Concrete Lamp - "Cleaved Light"

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Introduction: Concrete Lamp - "Cleaved Light"

About: An engineer who likes to tinker with electronics and make stuff!

Welcome to my instructable on how to make a very stylish lamp out of a potentially un-stylish material - concrete! To be honest, style (or rather beauty) is in the eye of the beholder and so I'll leave it up to you to decide if it fits in your surroundings or not. What do you think?

All the necessary steps are here but if you don't like reading the just sit back, relax and watch the video instead. Please also subscribe to my YouTube Channel where you find lots of videos on projects and repairs.

https://www.youtube.com/user/MrSjowett

When I said to people at work that I was making a concrete lamp the first expectation/question was "is it for outdoors". In this case, emphatically no! It is very much an indoor lamp which has the harshness of the concrete and the softness of the light - a combination that I think works well in this case.


But how to make it?!

The concrete body of the lamp (which, to my eye look a bit like a leek) is made is two halves. The 1st and 2nd halves are cast in 2 steps using the same mould twice. I had a few failed attempts at making the mould entirely from standard PVC pipe but they were epic fails - see the last step for a video of my epic fails. I ended up designing a number or parts to use as a mould and printing all the parts out on my 3D printer. I've since used the parts a few times so they are perfectly reusable. Similarly the base (support) to the concrete is made on the 3D printer. If you don't have access to a 3D printer the these 2 parts could be made using other materials such as wood or metal if you have the equipment (Lathe probably).

The finishing is fairly basic - just spray paint the exposed plastic base and wire in a lamp holder. This builds can be done with minimal tools (except for the 3d printer -sorry) and limited manual skills - Go on have a go!

NB: For the American English speakers......Mould=Mold, I'm from the UK!

Step 1: Tools and Equipment

As I finished up saying in the introduction, you will need a 3D printer to complete this build. However, as this piece of equipment has already made and appearance in many hobbyist workshop I'm hoping this isn't an impediment to you completing this project. However, if you have yet to take the plunge maybe this is the time to do so!

FYI = I have a Lulzbot mini - its not a large machine and indeed I had to split part of the mould into 2 separate pieces to enable the printer to print them.

Aside from the printer very minimal tools are required.

1) An old bucket and trowel to mix the concrete - the volume is very low so only a small container is required

2) Cable preparation and installation will require only the basic of tools such as a knife and screwdriver

Step 2: Safety

Hmmmmm, well the lamp is powered from the mains so the usual warnings apply.

DO NOT wire the plug/lamp holder if you are not confident/competent !

However, I will detail what is required in this instructable and then leave the decision up to you as to whether you do this yourself or employ the skills of a qualified electrician.

I may follow up this project with a low voltage version that will work from a 12v plug pack (so no mains wiring at all). Please subscribe to my YouTube channel to watch out for this development (see link on introduction).

Step 3: Parts List

There are not many bought parts to this project and for once the materials are quite cheap! Below is a summary list however, direct links to the sources I used are on the respective steps. The main ingredients are the concrete - which is the plain vanilla stuff available at any hardware store and the filament used is just standard Polymaker PLA.

1) Bag of concrete - 'bog standard' no frills concrete. Maybe quick set concrete would work also but you'd have to work fast!

2) Lamp Holder - ES screw fitting + cable clamp - both from ebay

3) Cable - I used 1.5metres of fabric covered cable - depending on your choice of colour you may want to match it will the spray paint?

4) Plug - this is a rewire-able plug - suitable for my country (Australia)

5) Lamp(s) - I have used 2 types of LED lamp (see step 5)

I) Golf Ball Style - this is matched with the long lamp holder

II) Test Tube Style - This is matched with the short lamp holder

4) Spray paint - Your choice of colour from the local hardware store

Step 4: Creating a Mould for the Concrete

Ok, included in this step are all the 3D (stl files) parts you need to 3D print out to complete the casting part of the project. In addition you will need to create a wooden base to support all the parts and also a length of 40mm PN12 PVC pressure pipe (see link below) plastic pipe. If 40 mm plastic pipe is not available in your area don't worry as you can use sched 40 1.5" tube which has a very similar outside dimension (48.3mm vs 48.2mm). Alternatively you could print out your own tube!


The wooden base is made from 2 different sizes (thicknesses) of plywood which I had lying around the garage (12mm- 1/2" and 18mm - 3/4" thick). Accuracy and sizes are not too important here so I'll give you my dimensions but leave it up to you to modify depending on your local availability. The only thing to note is that the depth of the gap in the middle has to be close to 30mm (1.5") and about 190mm wide. The 12mm plywood base is approx 475mm x 170mm and the step at either end is made from a sandwich of 12 + 18mm ply making a total 30mm

https://www.bunnings.com.au/holman-40mm-x-1m-class-12-press-pvc-pipe_p4750050

Step 5: Cast the 1st Half

The main parts of the lamp is cast in 2 separate halves. The same mould is used twice but in the 2nd step the 1st casting is joined to the 2nd casting as part of the 2nd casting process.

The first step is to apply a thin smear of cooking oil to the surface of the mould - this will aid the release of the cured concrete. I used a paintbrush to do this but perhaps you have some spray oil which would be easier to use.

Mix a small amount of concrete - I used about 7 small "trowel fulls" for each half - the quantity is quite small really. Place about 1/3 of the concrete in the base of the mould. Take particular care at the upper edges and tap the mould several times to remove the large air bubbles.

NB: Bubbles and discontinuities in the resulting casting are part of the character of the finish product and personally I prefer more rather than less of these. Tap too much and you will end up with a perfect smooth finish which is a bit boring!

The centre pipe can then be slid into position and the rest of the mould filled to the brim. Remember to oil this also.

The 4 rawl plugs then need to be added and embedded into the wet concrete. This takes a bit of wiggling/taping but is quite easy.

After the mix has started to solidify (after an hour or 2), resurface the top edge with the trowel and ensure this top surface is even all the way around the mould and the centre pipe.

Leave the mould for at least a couple of days to cure to the point where its structurally sound. Remove the centre pipe first with a twisting motion then remove the end pieces of the mould and the casting will come away easily. You can now proceed to the next step but if you're not in a hurry its best to leave it to fully cure for about a week or so.

Link to Concrete used:

https://www.bunnings.com.au/australian-builders-20kg-concrete-mix_p0761537

Link to rawl/wall plugs

https://www.bunnings.com.au/ramset-6-x-35mm-red-frame-wall-plugs-pack-of-25_p2260649

Step 6: Cast the 2nd Half...

Essentially this is to repeat the previous step but, this time we need to mate the 1st half to the 2nd half...so that they stick together...forever!

Again mix a small amount of cement and prepare the mould with a thin smear of cooking oil. You can then fill the mould to about 1/3 before adding the centre pipe back in position. Complete filling the mould to the brim then the 1st half can be carefully lowered into position. The 4 rawl plugs need to be 'nestled' into the lower mould until the 1st mould is laying on the centre pipe. Ensure everything looks centred and go around the edges with the trowel again to ensure the cement is still up against the brim of the mould - do this again after 1-2 hours.

Leave the cement to cure for at least a couple of days before removing the completed assembly from the mould. Release from the lower mould should be easy whereas removing the centre pie is a little more difficult. Use a twisting/rotating movement to release the PVC pipe from the surrounding concrete.

Step 7: 3D Printing the Base and the Lamp Holder

Whilst the concrete castings are curing off the other 3D parts required for the lamp can be printed out and prepared.

You will need to print out 2 of the 3 parts contained in this step. The decision on whether you print out the long or the short holder will depend on:

1) The type of LED lamp you choose. and/or

2) The "look" you prefer, ie: With the bulb hidden or exposed.

You are limited in the size/shape of the lamp you can use. I've used both the round 'golf ball' style and the more tubular (a candle style would be ideal). You just have to make sure that no part of the lamp has a larger diameter than the PVC pipe used for the casting.

NB: When the bulb is hidden the light just projects predominantly upwards whereas when the bulb is exposed it also shines outwards. It can be a bit bright in a low lit room to view the bulb directly (as you can see it in the base of the concrete split.

Here's a link to the PLA I'm using:

https://core-electronics.com.au/polylite-true-blue-pla-filament-1kg-3mm.html

Here 1 of the lamps I choose:

https://www.bunnings.com.au/osram-7w-700lm-warm-white-led-value-stick-e27-globe_p4320889

...and here is the other (golf ball type)

https://www.bunnings.com.au/osram-3-3w-250lm-led-classic-p-warm-white-fancy-shape-e27-frosted-globe_p4320946

Step 8: Spray Painting the Base

To date I've made 2 complete lamps. For 1 I used the light blue paint and for the other the metallic paint. I think the blue is more suitable for a bedroom/lounge whereas the silver may go well in an office environment - which do you prefer?

I simply spray painted the parts with 2 coats - no preparation of the surface of the 3d printed part was done as the natural look of the plastic layers look similar to a metal turned part.

Here are links to the paint I used:

https://www.bunnings.com.au/dulux-duramax-340g-gloss-spray-paint-fish-pond_p1400712

https://www.bunnings.com.au/dulux-duramax-325g-met...

Step 9: Cable, Lamp Holder and Plug

The wiring for these are easy but as I stated in step 2 if you are not a competent or confident in wiring then get this done by an electrician. As all the parts are insulated (non metalic, concrete and plastic) this portable electrical appliance does not require an earth connection (Class 2). Therefore - I'm just wiring the live and the neutral up.

NB: The 2 most common wiring colour combinations for lamp cords are:

Australia/UK/EU Brown = Active/Live Blue = Neutral

USA/Canada Black = Active/Live White=Neutral

The cable needs to be fed through the various holes and cable retention ferrules then stripped and terminated to the lamp holder at one end and the plug at the other. Pay attention to cable retention and ensure that pulling in the cable does not stress the terminations

You may want to include an inline switch if you don't want to switch off the lamp at the socket all the time. Just remember if the switch is a single pole switch to break the live wire not the neutral - its safer that way!

Finally - regardless of whether you are in the UK using on of their "built like a battleship 3 square pin fused loveliness of a plug" or using one of those flimsy 2 "round pin jobs" - be safe - mains AC can kill!

Link for lamp holder:

https://www.ebay.com.au/itm/E27-Light-Bulb-Socket-Lamp-Holder-Pendant-Socket-Screw-Cap-Bases-Adapter-Black/263632480789?epid=20018484780&hash=item3d61b86a15:g:Pz0AAOSw2q9a32Dj

Link for Cable (grey):

https://www.ebay.com.au/itm/Grey-Round-Electrical-cloth-covered-fabric-Cable-1m-aus-nz-approved-italian/202066320220?ssPageName=STRK%3AMEBIDX%3AIT&var=502062392587&_trksid=p2057872.m2749.l2649

Link for Cable (blue):

https://www.ebay.com.au/itm/RM17-Baby-Azure-Round-Rayon-Electrical-Fabric-Cloth-Cord-Cable/192292398736?ssPageName=STRK%3AMEBIDX%3AIT&var=492227730232&_trksid=p2057872.m2749.l2649

Link for cable clamp:

https://www.ebay.com.au/itm/10pcs-Thread-Adjustable-Clamps-Ceiling-Light-Cable-Clips-Grommet-Black/401494044702?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Step 10: Fix the Lamp Holder to the Base

The lamp holder will simply slide into the 3d printed part. To stop the lamp holder rotating in its base add a smear of RTV (Silicone) or epoxy to the outer surface of the lamp holder before pushing it home.

Allow the RTV to cure before screwing in the lamp.

Step 11: Assemble the Casting to the Base

Simply slide the casting onto its base. For ease of replacing the lamp I have not attached the casting to the base in any way - just let gravity do the work.

Step 12: Energise!

Plug in, turn on and enjoy!

Comments, questions and suggestions most welcome.

Step 13: Eplilogue Epic Failures - TBA

Here is a video montage of failed attempts to make the lamp casting - I'll let the video do the talking!

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    4 Discussions

    Very fun lamp design! I agree with Seamster, the flexible shape is very appealing to see in concrete :)

    1 reply

    Thanks Penolopy - I'ts my first time using concrete as a project medium....I think I may have another few designs I'd like to try! Thanks for the comment.

    This is a great design. The appearance of a flexible shape but cast in concrete creates a nice mental conflict. Great execution too. I like it! :)

    1 reply

    Thanks Seamster - your positive feedback is always a great tonic!