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Do I need a magnetic square?

Cannonmn

Stainless
Joined
Jun 25, 2016
My question was inspired by acquisition of grinding accessories pictured, from a retiring toolmaker. He said he’d made them all with the aid of a magnetic square. I should have asked him at the time if a magnetic square is considered necessary to produce the most accurate tools possible on manual surface grinders. But I didn’t. Anyway, that’s my question. We have a few surface grinders in the shop but haven’t used them much, but expect more grinding work this year. We don’t have an experienced grinder operator now. Also, if I buy a used mag square, is it likely to lose its magnetism, and if so, can that be restored?
 

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eKretz

Diamond
Joined
Mar 27, 2005
Location
Northwest Indiana
Not necessary at all. If you were doing a lot of high number run parts it might be nice, but otherwise an angle plate and a clamp or two or a good grinding vise will do the job just fine.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
That is a nice-looking set of blocks and stuff in your photo.

Perhaps the best magnetic square I have used is a small magetic chuck with having a double face rail, and squared up to near zero. *Most of my square grinding has been /is just clamping to a block. A block is clean and so little chance of bugs coming with it. Solid blocks can be cleaner than ones with holes.

You set the add-on mag on your surface grinder chuck so have the horizontal with your surface grinder chuck and the vertical positioning with your small add-on chuck.

For squaring off a row of parts the add-on chuck is the berries.

The common solid magnetic square for about $130 to $250or so can be handy if doing a lot of grinding but often you can get the small chuck for that price...and the squaring mag and the add on chuck may have places for bugs to follow.

A higher grade surface plate and a square checking device/set-up are first needed along with true tested square blocks, some very good clamps, an indicator that can be attached to your wheel head.
Pairs of shim stock can be handy so to go between, and to correct a square error. Parallel clamps can be better than C clamps, but C clamps are often OK.
I have used gun blue to mark my best side of blocks. I would check any bought blocks and shoot for 12 millionths for my good side. And set of JoBlocks, a 45* block, and a bar diamond dresser for dressing a wheel for edge bevel

Here is a double rail magnet chuck:
Brown & Sharpe Model 510 Permanent Magnetic Chuck 5" x 10" | eBay
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
I have found that many newbies to grinding over tighten a grinding vise and so the vise is distorted by the moving jaw pressure... so, not squaring well and making the vise hold mostly at the bottom edge of the part.

Plus I have seen newbies and apprentices try to vise hold parts wider than the vise and fail a part with doing so.
 

Cannonmn

Stainless
Joined
Jun 25, 2016
Thx, what a wealth of info there. I bought more stuff over the years that has to be for grinding, and haven’t had chance to use for lack of grinding jobs. One was a small add-on chuck maybe 4 x 8 or so but distinctive in having a tilting feature, looking like a pivoting sine plate on one side. I’ll drag it out and see if it’ll work as add-on you describe. I have a few more mag pieces from estate of Todd Vitt who was the TDM at Whirlpool in OH for 40 years, most items signed. There’s one or two pieces I’d like to post here, one large holey block otherwise solid, where he’s got setscrews in most of the holes, has its own pair of big brass clamps, and a built-in diamond dresser. Quite something, may give someone ideas. I prefer signed items and spend some time looking up obits, unfortunately due to high cost of published obits, half the time I find obit with right name and area the thing came from but no info on the guy’s career to confirm that’s the correct individual.
 

Cannonmn

Stainless
Joined
Jun 25, 2016
A few photos of the some of Mr. Vitt’s tools as received. This is about the worst packing job I’ve ever seen from an Eboo purchase, hardened, ground items bumping into each other, and placed in corners of thin box without even taping over the edges which of course split in shipment.
 

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cyanidekid

Titanium
Joined
Jun 4, 2016
Location
Brooklyn NYC
So what does it do that my old-style mag chuck doesn’t?

they hold smaller parts.

a magnetic chuck is just a switchable magnet after all, and magnets like to have both their "north" and "south" poles firmly in contact with a piece of ferromagnetic stuff to hold on to it. this is a big safety consideration, to avoid slinging blades and blade like parts about the shop. also why we use fences, auxiliary blocks and hold downs.

also smart to consider the area to the left of a surface grinder as "down range" :D
 

Cannonmn

Stainless
Joined
Jun 25, 2016
they hold smaller parts.

a magnetic chuck is just a switchable magnet after all, and magnets like to have both their "north" and "south" poles firmly in contact with a piece of ferromagnetic stuff to hold on to it. this is a big safety consideration, to avoid slinging blades and blade like parts about the shop. also why we use fences, auxiliary blocks and hold downs.

also smart to consider the area to the left of a surface grinder as "down range" :D

Ok they hold smaller parts. If I don’t want to go to the trouble and expense of swapping out the whole chuck if I have small parts to grind, are there fine-pole mag blocks I can place on my coarse-pole chuck to accomplish the same end, or won’t it work that way.
 
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otrlt

Guest
Hello Cannonnm,
The tools that you have potentially can be extremely accurate. It is most likely that he did not use a magnetic square in their construction.

What's most likely; he used "squaring blocks" , do you see any large plain blocks in your group? Hopefully you do, these blocks are Masters, they were made with one purpose; to grind any tool component to exact squareness.


I want to hear from more Die/Mold guys out there about this.
 

Cannonmn

Stainless
Joined
Jun 25, 2016
Hello Cannonnm,
The tools that you have potentially can be extremely accurate. It is most likely that he did not use a magnetic square in their construction.

What's most likely; he used "squaring blocks" , do you see any large plain blocks in your group? Hopefully you do, these blocks are Masters, they were made with one purpose; to grind any tool component to exact squareness.


I want to hear from more Die/Mold guys out there about this.

Thx, I have one plain block, see pic, there’s a U.S. quarter dollar on it, anf former owner kept it in that box.
 

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TheBigLebowski

Aluminum
Joined
Sep 9, 2018
Magnetic cylinder squares can be finicky to use. Vises are good but as was already stated tightening them too much leads to poor results. Using C-clamps and known angleplates/master blocks works great as you can't really overclamp the part. The absolute best method is self checking via flipping - this is the method that is used to produce your master gauges/angleplates and it's very easy so long as you are grinding parallel.
 

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Cannonmn

Stainless
Joined
Jun 25, 2016
Thx, the pdf only has steps 3, 4 when I opened it, should there be more? Maybe don’t need 1?2 ?
 
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otrlt

Guest
Thx, I have one plain block, see pic, there’s a U.S. quarter dollar on it, anf former owner kept it in that box.

Yes,
That is your Master, I must say that I only see one. I made two.

It would be good if some Die/Mold guys to join in to comment.
 

AD Design

Stainless
Joined
Jun 27, 2012
Location
Tennessee USA
This is just my opinion. I have mag blocks but have only used them a few times in 35+ years of surface grinding on an almost daily basis. I used them for irregular shaped work or raising the piece off the mag chuck due to a projection. I much preferred to use a grinding vise (several sizes) or one of a couple of small angle plates I made as I don't like to have too much confidence in magnets on small parts or while grinding D-2 parts. Your preferences are largely formed by the type of work you do, the methodology you use, and the quantity of parts required. I usually worked in batch sizes of 1-10 parts, indicate in the work holder on the surface plate, and then transfer the workpiece/holder to the mag chuck. I wouldn't find the need to obtain another magnetic chuck/square but that's just what suits me and what I did. YMMV.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
Clamp to a known square something like a block or angle plate seems the best method IMHO. A really good angle plate can set with its V facing down on the mag chuck so clamping two ways and with the ground-in mag chuck squares a part all three ways. An angle plate alongside of a good square block can do the same. One can run an indicator along a block or an angle plate to check its position before adding the part to be ground. An angle plate can be shimmed under if a tickle off square is needed, if a plate check shows a tickle is needed.

Good 123 blocks can lay down or stand up to give different part sizes good surfaces to clamp to.

Still, a solid magnetic square could be handy for some jobs, but I have never owned one.
I have made good use of mag V and specific angle blocks because they can be Ok and quicker than clamp-downs for some parts.
 








 
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