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PeteF
07-08-2011, 07:26 PM
I was about to buy a cylindrical square from Shars to use as a standard, however wonder if a granite angle plate may be a more useful option?

I will need to airfreight them out to Australia, so the cylindrical square would be more robust in this regard, but the granite angle plate is both more accurate and I can't imagine anything I couldn't do with it that I could do with the square.

Does anyone have any first hand experience with these two standards and suggest which would be the better to purchase?

Here are the two I'm considering:

http://www.shars.com/products/view/2393/4quot_x_4quot_x_4quot_4_Face_Granite_Angle_Plate

http://www.shars.com/products/view/2308/3quot_Precision_Cylinder_Square

The second question is, does anyone know the weight of the 4 x 4 x 4 angle plate? USPS have international pre-paid boxes that are an efficient way to freight goods, however their maximum weight is 20 lbs.


Pete

Dave S.
07-08-2011, 07:56 PM
Pete

When hand scraping machine tools to recondition them a granite angle plate can be used with a surface plate to apply spotting blue to a piece that has to be at right angle to another face.
You can check for square with a cylindrical square but not spot for scraping.

I would like to have a granite angle someday. Could use one right now because I am scraping in my milling machine.

Dave

PeteF
07-08-2011, 08:24 PM
Thanks Dave, yes I can see plenty of advantages with the angle plate, particularly the point you mention, however the only advantage I can see with the cylindrical square is that it can easily be checked by rotating it on the plate. However I could easily be missing something, and I will need to buy either one OR the other as I certainly can't justify both (or either if the truth is known :D )

Pete

Robin R
07-08-2011, 08:33 PM
The weight of a 9"x12"x2" surface plate is 30lbs, which works out to 7.2 cubic inches to the pound. So if the granite angle is as much as 2" thick, that's only 48 cubic inches, divided by 7.2 is 6.6lbs.

wierdscience
07-08-2011, 08:40 PM
A cylinder square is a good weekend lathe project.

I'd buy the granite angle plate and machine my own cylinder square;)

Dave S.
07-08-2011, 08:45 PM
Pete

here is a better buy on cylinder square.

http://www.use-enco.com/CGI/INPDFF?PMPAGE=439&PARTPG=INLMK3&PMITEM=638-7630

dave

J Tiers
07-08-2011, 08:52 PM
Or you can be a masochist, and generate a cast iron square reference......

it takes a while, but surprisingly less time than one might expect to get a very good square. You'd have it before the airfreight, but you'd neglect something else to make it.

A hint...... the other two pieces that are made may not need the whole surface.... you are mainly interested in the ends. If the ends match up and blue all around, you can alternate scraping against a granite flat to get the planar surface.

The ends get you the angle, the flat gets you the rest of the surface.

I am suspicious of shop made cylindrical squares. While consistent diameter can be measured with mics etc, it appears that one is "assuming" the machine gets the angle correct. While it "should be" inherent, it might not be accurately "inherent" on *that* machine.

Scraped parts get , I believe, to smaller errors than measured parts, which may or may not be accurate cylinders, with bases that may or may not be accurately in one plane, free of cam error etc. Any "correction" of "minor" imperfections cannot be guaranteed to be accurate.

lazlo
07-08-2011, 08:56 PM
Pete, as a commercial airline pilot, you have the unique ability to sneak damn near anything on the plane. Why don't you watch for a good used granite reference near one of your hubs?

PeteF
07-08-2011, 09:01 PM
Ah, from what I can see the Enco one is over twice the price for the same accuracy (and possibly the same factory just with a different badge!).

As far as machining on a lathe, machining one to this level of accuracy is no trivial task. I think they're normally finished on cylindrical grinders. Turning up cylindrical squares accurate enough for setting up work is certainly much more doable, but I will also simply submit an order for a precision steel angle plate as I need a better alternative to what I'm currently using in this area too.

The two alternatives I'm considering here however are basically just references so I would like them to be as accurate as practical.

Pete

PeteF
07-08-2011, 09:07 PM
Pete, as a commercial airline pilot, you have the unique ability to sneak damn near anything on the plane. Why don't you watch for a good used granite reference near one of your hubs?

Ha ha, yes and I have done so. Not just good stuff either, half my workshop looks like a HF store, so I sneak back crap too :D However sometimes these things are just so specialised (in general population terms) that they're not easy to find. Ironically for example it's far easier (and cheaper) to buy Chinese products like this from retailers in the US than the ones in mainland China or Hong Kong, go figure. I used to be up in the US literally one day a week, but I don't go up your way very often at all these days. A shame, as LA was like my second home. For something under 20 lbs it's much easier to simply pay the USPS postage rates and get it within a week.

Pete

PeteF
07-08-2011, 09:14 PM
I am suspicious of shop made cylindrical squares. While consistent diameter can be measured with mics etc, it appears that one is "assuming" the machine gets the angle correct. While it "should be" inherent, it might not be accurately "inherent" on *that* machine.

Jerry a good hint on auto generating a right angle, thanks.

If my logic is working correctly I think a cylindrical square should be easy to check. Mic it as you say to ensure correct diameter, then place it on end and indicate a DTI off the top with a V base hard up against the square. Rotate the square in position and the DTI should indicate the error.

Pete

alcova
07-08-2011, 09:15 PM
I managed to score a Wrist Pin ( Gudgeon Pin ) from a large Cat engine, about 3"x6"...works great for some of the stuff I do

Walt

J Tiers
07-08-2011, 09:24 PM
Diameter measuring only gets you so far..... you do not know how lobed the part is, since there are ways it can be perfect on diameter and yet not round..... and you don't know that the lobing is parallel to the axis, which means you really don't know if the square is consistently square.

Maybe you can blue it in "stripes" axially against a flat and be "pretty sure".

Yes, this is VERY fussy..... but we are discussing a reference square, which needs to be made in a fussy way.

I think the scraped parts can be made flatter than a DTI can pick up, unless you have one that goes another decimal place.

PeteF
07-08-2011, 09:34 PM
Diameter measuring only gets you so far..... you do not know how lobed the part is, since there are ways it can be perfect on diameter and yet not round..... and you don't know that the lobing is parallel to the axis, which means you really don't know if the square is consistently square.

It it were lobed wouldn't that show up by rotating it on end as I suggested above?

Pete

J Tiers
07-08-2011, 10:11 PM
It it were lobed wouldn't that show up by rotating it on end as I suggested above?

Pete

I don't think so. You'd have to rotate it in contact with a good v-block to discover "diametric" lobing. Which you could do.

Maybe I didn't understand what you meant.

I guess the point is that the cylindrical square is so often touted as "self-generating", that it is sometimes missed that it needs to be checked as much as anything else.

Scraped squares are checked consistently during, and as part of, the process of making them. And they are to a great extent "self generating".

lazlo
07-08-2011, 10:20 PM
You can determine the taper and lean of the cylindrical square on your mill with a DTI:

http://bbs.homeshopmachinist.net/showthread.php?t=29483&page=2


To check a cylindrical square:


Mount it on your mill table, and put a DTI in a Zero-Set holder in the spindle.

Find the tangent at the bottom of the cylinder on one edge of the square by feeding the saddle in and out and finding the high spot.

Preload the DTI, and wind the spindle/DTI from the bottom to the top. Measure the difference.

Without touching the cylindrical square, spin the indicator holder to the opposite site (180 from where you were), find the high spot again and wind the spindle/DTI from the bottom to the top. Measure the difference.

Now rotate the DTI holder 180 (back to where it was), rotate the cylinder 1/2 a turn and repeat the process.


From those three measurements, you can calculate the taper and lean of the cylindrical square with simple trig:

If you use that method to take three readings that are spaced 90 apart, you can derive the taper and lean of the cylindrical gage. Say the first measurement was D1, and the second measurement 180 opposite was D2:

Taper = (D1 + D2) / 2

Now the third reading, with the cylinder rotated and the DTI back at the start is D3:

Lean = [(D2 - Taper) - (D3 - Taper)] / 2

I scratch those numbers on the top of the cylindrical square, so I always know what I'm working with...

If you're paranoid about lobing, put it in a V-block and rotate it under the DTI.

Someone will be along shortly to argue that this only works for odd numbers of lobes, but centerless ground parts (like the Chinese cylindrical squares) are almost always odd lobed :)

Paul Alciatore
07-08-2011, 10:34 PM
J, just how out of round do you think a typical lathe may turn a part? A headstock bearing that is measured in tenths of runout should do a fairly good job of making truely round parts.

The idea of self generation as applied to making a cylindrical square depends on the diameter at both ends and at least one face being turned (ground) in a single set-up. If this is done on a reasonably "tight" lathe and the diameter at both ends (and in the middle) is the same within tenths, then the cylinder should be very close to square and round. Some designs eliminate the middle area and just have two bands at the two ends. This allows the diameters to be matched in an easier manner. Likewise, the central part of the square end can be hollowed out, leaving just an outer ring for it to rest on.

A good tool post grinder would provide a better finish.

If you make two such squares, you should be able to check them against each other on a surface plate. Print one point on the circumference of one against the other. Wipe it clean and rotate the second one and print the same point again. Repeat at 4-10 points around the second square. If all readings match, then the second one is reasonably round. Swap the two and do it again to check the first one. If both print well against each other in most/all orientations, then they are pretty good.

I am sure that such a shop made square will not be as good as a carefully scraped one, but I am also sure you can get it to +/- a few tenths which should be good enough for most purposes.

lazlo
07-08-2011, 10:39 PM
J, just how out of round do you think a typical lathe may turn a part? A headstock bearing that is measured in tenths of runout should do a fairly good job of making truely round parts.

Agree completely. But I have no idea which would have better accuracy: a Chinese centerless-ground cylindrical square, or a lapped Chinese granite angle.

Mcgyver
07-08-2011, 10:42 PM
Yes, this is VERY fussy..... but we are discussing a reference square, which needs to be made in a fussy way.

I think the scraped parts can be made flatter than a DTI can pick up, unless you have one that goes another decimal place.

agreed, not hard to scrape to within a 10th square over 6", as good as anything you'll buy. A cylindrical sq is a good tool maker apprentice project - how accurately can you grind...whereas the granite square (or scraped cube/angle) is locked away in a wooden box. Point being, if the flat faced squares didn't have advantages such as you can clamp to it, or spot with it, they wouldn't exist as any good toolmaker could make a very accurate cylindrical square

I like flat faced cubes/angles or a bevel edged precision squares. If you can't clamp to it or spot with it, I like it to be bevel edge....the broader surface of a cylindrical or even a regular blade precisions square is a pita given there always seems some spec of something getting in the way on these (compared to bevel) broad surfaces

PeteF
07-08-2011, 10:48 PM
I don't think so. You'd have to rotate it in contact with a good v-block to discover "diametric" lobing. Which you could do.

Yep, that's what I was referring to above in my description, after confirming the cylinder isn't tapered (by using a mic), place it on end against a V on which the indicator sits atop. I don't think it would even need to be an especially accurate V Jerry, so I think pretty much anything would do as it's static on the surface plate. I was thinking a V cut into some relatively thick steel plate should do the trick, that way a magnetic indicator holder would be able to stick directly to it. Push the cylinder on end up against the V and then rotate it. I have never checked a cylinder this way so it's just my theory that it should work to determine both any lobing and lack of squareness. I have however a number of times seen this done against a flat, but I'd expect the V would make it easier by holding the cylinder and DTI in the same relative positions.

An angle plate would be more difficult to check, but if I bought the one finished on both sides that's also possible to check. I think if it's just the faces that are lapped then you're buggered without another reference.

Pete

PeteF
07-08-2011, 10:58 PM
Agree completely. But I have no idea which would have better accuracy: a Chinese centerless-ground cylindrical square, or a lapped Chinese granite angle.

The Angle plates are 0.00005"/6" while the cylindrical squares are 0.0001"/6". We can all bag the Chinese products until the cows come home, but in fairness when I've checked other products against their claimed tolerance they've all met spec.

I'm keen for you guys to show me the references you've turned off your lathes that have been within 0.00005" in 6, because that's really getting down there.

Pete

J Tiers
07-08-2011, 11:14 PM
J, just how out of round do you think a typical lathe may turn a part? A headstock bearing that is measured in tenths of runout should do a fairly good job of making truely round parts.




I expect it can do a pretty good job.

However, it may depend on your workholding. A crummy chuck might be better than other means.... if it holds tight and you don't ever move the part until you are done.

I have seen working between centers recommended for this, but solid centers have lobes, etc, too, and are dependent on the goodness of the cut center in the work in any case.

Rotating centers are not in the running, too many error sources.

I expect the cylindrical center can be made "pretty good"..... I think a generated flat angle can be made better, and is more generally useful for many things I do.

Yes, I am being fussy..... I assumed we were discussing a "reference tool", and not a "fairly decent shop floor tool". The cylindrical square is usually a reference tool.

YMMV.

wierdscience
07-09-2011, 01:16 AM
The Angle plates are 0.00005"/6" while the cylindrical squares are 0.0001"/6". We can all bag the Chinese products until the cows come home, but in fairness when I've checked other products against their claimed tolerance they've all met spec.

I'm keen for you guys to show me the references you've turned off your lathes that have been within 0.00005" in 6, because that's really getting down there.

Pete

Pete,I have at least one Machinist textbook that lists a cylinder square as a first year apprentice project.It takes care to make one,but it's doable.Look at it this way,unless you develope the skills to use them,what good are the fancy high dollar tools?

The cylinder square I made for my home shop is a 3" round slug of hard chrome rod 4-1/2" long just the same size as the T-P ones.A check with the mic confirmed it to be within .0001"in roundness.Some careful work in the fourjaw had it trued,relieved and squared.It took about three hours to make.

When set next to the T-P one at work with the gap backlit no visable light shown between the two.If a few photons can't mange through that's just about good enough isn't it?If there had been some showing,the quetion then would be is it the squares or the surface plate?A quick few rotations of 45*and re-checks would quickly sort that.

wierdscience
07-09-2011, 01:25 AM
Agree completely. But I have no idea which would have better accuracy: a Chinese centerless-ground cylindrical square, or a lapped Chinese granite angle.
But,they aren't centerless ground,least not the ones I have seen,pluss the centers in each end are a dead giveaway:)

wierdscience
07-09-2011, 01:26 AM
Double post

Mcgyver
07-09-2011, 08:59 AM
centreless ground is prone to lobbing, squares are cylindrically ground. I've had some pretty skilled toolmakers tell me its a challenge to grind to a tenth over a cylinder, .00005 is very good.... but at that level of accuracy its a grinder project in hardened steel not a lathe project, if you're saying making a 6" one. Mind you, getting the lathe turn something to a say a 10th or even 2 over a length would be very challenging but I think doable - no sandpaper or files! Just read Darren's post - so its doable :)

The cylindrical grinder has head bearings too....at some level the ability of the bearing to move things in a perfect circles comes into play.....but if you can get to .0001 or .00005, well, good enough for the girls i know.....greater accuracy than that is barely measurable or usable.

I've a small grinder with a rotary work head, doing some experiments is something i want to get to...just how accurately can i grind on this little machine. With its pivoting table I suspect getting it dead on is the toughest part...to aid in that the front of the table is scraped to .0001 parallel to the axis of motion. We'll see if i can pass the apprentice challenge and grind to a tenth :)

The China issue is as always, one of trust not tolerance. The most accurate square or plate is fundamental to everything and is likely supposed to be accurate to a level not easily measured, that and was it properly manufactured such that it will stay in that condition. If it really is .00005", round straight and parallel of the right material and properly heat treated and stress relieved what more could you want?

What are you planning on doing with it? just checking squares and such? One that claims .00005" accuracy should be more than up to the task.

PeteF
07-09-2011, 09:15 AM
What are you planning on doing with it? just checking squares and such? One that claims .00005" accuracy should be more than up to the task.

Pretty much, yes. In addition, the machines I have are in reasonable condition but even the youngest is probably 30 years old! Eventually I will recondition them back to as accurate as possible. I can do flat and straight, now need to sort out square and I should have all the references I need.

Pete

wierdscience
07-09-2011, 10:12 AM
centreless ground is prone to lobbing, squares are cylindrically ground. I've had some pretty skilled toolmakers tell me its a challenge to grind to a tenth over a cylinder, .00005 is very good.... but at that level of accuracy its a grinder project in hardened steel not a lathe project, if you're saying making a 6" one. Mind you, getting the lathe turn something to a say a 10th or even 2 over a length would be very challenging but I think doable - no sandpaper or files! Just read Darren's post - so its doable :)

The cylindrical grinder has head bearings too....at some level the ability of the bearing to move things in a perfect circles comes into play.....but if you can get to .0001 or .00005, well, good enough for the girls i know.....greater accuracy than that is barely measurable or usable.

I've a small grinder with a rotary work head, doing some experiments is something i want to get to...just how accurately can i grind on this little machine. With its pivoting table I suspect getting it dead on is the toughest part...to aid in that the front of the table is scraped to .0001 parallel to the axis of motion. We'll see if i can pass the apprentice challenge and grind to a tenth :)

The China issue is as always, one of trust not tolerance. The most accurate square or plate is fundamental to everything and is likely supposed to be accurate to a level not easily measured, that and was it properly manufactured such that it will stay in that condition. If it really is .00005", round straight and parallel of the right material and properly heat treated and stress relieved what more could you want?

What are you planning on doing with it? just checking squares and such? One that claims .00005" accuracy should be more than up to the task.

Micheal,the book I have has the apprentice going through the procedure of wringing that last few tenths out of his lathe setup,grinding and setting a tool to make a fine cut,carbon case hardening and so on.
The cylindrical grinder is the production method for making one the book has him making a brass spring lap and putting it to use,You know all that theory and practice nonsense:)

J Tiers
07-09-2011, 10:41 AM
There are machines, and there are machines.......

Making a square on a worn Atlas with 50 year old automotive grade roller bearings is entirely different from making it on a grinder....... And I don't think that is unrealistic with all the "them standard bearings will git yuh by just fine" info handed out here (which I don't necessarily disagree with).

The grinder was designed and intended to get under a tenth, most likely. Subsequent wear is wear, take it at face value.

As for the Atlas , well, let's just leave it at "the machine was made to a price"...... and we'll just throw in the wear for lagniappe.

CAN it be done? Sure.....

Is it "self generating"? That depends on the machine.

With what many/most of us have to make it, I'd suggest some checking before depending on the manufactured square for an ultimate shop reference tool...........

A scraped part is self generating, and self checking. Of course you do need a flat reference, but if you do not have that, why are we having this discussion to begin with?

wierdscience
07-09-2011, 11:41 AM
Making a square on a worn Atlas with 50 year old automotive grade roller bearings is entirely different from making it on a grinder.......

Which raises the point if your lathe is that bad off then you have no need of a square that's accurate to .0001"

Mcgyver
07-09-2011, 12:25 PM
The cylindrical grinder is the production method for making one the book has him making a brass spring lap and putting it to use,You know all that theory and practice nonsense:)

A good project for either toolmaker or machinist. A friend who's a tool maker tells of how they all did time on the cylindrical grinders and making these squares was a standard project; I figured most toolmakers would have access to a cylindrical grinder but I suppose the type of shop determines what's available. These guys all did them hardened on cylindrical grinders in a GM tool room, probably pretty top shelf in so far as the equipment that had access to....now a man without who achieves the same via making and using an external lap is indeed one who's learning some skill at the apprenticeship!

lazlo
07-09-2011, 12:46 PM
But,they aren't centerless ground,least not the ones I have seen,pluss the centers in each end are a dead giveaway:)

I have two of the Fowler 6" cylindrical squares. I'll have to check the tops and see if there are center points on it...

wierdscience
07-09-2011, 01:19 PM
A good project for either toolmaker or machinist. A friend who's a tool maker tells of how they all did time on the cylindrical grinders and making these squares was a standard project; I figured most toolmakers would have access to a cylindrical grinder but I suppose the type of shop determines what's available. These guys all did them hardened on cylindrical grinders in a GM tool room, probably pretty top shelf in so far as the equipment that had access to....now a man without who achieves the same via making and using an external lap is indeed one who's learning some skill at the apprenticeship!

Right,that's why I did my own though I started with ground and hardened stock,I was 97% certain cylinder squares predated cylindrical grinders.

Sad part is I seldom ever use it,last time was to check an 8" machinists square I had dropped,about a year ago.I find the 4x6 granite angle I have far more useful.

J Tiers
07-09-2011, 11:25 PM
Which raises the point if your lathe is that bad off then you have no need of a square that's accurate to .0001"

Well, now, that might just not be correct.......

You might be wanting to correct the problems, i.e. rebuild it*..... in which case you are going to need some reference tools...... and most of us would first think of making them. One thing you generally do need in rebuilding, aside from a flatness reference, is a 90 deg reference.

But it might be asking a bit much to generate the reference on the same machine.

Mind, it CAN BE DONE. But you cannot expect to make it just using the "properties" of the machine. You will need to check, so likely you need to make three, not one. That way, not only can you check two against each other, but both against a third.... if all three fit each other, you can be pretty sure your square IS square.... or more accurately stated... that your squares are square....

* I make no comment on the advisability or practicality of doing that.

Michael Moore
07-10-2011, 01:03 AM
I bought a granite angle direct from

http://www.standridgegranite.com/accessories.htm#30

It wasn't cheap but it didn't seem an outlandish price to pay for traceability and certifications from a company here in California.

cheers,
Michael

wierdscience
07-10-2011, 03:04 AM
Well, now, that might just not be correct.......

You might be wanting to correct the problems, i.e. rebuild it*..... in which case you are going to need some reference tools...... and most of us would first think of making them. One thing you generally do need in rebuilding, aside from a flatness reference, is a 90 deg reference.

But it might be asking a bit much to generate the reference on the same machine.

Mind, it CAN BE DONE. But you cannot expect to make it just using the "properties" of the machine. You will need to check, so likely you need to make three, not one. That way, not only can you check two against each other, but both against a third.... if all three fit each other, you can be pretty sure your square IS square.... or more accurately stated... that your squares are square....

* I make no comment on the advisability or practicality of doing that.
Like I said,theory and practice,since the T-P ones say the ends are lapped square.I am confident anything can be made by hand given application of theory and practice.

J Tiers
07-10-2011, 11:15 AM
Like I said,theory and practice,since the T-P ones say the ends are lapped square.I am confident anything can be made by hand given application of theory and practice.

You might notice I said it CAN BE DONE.

I HAVE NOT SAID that you can't make them. Don't put your words in my mouth.

However, perhaps we have lost sight of the fact that the *whole point" of a cylindrical square, as mentioned in the 2 or 3 HSM articles on making them, is that "you use the properties of the machine to guarantee the square".....

That way you do not need an outside reference, the machine serves that purpose.

Now, that is all very well, but if you can't be sure of that within the error you can tolerate, and you want a part better than your confidence in the machine, you are going to do *hand work* to fix the errors.

BUT, if you have to do a bunch of hand work, then you forfeit the "advantage" of cylindrical squares, which is that if you make them on a decent lathe, they are pretty close to square due to the "properties" of the machine, and the fact that you can measure to ensure decent cylindricity.

Unless you *must have* a cylinder square for some reason, you are nearly as well off to scrape a set of flat squares as to correct errors on a cylindrical square set.

wierdscience
07-10-2011, 06:07 PM
You might notice I said it CAN BE DONE.

I HAVE NOT SAID that you can't make them. Don't put your words in my mouth.

.

FFS! I was AGREEING with you Jerry:D

PeteM
07-11-2011, 01:12 PM
Back to the original question -- which is better to buy? The answer is that they serve pretty much different purposes.

The granite or precision cast iron angle is good for measurement setups (where you may want a flat surface to clamp a part) and also scraping.

The cylinder square is better for actual inspection, since there is a thin "line" between the cylinder and the part which makes it easier to see squareness with a light shining behind. In addition, many better cylinder squares are capable of direct measurement (built with a slight lean, rotated to fit the workpiece, and with .0001 per 6" etc. tally lines on the cylinder itself). Precision knife edge squares are even easier to see variations, but expensive to make and easier to abuse.

There are also cylinder squares with a magnetic base. These are a good choice for both some kinds of setup and inspection.

willmac
07-11-2011, 01:55 PM
I have seen pictures of 'cylindrical squares with a lean' - I think B&S made one. I can understand how they can be used to measure small angles via the markings on their surface. However I have never seen one in real life. I'm curious - just how accurate can you measure with one of these? Who has actually used one?

SteveF
07-11-2011, 01:56 PM
However, perhaps we have lost sight of the fact that the *whole point" of a cylindrical square, as mentioned in the 2 or 3 HSM articles on making them, is that "you use the properties of the machine to guarantee the square".....



This is a project I've thought about doing for a while now. Any idea about which HSM issues that might have been? Stack is too big to look through one at a time and reference articles are always educational. Is there any multi-year index out there?

Steve

PeteM
07-11-2011, 03:20 PM
. . . I'm curious - just how accurate can you measure with one of these? Who has actually used one?

I've used one. Seems just as accurate as any of the common surface plate methods and faster as well.

wierdscience
07-11-2011, 09:16 PM
Back to the original question -- which is better to buy? The answer is that they serve pretty much different purposes.

The granite or precision cast iron angle is good for measurement setups (where you may want a flat surface to clamp a part) and also scraping.

The cylinder square is better for actual inspection, since there is a thin "line" between the cylinder and the part which makes it easier to see squareness with a light shining behind. In addition, many better cylinder squares are capable of direct measurement (built with a slight lean, rotated to fit the workpiece, and with .0001 per 6" etc. tally lines on the cylinder itself). Precision knife edge squares are even easier to see variations, but expensive to make and easier to abuse.

There are also cylinder squares with a magnetic base. These are a good choice for both some kinds of setup and inspection.

If I had to do it over other than a fun project I wouldn't bother with the cylindrical square.I have it,but hardly ever use it,it's just as easy to use one of my fleet of machinists squares which are out of the tool cabinet all the time anyway.
So my money is still on the granite as a must have.

EVguru
07-12-2011, 04:39 AM
I've got a couple of nice cylindrical squares and they were both free. They're gudgeon pins from industrial Diesel engines.

Mcgyver
07-12-2011, 06:53 AM
I've got a couple of nice cylindrical squares and they were both free. They're gudgeon pins from industrial Diesel engines.

I can see why the cylinder needs to be an accurate, but why would the end be particularly square? Or do you grind them?

noah katz
07-12-2011, 03:35 PM
The second question is, does anyone know the weight of the 4 x 4 x 4 angle plate?

I get just under 4 lb, assuming the L thickness is 1.5" and the density of granite is .1 lb/ cu. in.

PeteF
07-12-2011, 08:31 PM
FWIW I asked the seller and the reply I received was that he didn't know the weight and besides they have no stock. I haven't exactly been overwhelmed by the customer service there thus far that's for sure.

Just to muddy the waters, I now have a realistic 3rd alternative I'm seriously considering, a granite square. This would have the advantage of being much taller than the granite angle plate.

Pete

Arcane
07-12-2011, 08:33 PM
Oops! Didn't mean to post to this thread.

PeteF
07-12-2011, 08:39 PM
Oops! Didn't mean to post to this thread.

Oh come on, don't be shy, speak up man!

J Tiers
07-12-2011, 09:46 PM
Just to muddy the waters, I now have a realistic 3rd alternative I'm seriously considering, a granite square. This would have the advantage of being much taller than the granite angle plate.

Pete

now that WOULD be nice....

wierdscience
07-12-2011, 10:01 PM
Come on Pete,get off the money and buy all three:p

PeteF
07-13-2011, 06:41 PM
Come on Pete,get off the money and buy all three:p

Ok ... what's your account number? :p

wierdscience
07-13-2011, 08:23 PM
Ok ... what's your account number? :p

Same as Alistair's:D