Tensegrity Lampshade

This is the fourth in a series of Tensegrity projects having previously made projects with 3D printing and wood, this time I make use of Acrylic sheet. Previous projects include: Tensegrity Planter & Tensegrity Shelf

This would employ Tensegrity at multiple points on multiple levels to create a Lampshade.

Using eight C suspensions over two levels with shared wires over the two levels to reduce the number of tensioning wires.

Acrylic sheet White: 5mm x 160mm x 160mm - Qty 2

Acrylic sheet Black: 5mm x 160mm x 160mm

Acrylic sheet Clear: 5mm x 60mm x 60mm

Acrylic sheet source.

Acrylic Clear Tube: 25mm(Outer dia.) x 21mm(Inner dia.) x 155mm(L)

Brass Wire: 0.4mm diameter

M3 Grub Screws: 3mm - Qty 24

M3 bolts: 16mm - Qty 3

M2 bolts: 4mm - Qty 16

M2 bolts: 20mm - Qty 12

Chrome plated copper pipe 50mm dia. x 155mm (L)

Plastic plant pot 100mm dia. x 80mm (H)

Ready mix cement

Cork mat or felt

Acrylic Adhesive

Multi purpose Adhesive

No affiliation to any of the suppliers used in this project, feel free to use your preferred suppliers and substitute the elements were appropriate to your own preference or subject to supply.

Many of these items are also available at DIY stores.

Tools

Pliers

Cutters

Hole saw 54mm

Hole saw 50mm

Hole saw 38mm

Hole saw 32mm

Saw

Combination square

Marker/Scribe

Compass

Screw drivers

Allen keys

Drill

2mm drill bit

3mm drill bit

15mm masonary drill

Clamps

File

Sanding paper

Circular bubble spirit level

Know your tools and follow the recommended operational procedures and be sure to wear the appropriate PPE.

Using black Acrylic sheet.

Identify the centre of the circle to be cut in the Acrylic sheet and draw a horizontal or vertical line to create 2 equal segments.

Clamp the Acrylic sheet to a sacreficial piece of wood and secure in place.

Using a 38mm hole saw cut out a circle.

With a 54mm hole saw align the centre drill bit into the hole made in the wood by the previous process and carefully cut out an Acrylic ring ring.

Repeat this process for a total of 4 rings

Using a saw cut each ring in half along the remnants of the line.

Repeat this process using white Acrylic sheet.

This will result in 8 black and 8 white arcs.

Note:

From experience I have found that Acrylic sheets have different thermal properties which effect the cutting.

Running the saw at very high speeds can result in the Acrylic sheet melting which can clog and trap the saw.

Each arc requires two holes to be drilled in the perimeter edge close to the vertical cut.

Measure 2.5mm in from the vertical edge and mark with a line across the perimeter.

Measure 2.5mm in on the perimeter edge and draw a line along the perimeter.

Mark at the intersection of the cross.

Supporting the arc in a vice or clamp drill a 2mm hole through the outer perimeter to exit at the inner perimeter.

Repeat at the other end of the arc.

Perform this process on all 16 arcs.

Smooth any rough edges with sanding paper or a file.

Note.

Do not apply too much pressure when drilling the arcs to prevent damage.

Refer to the diagram which shows the relationship between the outer platform and the inner platform which are aligned to enable coincident holes. Although the radius of the outer platform is 63mm whilst the radius of the inner platform is 83mm.

With a 5mm Acrylic sheet of 160mm x 160mm.

The measurements on one platform are used to create the alignment for the other platforms.

A total of 3 platforms are required.

The process is simplified by stacking and clamping the three platforms and using the top platform for drill alignment.

In the finished form the platforms are stacked with the following colour pattern of White, Black & White.

Begin first by marking out the first platform.

Mark the centre of the sheet. (80mm, 80mm)

At the centre with a compass draw a circle with a radius of 63mm.

Draw 4 straight lines that start at the edge of the sheet and pass through the centre hole to create 8 equal 45 degree segments.

Draw a line from each of the points were the straight lines cross the perimeter to create an Octagon.

At the 90 degree points to the straight edges were the line cross the edge of the circle perimeter mark a centre point.

These 4 center points will be used to drill the 58mm cutouts.

At the centre with a compass draw a circle with a radius of 21mm. (Inner tension hole radial alignment)

At the centre with a compass draw a circle with a radius of 36mm. (Arc attachment point)

At the perimeter of the 63 mm radius circle crossing point of the 45 degree angle line (45, 135, 225 & 315 degrees), from this point draw a diagonal line that crosses the perimeter of the 36mm radius circle were it meets the perimeter of the 58mm diameter cutout.

At the perimeter of the 36mm radius circle crossing point of the 45 degree angle line (45, 135, 225 & 315 degrees), from this point draw a diagonal line that crosses the perimeter of the 63mm radius circle were it meets the perimeter of the 58mm diameter cutout.

This process needs to the repeated for a total of 8, outer tension hole centres.

From the centre of one of these points draw a line (parallel to the 45 degree centre line), and extend it to cross through the perimeter of the 21mm radius circle creating a chord and continuing to the outer tension hole centre at the far point.

Repeat this process to create 8, inner tension hole centres.

This will result in 16 crossing points the centres of which will be drilled a 3mm hole

At the perimeter of the 36mm radius circle crossing point of the 45 degree angle line (45, 135, 225 & 315 degrees), drill a 2mm hole.

This process needs to the repeated for a total of 4, arc attachement holes.

For simplicity, once all the markup is complete stack the 3 platforms on each other with the template at the top and clamp together on a sacrificial board.

Alternatively, the boards can be marked up and drilled individually.

Drill the 2mm holes for the arc attachment points (4).

Drill out all of the 3mm holes (outer tension points (8) & inner tension points (8).

Drill the four 58 mm cut outs.

Drill the 32 mm centre cut out.

Smooth any rough edges with sanding paper or a file.

Cut along the edge lines with a saw to create four obtuse points on each platform.

The arcs are aligned to overlap, offset by half the diameter with the holes all inline along the horizontal.

One orientated as a standard arch and the other as an upturned arch.

One black and one white.

Measure ~50mm of Brass wire and insert through one of the holes of the inner facing overlaps with ~5mm protruding.

From the outer perimeter of the arc insert a 5mm screw and tighten.

Don't try and over tighen the screw if it resists a process of slackening and retightening a few times has been found to work without causing damage. Alternatively, insert the screw without the wire first or using a round needle file to widen the hole slightly.

If the screw is too slack insert a second short length of wire in the hole or slithers of foil.

Using the first arc assembly as a template.

Align all subsequent arc assemblies to the template to ensure that they are all the same with a wire length between the gap of ~1.5cm.

Repeat the process to create a total of 8 arc assemblies.

First take a smaller outer platform and orientate horizontally.

Position an arc assembly with a black arc to the white platform with the arc hole aligned to the middle of the three outer holes.

Inser a 20mm screw up through the platorm to pass through both the platform and the arc.

Plate a nut over the bolt and tighten, securing the arc to the platform.

Rotate the black arc such that the open part of the arc is facing outward, the open part of the upper arc will therefore be facing inward.

Position and attached the other three arc assemblies as per the first one.

Align the larger centre platforrm horizontally over the arc assemblies previously installed and fit a 20 mm screw through the upper arc of the assembly and through the middle of the three outer holes.

A little tape can be used on the screw head to stop it falling out.

Position an arc assembly with a white arc to the black platform, place over the screws fit a nut and tighten.

Rotate the white arc such that the open part of the arc is facing outward, the open part of the upper arc will therefore be facing inward.

Align the white smaller platforrm horizontally over the arc assemblies previously installed and fit a 20 mm screw through the middle of the three outer holes and through eacxh of the black arcs, fit a nut an tighten.

Measure ~190mm of brass wire.

Feed up through the lower platform via one ot the pair of holes either side of the arc and thread through the aligned holes in the middle and upper platform to create a straight aligned wire hold in place by fitting a 3mm grub screw from the underside and tightening until flush with the bottom.

Repeat this process for all 8 wires.

Place the Lampshade on a known flat surface using a circular bubble spirit level to confirm its level.

Place the circluar bubble spirit level on the top platform.

Pull and bend the wire over the edge of the platform with pliers to create alignment with the level.

Apply tape to hold in place.

Fit a 3mm grub screw into the hole and tighten whilst holding the free end of the wire with pliers to maintain tension.

Next fit a 3mm grub screw into the hole on the far diagonally opposite side and ensure its still level, hold the free end of the wire with pliers and tighten.

Repeat the process with the next pair.

At this stage 4 wires have been tensioned one per platform arm.

Repeat the process with the remaining 4 arms tensionsing diagonally opposite pairs.

If necessary making minor adjustment by slackening or tightening wires to level the top platform.

Insert the circular bubble spirit level between the arcs and place on the middle platform

Press the down or push up on the middle platform to adjust the level whilst fitting and securing with 3mm grub screws to the holes.

Fit grub screws in all 8 outer hole pairs.

Note:

If the screw is too slack insert a second short length of wire in the hole or slithers of foil.

For added security a drop of clear varnish can be placed on the screws whilst at the same time are relatively easy to remove should wire replacement be required.

The main Lampshade is complete. 155mm(H) x 160mm(Dia.)

There are several ways to mount the Lampshade.

1: Free standing

2: Vertical pole stand

3: Pendant

The stand is made using a plant pot filled with quick drying readmix cement.

Seal the drainage holes with adhesive tape.

Fill the pot with the premixed cement.

Leave to dry in a warm location for a few days to dry out with the pot upright to maximise the surface to the air as the plastic pot is non porous.

Once dry, rub the surface of the cement with a stiff brush to remove loose material.

Cut a square of cork or other robust non porous, non slip material, sufficient to cover the large area of cement.

Apply a strong adhesive to the cement and stick down the cork and allow to dry.

Cut 340mm of 15mm diameter chrome plated copper pipe.

Drill a hole in the centre of the underside of the pot with a 15mm masonary drill to a depth of 40mm.

Put some adhesive in the hole and fit the pipe

Lightly roughen the plastic pot with a fine sandpaper and wipe with IPA, methylated spirit or similar.

Put masking tape around the tube were it meets the pot.

Apply an under coat and once dry apply a top coat and set aside to dry.

Cut off the excess cork.

The pole hanger is made from transparent acrylic.

Cut a 50mm disc of acrylic with the hole saw.

Cut a 155mm length of 25mm diameter acrylic tube

Centre the disc over the end of the tube and stick with adhesive and allow to dry.

File three notches in a triangular formation into the acrylic disc.

Lower the tube down through the centre of the lamp and align the cut outs with the holes and fit three M3 16mm bolts.

Pendant mounting can be accomplished by fitting wires or cord to the holes which surround the central hole in the outer platform.

Lighting is accomplished with a white LED that sits over the top of the clear acrylic disc using a combination of direct and channelled light.

The project is complete, all that remains to be done is to decide on the method of mounting and illumination.