Development and testers

As a method of adding texture and antiquing the zip, i experimented by melting wax and pouring it over silicone, quickly dabbing with an dry paint brush, I would do this on the insides of the silicone moulds, and once cast, could easily melt the wax out of the final casts using a lighter giving me an varied texture through out,
This small experiment allowed me to also become familiar with the moulding process.

This is the effects that were created using this method. I think they will be suitable for this purpose. Another method to achieve this desired effect was to dremal in the master, to create the surface wear. I chose not to do this as I wanted to create a variety of finish effects, and wanted each cast to vary in texture.

To create a brass effect on chemi wood, i experimented by coating in thick black paint, and sprinkling brass metal powder, between the layers of paint. Once dry sanded.







Here is the result when sanded ( bottom half) i used copper powder for this tester. this method worked well, and if i have enough time, i would like to apply this finish to my master model.







This image shows the resin tests i did to match the color of the original zip. The best result i found was

20g brass
50g poly
1g catalyst

I will use this ratio for my final.

Development of zip

I have made the zip body,and today CNC all parts necessary. i have made this piece as a whole and then sawed off the desired measurements, this was to save time matching up the curves later, as it was quicker to create the curve first, sand down and then cut to ensure they will all match perfectly

Routring and development

To ensure and even and accurate curve I decided to router the edges of the zip puller. I made a jig for the base of the router to sit upon to ensure a consistent depth was obtained while routing

Thi is how the model stands at this current stage.

CNC Contiuned

Once all the technical drawings were completed, and had set all the right settings in the program Excalibur. I was ready to CNC

Zip puller

To make the zip puller i laser cut acrylic and stacked them up, as
this was far faster than to CNC out as an whole object

To add the texture on the zip puller i looked at dry spraying, speckling and sandpaper. i found the sand paper worked the best as it gave the right grip and texture that i was looking for. I used grade 180.

CNC pocket

I decided to replicate the engraved detail on the back of the zip, using the CNC machine. This evolved technical drawings on the program Rhino. To get an exsact replica of the numbering and lettering, I scanned in the zip, and used the zip image as a template to form the letters. I did spend time researching whether their was an existing font within the program that would match the text. The closest font I could find to match the number five was:

BankGothic Lt BT
Eras Light ITC
Isocpeur
Nerdna

However, these were close, but not exact so I drew the number in Rhino myself

For the letter A the closes match was
Agency FB- which I used, as this was exsact.
BankGothic BT, came close.

Development and process

Here I started out by doing technical drawings and templates. By scaling up all measurements taken from a normal zip, and converting to the Borrowers scale of 14:1.

The next stage was to get the basic shapes machined out of chemiwood, ensuring their was at least 2 mm excess to sand out the machine blade, to ensure in a crisp and accurate finish

Next I experimented with heat bending chemiwood, to achieve the curve as shown in the image. This process worked, but was chemiwood was harder to bend as the material thickness increased. This process was a good solution. But not the quickest.