Building Bridges
- Thread starter ScottyT
- Start date
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ScottyT
Established Member
Thanks Johnny. The size of the main beams off the top of my head are 5.1 long, 300 deep and 100 thick. The Oak is arriving from France in 2-3 weeks so it’ll all kick off then. Thanks for the interest
johnnyb
Established Member
Is it me or is france the source for amazing bits of wood.
johnnyb
Established Member
I'm pondering how that's going to be shaped but I'll wait for the next exciting installment.(must be with the spiNdle)
Cabinetman
Established Member
My understanding is that both France and Germany set out and grew forests as an agricultural crop, well maintained to grow tall clean trees (few knots) and certainly in my experience it has worked, but if you want a piece of Oak with character and interesting grain it tends to come from the uk. The Chinese buy a LOT of the European Oak and sell it back to us as crappy low end furniture.
Ian
Jacob
What goes around comes around.
I've seen it somewhere too, if not in Sturt it could be in "The Village Carpenter" - Rose https://books.google.co.uk/books/about/The_Village_Carpenter.html
I'll have a read. Both excellent books.
What's interesting about the idea is that things can be made accurately and precisely, but without a tape measure, no measuring or calculating anything.
So e.g. for a chest of drawers you could turn up with your lath and a pencil and take marks directly from its proposed position in a room, for the width, height, depth. Then back at the bench, with the aid of simple sketch design, or just the idea, turn that into a fully detailed accurate and precise rod, with aid of straight-edges and dividers.
Being able to count would help, but even that not necessary as you could make the traditional marks of 4 vertical strokes and a horizontal through, for 5, with your fingers for a check, (if you still have all of them).
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ScottyT
Established Member
Yeah it’ll be the usual template on top of the stock and run round on the spindle. I’ll put the 4” block in but instead of the ring fence I’ll have to use the follower. I’m not the biggest fan of the follower as I can’t regulate the cut like you can with the ring, however, it does have its plus sides and it’s the fact you can cut from anywhere on the block that I’ll use this method. I have the room in the machine shop but only with the follower, i won’t be able to swing the 5m on the ring fence cutting point without the top or tail (or both) hitting other machines.
All will be documented as well as I can when i kick off with the very first processes.
Scotty
Jameshow
Established Member
French oak is softer than English and faster growing die to it's latitude and climate. Straighter and fewer knots too.
johnnyb
Established Member
I think I would be concerned with the off kilter weight after it's bandsawn close to the template. Must be an awkward thing. Maybe 2 helpers. Anyway don't spoil it.
Jameshow
Established Member
You need some rollers that fit sure probably 4-5 each side of the SM.
ScottyT
Established Member
Well, the Oak bridge is now underway. I had a few jobs come up that I needed to clear before I started this, plus the timber didn’t arrive until last week anyway so it’s all come together quite nicely.
The two large carrying beams arrive tomorrow, I have started to prepare the rest of it, of which there is quite a bit but not masses and masses. It’s mainly green so heavy work but the trade off is it machines superbly so I’ll take that. Expect frequent updates from now on on the how the job progresses.
From what I can see from my rod it’s a simple enough job just the size of it for mainly myself alone will be the challenging part, but I think this one will be interesting all around and will hopefully look great when I’ve finished it.
The barn smells of that lovely green oak fragrance. I will post a up a photo of the main beams as soon as I can. I shall be in touch shortly.
Scotty
The two large carrying beams arrive tomorrow, I have started to prepare the rest of it, of which there is quite a bit but not masses and masses. It’s mainly green so heavy work but the trade off is it machines superbly so I’ll take that. Expect frequent updates from now on on the how the job progresses.
From what I can see from my rod it’s a simple enough job just the size of it for mainly myself alone will be the challenging part, but I think this one will be interesting all around and will hopefully look great when I’ve finished it.
The barn smells of that lovely green oak fragrance. I will post a up a photo of the main beams as soon as I can. I shall be in touch shortly.
Scotty
Jameshow
Established Member
Will it not twist or warp as it drys? Or will the strength of the bridge as a whole prevent that?
Cabinetman
Established Member
Looking forward to watching the bridge take form, know what you mean about the smell of the green Oak.
ScottyT
Established Member
Yeah there will be an element of twist, warp, splits and general opening up and settling down, but nothing that is not to be expected or that will detriment the structure.
I have found In the past, given the time of the year in England, it’s all about trying to control the pace in which the moisture escapes. A mix of tung oil and white spirit sprayed over it as soon as it’s finished semi seals the timber, stops it turning black on contact with ferrous and most significantly slows the rate in which the moisture can escape in the blazing (sometimes) july/august sun which makes splits and warps and opening of the timber less extreme.
It’s very effective in my experience and also as it’s thinned down and penetrates well it hardly looks like there is a finish on it.
It does not seal the wood entirely, that would be a bad idea, it’s more of a regulator that’s very handy for this time of the year.
Scotty
Jester129
Established Member
Looking forward to this!
ScottyT
Established Member
So this is the first proper post of the bridge build on the machining side of things, as i have now started taking the tools to the Oak. The Bursgreen UOS over/under has been hammered the last two days, I’ve filled three 1 ton dumpy bags with shavings already, it’s a big shaving that comes off this wet oak as opposed to fine dust so it’s filling up fast.
It starts with my rod, a cutting list and knowing in my head where it’s all going, which I get from the rod.
I’ll apologise in advance as I’ll be in a lot of the photos as they are stills from videos I have been taking for another platform.
I am squaring the fence on the planer ready to machine 4 posts at 150 square and 6 posts at 120 square. It is critical that the posts are 90 degrees, if they are not I’ll be fighting the tide from here and there’s only 1 winner.
Nice and simple to start with, the finish is really nice straight off of the machine. I like to use the Bursgreen for the over and the under as there is virtually no snipe whatsoever even on the really large stuff.
With the posts sorted and not needed until marking/morticing/cutting its onto the next sections, I need 8 bottom rails and 8 hand rails, 100x70 and 100x100 respectively, they have a really gentle curve on them so it’ll be planed, thicknessed and then profiled up on the ring fence for the edges.
You can see from above shot how gentle the rails are, the handrail is running out at a 10m radius so very shallow. This was about the worst of the timber, I can be picky what I cut so I aim for the cleanest section I can
Run it through the mighty 1950 28” Sagar bandsaw, what an immense machine this is, a proper bandsaw that’ll stop at nothing, it’s an old friend of mine now and I very much appreciate it.
Once I’ve cut round them all on the bandsaw (using my templates from the rod that I draw around) it’s time to set up the spindle and ring fence to face them up off the template. Really easy to machine as they are almost straight, so no worries about short grain or block grab from running in a really tight radius etc!!
Basic set up of the machine. This a 4” whitehill block cutting 4” stock, I made it work thickness wise so I could run these out in one pass.
For those who don’t know what the ring fence is or haven’t used one before, they are phenomenal bits of kit for creating curved work. it’s a very versatile tool that I use on a weekly basis.
A terrible picture, again this was taken from a video but it shows the template up against the fence and how it’s worked around. 32 passes sees it all done.
And here’s one straight off the block, it’s a great finish. Once these have been tennoned either end it will be back on the ring fence to put a quarter round on the top edges.
Again I am checking for absolute squareness off the spindle, it’s all set up lovely so it’s bang on. I check every other one as I go, just for peace of mind.
First little bits offered up to the rod to see the lie of the land, I can just check that all the dimensions and the curves are checking out on the 1:1. So far all is well. I will be morticing next, I’ll be sinking an 1” chisel in for the handrails/bottom rails and probably a 7/8 or a 3/4 for the infills, I’ll see what happens on the day. I’ll post that up when I’ve got it done.
Here’s the main beams, some big old hunks of Oak here, really really straight and flat which is a bonus. The short one is 5.3 metres long, 605mm wide and 110mm thick. It’ll be a good job getting these machined out from the template, I’ve got a few ideas in my head, there’s always more than one way to skin a cat and all that caper but either/either they’ll come up a treat I’m fairly confident!!!!
Scotty
It starts with my rod, a cutting list and knowing in my head where it’s all going, which I get from the rod.
I’ll apologise in advance as I’ll be in a lot of the photos as they are stills from videos I have been taking for another platform.
I am squaring the fence on the planer ready to machine 4 posts at 150 square and 6 posts at 120 square. It is critical that the posts are 90 degrees, if they are not I’ll be fighting the tide from here and there’s only 1 winner.
Nice and simple to start with, the finish is really nice straight off of the machine. I like to use the Bursgreen for the over and the under as there is virtually no snipe whatsoever even on the really large stuff.
With the posts sorted and not needed until marking/morticing/cutting its onto the next sections, I need 8 bottom rails and 8 hand rails, 100x70 and 100x100 respectively, they have a really gentle curve on them so it’ll be planed, thicknessed and then profiled up on the ring fence for the edges.
You can see from above shot how gentle the rails are, the handrail is running out at a 10m radius so very shallow. This was about the worst of the timber, I can be picky what I cut so I aim for the cleanest section I can
Run it through the mighty 1950 28” Sagar bandsaw, what an immense machine this is, a proper bandsaw that’ll stop at nothing, it’s an old friend of mine now and I very much appreciate it.
Once I’ve cut round them all on the bandsaw (using my templates from the rod that I draw around) it’s time to set up the spindle and ring fence to face them up off the template. Really easy to machine as they are almost straight, so no worries about short grain or block grab from running in a really tight radius etc!!
Basic set up of the machine. This a 4” whitehill block cutting 4” stock, I made it work thickness wise so I could run these out in one pass.
For those who don’t know what the ring fence is or haven’t used one before, they are phenomenal bits of kit for creating curved work. it’s a very versatile tool that I use on a weekly basis.
A terrible picture, again this was taken from a video but it shows the template up against the fence and how it’s worked around. 32 passes sees it all done.
And here’s one straight off the block, it’s a great finish. Once these have been tennoned either end it will be back on the ring fence to put a quarter round on the top edges.
Again I am checking for absolute squareness off the spindle, it’s all set up lovely so it’s bang on. I check every other one as I go, just for peace of mind.
First little bits offered up to the rod to see the lie of the land, I can just check that all the dimensions and the curves are checking out on the 1:1. So far all is well. I will be morticing next, I’ll be sinking an 1” chisel in for the handrails/bottom rails and probably a 7/8 or a 3/4 for the infills, I’ll see what happens on the day. I’ll post that up when I’ve got it done.
Here’s the main beams, some big old hunks of Oak here, really really straight and flat which is a bonus. The short one is 5.3 metres long, 605mm wide and 110mm thick. It’ll be a good job getting these machined out from the template, I’ve got a few ideas in my head, there’s always more than one way to skin a cat and all that caper but either/either they’ll come up a treat I’m fairly confident!!!!
Scotty
Cabinetman
Established Member
Wonderful stuff! I did a job once using sections of Oak almost those sizes, I had to get the yard to plane it up for me, I haven’t got the really big equipment like you. The noticeable thing fairly obviously is the weight of one of those beams, how you are going to cut the curve (I imagine that’s what you’re doing) I will wait to see with interest. what does one weigh?
ScottyT
Established Member
Having the big and mostly vintage machines is fantastic, they are very capable, very robust and simple to maintain. That said I do appreciate that they take up an enormous amount of space and require considerable start up power.
at a guess, with the water content I would say each beam weighs somewhere in the region of 175-200kg. They are massive.
There is a possibility I’ll use my Wadkin FM to prepare these, it has the capacity to do it over and under (710 and 615 wide respectively) just to see how it performs really
I’ll cut the curves out with a portable bandsaw. It’s an amazing tool
As always, thanks for the interest
Scotty
ScottyT
Established Member
Simply put, I am creating two identical frames in my head at the moment, I am not thinking about any infill work or the beams or anything else, just 5 posts joined top and bottom with 10 curves x by 2.
I lay the posts down on the rod, and take the necessary marks from it and transfer them directly to the work, position of mortice in the case of the posts, and the shoulder angles and positions of the tenons for the rails. Nice and simple, no haunching to do just simple M&T’s!
Laid down like this 1:1 on my marks makes it simple to mark up my work. It’s a case of being accurate and methodical. The hard part was creating the rod accurately, it’s simple enough now it’s just very heavy work.
Sinking 1” mortices into this wet Oak is light work for the Wilson. Setting up a hollow point chisel morticer is simple enough, it is however easy to get wrong too. You want plenty of clearance at the business end between the flanged end of the auger and the end of the chisel itself, too tight a gap doesn’t allow the chips to find there way up the flutes and out of the slots in the chisel. Resulting in poor cutting performance and heat build up which dulls the tool and eventually cracks the chisel. 1/8 gap is good for dry wood, i go slightly bigger on wet wood.
If you give it too much stick out the mortice can be raggedy on entry.
With all the morticing done on the posts I can now set about making tenons. I want to avoid tight tenons here, it all just wants to slide together without any persuasion.
I can lay my first two posts down on the rod, get them exactly where they need to be and then mark the position of the rails up from the rod onto my posts, I can then lay my hand rail and bottom rial on those lines, strike a pencil line along both rails and take it to the machine.
We have both types of tenon machine, horizontal and vertical blocks, the horizontal blocks machine is much easier to set for middle, I just need to look for both knives (top and bottom) to strike the work at the same time and then I know I’ve got it (that’s after it’s been set up for 1” mortices)
The above photo shows my work in the machine, with a square running off the fences machined shoulder, all I do is line up my pencil mark on the work with the square off of the fence, when it’s all set and running good I clamp it down and push it through.
It’s just repeat repeat repeat, changing lining up each one and running it through. Some are the same so can be set stopped off the machines bed, then change the setup when it’s on to the next shoulder
I crack off the shoulders by hand as it’s easier for this small quantity.
The thing is slowly taking the basic shape of a gentle bridge. Im unfortunately on site for the rest of this week so this’ll have to wait until atleast next week. Shame really, nothing worse than stop/starting on jobs.
I’ll post up a photo of the complete side as soon as it’s done
Scotty
I lay the posts down on the rod, and take the necessary marks from it and transfer them directly to the work, position of mortice in the case of the posts, and the shoulder angles and positions of the tenons for the rails. Nice and simple, no haunching to do just simple M&T’s!
Laid down like this 1:1 on my marks makes it simple to mark up my work. It’s a case of being accurate and methodical. The hard part was creating the rod accurately, it’s simple enough now it’s just very heavy work.
Sinking 1” mortices into this wet Oak is light work for the Wilson. Setting up a hollow point chisel morticer is simple enough, it is however easy to get wrong too. You want plenty of clearance at the business end between the flanged end of the auger and the end of the chisel itself, too tight a gap doesn’t allow the chips to find there way up the flutes and out of the slots in the chisel. Resulting in poor cutting performance and heat build up which dulls the tool and eventually cracks the chisel. 1/8 gap is good for dry wood, i go slightly bigger on wet wood.
If you give it too much stick out the mortice can be raggedy on entry.
With all the morticing done on the posts I can now set about making tenons. I want to avoid tight tenons here, it all just wants to slide together without any persuasion.
I can lay my first two posts down on the rod, get them exactly where they need to be and then mark the position of the rails up from the rod onto my posts, I can then lay my hand rail and bottom rial on those lines, strike a pencil line along both rails and take it to the machine.
We have both types of tenon machine, horizontal and vertical blocks, the horizontal blocks machine is much easier to set for middle, I just need to look for both knives (top and bottom) to strike the work at the same time and then I know I’ve got it (that’s after it’s been set up for 1” mortices)
The above photo shows my work in the machine, with a square running off the fences machined shoulder, all I do is line up my pencil mark on the work with the square off of the fence, when it’s all set and running good I clamp it down and push it through.
It’s just repeat repeat repeat, changing lining up each one and running it through. Some are the same so can be set stopped off the machines bed, then change the setup when it’s on to the next shoulder
I crack off the shoulders by hand as it’s easier for this small quantity.
The thing is slowly taking the basic shape of a gentle bridge. Im unfortunately on site for the rest of this week so this’ll have to wait until atleast next week. Shame really, nothing worse than stop/starting on jobs.
I’ll post up a photo of the complete side as soon as it’s done
Scotty
