艺术
美容与健康
工艺
文化与历史
娱乐
环境
食品与饮料
逆向工程
科学
体育
技术
可穿戴设备
Setting a Gradient: Drainage Falls and the Boning Rod
The drainage tile, the septic tank and the constructed wetland already published here all share a requirement none of them explains: the pipe must fall at a specific, constant gradient, and both too little and too MUCH will stop it working.
Too little and solids settle. Too much and the water runs away and leaves the solids behind — which surprises people, and is why a steep drain blocks as reliably as a flat one. The traditional figures, one in forty for a small foul drain and one in eighty for a larger one, are not arbitrary: they are the range where the flow stays fast enough to scour and slow enough to carry.
Boning rods are how that gradient gets built without an instrument in the trench. Three T-shaped rods, two set on the known ends and one carried along, and your own eye does the interpolation.
中级
1 day
说明
1
1
Fix the two ends before anything else
Fix the two ends before anything else
Establish the invert level — the inside bottom of the pipe — at the start and at the outfall, using the levelling method from earlier in this batch.
The outfall is usually fixed by something you do not control: an existing manhole, a ditch, a soakaway. Level it FIRST and work backwards, because discovering at the end of the trench that you needed 300 millimetres you have not got is the failure this whole rung exists to prevent.
此步骤所需材料：
木销6 个所需工具：
光学水准仪（测量）
水准尺2
2
Choose the gradient, and check it against both limits
Choose the gradient, and check it against both limits
Work out the fall available over the run, and compare it with what the pipe needs. For a 100 mm foul drain, 1 in 40 is the usual figure; for 150 mm, 1 in 60 to 1 in 80.
Check BOTH ends of the range. A gradient far steeper than needed is a real fault, not a safety margin, and where the ground falls faster than the pipe should, the answer is a steep section plus a manhole or a backdrop — not a uniformly steep pipe.
3
3
Make a set of boning rods
Make a set of boning rods
Make three identical T-shaped rods — a vertical leg with a horizontal crosspiece — all exactly the same length, with the crosspieces painted a colour that stands out against soil.
Identical is the whole trick, and the only tolerance that matters is between the three: cut them together and check them against each other, not against a tape. If they differ by 10 millimetres, your trench is wrong by 10 millimetres everywhere, and nothing in the method will tell you.
此步骤所需材料：
坡度瞄准杆3 个
花旗松大梁2 length所需工具：
手锯
卷尺4
4
Set sight rails at each end and bone between them
Set sight rails at each end and bone between them
Set a sight rail at each end of the run, each one exactly one boning-rod height above the intended invert at that point. The line joining the two rail tops is then parallel to the pipe, one rod height up.
Stand behind one rail and sight across both. Anyone in the trench holds the third rod on the formation: when its crosspiece lines up exactly with the two rails, the trench is at the right depth. Your eye is doing linear interpolation over thirty metres, to a few millimetres, with no instrument.
此步骤所需材料：
花旗松大梁4 length
镀锌钉20 个所需工具：
手锯
羊角锤光学水准仪（测量）5
5
Lay to the invert, not to the top of the pipe
Lay to the invert, not to the top of the pipe
Bed each pipe so that the INSIDE BOTTOM sits on the line, and check every single one before backfilling.
Pipes vary in wall thickness, so laying to the top of the barrel puts a step in the invert at each joint — and a step is where solids catch. Support the barrel along its length, never on the collars, and never pack it up on a stone: a pipe bearing on two hard points cracks under backfill.
所需工具：
坡度瞄准杆
水平尺6
6
Why too steep blocks a drain
Why too steep blocks a drain
正在加载 Jupyter 笔记本…
7
7
Prove it with water before you backfill
Prove it with water before you backfill
Run a bucket of water down the finished pipe and watch it at the outfall. It should arrive promptly and completely, leaving nothing standing.
Water is the only test that matters, it costs a bucket, and it is available exactly once — after backfilling, finding a reverse fall means digging the whole run out again. Put a spirit level in the trench along the pipe as a second check: at 1 in 40 the bubble should sit visibly but only slightly off centre, and a bubble that looks central means the fall is not there.
所需工具：
水平尺相关蓝图
这些蓝图共享知识——技术、材料或原理
CC0 公共领域
此蓝图以 CC0 协议发布。你可以自由复制、修改、分发和使用此作品，无需征得许可。
通过购买蓝图中的产品支持创客，他们将获得 创客佣金 （由供应商设定），或创建此蓝图的新版本并将其作为连接包含在你自己的蓝图中以分享收入。