Calculate the required tube length for key clamps

Calculating the right tube length

Determining the correct length of a steel tube is one of the most frequently asked questions at Keyclampshop. To assist you with this, we have written this guide in which we explain step-by-step how to calculate tube lengths.

1. How far does the tube insert into the tubeclamp?

The extent to which the tube inserts into the tubeclamp varies depending on the type and diameter. There is therefore no clear answer to this question.

Usually, you do not need to know the exact depth. Why? Because what really matters is how long the tube needs to be or how much the tubeclamp extends this tube length. To calculate this, we work with an inner and outer dimension. 

Helpful guideline: Generally, tubes in the key clamp meet each other or should be mounted so that their ends meet. In the below open-cut key clamps, you can see that they are completely open inside. Therefore, the tubes can fit tightly against each other.

2. How do I calculate the tube lengths in a frame or railing?

When working with tubes, you often already know a desired inner or outer dimension. The outer dimension is the total width of your frame or structure. The inner dimension is the distance between the tubes.

Do you need to convert an outer dimension to an inner dimension or vice versa? You can easily calculate this. See below for an illustration of how to calculate the different dimensions.

For the most key clamps, the inner dimension corresponds to the required tube length.

Calculate outer dimension (A):
Take the internal dimension (B) and add 2 times the tube diameter*.
A = B + (2 x Ø)

Calculate inner dimension / tube length (B):
Take the outer dimension (A) and subtract 2 times the tube diameter*.
B = A - (2 x Ø)

Calculate tube length (D):
Take the total height (C) and subtract 1 times the used tube diameter*.
D = C - Ø

* Use rounded tube diameters for calculations. This makes the math easier and accounts for the wall thickness of the fittings.
For 26.9 mm, use 3 cm, for 33.7 mm use 3.5 cm, and for 42.4 mm use 4.5 cm, etc...

Example: Calculate the right tube length for a table.
For a tabletop of 150 by 64 cm and using a tube diameter of 33.7 mm, the calculation is as follows:
Tube length (B) = Outer dimension (D) - (2 x tube diameter)
150 cm - (2 x 3.5 cm) = 143 cm
64 cm - (2 x 3.5 cm) = 57 cm.

3. How do I calculate the length of a tube between two walls or between floor and ceiling?

For applications like handrails or curtain rods between two walls, you often use base plates ow wall flanges. To calculate the correct tube length for this handrail or clothing rack, follow these steps:

1) Measure the distance between the walls or between the floor and ceiling (distance A).
2) Subtract two times the margin (F) from this. The margin depends on the tube diameter and accounts for the flange thickness of the base plate.

The formula is: Tube length (B) = distance (A) - margin (F) - margin (F).

Tip: Round the tube length down to the nearest whole cm for play during assembly.

4. How do I determine the tube lengths for an advertising frame?

The tube length is determined in the same way as explained in question 2 above. What is important to know is whether you are working from an inner dimension or an outer dimension. The inner dimension corresponds to the tube length.

If you are working from a banner size or an absolute outer dimension (the available space on the wall), we also have convenient calculations for this. However, it is essential to know which tube diameter you are using and which tensioners you wish to apply.

Questions?

Do you have any questions after reading this guide? Please contact us. We're happy to help you!