Compound curves in flat bar

[Domdom]

As per title please chaps. A pal of mine wants some railings making like these.

Which is relatively simple if the wall was straight. Except it has a slight curve in it like this.

So the question is, how do I get it to match the curve of the wall once there is the up and down curve already in it?

Thanks

Dom

 

[Mick Annick]

@nickk is the man for this, but if you’ve got a ring roller I don’t think it matters which bend you do first, personally I’d do the one one the first photo first, then the more gentle curve to match the wall, but I’m an amateur.

 

[hotponyshoes]

Make the railings flat as in the first photo.
Leave the ends over length and cut to size once its shaped.
Drill all the holes for the uprights over size, (ie 13mm holes if its 10mm round bar)
Only tack the uprights on what would be the road side of that fence.
Run a grinder through the flat behind every upright to slot the holes on the garden side.

Get 2 big mates to push it up against the wall and bend it into shape.
It will try and spring back but start in the center and work to the outside welding them up (weld the slits first) and it will hold its shape nicely.

Beware that any passers by will want to watch so you might want to make a plywood former first and weld the railings somewhere else.
Just cut a bit of ply that fits in the gap and trace the wall with a marker pen.
Once you have made one you can use that as a former for the others.

 

[gordon stephenson]

What size is the foot and header bar? I would bend to suit the wall first, Quite a gentle curve that I don't think will be a problem,

 

[Domdom]

I don't have a roller BTW chaps. Might be able to borrow one though, asked my mate. Asked him if he wanted the job but he doesn't do anything outside his workshop which is fair enough.

 

[hotponyshoes]

I have seen proper blacksmiths (no idea what skills the op has so no offence!) form compound curves over the anvil but that's working in pairs/teams and they all looked like they knew exactly what they were doing.
I have tried to do it myself with no luck whatsoever.
I have also made the first curve fine (anvil) then tried running the through a roller and it's all gone to pot.
Again, somebody with skills using a roller would probably do it fine.

 

[waddycall]

I would make it flat, fullly welded. Then I’d rest the ends on some blocks of timber/concrete and persuade it into the radius (it doesn’t look like much).
N.B. I’m no pro but my old neighbour was a blacksmith and he did curved panels that way.
Trying to make it with curved top and bottom rails would be a nightmare.

 

[Pete.]

I would make the panel then run it through a bending roll.

 

[hotponyshoes]

The curve is not that much really,
You could just make them flat, lay a couple of bits of scaffold tube on the floor a few inches apart then get a mate to roll it forward and backwards while you knock it with a sledgehammer between the scaffold bars.

 

[Brad93]

As said, make the bow top first. Then run through the rollers again on edge to put the sweeping curve in.

I recently got a set of rollers but it’s a bit of a dark art.

 

[Domdom]

I have seen proper blacksmiths (no idea what skills the op has so no offence!) form compound curves over the anvil but that's working in pairs/teams and they all looked like they knew exactly what they were doing.
I have tried to do it myself with no luck whatsoever.
I have also made the first curve fine (anvil) then tried running the through a roller and it's all gone to pot.
Again, somebody with skills using a roller would probably do it fine.

Yeah, the risk of looking a moron at site would be quite high. I think that’s why nobody wants the job TBH. Neither do I really, but he’s a good mate.

 

[pedrobedro]

I'd get a piece of wide plate and cut the curve out

 

[Mick Annick]

What size top and bottom rails are you planning on using? 25mm x 5mm will bend easy enough

 

[Domdom]

That’s about the size I was thinking with 10mm round for the uprights.

 

[Country Joe]

I'm no expert, but I would imagine those sized materials might be a bit too light for gates of this span.
It might be that I just over-engineer things to some extent, though, so it could just be me, but that just doesn't sound beefy enough.

It might also be that I always think of these things in terms of security - which they're evidently not for!

All the Best,
CJ

 

[nickk]

Easy with bar that light,as said once rolled weld it complete ,then spacers to lift off the ground,stand on you’ll need more effort at the ends and maybe make the flat top and bottom rail over long to get the required leverage to give a consistent radii.
I’ve done channels and rsj like this,instead of manpower,drove along with the fork lift,will try and get a photo of the last ones and post.
@Brad idea will work but needs wide rollers.
I think another way would be to punch all the holes very slightly off centre,but who knows how much? I found this out by accident.
When I do variable radii curves I use the flypress bending each rail individually,also use fly press for radii that’s too tight for first method.

 

[Welderpaul]

Depends what kit you have.

The normal way is as Pete says, make the panel flat and put it through a set of plate bending rolls.

The other way i have done it with just a ring roller is to make the panel flat and don't put the finals on it. Between two of you run one end of the panel through the ring roller to start to bend it. The bottom is easy, the top needs a bit of dexterity to follow the line of the panel with the rolls. Do it a bit at a time to get the curve in.

Or batter it with a sledge hammer. Depends what gear you have.

 

[steve t]

25x5 very light for a railing frame keeping that straight will be more of a problem. Personally I'd go no lighter than 30x10