Quality of Engineer’s squares

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I also agree that the turn around test is the best method for general use. There are a couple of things to consider though, firstly using this method you are only checking the inside edge of the stock to the outside and/or inside edge of the blade, therefore you will have to either accurately measure parallelism of the inside to outside edges of the stock, or have a reference for the outside of the stock to rest onto which has a rebate wide enough for the stock to lay into, to at least the depth of the stock to blade sides. Also the reference edge must be reasonably flat and straight and square to top of the side you will scribe your test line onto.

 

Checking a square against a cylinder square has some of its own problems to get a true interpretation, apart from the cylinder squares accuracy. Firstly the blade must not have any significant curve long its length in its flat dimension, and secondly the base of the stocks face, sideways, must be square with the sides of the blade, because the side of the blade will have to stand exactly in the same plain as the side of the cylinder square when the stock is sitting on the same surface as the cylinder square, i.e. assuming that the cylinder square is perpendicular to the reference surface, the side of the blade must be also, to get a true reading.

 

Regards Nick.

[John McNamaraParticipant @johnmcnamara74883]

Hi all

 

Cylindrical squares have many practical uses.

 

In the setup below I needed to bore two holes at 90 deg to the two slide rods

Two cylindrical squares were first bolted to the table then the work clamped to them

some packing under the work to make it parallel to the table and the setup was done.

(I drilled then bored)

 

The second square is at the back and a little hard to see.

 

Cheers

John

 

[TerrydParticipant @terryd72465]

Posted by MICHAEL WILLIAMS on 07/01/2012 10:33:34:

(1) Squares with settable blades are quite common in inspection departments . The normal method of making the hinge is to use a fitted dowel pin as the pivot and a ring of usually three holes around with small locking screws . The stocks of these squares are often more chunky than than on workshop squares so that they can sit solid on a surface plate . The blade never works in a slot but seats against a half cutaway in the stock thus giving a solid against solid lock down .

 

MW

Hi Michael,

 

That parallels almost exactly my experience in inspection during my apprenticeship.

 

One question regarding the use of cylindrical squares. How would one check the internal angle of the square? Is it sufficient to correct the external angle and then check the parallelism of the stock and blade? Or is there another method I’m missing here?

 

It is the internal angles which are most useful for marking out in benchwork (both inner and outer side of blade) and these are what the flip over against a straight edge tests.

best regards

 

Terry

Edited By Terryd on 07/01/2012 14:52:00

[TerrydParticipant @terryd72465]

Posted by Nicholas Farr on 07/01/2012 12:05:48:

Hi, I also agree that the turn around test is the best method for general use. There are a couple of things to consider though, firstly using this method you are only checking the inside edge of the stock to the outside and/or inside edge of the blade, therefore you will have to either accurately measure parallelism of the inside to outside edges of the stock, or have a reference for the outside of the stock to rest onto which has a rebate wide enough for the stock to lay into, to at least the depth of the stock to blade sides. Also the reference edge must be reasonably flat and straight and square to top of the side you will scribe your test line onto.………………..

 

Regards Nick.

Hi Nick,

 

in the ‘flip over’ test there are three to be carried out. First outer angle against outer angle which proves the angle correct at 90 . Then inner angle against inner which if satisfactory proves the parallelism and as a final check, inner against outer. Surely that automatically checks and confirms (or otherwise) parallelism of the blade. A long , shallow upright can then be clamped to your test edge and the outer part of the stock can be compared to the previous tests, or then use the cylindrical square to test the outer angle of stock/blade.

 

Best regards

 

Terry

Edited By Terryd on 07/01/2012 14:51:35

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

(1) I’ve never actually done this but it should be possible to make a ‘permanent square tester’ out of two straight edges – one short and one long – about 2:1 ratio .

 

Fix the short straight edge to the centre of the long straight edge in the manner of a very stubby T square with some means of allowing slight movement and then final hard lockdown .

 

The short straight edge has two edges checked to be exactly parallell .

 

On the first occassion of use true your square and set the short straight edge square to the long one on the tester by trial and error and correction of any errors in the square itself by filing/stoning . Essentially you are using the standard turn around test but using a bar as the scribed line and getting a permanent reusable reference at the end .

 

(2) Very high grade reference squares are usually only accurate on the outside faces . Inside squares are usually made by testing against an outside square .

 

MW

[Douglas JohnstonParticipant @douglasjohnston98463]

One thing I would like to see is the use of stainless steel for squares and other similar measuring equipment. I bought a stainless square a couple of years ago which looks like the Warco one mentioned earlier and it is a joy to use since it is very well made and does not need to be oiled to prevent rust.

The problem is the range of stainless items is very limited. The largest square I can find is only 100mm and I would like a larger one. If we can get dirt cheap hardened stainless steel calipers, why can’t we get other measuring stuff in this material?

 

Doug.

[Russell EberhardtParticipant @russelleberhardt48058]

A cheap source of cylindrical squares is old gudgeon pins from a car scrapyard. I have a pair of Rover 2000 ones that I have used for years. They are precision ground to a couple of tenths under 1″ dia. and just under 3″ long. I’m sure something bigger could be found from a truck.

 

Russell.

[Mike PooleParticipant @mikepoole82104]

I spotted on eBay hard chromed piston rod for hydraulic cylinders up to 70mm diameter, not exactly cheap but a short length could make a couple of squares just for the trouble of facing the ends square. I would hope they are parallel and round to better than I could make. If you make two then they can check each other.

Mike

[David George 1Participant @davidgeorge1]

I have three cylindrical squares made when I was an apprentice. I wouldn't be without them but I have two Moor and Wright blade squares of similar age which get used very frequently. I also have a Starrett square set of centre finder and protractor.

David

[HopperParticipant @hopper]

Posted by David George 1 on 03/03/2019 09:17:45:

… I have two Moor and Wright blade squares of similar age which get used very frequently. …

David

This seems to be the way to go very frequently. If you can find older tools and equipment still in good condition, as much of it is, even after 50 years or so. I've bought garage-sale M&W squares for $2 a pop that are still as good as new in use. Others that you see have obviously been knocked around, used do drive in nails etc (I kid you not!) and are best left alone.

[Nicholas FarrParticipant @nicholasfarr14254]

Posted by Hopper on 03/03/2019 12:43:36:

Posted by David George 1 on 03/03/2019 09:17:45:

… I have two Moor and Wright blade squares of similar age which get used very frequently. …

David

This seems to be the way to go very frequently. If you can find older tools and equipment still in good condition, as much of it is, even after 50 years or so. I've bought garage-sale M&W squares for $2 a pop that are still as good as new in use. Others that you see have obviously been knocked around, used do drive in nails etc (I kid you not!) and are best left alone.

Hi, unless you feel you need a good solid hammer to knock the nails in square!

As Russell suggests, I have had for a long time now, a few gudgeon pins from a lorry engine or two, that are in good nick

Regards Nick.

[KWILParticipant @kwil]

Cutwel sell hardened stainless steel squares up to 300mm x 200mm (usual disclaimer)

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