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

I am guessing but - the way to test a square is place it on a straight edge and scribe the right angle line - then flip the square and do the same and see if the 2 lines are parallel with each other!

I humbly suggest that the old timers eyesight was as good or better than ours sot hey could sight a straight edge and work a piece of wood until it was straight - thus they SHOULD have been able to make squares... and test them.

I am guessing they built the pyramids and must have used rudimentary tools such as plum bobs and squares...(depicted in their stellae?) to achieve this.

My 2c

There are plenty of methods used to generate flat surfaces - here are a few.
Pools of water were used by the egyptians to make large flat surfaces. Molten glass will also form a flat surface.
A polished metal surface can be made flat by checking reflections (Only a flat surface will make a regular reflection)
Three stones rubbed together as alternating pairs will all eventually form a flat surfaces

3-4-5 triangle has been around since egyptians, I think.
TM

Originally Posted by TermiMonster

3-4-5 triangle has been around since egyptians, I think.
TM

Since Pythagorus, anyway.
T-squares and framing squares have been around for years, checked as described by TT. For wooden surfaces, straight edges would show any humps and hollows. The Egyptians certainly had planes.

Cheers all！

I reckon that'd possibly make a good beginners' project - making your own carpenter's square using two pieces of wood, eyesight and trial and error.

Simple plumb bob will show a straight line, if you hold the edge in question up to it.

Originally Posted by TermiMonster

3-4-5 triangle has been around since egyptians, I think.
TM

Also 5 - 12 - 13. I guess a lot of us have used either of these two equations to set out something square at some stage.

We underestimate the accuracy you can get with fairly simple tools. Further to TT showing how to true a square and Alex reference to Pythagorus, a simple straight edge and compass is all that is needed easily generate angles with pretty good accuracy. No actual numbers or measurements are required. The Greeks of Pythagoras time knew this and extensively tried to develop more and different basic angle constructions. It was (is) taken to a high degree of complexity in some Islamic art.

I believe earlier people (Egyptians, Babylonians*, Chinese etc) would have known at least the basics of all of this. The Babylonians counting system of base 60 is why we have 360 degrees in a circle, so that sort of knowledge is getting on for 4000 years old. I seem to recall that the Egyptians may have flooded the bases of their pyramids to get the bottom courses level. The sad thing is, their tools were mostly wood and have long gone. We only have (poor) pictures and some written descriptions that have lasted.

I am pretty sure the Romans used water levels as per BobL's comment, in their constructions to get very accurate slopes in their aqueducts etc. An architect colleague of mine always used to go on about an aqueduct that took water across a valley, not in a straight line but down then up again (so the water ran "uphill" under it's own momentum). Not in pipes as a normal siphon but as an open air channel.

I visited Europe about 18 months ago and saw a 2000+ year old wooden coffin in one of the museums there. The edges were joined with a sort of mitre joint with a square section on top (I don't know the proper description). I took some notes and pix but I thought then, I could easily make something as good as that with the hand tools that I have (except for the surface carving). I suspect the woodworking shop and tools of a couple of millenia ago would not be too strange to any of the people who read these forums.Attachment 283473

Regards
SWK

They built their own squares etc. Have a look at Robert Ulrich's site for Roman woodworking.
Roman Woodworking Tools
It shows common tools such as the square and dividers. Basic dividers and geometry gives you a reference right angle. The chalk line and plumb bob is another important tool for straight lines.

Richard

When making regular square/rectangular objects I still check for square by measuring the diagonals. Easy to do with limited resources and gives good accuracy.

Some excellent comments in this thread. I remember a Time Team episode where they used Roman surveying tools to set out a camp and check the results with modern satellite based equipment. The difference was very small.
We tend to forget that woodworking was as accurate as it needed to be - measuring diagonals for instance rather than relying on all angles being square. Only with mass production does absolute accuracy matter as much.

Originally Posted by jimbur

We tend to forget that woodworking was as accurate as it needed to be - measuring diagonals for instance rather than relying on all angles being square. Only with mass production does absolute accuracy matter as much.

I was wondering about this too Jim. I was wondering how square the old furniture was and how necessary was it. I guess it was as important then as it is today, however they didn't have Starrett squares then, and what passed for square 200 years ago might not be the same today.

TT

what passed for square 200 years ago might not be the same today

.

I suspect dead the opposite!.

The freemasons make great emphasis I believe about plum and square and true etc. Their symbols being the square and compasses, and I understand that they also use allegory to how one should conduct oneself and family etc privately and in public - in terms of social and moral 'mores' - in reference to building terms like square and plumb etc.

I'm not a freemason, so only know what I've read, but my Father who i worked with for 20 years was a master mason... (and also a master builder) and he was ALWAYS on about straight, plumb and true...

I recall as a kid when he was supervising building for his own company and I'd accompany him on job sites (of a sat morning) that he would squint all the timber door jambs & frames...to see if the brickies had wire tied them into the new brickwork "in wind" (wyned?) which meant the two legs both plumb and in line with each other.

I recall seeing dad push a newly laid green brick wall over - with his leg & foot once - because the door jamb wasn't "in wind" and he could see it was out bye just standing back at an angle and sighting the inside edge of one side with the outside edge of the other side to see if each was parallel - and he made the brickies re lay that wall to get it right.

Years later when I brought it up - he mentioned that growing up and doing his apprenticeship as a carpenter (1946 - 51) and working in the trade, he had hung a LOT of timber doors in his time!.

If the sides of the jamb are "out of wind" with each other - when you hang the door - you have to throw it on the hinge, to get it to close, and when you do close it you have too push the door (after one of the top 2 corners strikes the rebated door stop first) to get the plunger in the door lock to hit the striker plate, which becomes a royal PIA if you have to live in that house for a period of any time.

The brickies all hated his guts I think - they nick named him "door jamb Lowy" - but the word went round the trade and any of his brickies teams knew the deal before they started - wire tie the door jambs and frames to the bricks "in wind" - or be prepared to re-lay that wall after he pushed it over.

These days just about everything's steel door frames and I don't see many that are "in wind" in display homes etc... I just know he was a bloody stickler for it, "square", "plumb", "in wind", True and so on... and he translated that to his furniture and cabinetry... as I learned the hard way working with him for 20 years, before he passed (on Jan 1st 2005), from throat cancer after working with MDF and particle boards etc full of urea formaldehyde glue and not paying any attention to dust extraction all his life.

It was a big bug bear of his when "project homes builders" (AV Jennings were one of the first in WA) started with the whole display villages system, and bulk buying materials - with standardized designs etc...at discounts that made them more competitive that your normal registered builder.

Many of these so called "delvelopers" are (are still today) just glorified real estate agents, who employ a reg'd builder so they can use his ticket.... to be a "project home builder"...

When you sign the contract and get the mortgage from the bank and pay the "project home builder" (read - real estate agent)...they take out all the built in "profits" from the construction of the house up front - then give their "tame builder" a contract to build this house for XYZ dollars including a "set fee" for the builder for his "supervision".

Dad always reckoned this was the start of the end of good trade skills in the home building industry - because the"tame builder" has no allowance built in for re doing poor trade standard of work (Re-laying a brick wall for E.G. that's out of plumb or square, or where the steel door jambs or frames are bricked in "out of wind' - and so they let tradie's get away with sometimes slip shod work, because they LOSE $ out of their contracted amount to build that house, (i.e their supervision "fee") if any "do overs" are required to maintain a tradesman like standard of construction.

As a result the "tame builders" employed on contract to 'developers' building "project homes" tend to look the other way, and then the next trades to come along (carpenters, tilers, etc) have to "get around" the stuff ups by the trades who were ahead of them!.

He bemoaned this was the death of the building trade in this country - letting real estate agents be in charge of building homes, and ripping out all "the profits" (That builders used to put back into their businesses) before the house was even built...all the profits & non of the responsibility...

It really bugged him a LOT to see the industry go this way...

In his days - you went to a local builder, who'd help you design the house (heck dad even drew the plans) and then he would build your house for you.

Now you deal with a sales person at the land sale and complain to the office lady on the phone (who couldn't give a round rats touche about your house build).

The entire building industry now days is owned and run by real estate agents who call themselves developers and builders etc - but you seldom get to acvtually have anything to do with a REAL builder.

The builders rego numbers in WA these days are now in the 15000's I heard the other day, Dad's reg bldr number was 938.

Lots has changed - I'd buy a well built old house these days LONG before I'd buy one of the new ones from a project home builder....

Others mileage obviously will vary...

Yep fair enough in the building trade. I was talking about furniture and was not talking about shoddy work either. More what passed for square 200 years ago. My dad could hang a door and cut the mitres absolutely perfect with just an old hand saw, a chisel and an old try square. I never saw how he did it. 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. Drawing on my experience of laying out artwork and printing, it was some times possible to "trick" the eye by balancing objects on a page to give the appearance of square. I sometimes wonder back then, was "square" the bench mark and dead square something for the future?

TT