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Fasttrack
12-01-2010, 05:49 PM
So I'm slowly tooling up to scrape my shaper. One of the items I will need is a large, accurate square. Enco has some large cast iron squares on sale. I'm thinking either something like this:

http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=951641&PMAKA=418-4145

or

http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=952519&PMAKA=418-4345

Now, I know that I can scrape them "perfectly" square if I have three of them. But I don't want to have to buy three of these beasts.

So is it possible to get away with two 6 by 6 squares and one big 12 by 12 square? Basically I would treat the big one like it was 6 by 6 but with an added step of scraping each surface flat after referencing one of the other squares. I.e. I indicate off of one of the other squares and the surface plate. Scrape as needed. Turn over and scrape the entire side into the plane that I just established using the small square. Turn around and reference the other square, etc.

Or should I just get one and fiddle with indicators to check for squareness as I go?

Mcgyver
12-01-2010, 06:13 PM
have you got some sort of reference square now that you can set an indicator to with confidence? (....You either need a reliable square or something reliably parallel that you can get square to set the indicator then you scrape those blocks. If you don't have a good square to start with you can either make one or tune up an existing one....but it needs to be either box or blade shape; something with two vertical and parallel surfaces.....but you probably know all that)

If so, I don't find scraping square using an indicator to be too much of a bother....scrape one flat, start scraping the second flat while checking squareness with the indicator....it'll be good practice as there'll be lots of scraping ahead of you where you're checking multiple relationships :D.

Scraping big projects is the marathon run of shop work, just finishing is an accomplishment. Those not in the run look at those in it as possibly insane and don't understand the motivation.....when scraping a big project i to look at myself as possibly insane and not fully comprehending the motivation.

of course take lots of pics

oldtiffie
12-01-2010, 06:33 PM
Get one of these - a "Framing Level". Accuracy is 0.02mm/m ie 1:50,000 or ~ 0.00024" per foot.

Should be available on eBay.

http://i200.photobucket.com/albums/aa294/oldtiffie/measuring/Machinist_Square1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/measuring/Machinist_Square2.jpg

Or make some cylinder squares which I used to "square-up" my standard angle plates.

It all turned out (sorry) very well:
http://i200.photobucket.com/albums/aa294/oldtiffie/measuring/Cylindermastersquares1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Master%20squares/Squaring6.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Master%20squares/Squaring5.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Master%20squares/Squaring4.jpg

beckley23
12-01-2010, 08:08 PM
Several years ago on PM, Forrest Addy posted about checking squares with an indicator and surface gauge.
Hopefully he will see this, and repost that advice. I've got it in favorite places on AOL, which I can't access for awhile as my computer took a big dump the other day, and I'm just currently limping along.
Harry

whitis
12-01-2010, 08:40 PM
There is a method that uses two squares instead of three described in Franklin Jones' Machine Shop Training Course. If you add "side by side" as well as face to face to your repertoire you don't need a third piece.

Basic idea would be to and clamp them together side by side, then lap or scrape the perpendicular sides together. If they mate both side to side as well as face to face while sitting on the plate in all orientations, then they are square. For this to work, though, the sides need to be parallel. They were also cutting all 4 sides of the "square" in addition to the two unimportant sides which where flat and parallel to start with. They had similar methods for making straight edges, 4 sided squares, cubes, and 60 degree triangles using two pieces instead of three.

You could easily cut a pair of squares that had a vertical surface that was tilted to the side, say 10 degrees, when cut side by side. When face to face, they would mate perfectly. When you flipped the mating surface down onto the surface plate, the new vertical faces would be flat against each other but leaning to either side. If the sides are parallel and you check that they are, then this error will show up. It will also show up if you flip one of the blocks.

Note that lapping in this context refers to proper lapping against a flat lap or a piece of sandpaper on a flat surface, not throwing some abrasive between two surfaces being generated and rubbing them together.

If you have a surface plate and another precision flat surface which you can mount at approximately right angles to the surface plate and adjust the tilt, you can mate that with a single square then use an indicator on a squaring stand to test that both the vertical flat surfaces form the same angle with the surface plate. This doesn't take into account side to side angle, if that is important in your application.

If you don't have Connelly's book Machine Tool Reconditioning and Applications of Hand Scraping, you are going to have a harder time completing your project.

oldtiffie
12-01-2010, 08:41 PM
So I'm slowly tooling up to scrape my shaper. One of the items I will need is a large, accurate square. Enco has some large cast iron squares on sale. I'm thinking either something like this:

http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=951641&PMAKA=418-4145

http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=952519&PMAKA=418-4345

Now, I know that I can scrape them "perfectly" square if I have three of them. But I don't want to have to buy three of these beasts.

So is it possible to get away with two 6 by 6 squares and one big 12 by 12 square? Basically I would treat the big one like it was 6 by 6 but with an added step of scraping each surface flat after referencing one of the other squares. I.e. I indicate off of one of the other squares and the surface plate. Scrape as needed. Turn over and scrape the entire side into the plane that I just established using the small square. Turn around and reference the other square, etc.

Or should I just get one and fiddle with indicators to check for squareness as I go?

Some of the squares are pretty heavy:
http://www.use-enco.com/CGI/INPDFF?PMPAGE=462&PMITEM=418-4345

A square near the weight of your shaper vise means that you will have countered part of the table vertical deflection under load as compared to squaring just a bare/unloaded table. It will get closer to the situation that will prevail when you use the shaper to "make stuff".

If it were me and my shaper, my requirement would be that a dial indicator fixed to the ram and in contact with the table would show minimal dial deflection as the ram swept over the table (hand-powered - of course).

The ram and the table top both need to be square to the vertical dove-tail guide that holds the shaper traverse slide which in turn holds the table. That dove-tail needs to be very true.

I'd be looking at the ram dove-tail first.

Fasttrack
12-01-2010, 10:46 PM
OT - this is a 26" shaper. My vise is too heavy for me to pick up, and I can lift 150 comfortably and 200 with a little grunt. A 104 lb square shouldn't be too ridiculous. ;)

Thanks for all the suggestions. Beckley, I did read a description by both TGTool and Forrest Addy about measuring a square just using an indicator and surface gauge.

I'm leaning towards getting a selection of squares and scraping them all to "master" quality (O'Connely puts that at 35-40 spots per square inch, as I recall). I'd like something that is self checking, which is what is attractive about the three squares method. It just seems like there is less room for error since I'm not making any measurements.

But will the three squares method work with different sized squares??? I think it ought to, but I'm not entirely confident about this whole endeavor, yet. ;) :)

Also ... any thoughts about which square to get? I like the bigger ones, but the Interstate one seems to have a better design than those little wimpy ribs. What do you guys think?

Also, I do have some ground wrist pins out of a diesel - the edges are ground as well. I'm told they make great cylindrical squares, but I've no idea how square they actually are.

I should point out that these squares from Enco are already machined to be pretty decent. Even the cheap ones are 0.001 in 6", so I shouldn't have to do any machining. Just scraping.

gwilson
12-01-2010, 10:58 PM
I bought a granite square from CDCO. It checked out just fine against the 3 good old American granite squares I have,when blue was sparingly applied and the squares brought together on a granite surface plate. Surprisingly accurate,and not too expensive.

CDCO also sells that framing square. I had bought one of those also,and it checked out well against my Starrett master level,and granite squares.

Mcgyver
12-02-2010, 12:02 AM
I'm leaning towards getting a selection of squares and scraping them all to "master" quality (O'Connely puts that at 35-40 spots per square inch, as I recall). I'd like something that is self checking, which is what is attractive about the three squares method.

man, I'd not want to go that route....i guess you don't know until you do it, but it seems like soooo much scraping and iterations. If you create square via the indicator method, and you're using a quality tenths indicator in good shape (not sticky) and the surface plate is this accurate, you could do square to a 10th over 12".....that's better than any square you're going to buy and approaches the max resolution you can get via scraping.

Unfortunately even unfinished box parallel castings are expensive in large sizes. I've got a 2" thick slice of 12*12 cast iron that one day will be a square i hope - waiting until the cnc is done so i can mill a pretty ribbed/lattice structure to lighten it. I wonder you you could scrounge a similar off cut....or even if, choke, cough outright buying it would be reasonable? Working with this shape makes the indicator method much easier imo

12-02-2010, 12:53 AM
I'll look for that square checking how-to but until then consider this:

http://www.shars.com/product_categories/search/?search=granite+square

They're probably cheaper than buying three 12" tool maker's knees.

Adding. A good hard square is a good item to have. If you can calibrate it and know the amount and direction of the error you can compensate for the error and thereby work closer that the basic tool would otherwise allow. Note: this technique does not work for everything but it works for squares and other simple tools.

.RC.
12-02-2010, 01:19 AM
Why not just buy a machinist square and use it?

I just picked up a Brown and Sharpe 20" for \$50..

In that Mike Stet bridgeport rebuilding DVD that is all he uses to check squareness..

Fasttrack
12-02-2010, 02:59 AM

I guess I need to do some thinking.

oldtiffie
12-02-2010, 05:36 AM
I bought a granite square from CDCO. It checked out just fine against the 3 good old American granite squares I have,when blue was sparingly applied and the squares brought together on a granite surface plate. Surprisingly accurate,and not too expensive.

CDCO also sells that framing square. I had bought one of those also,and it checked out well against my Starrett master level,and granite squares.

Well well GW.

I'd have thought that would have had the "nutthinz az good az good old 'merican tools and iron = 'speshlly "Chinese" junk" etc. Brigade off and baying by now.

But for what its worth it accords with my experience as well as they are quite adequate for my purposes.

oldtiffie
12-02-2010, 05:49 AM
I'll look for that square checking how-to but until then consider this:

http://www.shars.com/product_categories/search/?search=granite+square

They're probably cheaper than buying three 12" tool maker's knees.

Adding. A good hard square is a good item to have. If you can calibrate it and know the amount and direction of the error you can compensate for the error and thereby work closer that the basic tool would otherwise allow. Note: this technique does not work for everything but it works for squares and other simple tools.

Thanks for that post Forrest as I will have a look into those squares and what the cost is to OZ is.

As the edge faces are square to each other and the main faces, using two of them together as a unit makes for a lot more uses and possibilities.

Mcgyver
12-02-2010, 09:39 AM

I guess I need to do some thinking.

buying a big machinist square or an import granite square are good options, but they hold some difference to either generation or how i would approach it, scraping with an indicator, which are worth considering.....

1) you just don't know how how accurate either the machinist square or shars square is . Machinists squares go for little money vs new because you never know if they've dropped or otherwise out of tolerance....I bet they're not cheap sold calibrated and warrantied as such by a reputable seller. Buying an import square, you're faced with trusting their claim. A new Starrett or Mitutoyo with a cert is also an act of trust I suppose, but they have the credibility that most would trust their cert. The import (not even a brand) lacks credibility; you will not know for sure and some shapes can't be tested via indicator (without a master to set it to)

and 2) neither will be as accurate as what he could do himself. You might not need or want that accuracy but i understand why someone would. When things are done on a comparative basis, each generation can lose a little so the end result will be a reflection of how good the start was....having a very accurate square to a tenth or two over a foot would be a nice thing to have for this sort of work - basically for checking other squares.

There's also the intangible that it is very rewarding to make a high quality tool, something as good or better to what can be bought.

lazlo
12-02-2010, 10:14 AM
man, I'd not want to go that route....i guess you don't know until you do it, but it seems like soooo much scraping and iterations.

I agree, unless you have a ton of free time, I think you'd be a lot better off buying a decent Chinese or Ebay reference, and spend your time scraping the shaper, instead of the references :)

beckley23
12-02-2010, 08:28 PM
I couldn't find the post by Forrest that I was looking, and thought I had saved it, couldn't find that either.
But I did a search on PM for precision squares and Forrest Addy, and this is what I found. There are 7 topics , I only checked a couple, but Forrest has summarized his advice.
http://www.practicalmachinist.com/vb/search.php?searchid=3039554
Harry

oldtiffie
12-02-2010, 11:53 PM
So I'm slowly tooling up to scrape my shaper. One of the items I will need is a large, accurate square. Enco has some large cast iron squares on sale. I'm thinking either something like this:

http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=951641&PMAKA=418-4145

or

http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=952519&PMAKA=418-4345

Now, I know that I can scrape them "perfectly" square if I have three of them. But I don't want to have to buy three of these beasts.

So is it possible to get away with two 6 by 6 squares and one big 12 by 12 square? Basically I would treat the big one like it was 6 by 6 but with an added step of scraping each surface flat after referencing one of the other squares. I.e. I indicate off of one of the other squares and the surface plate. Scrape as needed. Turn over and scrape the entire side into the plane that I just established using the small square. Turn around and reference the other square, etc.

Or should I just get one and fiddle with indicators to check for squareness as I go?

As I understand it, the biggest flat reference face will be on one of several 12" x 12" on the 12" x 12" angle plates.

Its a big ask to use that to accurately scrape the 26" shaper table or the vertical square of dove-tail guide-way. I'd have been looking at a good (Camel-back or similar) level that will span the table across its diagonals as well as the same for the face of vertical guide.

I'd agree with a precision square or block to check and scrape the top of the table to the vertical way as well.

The ram may need a pair of precision prismatic blocks to scrape the ram dove-tails as well.

Perhaps you have this stuff but it wasn't mentioned.

Best of luck - its a big job.

Any chance of a few pics?

12-03-2010, 01:06 AM
Here's the red meat from a post written some time ago discussing how to calibrate a machinist's hard square and how to quantify the error:

Part of being a machinist is knowing your tools and whether they are accurate enough for a particular set of circumstances.

Those of you having no need for calibrated squares sor for making verifiable squareness determinations should read no furthet. Nor need they scoff at the following text's applicability to their particular line of work. It's intended to illustrate calibration technique for those having an interest or a need for the topic.

Checking square against square only ensures that their stocks are parallel when their beams are butted together. Scribing a perpendicular, then reversing a square to eyeball the error is adequate for a framing square but laughably crude when applied to even rudimentary squareness determinations used in the machine shop. OTH, you need three squares to check in rotation. While this method can be used to verify absolute squareness it lacks the ability to quantify the squareness of any particular item needed to be square.

Quantify means "...express as a number or measure or quantity..." My definition of quantify as applied to squareness error means a measure of the error and its direction (ie acute or obtuse stated in terms of the interior or exterior angle.

A square is self checking, that is no standard is required to assess a particular square’s accuracy: it can be used to check itself.

Quantitatively checking a square to very close tolerances is bone simple with a minimum of equipment. All you need is a granite flat, a surface gage, a pair of matched 1-2-3 blocks, and a dial test indicator.

Clean and de-bur the square to be tested. Verify the parallelism and straightness of the stock and beam independently. Verify parallelism and equal size of the 1-2-3 blocks in the 2" dimension.

Reverse the surface gage mast so its ball end extends down through the notch of the surface gage base. Use the surface plate as a flat reference:

Mount the dial test indicator on the upper part of the mast.

Set the pair of 1-2-3 blocks on the 2" edge or on end so the stock of the square can pass between them

Set the surface gage base on the 1-2-3 blocks. Ensure the stock of the square can pass under the base and between the 1-2-3 blocks.

Position the square so the ball of the mast contacts the beam close to the stock.

Adjust the DTI so its ball contacts the beam towards the upper end. Note: work carefully and gently minimizing heat input to the square and the surface gage. The DTI contact has to be on a perpendicular over the tangency of the ball end on the square. This is necessarily a finicky adjustment. The DTI cannot be properly nulled unless this adjustment is within close limits.

Slide the square back and gently re-contact the ball of the mast rotating the square slightly in the vertical plane to null the reading. Zero the indicator. Re-test a few times to ensure consistency.

Slide the square out and reverse it 180 degrees on the surface plate. Contact the ball and the indicator again. Note the reading.

Reverse the square and run the stock back under the surface gage base. Note the repeat zero reading. If the reading is not zero, adjust and re-test until it is.

The indicator reading is DOUBLE the actual square error. Note the algebraic sign of the error. Calculate the raw readings to convert them to a slope. Apply a calibration sticker to the square or note in the calibration records (you meticulously keep). Place a certificate of calibration in the square's box. I suggest you use wording like "Error 0.000X per ft - interior angle ACUTE (or OBTUSE)." This provides enduring notice of the amount of square's error and its direction. Anyone using it can use the error information to compensate its known error. Thus it's possible to make squareness determinations that are more accurate than the square itself.

I discussed this procedure in some detail in my Home Shop Machinist article in Jan/Feb 2005 and there are some pictures to see. I didn't use a surface gage for the article. Instead I used a gadget I built. A surface gage is quite tricky to adjust for this evolution and, once set, its adjustments can easily slip.

The same procedure may be used to check other items. Angle plates may be checked by adapting this technique but a precision parallel must be added to the equipment.

lazlo
12-03-2010, 11:04 AM
I happened across this great picture showing Forrest's method. Unfortunately, I can't remember who created it:

http://i164.photobucket.com/albums/u15/rtgeorge_album/SquareCheck.jpg

TGTool
12-03-2010, 11:54 AM
I did. That's from the discussion Beckley mentioned a few posts back on this forum two or three years ago. Forrest had issued a challenge on how squareness could be checked with parallels, a surface gauge and an indicator and this is the graphic solution.

lazlo
12-03-2010, 12:23 PM
I did.

Thanks Jan -- it's a great picture! OK if I leave it up?

TGTool
12-03-2010, 01:41 PM
Thanks Jan -- it's a great picture! OK if I leave it up?

Sure, it's part of the record and one of those conceptual things that's good to keep track of when confronted with one of those "Now how the #\$%@ do I verify THAT." And if one can maintain a grasp of first principles you don't run into the situations of everyone in the toolroom making their squares off the lead man's and then finding out that the "standard" is off. :rolleyes:

Fasttrack
12-03-2010, 02:13 PM
So ... I have to ask. What prevents a ham-fisted guy like me from bumping the 123 blocks while trying to indicate them? I can see this becoming quite a long process as I continually bump the 123 blocks. :D

TGTool
12-03-2010, 03:52 PM
So ... I have to ask. What prevents a ham-fisted guy like me from bumping the 123 blocks while trying to indicate them? I can see this becoming quite a long process as I continually bump the 123 blocks. :D

I think it's called being careful and paying attention to what you're doing. :D There are lots of things for which there's just no substitute such as "feel" when using a depth mike. Forrest's description above includes that business of going back to check that the indicator re-zeroes which is your verification that nothing has shifted to give you an erroneous reading. Maybe the statistician's work around it just to take nine measurements, throw out the high and low numbers and average the rest. That tells him that the the dimension is exactly X.XXXXXX to a reasonable degree of certainty which he can also put a number on. :eek: