Unusual Engineers Block?

Hi all,

Got this today in alot, seems very well made by ECLIPSE.

What is its purpose please, I first thought it was a magnetic block?

Cheers,

Martin

Used on magnetic chuck - usually found on surface grinders for transferring magnetic flux.

Mark

Mark is spot on, if you haven't got a surface grinder I can't think what else you would use it for/

Tony

I have a vague recollection that you can use them to hold smaller items on a course pitch chuck (as long as the laminations are small enough). Perhaps someone with real experience (as opposed to speculation or google) might be able to answer?

Mark

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That should cull the replies down then

Yes the idea is to place these on a normal magnetic chuck to get finer gratings for holding finer parts.

They often work one way better than the other. You can get various shapes as well up to large section and also available in a vee block format.

Not quite the same but a similar type here.

I have some that I was given a few years back before I had a surface grinder. I now have a J&S but have not finished making space for it etc. I did the abrasive wheel course (I was designing machinery with abrasive cut-off) but never needed to do any grinding as I had a large toolroom at my disposal....

Do you have to locate the blocks with a plate on the chuck - like you would for a small part to stop it slipping?

Mark

Martin , Wish I'd got a pound for everyone of these I've assembled and ground up . These Adapter Blocks were normally supplied as matched ground pairs in a polished wooden box to protect them . I started my apprenticeship in August 1965 in Magnet Division of James Neil.

If a thin workpiece is placed across the chuck pole piece and the body of the chuck top plate , the throw of the flux is such that it passes straight through the work piece and so in effect only holds it in 2 places per line of flux .The purpose of the adapter block is to shorten the path of the magnetic flux such that all the flux stays within the work piece , and thus holds it much more securely . This shortening is achieved by using alternating laminations of magnetic (steel) and non-magnetic ( brass) materials . Similarly , brass rivets are used so as not to short-circuit the lines of flux .

For the block to work effectively it is important that both the chuck top plate and the working surfaces of the adapter block are finely ground and without imperfections . Similarly , as has already been indicated , positioning and orientation over the chuck pole piece and top plate are crucial.

We also offered far better solutions to the problem of grinding thin work pieces in the form of a far more complex structured Fine Pole Top Plate . This was available either as a supplementary top plate ( again in a protective polished wooden box ) which in the main removed the chances of poor positioning by the user , or was factory fitted in place of the standard top plate on final assembly .

Tractor, You, Trevor & John are exactly the sort of response I was trying to get! It is easy enough to look on Google or whatever and assume what is what, getting a "real" experience is often hard on here...

Trevor, My chuck has wear in the mechanism (I think) and sending it for refurb is going to cost well over 200 quid, is it possible to "safely" repair the linkage?

Mark

As stated, usually supplied in matched pairs. A use not mentioned is for grinding an under surface where the top surface has a protrusion of some kind, so it can't lie on the flat chuck. A pair of these allows the protrusion to be placed between them and still keeps the underside parallel to the chuck surface.

Mark , Depending on the source of the wear , yes it is possible , though as far as I am concerned , not advisable . Depending on age of chuck , the chuck is assembled using a combination of screws ( to maintain integrity ) and dowels ( to maintain relative locations) between the steel top plate , aluminium frame ( non-magnetic ) and the steel base plate . Most regular problems used to be caused by the oil leaking out and so needing excessive force on the handle and it's internal eccentric and connecting link to move the frame which carries the magnets . This in turn lead to excessive wear in the reamed hole in the aluminium frame carrying the handle shaft , which then leaked more oil and also prevented full and correct movement of the frame to the detriment of the chucks performance .

I obviously have no experience of Eclipse's present proceedures , but when we received repair items , we fully stripped them and replaced any worn parts . That included fitting new end and back stops on chucks which were returned without any . All were then de-magged and fully re-magnetised using special kit we had developed by Eclipse's chief designer Billy Bower and all built internally .

A Google search [ other search engines are available] shows Eclipse is still going & there is much interesting information on their website.

Hopefully the manufacturers own data is good enough?

Tony

Thanks Trevor. I might just try draining (if there is any in it) the oil and replacing.

Mark

Marc , Good idea . Sorry , but can't remember grade or quantities for various sized chucks . From memory it was quite light . More important though , is not to over-fill it because the internal volume in which the oil can move is very limited . This fact coupled with the close tolerances can result in the excess oil forcing the frame , and consequently the operating handle , back from the horizontal right hand position back up to an angle of about 25/30 degrees .