Building Bridges

[MikeJhn]

One page of calculations and all set out from a straight line, but I suppose its easier to physically set it out if you have the room.

 

[Inspector]

I'm pretty sure I know the answer Scotty but I'll ask anyway. Is what you call a "rod" what we would refer to as a story pole?

Pete

 

[ScottyT]

One page of calculations and all set out from a straight line, but I suppose it’s easier to physically set it out if you have the room.

the rod isn’t calculations as such Mike, in most instances the drawing (if I’m lucky enough to get one ) has all the salient details on it, it’s just a ‘to full scale’ drawing to enable me to actually make it accurately. When I prepare my various components from rough sawn, they will lay directly on this drawing by careful placement, I can then pencil on my shoulder lines for tenons, mortice positions, plumb and seat cut for the main beam, all the lattice work will be worked off it, O/A length of my posts and where they are drilled for the S/S threaded bar, etc etc etc the entire process down to screw placement!
With this rod finished I now know it works and where I am going with the job.
Without the 1:1 I would be blind and taking a punt with some expensive timber and winging it big style.
If I can’t rod it, I can’t make it.

Scotty

 

[ScottyT]

I'm pretty sure I know the answer Scotty but I'll ask anyway. Is what you call a "rod" what we would refer to as a story pole?

Pete

If a story pole is what aids you in making something Pete then I can only assume yes it is! Thankyou for the interest and I hope you enjoy the thread as it unfolds

Scotty

 

[Cabinetman]

Had you (or they) considered laminated beams? Love to try laminating something that large.
Ian

 

[Jacob]

I'm pretty sure I know the answer Scotty but I'll ask anyway. Is what you call a "rod" what we would refer to as a story pole?

Pete

Story pole or stick seems to mean measurements marked out on an actual pole or stick i.e in one dimension. Might have picked up the name from stair-making where you really do need a story height stick to record the floor to floor measurement and to divide it into equal risings.
But a "rod" is a full size drawing i.e. in two dimensions.
For flat things like doors and windows this would be the vertical and horizontal cross sections only and could fit on a narrow board. Chest of drawers you'd have sections the same for the drawer front, and ditto for the sides, etc. as necessary
For other things there are all sorts of ways and means, and used in a wide variety of crafts, from dress making patterns to sail makers lofting floors, and larger.
Model aircraft making is similar, with balsa struts laid out, cut and pinned to a drawing. How else could you do it?

 

[MikeJhn]

Model aircraft making is similar, with struts laid out, cut and pinned to a drawing. How else could you do it?

Mostly cut and glued to the drawing.

 

[Jameshow]

Mostly cut and glued to the drawing.

Both sides stuck too each other - DAMHIK!

 

[niall Y]

Looking at the drawings again, i noticed that where the the arms of the diagonal 'swastika' ( apologies but it's a convenient way to describe the shape) enter posts 2,3,and 4, from either side, they appear to getting progressively closer and closer together.

Now that you have sorted out the rods is this indeed the case, and a result of the asymmetric design of the panels coupled with the curvature of the bridge - or is it just an optical illusion ?

Niall

 

[Sgian Dubh]

I'm pretty sure I know the answer Scotty but I'll ask anyway. Is what you call a "rod" what we would refer to as a story pole?

I know your question has been answered already and similar questions have been asked here before. I'd call what Scotty's doing is creating a rod, and when I lived in the US I learnt what I knew as a rod was called a story stick.

It's always seemed simple enough to me, i.e., rod, story stick, story pole are essentially the same thing, i.e., stuff set out full size on a stick, a board, or boards, big piece of paper/card or even set out full size on a floor, stage set, etc. But I mentioned above that similar questions have been asked before, and I came to the realisation that for some here in the UK there seems to be real differences between a rod and/or a story stick or pole.

I have to admit I've never been able to get my head around the subtle(?) differences between a rod and a story stick in the mind and the the practice of some British woodworkers, but they seem to be real if I've remembered it correctly. Slainte.

 

[Jameshow]

If I were making such a bridge I would make the sides trussed just like iron bridges are. That way the top and bottom beams take the tension with the triangulation between??

 

[ScottyT]

Had you (or they) considered laminated beams? Love to try laminating something that large.
Ian

Not on this bridge as although it’s big for me on my own, it’s relatively tiny and no issue to get the timber in one piece.
We have however made a 22m bridge many years ago, that was massive and laminated.

Scotty

 

[Jacob]

I know your question has been answered already and similar questions have been asked here before. I'd call what Scotty's doing is creating a rod, and when I lived in the US I learnt what I knew as a rod was called a story stick.

It's always seemed simple enough to me, i.e., rod, story stick, story pole are essentially the same thing, i.e., stuff set out full size on a stick, a board, or boards, big piece of paper/card or even set out full size on a floor, stage set, etc. But I mentioned above that similar questions have been asked before, and I came to the realisation that for some here in the UK there seems to be real differences between a rod and/or a story stick or pole.

I have to admit I've never been able to get my head around the subtle(?) differences between a rod and a story stick in the mind and the the practice of some British woodworkers, but they seem to be real if I've remembered it correctly. Slainte.

I thought there was a difference because I've seen several youtubes of yanks explaining their "story sticks" as just a one dimensional scale; a stick with marks along it, not a 2 dimensional drawing.
Here's the first one I turned up with a search on "the story stick" https://www.google.com/search?q=the...ate=ive&vld=cid:1519f0a2,vid:hsjdWT6gqhE,st:0
Maybe they are all called story sticks one way or another?

 

[ScottyT]

Looking at the drawings again, i noticed that where the the arms of the diagonal 'swastika' ( apologies but it's a convenient way to describe the shape) enter posts 2,3,and 4, from either side, they appear to getting progressively closer and closer together.

Now that you have sorted out the rods is this indeed the case, and a result of the asymmetric design of the panels coupled with the curvature of the bridge - or is it just an optical illusion ?

Niall

That’s the great thing with the rod Niall, it became apparent quickly the computer had a hard time spitting it out. Sections 1&4 are the same dims and 2&3 are the same, so I’ve made both pairs run the same, it looks ok.
It’s funny you mention the Swastika as we were having a chat about this at the time I was rodding it.
Thanks for the interest

Scotty

 

[Jacob]

That’s the great thing with the rod Niall, it became apparent quickly the computer had a hard time spitting it out. Sections 1&4 are the same dims and 2&3 are the same, so I’ve made both pairs run the same, it looks ok.
It’s funny you mention the Swastika as we were having a chat about this at the time I was rodding it.
Thanks for the interest

Scotty

No worries about the swastika - the Nazis borrowed it but it was used in more benign circumstances for hundreds of years before. Just don't have a tattoo! https://en.wikipedia.org/wiki/Swastika#:~:text=The swastika (卐 or 卍,in the early 20th century.
"The word swastika comes from Sanskrit: स्वस्तिक, romanized: svastika, meaning 'conducive to well-being'." etc

 

[Jameshow]

I thought there was a difference because I've seen several youtubes of yanks explaining their "story sticks" as just a one dimensional scale; a stick with marks along it, not a 2 dimensional drawing.
Here's the first one I turned up with a search on "the story stick" https://www.google.com/search?q=the...ate=ive&vld=cid:1519f0a2,vid:hsjdWT6gqhE,st:0
Maybe they are all called story sticks one way or another?

I think of a story stick as a rod with the lengths marked on it.

A 2 dimension drawing particularly full sized is called a lofting (at least in boat building.)

Boats have often been described by a series of offsets (numbers from centre line - half breaths and heights off keel ) but thy usual led to the design being lofted full size before being built to get the frames accurate.

 

[Cabinetman]

In George Sturt's a wheelwrights shop, it describes how someone sets off to measure up for a well frame and roof (I think, it’s 50 years since I read it). All he took with him was a pencil and a long lat. The problem is I can’t remember what they called the lat. — If anyone has a copy?
It stuck with me and I’ve been doing things this way ever since.
Ian

 

[Jacob]

In George Sturt's a wheelwrights shop, it describes how someone sets off to measure up for a well frame and roof (I think, it’s 50 years since I read it). All he took with him was a pencil and a long lat. The problem is I can’t remember what they called the lat. — If anyone has a copy?
It stuck with me and I’ve been doing things this way ever since.
Ian

Everybody should have a copy! I've got one, I'll have a look.
They probably called the lat a "lath"? But not a "story lath".

 

[Cabinetman]

Everybody should have a copy! I've got one, I'll have a look.
They probably called the lat a "lath"? But not a "story lath".

I knew someone would have a copy! Just hope my memory of the event is correct haha.

 

[johnnyb]

This is another great thread scotty. Ps what size is the main curved beam can't see on the drawing!