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Grinding surfaces square.

I re-ground a couple of step angle blocks to get them near perfectly square and clamp objects to them for squaring. Normally they should not need re-grinding, but the larger one was a fairly cheap one, and the other was about 50 years old and a bit scratched beat up.

On the re-grind I used a .00005" DTI and a Jig Borer to sweep them and map the error, then set them up on the grinder to duplicate the error prior to grinding. Took some time, but worth it.
 

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Start off by grinding 2 surfaces parallel. Then put part in a good machinist vice, and leave 1 end hang out of side of vice while the other is inside the jaws. Grind the 1 side, then WITHOUT taking part out of vice turn vice on it side and grind your fourth side. Next take the part out of the vice and on mag with ground side down and grind fifth side, turn part and grind last side. If your mag is flat and you have a good vice and you dont have any crude under anything you will get a part that is square within .0001. Good luck.
 
The number one thing i find with getting things really square is measuring actual squareness and shimming to get things right on a surface plate, then and only then stick it on the grinder and grind it. Mind you i don't have and really do need a decent grinding vice.

Have been there and ground everything in sight to make it shiny, its good fun and a great way of learning. Have got a lot of little and not so little bits i made for the Bridgeport that could still do with some shiny too :-) Unfortunately im too busy. For what its worth i really like tooling done with a nice oil blackened and then ground on the working faces. Has some real bling value! The beautiful ground faces really clash with the blackened faces giving it a massive helping of contrast.
 
To grind parts square you really need a square part to start off with.

If you don't have a square block or angle then it is hard to do.
 
I do have a 20" Brown and Sharpe try square, and a scraped 10" cast iron square but they are a bit too big....

I thought they may have been some trick to getting something ground square.... I may just resort to using my self made cast iron cylindrical square that is pretty good...
 
There is a way to grind sides square without a fixture, but it's a little fussy to do so. It helps if you have something to gage from for an actual indicator reading. It would involve finding out how much error you have on the perpendicular side first (how out-of-square), then purposely step-grinding that amount of error into the opposite side (side facing the periphery of the wheel). By doing that, you have now created a 90* angle from those two sides, although it won't be true to the rest of the part. Next, you can then flip the part 180*, grind the opposite side to parallel of the first, then continue to finish the other face (or other 3 faces, if a cube). I seem to remember a thread on here in the past that had an illustration of this, but can't find it right now. It's a little difficult to describe, but once you see it, it'll make perfect sense.
 
Thanks... A couple of pictures of my first attempt..

square20003.jpg


square20001.jpg
 
Herman Schmidt makes a magnetic squaring block for this exact reason. A substitute would be Moore 123 blocks, they are ground and lapped to square. Mount something not square to something square, orient correctly and grind the non square item square.

if you have an accurate Cyl square, you can clamp an accurate V block to it (square into the V) and them mount your work to the bottom (now side) of the V block for grinding perpendicular to the Cyl square.

Lots of ways to skin this cat...
 
Here's something to keep in mind... If your work piece is about the same size / mass as the square or angle block, it is just as likely to stick to the chuck and pull the angle block up, not the desired results any any means. What I typically do is stick the angle block to the chuck, and rest the work on a single dowel pin... so it is supported, but only with a line of contact, and it has to conform to the angle plate to which it is clamped.

Dennis
 
As it a J&S 540 you will not be needing to square of to large a work piece the best way would be to use a Tool markers vice witha couple of // 's
grind two op sides // the put the piece in the vice, use the // either end of the work piece lock down on vice and tighten the tool makers vice grind till its cleaned up, remove from vice use the side just ground to sit on the mag chuck and grind other side, If you wish put the pice back in the Tool makers vice and grind the very first face ground use the method just used with the //'s remove and grind opposite face, the tool makers vice should be good enough to grind piece Square ( at least with in 0,001 metric and at worst 0,002 Metric )
and using th //'s should also make sure the piece being ground is not bent as the Mag Chuck will pull a bend flat unless carefully pack or ground using the //'s .
 
I use a surface gage or mag base with an indicator setup to measure perpendicularity and with the work on a small sine plate on a surface plate, adjust the item square and plop it on the grinder. I made a squaring block using that method that I clamp everything to now, but you can make a something square with an indicator and some shims first.
 
I watched another video last night to see one, they seem to be a nice grinder.
The only J&S I’ve ever used is an old universal cylindrical grinder.
 








 
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