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Making new plastic dials

Hints and tips for vintage technology repair and restoration
 
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Making new plastic dials

Post by Pamphonica » Sat Oct 06, 2012 12:36 pm

Earlier this year I bought a KW2000B SSB all-valve transceiver and although supposedly in "full working condition" it needed a lot of coaxing to get going properly. But that was done and I got it on the air.

However, the final job to make it sparkling new again was to replace the badly cracked and crumbling frequency dial.
New_IMGP5650.jpg
New_IMGP5647.jpg

Re-doing the design on a photoshop basis was going to take a very long time due to the damage. I had some experience of the Galva program from F5BU. This is fantastic for making up meter scales, sliderules, anthing log or linear, with all scale marks etc.

After a day or so of experimentation and comparison to photos of the original, I had a scale. When printed on transparency film to check the match it was wrong for various places on the arc. It dwaned on me that it was non-linear (not linear or log). The designer had hand-calibrated the original scale every 5% of the scale and passed those marking to a drawing shop.

So I measured every 5 degrees and re-created the scale exactly. I found a suitable typeface and sizing for the legends and finally got a perfect fit, again using prints on transparency film for checking till there was no "shadow" of misalignment when superimposed. The addition of the tiny mounting holes completed the job.

I started the job with white plasticard. Easy to get from model shops or Ebay and simple to cut. The backing plate for the main dial was initially selected to be 1.5mm (60 thou) but I moved to 1mm (40 thou) when it became clear that the dial was not sufficiently translucent to mimic the original. I cut the circle using an old pair of dividers with a proper wheel-controlled separation. 20 or so rotations leaves a deep enough groove to break out the circle. Small relieving cuts at the thinnest point allow the scrap to be removed in 4 bits.
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The scale was printed on laser-printable self-adhesive clear plastic film (Ebay again), with a peel-off backing. Getting this stuff to stick properly with no bubbles seemed initially impossible. Then I remembered the trick when applying translucent security films to windows. Use water with a couple of drops of detergent in it. Wet your hands completely before removing the backing. Spray or splash water on the sticky back as soon as it is recealed. It can now be handled easily, leaving no finger prints, and slid into position. I used a pin therough the centre of dial print and the dial plate to ensure alignment. Try to work in a dust-free environment, in my case with a sheet of clean paper underneath.

Now all you do is take a credit card, also suitable wetted and very gently smooth the dial down, from the center out. If you press too hard you can remove the print. If you get trapped hairs or dust underneath, just gently lift up the film before it is fully pressed down and remove them.
New_IMGP5667.jpg

Leave to dry for a few hours and it will be perfectly stuck. No bubbles! It can then be drilled and mounted. Hint for the large centre hole. Don't try to drill it full size. Any normal big drill will grab the plastic and make an ugly hole. Drill much smaller and use a reamer to enlarge the hole cleanly.

So, job done and the KW2000B looks factory new now. All clean inside and out with a lovely new dial. very pleasing.
New_IMGP5669.jpg
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The Galva software is available here: http://f1frv.free.fr/telechargement/Galva_187-3L1.zip.

My Galva script for the 2000B dial is available here: http://www.callx.co.uk/Shared/KW2000B.dat

A pdf of the scales is available here: http://www.callx.co.uk/Shared/KW2000B.pdf

 
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Re: Making new plastic dials

Post by CTV » Sat Oct 06, 2012 12:40 pm

Hi Jeremy brilliant! what an excellent result too. Thanks for posting this, I'm sure it will inspire others to have a go. :thumbl:

Chris

 
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Re: Making new plastic dials

Post by Michael Watterson » Sat Oct 06, 2012 12:50 pm

:thumbl:
Excellent.
I discovered that the local Drawing Office supplies/Plan copying shop will Laser print in colour on A3 transparent plastic from USB stick about €5.

Inkjet printing, B&W or Colour is very poor even on expensive inkjet film.

 
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Re: Making new plastic dials

Post by Pamphonica » Sat Oct 06, 2012 1:04 pm

Michael, you ar right about inkjet. It's just too wet and streaks off easily. Since small laser printers are so cheap now, that's a nice option. I splashed out £150 and got a 5-year-old HP office laserjet (huge one - HP5500) that does A3 in colour if required. Built like the proverbial ...

I have tried transparent plastic film for front panels but even with a nice spray-adhesive it still does not look completely adhered. This self-adhesive film, plus the wetting method produces really good clear adhesion and simple positioning.

 
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Re: Making new plastic dials

Post by Pamphonica » Sun Jun 28, 2015 1:57 pm

Please note that the link I gave above for the GALVA software no longer works.
But this new link does work.
http://www.f5bu.fr/wp/?page_id=13
All the best
Jeremy

 
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Re: Making new plastic dials

Post by Michael Watterson » Tue Jan 12, 2016 12:40 pm

Pamphonica wrote:Please note that the link I gave above for the GALVA software no longer works.
But this new link does work.
http://www.f5bu.fr/wp/?page_id=13

Thanks.
Also you can get clear water slide for Laser printers. Like the transfers that came with plastic kits. The backing soaks off in the water.


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