Thread: How did pre-industrial woodworkers check for squareness and flatness?

Originally Posted by IanW

John, what about a cheap 'disposable' saw? The steel should be just about the right thickness. Bit of an exercise cleaning up the blade after you cut it out, but with patience and care, you should get it sufficiently straight & parallel. I don't use this one for everyday bench work, as it's a bit bulky for that, but it's very handy when I need a bit of extra reach. I could occasionally do with one with a 500mm or longer blade, too, so one of these days....
Cheers,

Ian,

Considered a cheap saw blade. It certainly is the right type of material, and I have an old saw that could be sacrificed for the cause.

My issue is that I have very limited tools for working with metal ... angle grinder, bench grinder, hacksaw and a couple of files. The thought of making up a reasonably precise 600 mm long rectangle from a saw blade with these tools leaves me cold right now. I'm sure it could be done, but lack the enthusiasm. When I think about it, my head hurts and my elbows and wrists beg me not to do lots of repetitive filing etc. Then I reach for the timber one I made.

The other wild and irresponsible idea I had was to make it out of brass, if the right alloy could be found.

Eventually, I will do something about it, but right now I don't want to spend the time it would take to do a decent job.

Originally Posted by John Samuel

......My issue is that I have very limited tools for working with metal ... angle grinder, bench grinder, hacksaw and a couple of files.....

Not to labour the point too much, but that is precisely the theme of this thread - how to achieve square from scratch, using basic technology... The equipment list you've given is pretty much all I used for the square pictured. It didn't involve any heroic manual work (I'm past that, too!), just patience and care with the critical parts of the build.

Another option that won't bust the bank would be to use a 600mm SS rule for your blade, though they are probably a bit thinner than ideal. Yet another would be to chop the arm off a steel rafter square, which would be plenty thick & stiff enough. Both these options minimise the work required to get your blade ready.

The hardest part of making one of these types of squares is drilling the two holes in the stock to take the 'slugs' that push on the blade, & of course, the longer the stock, the more difficult it is to drill a perfectly straight hole. You want the hole to end up no more than plus or minus a mm from dead centre of the blade slot, so there's not a lot of room for error. I first tried it using the drill press, carefully setting everything up just so, but 50% of the time, the drill wandered off-course, despite constant withdrawal & cleaning. Also, because the throw on my drill is only about 90mm, the table has to be moved up during the drilling, which introduces more potential error. After some mucking about, I found the most reliable way was to start the holes in the drill press, then finish them off using an extra-long bit in my battery drill. By sighting along the drill, I was able to 'steer' it better & keep it on course. So you see, the simpler the technology, the better.....!

Cheers,

Originally Posted by IanW

Not to labour the point too much, but that is precisely the theme of this thread - how to achieve square from scratch, using basic technology...

Ian,

There is no doubt that it could be done, or that I could do it. However, for now I have a square that works, one that I made myself.

Equally, there is no doubt that I will eventually replace this square with a more permanent item. Maybe I'll make it ... maybe I'll buy it. My workshop is a source of satisfaction and joy, so if I don't feel like doing something, or doing it in a certain way, I don't. Right now, I don't feel like cutting down a saw blade and filing it to shape. That may change in the future. All will be revealed in the fullness of time.

The biggest problem I face right now is that I am not yet clear on what I want. I might make it out of brass ... and I might make it out of a mixture of brass, steel, wood and even polycarbonate is on the list of possibilities. For some reason, being able to see through the blade seems like a good idea. One idea I am toying with is (say) making the square with a timber base and a polycarbonate blade, the reverse edge of which is a quarter of a circle and marked out as a protractor. This would preclude using the reverse edge to make a right angle mark, but it is an idea I am kicking around. I even found a new brass protractor on e-bay, much to my surprise, but it occurs to me that such an instrument would likely be handier in a smaller item rather than a 400 mm X 600 mm square.

John - I apologise if I seemed pushy - I wasn't trying to force you into something when you are clearly in the 'planning' stage. That part can take me anything from days to (many!) years, so I fully understand.....

I was just suggesting possibilities, as much for anyone else who is contemplating making their own square, and also making the point that you don't need a shed full of precision equipment to make quite accurate tools. Of course the more gear you have the easier it is - I'm not advocating we all build heirlooms with a pocket knife and a hammer...

Cheers,

Originally Posted by IanW

John - I apologise if I seemed pushy - I wasn't trying to force you into something when you are clearly in the 'planning' stage. That part can take me anything from days to (many!) years, so I fully understand.....

I was just suggesting possibilities, as much for anyone else who is contemplating making their own square, and also making the point that you don't need a shed full of precision equipment to make quite accurate tools. Of course the more gear you have the easier it is - I'm not advocating we all build heirlooms with a pocket knife and a hammer...

Cheers,

Aww, Ian ...

You are being way too tough on yourself. You did not come across as pushy, only as enthusiastic. As a relative novice I am forever in debt to people like you, Wongo and BobL, to name only a few. All of you have been generous and helpful, and many of us have good reason to appreciate that.

You are certainly right about not needing a shed full of precision gear to make good tools. The last crosscut sled I made was tested using the five cut method. The error was less than a thou ... or something ... the furriness on the edge of the panel means my measurement error will be more than that ... but that is still a pretty neat result for a sled made of MDF. In the far distant past I made a new blade for a very small plane, and was overjoyed that it worked like a bought one. I used a mate's grinder, a hacksaw and a file. I was so impoverished I could not afford sharpening stones, and made the bevel with wet and dry glued to a glass louvre liberated from the bathroom window.

I would not willingly be without my machines, but if the ancients could make great stuff with very basic gear, so too can we. More importantly (I think) is our ability to understand first principles. I know a bunch of folk who don't know how to test a square's right angle; or how to make a quick flat reference surface; or ... it goes on ...

And now for the funny part. As you were typing your response I was in the shed, filtering a little Chermside smog through a cigarette. That out of square steel square was sitting in my bin, looking at me pleadingly. Then the obvious solution hit me in one of those "how could I have been so stupid" moments. The square is nothing more than a flat piece of steel. How simple would it be to glue/bolt/rivet a couple of pieces of stable timber either side of the shorter arm in such a way as to make the timber and the long arm a true 90 degrees? The offending square will soon be square again ... but I still like the idea of a square with a built in protractor ... someday ... maybe.

Have fun!

Originally Posted by John Samuel

.....That out of square steel square was sitting in my bin, looking at me pleadingly. Then the obvious solution hit me in one of those "how could I have been so stupid" moments. The square is nothing more than a flat piece of steel. How simple would it be to glue/bolt/rivet a couple of pieces of stable timber either side of the shorter arm in such a way as to make the timber and the long arm a true 90 degrees? The offending square will soon be square again ... but I still like the idea of a square with a built in protractor ... someday ... maybe.
......!

A man after me own heart! What's that old saw? "Waste not, want not"? Well, I waste little around my shed, but still find I want for things.

Having been separated from my shed for 6 weeks, I've had lots of time to plot & plan some new tool projects myself - have ordered a couple of plane blades & other bits & bobs that should be arriving about the time I get home, so sometime in the next three years (or more ) I may put a couple more 'wants' to rest.

I will have lots of fun....
Cheers

Originally Posted by Twisted Tenon

Now as an old ex printer I can see a line of type running uphill a mile away. The trained eye can spot this stuff.
TT

Well ... I looked here ... Letterpress Lockup ... and enjoyed the printing jargon ...

but still need a definition of type running uphill.

Cheers,
Paul

Originally Posted by John Samuel

That out of square steel square was sitting in my bin, looking at me pleadingly.

Haha! Still have it ... well done that man.

Can it not be adjusted with a centre-punch to push the arms slightly out or in, by targetting the corner section?
I know I have read about it online or onpaper.
Cheers,
Paul

Originally Posted by pmcgee

Well ... I looked here ... Letterpress Lockup ... and enjoyed the printing jargon ...

but still need a definition of type running uphill.

Cheers,
Paul

Paul
it means a row of type is higher on one side than the other.
I never did Letterpress. That's a whole other world

TT

The centre punch is definitely the way to do it. I have done mine a few times after accidently dropping it. Dad taught me that one years ago, he was a chippy.

Originally Posted by pmcgee

Haha! Still have it ... well done that man.

Can it not be adjusted with a centre-punch to push the arms slightly out or in, by targetting the corner section?
I know I have read about it online or onpaper.
Cheers,
Paul

I prefer to add timber to the short arm. Makes it easier to use than the flat piece of steel it currently is.