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pinstripe
02-09-2017, 10:24 AM
I picked up an auction lot that included three cylindrical squares. I have some questions about two of them. The first two photos below show the ends of one of the squares. One end is relieved, and the other has some "0" marks engraved into it. The third photo shows a close-up of the engraving. There is a "Reference Only" sticker on the side which is not shown. If the Reference Only sticker is up the right way, then the engraved side is in contact with the surface plate.


Is the Reference Only sticker upside down? I would have thought that the relieved end is the one that should be on the plate. Maybe it was done this way because they stored it upside down? The other squares appear to have the Reference Only sticker in the correct orientation. They all came from one location.
Is the area between each pair of zeros the part that is considered the most square?
The last image below shows the end of one of the other squares. It has a small threaded hole, only on this end. I found an image that shows a handle screwed into a similar hole. Is that what it's for? This is the smallest/lightest square, about 6" long.
I put the squares side-by-side, and some light gets through. In the best orientations, it shifts towards blue with some white peeking through. The two largest squares are about a foot high. Does this sound reasonable, or should they let no light through? The surface plate is new, but I didn't get it calibrated. It's probably of reasonable quality for a Chinese plate (not the cheapest available).



http://i1168.photobucket.com/albums/r491/pinstripe2/HSM/cylindrical_square_a1_zps0fbydpij.jpg

http://i1168.photobucket.com/albums/r491/pinstripe2/HSM/cylindrical_square_a2_zpsnqgyki6u.jpg

http://i1168.photobucket.com/albums/r491/pinstripe2/HSM/cylindrical_square_a3_zpsruuhsk4f.jpg

http://i1168.photobucket.com/albums/r491/pinstripe2/HSM/cylindrical_square_b1_zpsysfo52bo.jpg

rkepler
02-09-2017, 11:04 AM
I expect that the end with the narrow land is the bottom end, the end that goes against the surface plate. The "0" lines are where the square is the most perpendicular relative to the plate, or was when the marks were added.

TGTool
02-09-2017, 11:10 AM
I don't have answers to all the questions. There could have been some squares with characteristics for special purposes for the organization.

I haven't seen a square with that kind of zero indication, and it looks like it was not done by the manufacturer but by someone later (for whatever purpose). The closest thing it suggests to me is some squares that are made with a slight angle on one end. Meaning of course that standing on that end they tilt. So "Squareness" as a reference won't be true all the way around, but they will be square at exactly 90 degrees transverse to that tilt. The benefit of this angled surface is that you can get a reading of angularity everywhere from zero to the max angle. The photos I've seen of them then have a line of dots marked on the side so you can rotate the cylinder, get a match to your workpiece, and then read off how much the workpiece is off of square. It doesn't sound like that's what you have.

I also gained an interesting insight since I now have two cylindrical squares, a tall and a short one. Both are solid and seem inordinately heavy, but I found on manipulating them with an indicator stand to check squareness of a workpiece that weight has an advantage. The square is less likely to move and compromise the indicator setting. I wouldn't have thought that big chunk of steel would be subject to slight moves on the surface plate, but I was surprised and found I really preferred the taller, heavier one.

I also have a small square with one end having that tapped hole as yours does. And it came with a small handle that can be screwed in there to lift it. I presumed that the hole was there to hold a drive pin in manufacturing so the piece could be ground on centers and the handle bit was just a free afterthought. In the photo of yours it's not clear that the centers are functional, so some might be finished on centerless grinders and the tapped hole is an added feature for a lift handle.

TGTool
02-09-2017, 11:13 AM
I expect that the end with the narrow land is the bottom end, the end that goes against the surface plate. The "0" lines are where the square is the most perpendicular relative to the plate, or was when the marks were added.


That's a reasonable hypothesis, but how could there be four places that are the truest perpendicular, and those not being at 90 degrees to one another? Two spots might suggest that, but four?

pinstripe
02-09-2017, 11:27 AM
That's a reasonable hypothesis, but how could there be four places that are the truest perpendicular, and those not being at 90 degrees to one another? Two spots might suggest that, but four?

I think the zero points are a "range". Within that range meets whatever tolerance they were working to. The ranges are directly opposite each other. I would therefore think that the middle of the range is the most perpendicular.

I'm pretty sure I have seen similar markings on another square that was for sale.

pinstripe
02-09-2017, 11:36 AM
I also gained an interesting insight since I now have two cylindrical squares, a tall and a short one. Both are solid and seem inordinately heavy, but I found on manipulating them with an indicator stand to check squareness of a workpiece that weight has an advantage. The square is less likely to move and compromise the indicator setting. I wouldn't have thought that big chunk of steel would be subject to slight moves on the surface plate, but I was surprised and found I really preferred the taller, heavier one.

I came to the same conclusion today. I was only after a small one, but those big ones really plant themselves on the surface plate. It's all relative of course, they had cylindrical and granite squares there that were two feet wide!

RichR
02-09-2017, 11:38 AM
That's a reasonable hypothesis, but how could there be four places that are the truest perpendicular, and those not being at 90 degrees to one another? Two spots might suggest that, but four?

Maybe those marks are to tell you which quadrants contain a perpendicular surface. A go/nogo gauge perhaps. Slide it against that angle plate
you just manufactured. Rotate until you see no/minimum light between the two. If the contact point is between the 2 zeros, it meets spec.

Rich Carlstedt
02-09-2017, 11:41 AM
Many shops require periodic "calibration" of all inspection and manufacturing tools /instruments.
It is true that having 4 marks of "0" seems confusing , but there are some cylinders made to special angles .
The 4 marks allow someone to recheck the exact former points that were measured previously

The threaded hole is for use of a handle perhaps when the instrument is needed on the manufacturing floor, or for when a DTI is needed to also check a height of an object being checked for squareness at the same time

Rich

J Tiers
02-09-2017, 11:51 AM
Is the Reference Only sticker upside down? I would have thought that the relieved end is the one that should be on the plate. Maybe it was done this way because they stored it upside down? The other squares appear to have the Reference Only sticker in the correct orientation. They all came from one location.

it would be most surprising if the users had engraved on the surface that should be against the plate, and which you then cannot see.

Usually, the "down" surface will show evidence of a fine finish, and will generally be a rim around at the the largest diameter. Pic 1 seems to show that.



Is the area between each pair of zeros the part that is considered the most square?

No way to tell but to test. I would probably have expected either the line at the "0" to indicate it, or one of the spaces between two lines.



The last image below shows the end of one of the other squares. It has a small threaded hole, only on this end. I found an image that shows a handle screwed into a similar hole. Is that what it's for? This is the smallest/lightest square, about 6" long.

A handle or lift ring may be found on these squares, yes



I put the squares side-by-side, and some light gets through. In the best orientations, it shifts towards blue with some white peeking through. The two largest squares are about a foot high. Does this sound reasonable, or should they let no light through? The surface plate is new, but I didn't get it calibrated. It's probably of reasonable quality for a Chinese plate (not the cheapest available).
....

ideally, no light should come through if two perfect squares are set touching when on a perfect flat surface. Nothing is perfect. Everything has a tolerance. Light can get through a space which is smaller than you need to measure unless you are doing the most precise job in a temperature controlled area.

The error could be in the squares, or in the plate. If there are scattered areas of light, it may be the squares. If there seems to be a tilt, it could be the plate. You can lay a square down over the same area and see if the plate vs square lets through light. (gently does it).

Do the marks seem to indicate any greater precision than other areas? You may be able to determine if the area between likes, or between zeros is the better areas.

The squares which have a tilt made into them are marked to show the angle measurement along the OD, and have two lines of perpendicular diametrically opposite

mars-red
02-09-2017, 11:54 AM
I think the zero points are a "range". Within that range meets whatever tolerance they were working to. The ranges are directly opposite each other. I would therefore think that the middle of the range is the most perpendicular.

I'm pretty sure I have seen similar markings on another square that was for sale.

I have a theory about the 0 marks, that they aren't so much about perpendicularity, but rather out-of-round. I have a cylinder square that I made, and I started with some steel pipe. I gripped from the inside, using my 3 jaw chuck. I didn't want the jaws to stretch the work so I was careful how much I tightened them, and took real light cuts. Despite that, I was getting strange results on the surface plate. After a bunch of testing and head scratching I discovered that the jaws had indeed stretched the work a little bit, and the 0.002" variation I was seeing was due to the part being a rounded triangle. I have put similar marks on mine, indicating where all the bulged or high spots are. Perhaps these squares were turned in a 4 jaw chuck and had the same condition?

pinstripe
02-09-2017, 12:09 PM
Do the marks seem to indicate any greater precision than other areas? You may be able to determine if the area between likes, or between zeros is the better areas.

I didn't spend much time with them today, but yes the two larger ones seemed to fit better within the zero ranges. The other large one has no markings. It was a very hot day, no AC in my shop.

pinstripe
02-09-2017, 12:18 PM
Perhaps these squares were turned in a 4 jaw chuck and had the same condition?

They may indicate out-of-round, but not because of a four-jaw. The lines are not 90 degrees apart.

BTW, I was listening to you and Justin while I was cleaning them up :)

JoeLee
02-09-2017, 12:29 PM
First you have to stop and think about how these are made. There are a couple ways I can think of. I would imaging they are centerless ground.
Some may be ground on centers. Either way, then the ends would have to be ground square to the sides.
I've seen some where the center hole is threaded and I've seen them bolted to a slotted angle plate.

JL..............

Jaakko Fagerlund
02-09-2017, 01:44 PM
Have you actually measuresd those squares for squareness? I'm asking because it is the first thing to do with unknown cylindrical squares. As they are pretty much self-checking with an indicator, there is hardly no point in trying to vaguely guess why someone has engraved something on them or what it means. Even checking them against each others tells nothing about their squareness othen than "it might be close". You have a surface plate, I presume you have an indicator and thus you have all you need for verifying their accuracy.

pinstripe
02-09-2017, 01:59 PM
Thanks Jaakko. I have an indicator and stand, but I thought that I needed a stand with the curve along the bottom to check for squareness? I've got one of these. I was planning to add a curved foot to it later. Is there some other way to do it?

http://www.mitutoyo.com/Images/003/313/7002-10.jpg

J Tiers
02-09-2017, 02:01 PM
... Even checking them against each others tells nothing about their squareness othen than "it might be close". ...

Could be BETTER than an indicator, which is unlikely to be better than a "tenth" type (.025 mm).

If several things square up against each other in any random combination, then they must all have equal and opposite errors. But if A squares against B, then the errors of B fit against A. If BOTH A and B then fit against C, then that proves the errors of BOTH A and B are equal and opposite to the errors of C.

This is a conundrum, because we just proved that A and B had equal and opposite errors, so only one can fit the errors of C by being equal and opposite to them.

The only way for that to be true is if A, B, and C have NO errors that your procedure can detect.

Paul Alciatore
02-09-2017, 02:13 PM
Since they are used, the best thing you can do is test them.

I believe one of our more experienced members has published, either here or in one of the parent magazines, a very good method for testing a square. It uses a sensitive DI on a stand that has a bumper near the bottom, near the surface plate and the DI mounted some distance above that. With it you take readings on opposite sides of a square that has sides that are parallel to a tight tolerance. You can check your squares for parallel with a tenths or better micrometer at both ends. Then do the DI test.

The zero lines puzzle me. If they were intended to indicate the best position for square, then there should not be two of them. Perhaps, as someone above said, they show the limits of a certain tolerance on that square condition. But then, is it the larger angle or the smaller angle between them? I would not attribute any significance to them that I can not verify with tests.

BCRider
02-09-2017, 02:15 PM
I can see the electro pencil marks being there as proof that the square was checked for square by some owner. The fact that there are four zeros suggests to me that the square is indeed actually square in any direction. As for there being any tilt in the quadrants between then that would indicated an out of roundness of the cross section. What the four zeros says is that at the time of the testing and marking that the square was actually properly square to the best of the ability to measure.

Of course that was then and this is now. One would want to run some tests to confirm or correct the readings.

Pinstripe, you will want a stand with a flat nose to it. And solid feet of some sort. The stand you showed is intended for measuring stuff off the small platten. So it's possible that it has soft non marring feet. That's not what you want for a squareness test stand. On top of that the rough texture of the edges will make it hard to tell anything at all for testing for square. You need at least a smooth border even if it's not an arc shaped one.

pinstripe
02-09-2017, 02:25 PM
Does the radius of the bumper/foot matter? This auction lot also included some precision disks and pins. It was from a calibration lab that was closing down. I'm wondering if one of them will wedge into the gap at the front of the indicator stand until I have time to make something more permanent.

BCRider
02-09-2017, 03:39 PM
I don't think it even needs to be radiused. The arc just makes the high point more noticeable. It could be a straight across bar of something like drill rod. The nicely ground finish would ensure there's no dips or bumps which is far more important. Consistency counts in this application

mars-red
02-09-2017, 05:48 PM
They may indicate out-of-round, but not because of a four-jaw. The lines are not 90 degrees apart.

BTW, I was listening to you and Justin while I was cleaning them up :)

LOL I should start drinking so that I at least have an excuse. :)

Thanks for listening!

Jaakko Fagerlund
02-10-2017, 03:49 AM
Could be BETTER than an indicator, which is unlikely to be better than a "tenth" type (.025 mm).

If several things square up against each other in any random combination, then they must all have equal and opposite errors. But if A squares against B, then the errors of B fit against A. If BOTH A and B then fit against C, then that proves the errors of BOTH A and B are equal and opposite to the errors of C.

This is a conundrum, because we just proved that A and B had equal and opposite errors, so only one can fit the errors of C by being equal and opposite to them.

The only way for that to be true is if A, B, and C have NO errors that your procedure can detect.
True, when you have several equal length squaes to check against each other on a known flat surface. But here the OP has different length squares on an unknown surface, in which case it is impossible to compare them to be better than an indicator. The unknown surface is the issue of being actually sure of any readings taken, be it with an indicator or another square. With a non-moving reference edge and an indicator you are using the same spot to check the square, so it gives the best result in this situation. For better reliable results the surface plate has to be checked first.

pinstripe, if you want to use that indicator platen thingie, mill a flat in front of it or grind it. You want a flat surface as you are measuring a round object. If you were measuring a flat object you would want that radiused edge. But as others pointed out, that thing is not meant for this sort of measuring job as it is soft as a kitten from the bottom and can ding/wear easily.

If you just want to check it, you do not need anything fancy, just a nice flat edge to push your square against and an indicator which doesn't move relative to that flat edge.

pinstripe
02-10-2017, 09:27 AM
Thanks all. The stand doesn't have soft feet. It does look like soft metal though. It's very stable, I couldn't measure any rocking with a 0.001 mm digital indicator hanging off the side against the surface plate. That's the only one I have for now, so I will use it. We're in the middle of a heatwave, so I didn't try today. Forecasted to hit 45 degrees tomorrow (113 Fahrenheit), so I guess it won't be happening tomorrow either.

J Tiers
02-10-2017, 10:40 AM
True, when you have several equal length squaes to check against each other on a known flat surface. But here the OP has different length squares on an unknown surface, in which case it is impossible to compare them to be better than an indicator. The unknown surface is the issue of being actually sure of any readings taken, be it with an indicator or another square. ....

And that IS the main issue. But he can check that, by performing the test, one against the next, at several locations on the plate. If the results match at all locations, then the plate has been checked as being flat enough for the measurement.

if the results are different at different locations on the plate, then the plate is "out" to some degree. The squares need to have the same place in contact for all tests. A dot can be put on each, and the dots matched up to ensure that.

As for the different lengths, all can be fully checked except the tallest one, by checking against one another.

pinstripe
02-10-2017, 04:16 PM
I went out and tested this before it got too hot. The result was inconclusive. The most variation I could measure was 5 microns (two tenths), which is the limit of accuracy for this indicator. I was rarely getting a reading over two microns, so it should be more than good enough for my needs.

So the markings remain a mystery for now.