eye on magnetic chucks, maybe next Christmas

Mark

My guess is if you have to ask you don't need one!

Useless for Stainless Steel, Brass and Aluminium, I see magnetic chucks as good for holding thin steel workpieces that would otherwise have to be glued to a mandrel and boiled off after. Magnetic chucks save time if a lot of thin steel turning needs to be done, and I rarely do that. In my bumbling retired-amateur workshop, time and super-glue are excellent alternatives, especially as super-glue works on all metals, not just ferrous.

Needing to turn dozens of thin steel workpieces in a hurry, I'd consider a magnetic chuck, but as it is my money is better spent on other toys! I'd be delighted to be given one though...

Dave

Another use?i0

Perhaps a little on the heavy side, but presumably good for picking up magnetic swarf from the floor, to dump elsewhere?🙂

Strongest magnets?

Neodymium by far, but cheap strong ones may lose magnetism progressively, if heated over about 80 degrees Celsius.

I can image they are good for centrally placed, and uniformly shaped, items - but how good are they for off-centre or non-uniform shapes? Out-of balance-forces can move a lathe if not bolted down securely, so apparent weight of an item must increase sharply with angular momentum. Same with milling far away from the centre with a sizeable cutter?

I purchased a rectangular magnetic chuck/table many years ago - at a ridiculously low price - but have never used it. I had visions of a cheap surface grinder arriving one day. I don’t think it is likely to replace the vises on my mills too soon, unless milling at very high speed with tiny cutters?.

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If your ‘use case’ if mostly thin workpieces, Dave ... be sure to look at the technical information kindly provided by Eclipse

MichaelG.