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Ti Pwun · 17th Feb 2019, 10:30 am

I thought some may be interested in seeing how I'm reproducing some replica knobs for knobs for Vince (FIXITNOW), so I started this thread.

The sample knob Vince sent to me was slightly damaged so I first needed to 'repair' that damage using clay to fill in the missing plastic. I used foam core board and a hot-melt glue gun to build a rigid casing. I then softened the clay in the microwave oven and built up the clay to the centre line of the knob.

I then used a wood screw and a steel rod to press some registration marks into the clay. As you can see, I added clay to build up the area where the plastic is broken.

I sprayed this half with a mould release spray, degassed some Silicone and poured the first half of the mould, before putting it in the pressure pot overnight.

Once dry, I removed the knob to reveal the first part of the mould. This worked very well. A very smooth, bubble free mould.

In the final image here I have adjusted the contrast so that the actual damage to the knob can be seen against the first half of the mould. I again used clay to 'repair' this damage. I also filled in the indicator mark indent because not all of the set of knobs will need this indent. I can drill that later for those knobs where an indicator is required.

With that done, I gave it a blast with mould release spray and poured the second half of the mould, before putting this in the pressure pot at 40 PSI overnight.

Later today I will continue the process when the Silicone has cured. With the two halves of the mould fitted together I will first need to determine where best to cut my resin pour spout into the Silicone. This will be somewhere in the underside of the knob where it cannot be seen.

One thing worthy of note is that this knob is extremely thin, the plastic is old and brittle, so if anyone is thinking about making their own reproduction knobs in this way, you MUST soften your clay so that you can easily shape it without applying much pressure against the plastic. The plastic WILL break if you do not take great care at this point.

To be continued...

17th Feb 2019, 10:30 am	#1
Ti Pwun Heptode Join Date: Aug 2013 Location: Bradford, West Yorkshire, UK. Posts: 888	Casting a set of Vidor knobs I thought some may be interested in seeing how I'm reproducing some replica knobs for knobs for Vince (FIXITNOW), so I started this thread. The sample knob Vince sent to me was slightly damaged so I first needed to 'repair' that damage using clay to fill in the missing plastic. I used foam core board and a hot-melt glue gun to build a rigid casing. I then softened the clay in the microwave oven and built up the clay to the centre line of the knob. I then used a wood screw and a steel rod to press some registration marks into the clay. As you can see, I added clay to build up the area where the plastic is broken. I sprayed this half with a mould release spray, degassed some Silicone and poured the first half of the mould, before putting it in the pressure pot overnight. Once dry, I removed the knob to reveal the first part of the mould. This worked very well. A very smooth, bubble free mould. In the final image here I have adjusted the contrast so that the actual damage to the knob can be seen against the first half of the mould. I again used clay to 'repair' this damage. I also filled in the indicator mark indent because not all of the set of knobs will need this indent. I can drill that later for those knobs where an indicator is required. With that done, I gave it a blast with mould release spray and poured the second half of the mould, before putting this in the pressure pot at 40 PSI overnight. Later today I will continue the process when the Silicone has cured. With the two halves of the mould fitted together I will first need to determine where best to cut my resin pour spout into the Silicone. This will be somewhere in the underside of the knob where it cannot be seen. One thing worthy of note is that this knob is extremely thin, the plastic is old and brittle, so if anyone is thinking about making their own reproduction knobs in this way, you MUST soften your clay so that you can easily shape it without applying much pressure against the plastic. The plastic WILL break if you do not take great care at this point. To be continued... Attached Thumbnails __________________ Jon.