Thread: Using a surface grinder but not for surfaces

Hi Michael,

That's a very simple and nice idea. BTW, how well do those mantic transfer blocks work? Do they transfer a good proportion of the magnetic force or is there a fair amount of "attenuation" once the field emerges?

Cheers,

Simon

Originally Posted by simonl

That's a very simple and nice idea.

I had to come up with something that would justify you having that massive SG otherwise your other half would think it a waste of money

Originally Posted by simonl

...how well do those magnetic transfer blocks work? Do they transfer a good proportion of the magnetic force or is there a fair amount of "attenuation" once the field emerges?

All I can say is that they seem to. I used one here because I was in a hurry and wanted to see whether the idea worked. If I hadn't the long thin nature of the jig would mean that it would push over easily and only being 10mm thick there was only one pole grabbing the steel. It's a "more is better" situation. If I was using it as a straight through spacer in line with the chuck poles I would expect to get very little loss. At 90 degrees holding onto the side like I have I would expect more losses but it was still good enough. My test for holding things on magnetic chucks is whether I can move it with firm hand pressure (and how precarious it looks). It worked.
(Originally I tried holding the jig plate in a drill press vice but ran out of headroom. Pete's suggestion of a replaceable back would probably give a firmer hold)

Michael

Massive SG? Well you're never gunna let me live that one down! There's only so much ribbing I can take before I remind you of how much headroom MY SG has! Besides, my misses has resigned herself to the fact that I probably can't justify a NEED for most of my stuff in the shed, but as you and I both know, when it's a hobby WANTS are almost as important as NEEDS!

wrt the transfer blocks, I didn't even think of the fact that it's gripping something that's not parallel to the chuck. I'm amazed it works at all, (quite impressive) but then I have no experience with such items (Yet). I have noticed that CTC tools has some that are quite reasonable. I've never had a need for them in the past but considering them now...

Simon

Originally Posted by simonl

BTW, how well do those mantic transfer blocks work? Do they transfer a good proportion of the magnetic force or is there a fair amount of "attenuation" once the field emerges?

Cheers,

Simon

By all rights the one Michael is using is not really working as he is shorting his poles with the block and not the work.....
As far as i see it it's just working like a backing block.

Making them is not that hard, and that way you can match them to the pitch of your chuck which will give you all the power possible.

Ew

PS, Simons grinder is hardly massive......

Originally Posted by Ueee

By all rights the one Michael is using is not really working as he is shorting his poles with the block and not the work.....
As far as i see it it's just working like a backing block.
.

The way it's orientated at right angles, it would be clamping the transfer block on the next pole. And the work is right over the top of one pole, so there will be "some" flux paths through mag transfer block then through the work back to the table. It should hold ok, but not ideal.....

It would be better if the work was positioned so that it covered part of both poles. The idea is to get lots of flux lines through the work.

Ray

Originally Posted by Ueee

PS, Simons grinder is hardly massive......

Hey wait a minute. Yes it is! Besides it's not the size, but how you use it that counts!

Simon

So, wrt to flux lines and magnetic fields etc. for optimal clamping force, is it more ideal to match the space of the transfer plates with the spacing of the plates on the mag chuck? Also does it make a difference if the transfer blocks run parallel or perpendicular to the plates on the chuck?

Learning new stuff every day!

Simon

Originally Posted by simonl

So, wrt to flux lines and magnetic fields etc. for optimal clamping force, is it more ideal to match the space of the transfer plates with the spacing of the plates on the mag chuck?

Yes. In reality you are using the transfer block to extend the field of the chuck, so as Ewan points out, you want the iron laminations and the mag chuck to match for maximum effect

Originally Posted by simonl

... does it make a difference if the transfer blocks run parallel or perpendicular to the plates on the chuck?

Again, ideally the transfer block lamination direction should match the poles of the chuck. Strictly speaking I'm a naughty boy for doing what I've done but for the small cut it works. One of the reasons a 'proper' base is desirable is that it will make the whole thing a little more solid and less likely to move (spread over more poles = stronger magnetic attraction) . I'm not buying a new chuck any time soon and this one has coarse pitched poles, so grinding something that narrow is probably considered a liberty too.

Michael

Originally Posted by simonl

Besides it's not the size, but how you use it that counts

I'm glad you've finally come to that realisation.

Michael

Originally Posted by simonl

So, wrt to flux lines and magnetic fields etc. for optimal clamping force, is it more ideal to match the space of the transfer plates with the spacing of the plates on the mag chuck?

No it's not essential to match the pitch, most transfer blocks you can buy are fine pitch, they work just fine with different pitch chucks. Effectively the fine pitch transfer block matches the chuck pitch.

Originally Posted by simonl

Also does it make a difference if the transfer blocks run parallel or perpendicular to the plates on the chuck?

Yes, you have to arrange the transfer block so that it transfers the field, not shorts it out. You want the work to short out the field.

There are special transfer blocks that will rotate the field, I seem to remember Josh and Ewan working on a design that did just that.. There is some eclipse documentation somewhere on how to do it...

Ray

Originally Posted by simonl

So, wrt to flux lines and magnetic fields etc. for optimal clamping force, is it more ideal to match the space of the transfer plates with the spacing of the plates on the mag chuck?

Just stand on the right hand side. Your over thinking it. It is only ever going to plink one right to left, going with wheel direction.

Newbi grinder. Your going to take 2 tenths at most. And that would be roughing.

Flux / magnetic fields. If it doesn't wibble wabble by hand, its stuck on the chuck. Talk to me in 12 months, I talk you though no magnet.

(I blew up a wheel this week. I was grinding off a bearing inner, when it got down to bearing journal it spun, and that presented a whole lot of meat to grind)

Phil;.

Originally Posted by Machtool

Just stand on the right hand side. Your over thinking it. It is only ever going to plink one right to left, going with wheel direction.

Flux / magnetic fields. If it doesn't wibble wabble by hand, its stuck on the chuck. Talk to me in 12 months, I talk you though no magnet.

(I blew up a wheel this week. I was grinding off a bearing inner, when it got down to bearing journal it spun, and that presented a whole lot of meat to grind)

Phil;.

Outch, I hope you were out of the firing line...

Grinding generally doesn't need a lot of clamping force, not like milling,

As Phil says if it doesn't "wibble wabble" ( Phil's words.. ) you are probably good.. on the other hand don't use double stick tape with coolant....

Ray

Originally Posted by Michael G

My test for holding things on magnetic chucks is whether I can move it with firm hand pressure

Originally Posted by Machtool

If it doesn't wibble wabble by hand, its stuck on the chuck

Damn. I should have gone to trade school - I just don't know the technical terms!

Michael

Originally Posted by Michael G

I just don't know the technical terms!

I can give you a few others. You best call me in the morning, I thought Marko covered most of them.