Home Forum Chat Forum Formula?? ( not brakes but mathematics ) Question for the builders!

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• Formula?? ( not brakes but mathematics ) Question for the builders!
• Haze
Member

Draw it to scale?

willyboy
Member

You need to know the ‘going’ and the ‘rise’ when building steps
They are the overall height and the distance to be travelled. Look at building regs for advice. The formula is 2r + g = nlt 550/ nmt 700

tymbian
Member

I’m after curving some decking steps thus…

Your looking at the decking, 4 steps left, 4 on the right. each step/ tread on the left is 250mm deep, each on the right 500mm deep, space in between 4m.
I need a steady curve from 0 to 250mm ( which is the difference between 250 & 500mm ) over a distance of 4 meters. Say at an equal spacing every 400mm.

Is there a formula?

tymbian
Member

I know the rise but thats not important atm. the treads are going level from right to left. If you were to look along the ‘ nose ‘ of the step it would curve outwards from 0mm to 250mm over a distance of 4.0m.

tymbian
Member

Bumping up.

mrben100
Member

Haze – Member
Draw it to scale?

Probably a formula, but drawing is easier – also different types of curve possible.

Edit: drawn in plan obviously

tymbian
Member

That’s it. The red curve is the one I’m after. I need to transfer it to the decking though. If I was to devide the 4m up into 10 equal bits how much, going from L to R is each section bigger than the previous?

trail_rat
Member

lay it all normally with an overlap – then mark the overlapped decking in situ with the curve you want

cut.

tymbian
Member

I have to curve the ‘ Rise ‘ which is a length of decking face on. Once I have the rafter ends cut to length to form the curve I can fix the decking riser. Once the ‘ rise ‘ is fixed i will overhang the decking tread and cut to length.

pymwymis
Member

Trail Rat has it in one.

The pro’s preferred method. No fannying about. Quick. Easy.

trail_rat
Member

got a good jigsaw ?

tymbian
Member

Yep, my trusty Festo.

mrben100
Member

Well, for the puroposes of closure……….some check dimensions to the nearest mm based on a steady curve (radius shown).

tymbian
Member

Thanks mrben. What formula/ program did you use?

I lined up the riser today and clamped it into what I thought was the right position. When measuring I had 310mm and 370mm right.

Just goes to show that you can’t beat the squint of a tradesmans eye.. ðŸ™‚

chives
Member

It’s a beam camber (assuming you want the curve to be part of a true circle as shown by mrben above) there are a few different ways to lay it out, a compass method and a straight line method – google beam camber calculations (boatbuilding) and you’ll probably find them.

mrben100
Member

tymbian – Member
Thanks mrben. What formula/ program did you use?

Just did it in CAD innit (as use it for work), what your seeing is just a screen shot, drawn 1to1 scale and measured the results. I would only be able to figure out a formula having already drawn it.

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