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Old 16th Mar 2019, 10:37 pm   #1
sven_swe
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Default AVO MK3 VCM Dial scale

Hi all,

I got hold of a AVO MK3 but the dial scales are a bit "bleached" and no longer really see-through. Anyone got any tips for fixing this by perhaps polishing or rubbing the plastic? Any chemical that could be used? Never seen this before so I thought I'd ask if someone has seen this before. See picture.

Thanks
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Old 16th Mar 2019, 11:07 pm   #2
Craig Sawyers
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Default Re: AVO MK3 VCM Dial scale

They tend to craze and crack too. One of mine is OK, and the other one not so good at all.

I wonder whether it would be possible to 3-d print them?
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Old 16th Mar 2019, 11:22 pm   #3
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Default Re: AVO MK3 VCM Dial scale

I've just been discussing laser-cutting other items from Perspex and then heat treating them to bend them, this could possibly be done with this dial too.

There are tons of people showing how to do this on YouTube and other places on the Internet today.
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Old 16th Mar 2019, 11:52 pm   #4
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Default Re: AVO MK3 VCM Dial scale

Yes for sure an option, I guess it's only a matter to have access to the resources to 3D print and possible laser. If it was metal I could

If someone has that I could take measurements and perhaps get a CAD drawing.

One of mine is not cracked but the other is. Would be great to have new ones.

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Old 17th Mar 2019, 12:19 am   #5
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Default Re: AVO MK3 VCM Dial scale

The simplest designs for this that I've seen is when people make simple molds from clay, used for pottery making. If you make one top and one bottom piece with a shaft in the center you can both cure and preheat them in your home oven and then preheat the perspex with a hairdryer and press it between these mold pieces.

There are other materials you can use for the molds that will have a more shiny surface so the perspex will look nicer, no scratches and marks after pressing, or you can cut out pieces of baking paper and put on to of the mold to protect the perspex surfaces. Some people use silicone spray or silicone baking papers.
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Old 17th Mar 2019, 9:38 am   #6
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Default Re: AVO MK3 VCM Dial scale

Any idea of the part number? I may be able to get hold of the original drawing for dimensional accuracy. I could also model it up and produce a 3D ready file.
I have access to a decent 3D printer, but probably can’t use it for a home jobs! Lol

Andy
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Old 17th Mar 2019, 12:21 pm   #7
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Default Re: AVO MK3 VCM Dial scale

Quote:
Originally Posted by AndyGilham View Post
Any idea of the part number? I may be able to get hold of the original drawing for dimensional accuracy. I could also model it up and produce a 3D ready file.
I have access to a decent 3D printer, but probably canít use it for a home jobs! Lol

Andy
That would be very helpful!

This is the number I could find for the part :

Transparent cursor for item 6 - 14806-1
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Old 17th Mar 2019, 6:09 pm   #8
David Simpson
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Default Re: AVO MK3 VCM Dial scale

Best bet would be to reinforce the cracked inner concave part of the dial with a strong clear plastic cement. Once it has hardened - carefully cut off the damaged outer 13mm circumference, and replace by gluing on a new ring of pre-cut clear plastic of a similar thickness. If its definitely made of Perspex, I'm sure you can purchase specific Perspex clear cement. Practice your cutting, filing, smoothing with fine abrasive paper, gluing, etc. on some gash pieces of clear plastic or Perspex, just to get it right.

Regards, David
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Old 17th Mar 2019, 9:17 pm   #9
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Default Re: AVO MK3 VCM Dial scale

On my Avo VCM Mk3 I just gave up on the badly cracked and faded knob skirts and installed some nice matching aluminium-skirted knobs from a scrap Avo CT446 Transistor tester. They match perfectly of course and are virtually as easy to use. And will last forever!
I may even have a pair left somewhere if you need them.
-Jeremy
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Old 17th Mar 2019, 9:33 pm   #10
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Default Re: AVO MK3 VCM Dial scale

Here you can find all the necessary

https://www.alumilite.com
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Old Yesterday, 7:23 am   #11
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Default Re: AVO MK3 VCM Dial scale

Aitor Eneko, thanks for posting that link, they seem to have very nice products at reasonable prices!
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Old Yesterday, 8:01 am   #12
AndyGilham
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Default Re: AVO MK3 VCM Dial scale

Quote:
Originally Posted by sven_swe View Post
Quote:
Originally Posted by AndyGilham View Post
Any idea of the part number? I may be able to get hold of the original drawing for dimensional accuracy. I could also model it up and produce a 3D ready file.
I have access to a decent 3D printer, but probably canít use it for a home jobs! Lol

Andy
That would be very helpful!

This is the number I could find for the part :

Transparent cursor for item 6 - 14806-1

I had a look through the archives, but sadly this part number does not come up. Worth a look though!

Andy
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Old Yesterday, 2:01 pm   #13
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Default Re: AVO MK3 VCM Dial scale

I mentioned this problem with cracked dials at work and got a good tip from a colleague who had made fish hooks and other molded things - if you have an item that is cracked or has become rough on the surface you can spray it with clear lacquer and then sand it down with 1200 grade water sandpaper and then repeat lacquering and sanding until you have a smooth surface before making a mold to get a clean result, this is really important when using silicone based molding material he said as they otherwise will copy every crack and the rough surface.
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Old Yesterday, 3:30 pm   #14
sven_swe
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Default Re: AVO MK3 VCM Dial scale

Quote:
Originally Posted by Pamphonica View Post
On my Avo VCM Mk3 I just gave up on the badly cracked and faded knob skirts and installed some nice matching aluminium-skirted knobs from a scrap Avo CT446 Transistor tester. They match perfectly of course and are virtually as easy to use. And will last forever!
I may even have a pair left somewhere if you need them.
-Jeremy
For sure that's interesting, I will PM you.

Thanks Andy for having a look.

Martin and Aitor, thanks for the tips and links. I will have a look! It's quiet often this issue comes up with cracked knobs etc, especially with old vintage gear. Maybe worth trying to do a mold.
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