Re: Tek Knob Project - scan and make


A vacuum chamber is not that expensive to set up and very effective.
Vibration is another option, but less effective.

As Vince says using the right materials and technique may eliminate
the need for degassing.

I bought some two component silicone molding material a while back
planning to try to copy a part, but never got around to it.
At work I pot a lot of prototypes, so I have the equipment set up.


On Wed, Dec 20, 2017 at 3:41 PM, Colin Herbert via Groups.Io
<> wrote:
As I understand it, an ultrasonic cleaner works by "cavitation", i.e. making bubbles form and then collapse. You would have to turn the cleaner on initially to "degas" the poured liquid, but then turn it off before it has a chance to set to any extent.

-----Original Message-----
From: [] On Behalf Of Herbert
Sent: 20 December 2017 14:33
Subject: Re: [TekScopes] Tek Knob Project - scan and make


Against bubbles, try to use a ultra sonic cleaner ( third tooth bath ).
Should work !


Am 20.12.2017 14:19, schrieb Chuck Harris:
I have done it with a pourable metal filled epoxy to copy gears with
good success.

The big problem is bubble migration. You have to have a plan for
making the inevitable bubbles go away... both in making the mold, and
in making the knob.

-Chuck Harris

Brad Thompson wrote:

On 12/20/2017 8:53 AM, Chuck Harris wrote:
The knobs are plastic primarily for cost of manufacture.

Has anyone explored using RTV silicone rubber to form a mold of an
existing knob, followed by using the mold to cast a replacement knob
using acrylic resin (or another compound)?


Brad AA1IP

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