Review of the Module

Overall i feel that i have learnt rather a lot over the course of this module. Initially i wanted to use traditional tools to show my level of skill but in the end it was a bad choice of wood sealer that killed the model off. I have used Solidworks to create the 3D model. This is a piece of software that i had not previously experimented with.

I have become far more confident with spraying items and learnt how to achieve a high quality finish by using fillers.

I am disappointed that the wooden model did not work, with hindsight i would use a different sealer and experiment more with sealers and sprays. I am over the moon with the quality of the finished piece especially as i thought i would not make the hand in date. The Blogs, Prezi presentations and QR codes have highlited the many ways that modern technology can be used. I feel the Blog has given a better incite into my feelings throughout the build than a traditional paper portfolio ever could.

All the photos on this blog and on the images site have been taken on my Mobile phone. The joy of this and the fact that the MATEC has WIFI, has meant that every picture taken has been uploaded to the internet instantly. This has meant all my pics are in one place and not scattered over pen drives, memory cards and folders over several computers.

Honestly i have enjoyed this module although at times i have felt like destroying everything and throwing it in the bin. At the end of the day, most of my problems have been overcome and i am happy with the result

Building the board

So, by this point i had decided on a name. MediSeal and i had already come up with an idea for the display. I wanted to keep the board and display box simple and "clean".

I had thought of using a light box to show off the model but in order to keep the lines of the display clean i wanted to hide any obvious lights.

I decided to create a light box stand with a reverse etched top face. this would allow any writing to show through when lit but not be obvious when not lit.

I chose a font and cut out the design on the laser cutter. Then used a thinner piece of plastic over the top. Initially i intended to light the box with red fairy lights, this proved to be a problem as the lights gave of varying intensities of light depending on how far away they were from the surface of the box. In the end i used some  Surface mounted Light emitting diodes (SMLED). These give of a high intensity constant light and can be cut to any length.

 

Once these had been stuck to a perspex sheet and placed behind the light box the lettering would shine through.

So time to attach my images to the board... also i created a mock up of the device in use. This would show what the model was intended to do without having to write a detailed explanation.

To be honest and without blowing my own trumpet i am quite good with Photoshop. Years of photo-manipulation has stood me in good stead for this task.

I found an image or surgeons on the Net. Took one of my shots of the model. Reduced the size and masked the model image so it looked like one of the surgeons was holding it. Next i created a red gradient over the image and then masked a triangle to look like a beam coming from the device. Et Voila. One finished image of the MediSeal in use.

So i had the images, the display box and the light. all i had to do was put them all together. The finished board looks like this.

And that is the end of the modeling task.

Final details and colour

The model was sanded around the join and then sprayed again with high build primer, this gave an even coloured surface to start applying colour. The model was placed in the spray booth and i started to apply a fine coat of my apple jack colour. This was left to dry overnight then lightly sanded to remove any imperfections and get a smooth base coat of colour. These steps were repeated a further three times until the model had a smooth even coat of paint.

 

Finally the model was finished. Now it was time for the display board

Comparison of the two

So now i have a nearly finished model made of plastic and a nowhere near finished model made of wood and filler. I wanted to highlight the differences in build quality between the two. and so this is the stage to show that. From the point i was at with the wooden model i would of had to spend literally all my time sanding the filler back down. The problem was that as the filler was sanded down it started to reveal the wooden skeleton of the model. This was the material that i was trying to cover as it was the surface that was reacting with the paint, so more filler had to be applied before it could be shaped and smoothed.

The plastic model also took some hard graft to get to this stage but the joy was i could leave the printer to do its magic and give me a much better starting point than the wood model i already had.

As you can see there is a difference with the shape of the hand grip. this is because i found the curvature of the new model was more comfortable. So... on with the blog and the build

Priming and building

I was now at a stage where i could finally prep the surface of the model for the final coats of colour. Again the pieces were sprayed but this time with a high build car spray. This would fill any of the tiny holes that i had neglected to fill with body filler.

 

Finally i had a respectable finish on the model. again this was a case of spraying sanding back and re spraying but the 2 days were worth it. 

Time to fix the pieces together.

For this i wanted a strong joint that would completely seal the edges. For this I chose Araldite. This is a two part adhesive again consisting of a resin and a hardener. once it is mixed it heats up and starts to "cure" and harden so it has to be worked with quickly. The Araldite was applied to the inside edge of the hole to minimise seepage to the outside of the model. Once applied and the handle inserted it was left for a couple of hours to ensure it was hard. After this the join was covered with body filler and sanded to make the join less obvious

Light at the end of the tunnel

The pieces got a quick sand down to remove any sharp edges. The problem with the 3D printer is that although it reproduces accurately whatever you feed in to it, it does it in steps. That means that every curve is made up of small steps of plastic.

 

After sanding the pieces were sprayed with a specialised plastic primer. This would start to fill any holes and stop the paint from reacting with the plastic.
After the first coat it was obvious that a lot of work would be needed to achieve a high quality smooth finish. As you can see from the photos this is not the rounded final finish that i wanted. So again more sanding and spraying and sanding and spraying. This was repeated over 3 days leaving the model overnight each time for the paint to dry before sanding again the next day. Slowly the plastic started to resemble the finish i was aiming for.

But yet again i hit a problem. The plastic handle was starting to peel at the edges. Now it was time for the dreaded body filler. Again this was used to fill any gaps and get a smooth finish. Fill, wait for it to dry, sand and repeat. At the same time there were still some ridges in the upper part of the model so the top was filled at the same time. Yet again over another 3 days the model was filled and sanded

 

Time for CAD/CAM

During the night i created the model using solidworks. This is a 3D modeling program. Once a model has been built you have the ability to save the model as an .STL file. This can then be transferred to a rapid-prototyping machine or 3D printer. All the measurements of the wooden model were replicated on the 3D modeling software. The only difference was that this time i created a slot in the bottom half of the upper part of the model, This would allow both parts to be prepped separately before being glued together and sprayed.

Now it was time to print the parts. The pieces were fed into the rapid-prototyper and left to build the model. I made sure that both parts of the model were built to be 5mm thick. This would mean that the pieces could be sanded without breaking the model.

The model took 9 hours to print, so the next day i was able to start on the finishing of it.

Filler filler and more filler

So its time to give up my life and spend the next few weeks sanding. This is because I'm going to have to coat the ENTIRE model in filler and sand it back down to a high quality, even finish. So it begins. Filler is applied to the top of the model, this allows me to hold the handle with my left hand and attempt, i say attempt because i was useless at it. attempt to skim a fine but even layer of filler onto the surface of the model.

 

As you can see it looks more like a Mr Whippy Ice-cream than a futuristic device. So i spend all day skimming, waiting for it to dry and then sanding before repeating the process. The handle and botom of the model is dont in the same fashion untill we have what looks like a giant blob of blutak

 

 This Took the best part of three days to get to this stage. The problem with it is that you cannot get a smooth surface by simply slapping the filler on, it's not possible. you have to put some on, Sand it down, find any gaps and then apply more. Now this stuff dries like plaster, so you can imagine the time it takes and the dust it creates. 
At this point i realised i was going to have to make a rather important decision. Did i continue sanding and filling and loose more time on my other projects or did i use CAD/CAM.

Now if you do not know we have a thing called a rapid prototyper in EdgeHill. This lovely piece of equipment looks like an instant coffee machine but can actually print 3D models. While sitting and sanding i worked out that i could probably design the model on 3D software that night and feed it into the machine the next day. This would stop me wasting my life and lungs sanding.

First Spray and a chain of terrible mistakes...

So, my model had been sealed, hopefully i would not see any grain through my first coat of paint. It was time to spray the first coat of primer. the model was placed in a small hand vice between some modelling foam to protect it from the metal jaws.

This was it, the moment of truth. I sprayed the top half of the model and left it in the vice for a few hours until it was touch try. The model was removed from the vice and placed on a piece of modelling foam so i could spray the underside and handle. Again it was sprayed and then removed from the spray booth and left in a safe place to dry.

The next day i was excited to see if the last 4 weeks of work had paid off....... It hadn't.

The paint had stuck to the modelling foam so the two were attached. once this was carefully removed it was obvious that the foam had also at some point had some black writing printed on it. This writing had decided to remove itself from the foam and make the surface of my model its new home.

To top it off the grain was more than slightly obvious through the primer. Total disaster. I decided to sand down the model to remove the black marks and try again this time being more careful about what i put it on to dry.

So second try, again sprayed, left to be touch dry and sprayed the other half. Came back the next day to be greeted with the picture below.

Still more grain, which would have to be filled and for some reason the paint was still tacky. Mmmmm perhaps its this plasticote rubbish i bought from a hardware store i cannot mention, Lets call them Q&B. So i decided to place the model on a radiator and come back the next day. Next morning and we still have the tackiness, not as bad but still tackiness. The next day still about the same, Day 4 and i'm getting annoyed with this so i blast it with a hot air gun for 20 mins. This doesn't do anything to the paint but does keep me warm for a bit. At the end of the day and after a long conversation with Mr Wooff we agree that the best thing will be to coat the entire model with a thin layer of filler as it is probably the sealing mixture reacting with the paint.

Linseed and Acetone....

To seal the wood i used a 50/50 mix of linseed oil and acetone. The story behind this concoction was that i had been advised to use a acetone based sanding sealant, but it was not possible to find one . Some research on the net showed that model makers working with Jelutong used a 50/50 boiled linseed and spirit mix to seal their wood. I already had raw linseed oil as i play cricket and it is used to maintain the "spring" in a cricket bat. I found out (purely through chance) that ASDA actually sell pure acetone over the counter mainly for removing false nails. i thought this would be a good replacement for the spirits part of the mix as the only pure spirits i could get hold of was purple stained meths and i was worried about the added colouring ruining the wood.

So i mixed up a small batch and started to experiment with some scrap pieces of wood. these were rubbed with a wet rag of the mix and left on a radiator to evaporate away. The results were pretty pleasing so i went agead and rubbed down my model with the mix, again leaving on a radiator to evaporate off before repeating. This was done three times in total.

And then i droped it again. Right onto the lid containing the mixture. You see the problem with oils are that they make things slipery and while trying to take a picture with my other free hand the model again decided to take a little jump

So this meant some more filling, waiting sanding and then coating again. but eventually i got there