Roller Blinds

By Viewscape

What is a Roller Blind

A roller blind (also known as Holland Blinds) is a form of window covering that is made from a fabric material specially treated or stiffened so that it hangs flat against a window. Roller blinds have simple lines and are easy to install. They are an inexpensive option for decorating rooms, thereby making them a popular choice for window covering. They can come in a variety of fabrics, colours, patterns and textures to blend with the theme of the room.

Major component description: Roller tube (aluminium), cloth (skin), chain winder or spring mechanism, bottom pocket (bottom rail) and brackets.

How does it operate?

All Roller Blinds have a rectangular piece of fabric rolled up in an aluminium tube. The tube is attached with brackets on top of the window and operating the blind is by winding and unwinding the tube. The wind up operation can be controlled by:

• Chain Winder - This is the most common method of controlling the blind. The tube turns in either direction by pulling on the ball chain. The ball chain turns the pulley, releasing two internal locking springs. This allows the mechanism to turn, thereby rotating the tube. In the stop position, the spring clamps down onto the central spindle, preventing the tube from free wheeling and allowing the blind to stay in position.
  
  
  
  
• Spring Operation - As the name suggest, there is a special spring inside the 38mm aluminium tube. This spring is pre-tensioned, allowing the blind some pull tension at the start of the operation. The blind locks when one of the four brass pawls drops (by gravity) into the locking cavity. Therefore to engage the lock, the blind needs to be held and raised slowly – this gives one of the pawls the opportunity to drop and lock onto the cavity.
  
  To operate blind, dis-engage by pulling the blind down a bit and guide the blind to the new postion – the spinning action pushes the 4 pawls outwards, therby preventing the pawls from engaging.

Most common usage

Roller blinds can be fitted in the Recessed or Face Fit. An emerging trend is to fit screen fabrics in the Recess and block out fabric on the architrave as a Face Fit. It is getting popular to fit both types of fabrics as per above as a combination.

Aluminium Tubes

Different types of aluminium tubes are used depending on the size of the blind (width x drop) or when the blind is motorised.

A Booster spring is used to assist with blind operations when the blind goes beyond a certain size. The table below shows the relationship between blind sizes, the types of tubes used

The table below shows the relationship between blind sizes, the types of tubes used and when boosters are required/recommended.

Cassette Box

The New cassette box will be available in 12 colours (the same as all the oval bottom rail colours with the exception of Chrome). The end caps are colour matched. The aluminium profile comes in 4.5 metres length and the maximum roller tube size it can accommodate is the 49 mm Heavy Duty tube. This equates to a single span of 3330 mm and together with the Easy Link bracket, two or more blinds can hang off the cassette box.

Various components

EasyLink Bracket	Combo Bracket	Standard Bracket
Spring Blind Bracket	Double Ball Chain	Ball Chain Stopper
Chain Tension Device	Chain Winder and Pin End	Bottom Rail End Caps
EasyLink Female, Male Drive & Independent (Dummy) Plug	Spring Pin End Cap	Spring Assembly

Roller Blinds Components and their Colours

Terminology/Frequent Issues

Terminologies relating to Viewscape Roller Blind

• Recessed Fit – also known as (aka) Top Fix, Tight Measure, Inside Measure and Reveal. This indicates that the blind is positioned inside the window frame (architrave), and the measurements taken are within the window cavity.
• Face Fit – aka Outside Measure, Arc Measure and Front Measure, This indicates that the blind is positioned over the architrave, and the measurements taken are equal or larger than the distance between the outside edges of the architrave.
• Blind Size – Actual: this means that we will make the blind to the dimensions given.
  NAM: No Allowance Made – If the blind is to be Recessed Fit, our Sales Order Entry (SOE) staff will take 3 mm off the width only. If the given NAM is for a Face Fit Blind, no deductions will be made.
• Butt and Through Blinds – This applies to the situation where two blinds comes together at a corner, and where one of the blinds is cut smaller (Butt Blind) to allow the other blind (Through Blind) to take the full width.
  
  Example of Butt and Through Blinds:
  
  Note: Just because two blinds meet at a corner does NOT automatically mean that they are Butt and Through Blinds.
  
  Example of NON – The bottom 2 diagrams show two separate blinds (Not Butting Blinds), therefore should NOT be ordered as butting.
  
  Deductions for Butt blind – when customer orders blinds with NAM
  
  The 'Through' blind is the one that covers the whole window. The 'Butt' blind is the blind that has to be cut back to allow space the 'Through' blind has taken. Measure both blinds at full width at the point where the blind is to be installed. This applies for deep recesses. The allowance for the cut back of the butt blind in recessed fit is as follows:
  
  • Less 70mm for 38 and 43mm tube;
  • Less 90mm for 63mm tube; and
  • Less 125mm for combo blind.
  For blinds that are to be fitted to the front of the recess, it is easier to measure the width to the corner and add on for the Through Blind.
• Easy Link Blinds
  
  Maximum lifting weight of an Easy Link is 3.0 kg (~ 6 m sq) in total. With the aid of booster spring, the Easy link can lift 5.0 kg (~9 m sq) in total.
  
  A second use of the Easy Link is to be able to operate 2 blinds and to be supported by one centre bracket .By using an Independent plug adapter inside the female drive, the Easy Link allows the two blinds to be individually controlled (chain winders on both ends). When two brackets are placed back to back, the gap between blind fabric edges is approx. 28-30 mm. By using the Easy Link bracket system, the gap is reduced to around 20 mm.
• Bay windows – Measurements for normal 3-Bay windows (135° - 135°)
  
  Recessed fit – Measure the width and drop of the recess windows at the front of the recess (at the mounting point) - NEVER at the back near the glass. The blind size = NAM (recess measurement) less 3 mm. The blinds will be fitted flush to the front edge of recess.
  Face Fit – Measure the full length of the top architrave: the 3 sections. The deductions are as follows:
  

  Bracket Size	The 2 side blinds	The centre blind
  45mm (normal)	less 20mm	less 40mm
  55mm (long bracket)	less 28mm	less 55mm

Railroading – the pit falls

Railroading is the term used when the blind is made with the fabric turned sideways (90°). Customers normally request blinds to be railroaded because they may want a blind wider than the available width of the fabric roll.

All woven fabrics have warp and weft threads. The warp threads are the ones that run with the roll of fabric. The weft threads are across the direction of roll. During the weaving process, the warp threads are kept in high tension, and the weft threads are the ones that shoot across, thus cannot be in high tension. Therefore, blinds perform better when the warp threads (the ones under tension) are in the vertical direction – the drop of the blind.

When a blind is railroaded, the fabric is turned sideways and the warp threads are now in the horizontal position. The higher tension in the warp threads together with the hanging of the blind encourages the edges of the blind to shrink inwards, thereby creating a cupping effect (curling of the edges).

Contract Blinds does not recommend railroading fabric. Railroaded blinds do not carry our normal warranty & are manufactured completely at the clients' risk. Oversized blinds that require railroading will be automatically produced on receipt of the order without further client contact however; clients accept all risk and costs by forwarding oversized blind orders. All other blinds on that order will not be railroaded to match the railroaded blind unless specifically requested on the clients order (even in the same location). Clients should be aware of fabric patterns and textures.

Cupping

Cupping is when the side edges of the blind curls towards or away from the window. For roller blinds, cupping occurs mainly because the blind has been railroaded.

Not Rolling Straight

Out of square, fabric side hitting the edge, rolling out.

There are many reasons to why the blind is not rolling straight. Here are some of the reasons:

• The fabric skin is attached out of square to the tube.
• The fabric skin is not a rectangle.
• The blind is not installed level. This is especially important for 'long-skinny' blinds - that have width to drop ratio of 1:2.5 or greater.
• Window frame slightly out of square. The can be checked with a good quality spirit level – on the top for horizontal, and the sides for vertical 'squareness'.
• The thickness of the fabric is not the same across the width of the blind (this can be due the back rubberised coating of a block out blind).
• Certain screen fabrics has raised warp threads that acts like 'tram tracks' that can cause the fabric to wind itself out (screw thread effect).

Our production facility has been designed to minimise the above issues (a-c) and every blind is fully tested to ensure that they roll up straight.

Rolling Straight - How to balance the blind

For blinds that are narrow with long drops; with ratios more than 1:2.5 (width: drop), there is a tendency for the blind to roll to one side. Frequently, windows can be out of square; therefore, final on-site adjustment may be required even though the blind has been carefully balanced at the factory.

The way to re-balance

1. Locate the end with the overlapping edge exposed.
2. Roll down the blind and apply a piece of masking tape on to the aluminium tube at this end.
3. Roll up the blind and check that the blind is now rolling up straight.

More tape can be added or removed to 'fine tune' the balance. Note: Fine tuning should NOT require more than 3 full pieces – please ring Contract Blinds for further advice.

Freying

This is caused by excessive wear on the edge of the fabric. The most common occurrence is when the blind is severely rolling off to one side. The causes the fabric to rub against the Chain winder or Pin end.

Contract Blinds uses Crush Cut Knives to cut screen fabrics. Crush cutting has the added benefit of sealing the PVC edge. As the sealed edge is raw (not hemmed, bided or over locked, on occasions, there will be fine strands of fibre. Carefully trim off these fine fibres (if required) with a pair of sharp scissors. DO NOT pull the fibres as more fibres will be released.

Fabric coming off roller tube

The fabric is attached to the tube with a strong double sided tape. There are occasions where the fabric was peeled off the tube – the most common occurrence is overwinding the fabric. To prevent this, two ball chain stoppers are supplied with every blind. – one for the upper limit, and the second for the lower limit (the lower limit stopper prevents the roller from over unwinding). The blind is always made with additional fabric that allows the roller tube to be fully wrapped at the specified drop. The ball chain stoppers are to be fitted on site, after the blinds have been checked and balanced.

Blind coming off the bracket

On odd occasions, we had customers complaining that the blinds have popped out of the brackets. They were for the following reasons:

• The pin (at the Pin End) was retracted when the blind was put in placed. The pin in the Pin End is spring loaded. Check to ensure that the pin is fully extended (the wheel has spun the pin full out) before pushing the blind into the bracket - the bracket will self locate the pin into the hole and 'snap' the pin in-place.
• The blind is jammed very tightly into the brackets – mainly in the recessed fit situation. When the blind is operated, the Pin End is so tight that it is not spinning freely. The rotation of the roller tube turns the wheel of the Pin End, thereby retracting the pin. Once the pin is fully retracted, the blind can come off the bracket.

Balancing / adjusting the tension in the Booster Spring

Booster springs are used to assist in operating large blinds. When the blind is rolled down, a lot of the fabric is released and the blind gets heavier. The booster spring works by using the wind up energy (when the blind is lowered) to counteract some of the weight when the blind is being pulled up.

The booster spring is attached to the chain winder and assembled without pre-tensioning. This is done on site by the installer should pre-tensioning be required. Pre-tensioning is done in the following manner:

• Install the brackets and attach the blind. Ensure that the blind id operating correctly.
• Lower the blind half way. Carefully remove blind off the brackets and manually wind up the fabric.
• Re-attach the blind and test the weight on the chain when operating the blind FULLY. If the blind still feels 'heavy', repeat step b.
• You can over do the pre-tensioning – the blind gets harder to lower. To release some spring tension, remove the blind when it is fully roller up and manually unwind the fabric about half way. Reattach the blind with the fabric unwound, and retest the blind operation.

Note: Caution - NEVER pull out the chain winder when the blind is pre-tensioned.

Component Breakages.

The main component failure is as follows:

• Plastic chains breaking - This is supplier manufacturing error. The chain is joined to create a loop – this is the 'weak link' where the chain can come apart if the cord is not heat welded properly together.
• Chain Winder breaking – This may happen during transportation. The ends are wrapped in bubble wrap. However, a small percentage gets damaged.

To view this information as a pdf, click here