Setting out mitred corners in core rail.
One of the most common mistakes made when installing either metal or glass panels, that require a timber capping, is the transition from pitch to horizontal or pitch to pitch.
This stems from the handrail flow not being calculated before the stairs are designed.
Or designed with the first and last riser set adjacent to the landings and therefore the transitions are not allowed for.
The end result is a handrail made up from small sections, that do not flow correctly and may be just glued into place; as no mechanical fixing can be used.
Intersecting compound mitres rarely work when it comes to handrail; with the exception of completly round handrail and a fitter that likes danger but not his fingers!
The solution.
The way round this potential problem is to divorce the change of pitch from the change of direction by the introduction of Gooseneck transitions.
In order to achieve this, you will need to know the size of the handrail profile to be used.
This will allow you to calculate the size needed for the mitres in the gooseneck and any other corners.
This is also a good time to contact the handrailer and ask him what he needs for space in the corners.
Most handrail suppliers would rather help at this stage, rather than when it’s gone wrong.
Mitre space for the handrail.
Pitch to horizontal 90º bend.
The core rail.
In this image we can see a typical set up that we find happens all to often, the core rail comes down the pitch of the flight and turns through 90º onto either a landing or as in this example the top of a gooseneck transition.
The metalwork will work as it is the full width of itself and all the mitres are kept away form each other.
The handrail set over.
Here we have set the handrail over the core rail, as you can see, the bottom mitre on the top length of pitched handrail, intersects with the mitre turning through the 90º bend.
This is cuased by the mitre at the bottom of the pitch length being inside the handrail width coming from the lower pitch into the 90º bend.
The plan view.
When we look at this joint in plan view, you can see how the two mitres fitted into the space for one, do not allow for clean mitres.
The mitre for the upper pitch is set to into the space for the 90º flat mitre, this causes the face of the upper pitch to be cut above the line of the flat handrail, leaving exposed faces.
You can see that when we move the upper mitre outside of the flat mitre cut area, that we have two separate clean mitres.
Lift and separate.
In the situation I have drawn here, the only real way to solve this for the handrail mitres to work, is to lift the flat 90º bend by a minimum of 3/4 of the handrail height or ensure each leg of the flat 90º section is at least the handrails width from the core rail centre line.
When using a taller than wide handrail profile this may have to be increased further.
The leg leading into the top of the gooseneck can be slightly shorter than the leg leading into the pitch length, this will allow the visual look to be balanced but do make sure you have enough room for the gooseneck mitre.
By extending the flat 90º bend in this way. In most circumstances, it will at least leave room for dowels and possibly mechanical fixings.
In this image you can see the lifted core rail in green, over the original core rail position.
What is needed?
The handrail with separated mitres.
With the core rail adjusted to have longer legs on the flat 90º section, the handrail mitres are divorced from each other and can be cut cleanly.
As you can see in this image, the handrail profile now meets corectly at each joint.
I have left the handrail in different colours so you can see there are no anomolies as each piece of handrail joins to the next.
I have turnd all the core rail green as this is now ready to go.
The handrail over the stairs.
Here we have the handrail on the core rail over the staircase,
We have added a 3D model as before but with the new core rail and handrail setting out.
A look at some examples.
Gooseneck mitres.
The gooseneck from above, with plenty of room for the mitres.
Goosneck mitres.
The gooseneck from below, with plenty of room for the mitres.
Good and bad mitres.
Here you can see that some mitres are nicely separated, while the 2 in the bottom corner are on top of each other.
Mitres to close.
Looking down onto the core rail, showing the mitres to close together to allow the handrail to mitre round.
Pieced in handrail.
When the corner mitres are to close, round handrail may work but as you can see here No1 is an infill to lift the handral off the core rail. no’s 2 and 3 are small pieces that have been carefully fitted into the mitre.
