Mag Chuck

Looking for a new mag Chuck for my J&S 540.

Come across this on Amazon : **LINK**

Anyone got any experience of this type of fine pole Chinese mag Chuck?

Dave

The use of such words as ‘suction’ and ‘disc’ do not give me a great deal of confidence re the description.

I have a couple of Eclipse chucks, which do the job for me. Not fine pole but these have been around for years and still work

Fine pole is better for thin work where a coarser pole spacing gives less holding power. I would expect therefore that with thicker material the fine pole may not hold the work so securely, but I have no evidence or experience to back this supposition up.

The modern fine pole mag chucks are more flexible to use than older coarse pole ones. They all do somewhere in the region of 80N/cm^2 but, as Rob says, they work for thin stuff that the coarse pole ones struggle with. Thick stuff is hels as well with both varieties.

If you want the best holding strength when using transfer blocks, they need a matching pole spacing. This can be done by making your own.

I certainly wouldn't go back to a coarse pole chuck on my J&S 1400!

Agreed, Rob. Well that should be the case but I don’t know the force provided by the wider spacing type. I think the area in contact with the chuck is really the defining requirement.

A more economic option might be to use two mag chucks - thin stuff is unlikely to be 18” long! Further, care is needed when clamping larger, but thinner items, if one requires more than just a very smooth surface finish. Thin items are generally only a problem when small in contact surface area.

I am extremely careful when grinding small items (yes, I have needed a ‘bullet arrestor!).

Another thing I don’t like, about the suggested item, is that it doesn’t appear to have provision for side/end support.

I would likely have purchased a fine pole chuck but am using what I have. I doubt I would be paying that little money for a decent quality chuck, however. But the choice is up to the poster, not me. I will add that I’m most certainly not a fan of cheap chinese tooling.

The photos show a fence at the back, but no arrangement for one at the left hand end.

In the good old days cost was a better indicator than it is today. The gap between cheap rubbish and 'quality' was obvious.

Not now. Modern manufacturing can produce goods to almost any specification, from too cheap to aerospace, and everything in between. Stuff is aimed at whatever the market will bear, and a good deal of it is what I'd call mid-range: inexpensive rather than cheap, not Milspec, but good for a few years hard work. Plus the internet has globalised the market, much more expensive to make 1,000 magnetic chucks per year for a few UK buyers, than making 10,000,000 for sale world wide.

Makes it hard for purchasers - you can't tell simply from the price or the brand-name. 'Reassuringly expensive' is a deliberate sales tactic, and it's possible to pay well over the odds for the same item just because it has a desirable brand-name.

On the whole we've benefitted from cheaper goods. A serious problem with old-school manufacturing was that goods were slowly made in the most expensive way possible - skilled men in unsuitable premises using ancient methods on costly materials, doing everything slowly themselves regardless of cost, and badly managed whilst indulging Spanish practices, demanding high-wages, better conditions, and having expensive accidents! Plus inspection methods that rejected entire batches instead of implementing continual improvement programmes, and dreadful labour relations. End result - products costing more to make than customers were prepared to pay, with them deserting in a huff after finding fit for purpose could be had cheaper from abroad!

The problem wasn't shortage of skills or aversion to hard-work, many firms were scuppered by poor tactics and not listening to customers! Fear of change destroyed many enterprises. But worst of all, most people went without because stuff was simply too expensive.

Not all is rosy though! We've exchanged one set of problems for another...

Dave

Fine pole chucks have the focus point closer to the chuck face than the coarse pitch version.

The other major change is that mag chucks now use rare-earth magnets rather than Alnico or ferrite. They have a much higher energy density and can be made thinner. Almost the entire world's production of them also comes from China, due to them being the World's major source of the raw materials.

Edited By Mark Rand on 16/06/2023 11:48:30

This is the problem, hence asking if anyone had direct experience of this.

An equivalent Eclipse (to name one well known brand) chuck is out of my affordability.

The pics on the chinese one look 'ok'. The lack of end fence ( thin end) is not an issue for me - I never use an end fence anyway.

The Chinese are easily capable of producing a good (or at least "sufficiently not shit" chuck, but they are also capable of (shall we say) somewhat overstating the quality, and its not simple to tell. Poor english is not a good guide - their english is way better than my chinese...

My current chuck is too small for some work I need to do on the grinder, but its also chinese in origin ( I imagine anyway - it came from Arc many moons ago).

Maybe I should just buy one and rely on the 30 day amazon money back in case its truely rubbish...

Dave

I think Dave hit the nail on the head, once again ! There is a limit to how much someone will pay for anything, no matter how good it is claimed to be. There is only so much money available. Also, many firms went to the wall by not listening to their customers, the very people who kept them in business !, you do that at your peril.

As they say, "He who pays the piper, calls the tune ". Reminds me of the way the motorbike makers bit the dust some years ago. Seems like a few machine makers went the same way, no matter how good they were. Just too dear .