Tuesday, June 9, 2015

From virtual to actual!


Iron Lenin Rusty
3d CNC sculpture of Lenin in a rust finish

This is just an example of one of the many uses for the cnc router.

Before I start, I need to say that I have no political interest in Lenin. Nor do I think there is any excuses for the atrocities committed during his time in power.


The reason behind this choice of model is 3 fold. 1. It was a free download! 2. I quite like the blocky style. 3.This is a legitimate film prop regardless of the nasty history, and I am only a prop maker!
3D CAD model of head
Thingverse Model of Lenin

This prop began its life as a real sculpture, I believe. Its was captured with photogammetry and the resulting mesh was uploaded to the internet and made available to the public. I downloaded the .stl model and chopped the model into several virtual slices. Each slice was 50mm thick, the same thickness as was available as standard in XPS polystyrene, which was my material of choice.

Lenin bust cnc router
CNC router cutting a face

This is the first couple of slices just as they came out of the router. The head consisted of 5 layers in total, 2 back and 3 front. 
I PU glued the slices together and did a little sanding on the surface. The brown stuff is lightweight filler. I was looking for a filler that would have a low density so it would sand at a similar rate to the XPS. This filler is still quite tough once cured but worked ok for this.


50mm xps with filler
Layers assembled and with some filler applied

Retrospectively, I should have filled the diagonal grooves in the face a little. The router bit got clogged in the middle of the cut and left those grooves. Pity.
prop sculpture with reactive paint rust
Reactive paint layer


I decided to go for a rusty iron finish on this instead of bronze. I have a posting of how to do the DIY reactive paint here. I love the industrial quality of it and the weight it seems to have.


Sunday, December 21, 2014

A big poly sculpt for Dracula

A quick animated GIF of a polystyrene lion's head I did for Dracula Year Zero. As usual, time was tight but I managed to take a few snaps of the progress. Enjoy!

Wednesday, November 12, 2014

Faux Rust Effect

Above is a test paint effect I did a little while ago. It worked out well so I thought I'd share it here.
I saw that it was possible to buy reactive paints from a few companies, most in the US. But I'm in Ireland...$$$
So I decided to do a bit of research and make my own. It involves a reactive paint and a rusting solution.
For the paint you need:
  • Acrylic matt medium
  • Iron filler powder 
And for the rusting solution:
  • 100mls water
  • 10g Copper Sulphate
  • 10g Ammonium Chloride
And for it to work you need:
  • patience
 Mix iron powder into matt medium. You need a lot of iron in there but still the paint need to flow. 

Apply a layer all over your object to be rusty. Allow to dry completely (cure), ideally over night.
Apply a second layer of iron paint but before it dries, spritz lightly with the rusting solution.(you don't want to wash the paint off)
Leave it to dry.
Within a few hours you should see a rusty effect starting to appear. It will keep reacting for days and become more rusty.
I like to spray another mist over the top and heat it with a hair drier or heat gun to accelerate the reaction. I did this 3 times over a day.
Next day the result was much like the image above. It has reacted a little more in the past few weeks but not a massive change.
Easy!

If you use this I'd love to see the results. My email is on the contact page of my website.
 

Wednesday, October 29, 2014

Ross O'Carroll Kelly Statue

Commission: Make an imitation bronze statue of the fictional character Ross O'Carroll Kelly
Client: Penguin UK

This was a nice job for me as it was an indirect collaboration with my brother Alan Clarke,
who designed the original look of the character of Ross.
Alan had been illustrating these books by Paul Howard for many years. And with the release of the 11th book, "Keeping Up with the Kalashnikovs", Penguin UK decided to run a promotional campaign.
Alan sat in on the meeting and proposed me to do the job.


As usual budget and time were tight. So the job had to roll along in an efficient manner
but still give a convincing result.
The first thing to do was get a body shape. I know getting the exact pose was unlikely, so I just
bought a fairly neutral standing figure. Horrible really..




So the reposing took a little work. It is very plain to see as you reposition a figure like this
that any shift in the anatomy is reflected all over the body. If you just move one part
it looks wrong until you adjust the other. Hips and shoulders, heel and head, thighs and
hips. etc. There is a distinctive 'knock on ' effect as you start to shift limbs around.




Once the pose was set I fixed it in place with steel banding, 2x1 timber and screws. The mannequin
was very durable.
Next up was dressing. Now Ross is or was a rugby player so he is well built, the mannequin
was a little slight so I glued a layer of 1/2" upholstery foam all over the figure to bulk
it out a bit. Of course this only works because it will be dressed. It is a heavy handed way to solve this problem as you loose a lot of anatomy detail but in this case it looked fine.


Next up was the head. I took the upper torso of the mannequin as the armature stand and
to keep the head in proper proportion with the body. The sculpt was in regular pottery
clay. I find it a really nice material to work in. The down side is that it will dry out if your not careful. This sculpt happened over two days so a simple spray of water and wrapping in cling film did the trick over night.



I had decided the casting would be fast cast polyurethane. This was for speed and damp compatibility. A waste plaster mould was all that would be needed as I only needed to make one copy...risky.
I cut up a few aluminium beer cans shims and stuck them right into the clay. Even though this is a waste mould the split line must be in the right place. As always you want as few undercuts as possible. There is still a danger of the mould breaking as you remove it from the clay! I won't go into how to make a two piece plaster mould its covered many times.
This one came off in one piece. Phew!


Then I dried the two halves in the sun for a day. More time would be better but I had to keep going. I shellaced the surface, and when the it was dry I brushed on a generous application of beeswax mould release. I let that dry and reapplied anther coat of beeswax, let that dry and did a third. I was then ready to reassemble the two halves of the mould and  cast.
It was cast hollow. I simply rolled the resin in it by hand keeping an eye on the inside to be sure everywhere got covered. 1 coat of straight resin then a few more with polyfibre for strength. After breaking off the plaster this was the result.


The head slotted neatly down on the neck of the mannequin and I screwed it in place. I used the real Leinster Rugby top and Chino's trousers. And of course Doobs! (One of the  signature designs from Dubarry Shoes, Ireland).

I don't have any pictures of making the arms. The hands are mine. I moulded them all by myself in alginate from Smooth-on and cast in fast cast. I did remember to put a piece of 6mm threaded bar down the pointing finger. I bent a 50cm length so it fit into the alginate mould and filled around it. This gave me a reinforced finger and an anchor to fix the hands into the arms.
The fore arms are built on the mannequin arms but bulked out with polyester filler. This was the slowest part of the whole job...sanding filling sanding filling...
Building anatomy with filler is not a good idea.


It stands on an MDF plinth. The lower legs have 16mm threaded bar fixed sticking out  at the heels. I filled from the knees down with PU foam(a/b type, not from an aerosol can) this grabbed the threaded bar. Then I could bolt the legs to the plinth. The shoes are cut and fitted around the feet rather than putting the feet into them. The shoes were sealed up and filled with fast cast to grab the mannequin feet and hold it steady.

The top torso was fixed off and the arms attached and screwed into place. At this point it was ready for resining.




The resining was done in three distinct phases. I used polyester for this bit. For the following advise, I must credit model maker and friend Ed Rourke:
There is a distinct difference in how dry material hangs versus wet material. Wet(we are talking resin in this case)material hangs in steeper droops with sharper ridges on the curves. The inner material tends to cling to the backing.
Overall the material is heavier. Subconsciously we all know how wet material looks regardless of the colour or finish. The shape is wrong.
So we must do a little trick to avoid this pitfall.

We build a structure to "hang" the material from. With dry material the shape is already there but the strength to support the weight of the resin is not.
So the trick is to take a small amount of resin on a paintbrush and allow it to wet only the very tops of the folds. We must apply only enough to give a strip of 2cm or less on these high points.
Continue this all the way from where the fold starts to where it ends. Excess weight must be avoided. Once that has cured, a network of hard resined material will form all over your garment creating an open structure that is strong enough to allow the second phase to proceed.

This is quite simple we just need to widen the strips we have already resined. Never the less avoid the material which touches the backing(mannequin in my case). Let that cure and you can go on to apply resin to the rest of the garment. With this method you should have a shape very close to the dry material.




Once I had the clothes solidified, I stippled a texture layer of resin all over the entire statue and plinth. I used resin and cabosil for this. Once I was happy with the texture, I sprayed on a coat of 2 pack primer.



Then, with aerosol cans, I painted a coat of bronze metallic colour. This gave me a nice base coat to apply the patina effect to.




The patina consisted of two layers:
The first was- 1 raw umber:1 burnt umber:2 acrylic scumble.
and the second- 3 Burnt Umber and  1 Black: 4 acrylic scumble.
Here is a close up of the second layer being applied over the first.




These were both applied in the same way. They are stippled on and the highlights wiped clean. This is of course done in a way that is relevant to the location you are working. For example the upper shoulders are going to have more bronze showing through than say, the inner thigh.
And that was that. The clients were very happy with the end result and so was I. Here is a little video of the launch.

http://www.irishtimes.com/life-and-style/should-ross-o-carroll-kelly-replace-tort-with-the-cort-1.1966128

Thursday, October 16, 2014

How to polish Acrylic Ice Cubes


A photographer friend of mine asked me to make him a few acrylic ice cubes for a product shoot he was going to be doing and I thought 'no problem, how hard can it be!'
Well it was hard. And once the method was worked out, hard turned into slow.
This is the end result:



It all began with a commercial acrylic ice cube. They were beautifully finshed but a crappy shape in my opinion. So I went at it with the belt sander and reduced it to this shape.


Very rough and dirty. The next stage is to sculpt the vague surface features I wanted on the cube. It was to be nice and melty so the surface needed to undulate rather than change angle too quickly. I used a 120 grit sanding cylinder in the flexshaft:


Now that all six sides were sculpted morealess to the desired shape its time to reduce the surface texture. Its worth noting that the surface features even out alot in the following steps. So on to medium weight steel wool. This is a bummer as it must be done by hand. I ended up with a good method where I twisted it up into a rope and folded ot over. Giving me a dome shaped abrasive surface, good for getting into those hard to reach low points. You need to remove all evedence of the cutting marks of the sanding cylinder...its slow.


Then on to the fine steel wool. Same procedure here. The objective is to remove all the scratches of the medium steel wool. Again slow and labour intensive. Hand finishing like this really allows you to control where material is being removed. The high points will always be finished first and want to wear down before the lows will be smooth. It is nessasary to keep an eye on this and adjust where you are working to compensate:


On to the lapping, I hope I'm using the term correctly here. It is a really bad idea to let solvents anywhere near acrylic like this as it will craze and crack badly. Even from the vapour. So all lapping and polish mediums must be water based. If it smells don't use it.
Now you could go and buy some or...


use toothpaste and grit mixed together! I made a milky consistancy here of 400grit carborundum and the cheapest toothpaste I could find and water. It worked a treat!
I worked it with a felt mop. Its a bit messy if you don't watch the speed. Also dont let it dry out as you work it on the surface of the acrylic.


I was at the dental hygenist the other day and my mind wandered as the nice lady scraped below the gumline...and it hit me. Teeth are just like acrylic ice cubes!
So I spat out the blood and asked her how she managed to polish such difficult shapes as teeth?
She showed me this:


So the next polishing step is cheapo toothpaste with a cup shaped polishing mop. These have plastic bristles much like a toothbrush. But the clever thing is they tend to polish the outside edge of a dome rather than the tip. Just what I needed. At this point the acrylic is really becoming see-through:


The final step is flame polishing:



This is also a critical step. The acrylic will bubble very easily under a flame this hot. I litteraly pass the flame accross the surface in one smooth move and thats it. If you must go again, wait untill it is cool and go again. Donn't be tempted to go back over it again while it's hot, the corners will bubble and then you are back to square one!



Thursday, July 31, 2014

Bricklane Sign on the CNC.


I was in London the other day and visited Brick Lane.  It was fresh in my mind when I needed to do another sample on the CNC router.
So a London Street sign it was!
I worked from a reference photo from the net and drew up a CAD file.  


The sign is all made of foam PVC scraps. Two different brands which cut very differently.(Settings were 8k RPM at 1500mm/min cutting with a 1/8 O flute bit at 6mm per pass.)


 It was all glued together and a primer applied. I then added a texture layer of white emulsion paint with artex filler. This was stippled on and allowed to dry.


 Here is the sign with letters blackened and an ageing dirt wash(or two) applied. Which was a vey watery mix of black,white and burnt umber.


And here is the finished piece with nails and rust applied.(I know, I forgot to paint the E.I.!) 




Saturday, July 26, 2014

CNC router test cut

I did an interesting routing test with my new CNC router today . It has a 600 X 900mm cutting area, by 70mm high.
The object of this test was to go from a printed line drawing to a 3d cut shape.

I stared by browsing through a beautiful book on Celtic art.
I found a nice interlaced dog pattern redrawn from Lindisfarn Gospels. I photographed this page and converted it from a raster image to a vector. It involved a lot of editing of the image in order to get it ready for the CAM software.
Then the magic happens. The CAM software generates a toolpath which is fed to the machine control software and then to the router itself. After sometime and mess of dust and woodchips...
This piece is 50cm long.