Andy,
I had luck making a plastic knob from scratch a while back. I needed
a knob for a little Dremel jig I built for creating Manhattan style
PCB pads. I think my knob was about 2 in diamater.
Basic supplies:
- Polyester plastic casting resin
- Hardener (for resin)
- Mold
The casting resin and hardener can be had at local crafts stores
around here. I presume it wouldn't be hard to find across the pond
either. For molds, I have had good luck with Polyethylene (HDPE /
LDPE) and Polypropylene (PP), without using a mold release agent.
That being said, I also cut the mold off, so they end up being one
time use for me. Mold release (available according to the resin
manufacturer), or a better shaped mold (nice draft angles) might let
you reuse molds.
For my knob, I used an empty plastic single serving fruit cup. I
wanted a threaded rod coming out of the back of it, so after pouring
the resin in the mold, I gently set a bolt into the puddle of liquid
plastic. 24 hours later, and the bolt is a permanent part of the
knob. It's not exactly perpendicular to the knob face, but only a few
degrees off, and unimportant for what I needed. A little work and you
could find a way to embed one and make it square.
Once my knob was done, I faced the back a little bit by chucking the
bolt end into my little drill press. A little work holding a file
against the back edge, and I shaped it to my liking (flattened it out
a bit, and smoothed over the corner).
Link to the casting resin manufacturer's site (surely there are
others, but this is the brand I used):
http://eti-usa.com/consum/index.html scroll down a little bit
Picture of the style of fruit cups I used for a mold:
http://tbn0.google.com/images?q=tbn:lBqSO-1t6kwCAM:http://www.packworld.com/thumbsLarge/issues/03.03/images/Features/DelMonte.jpg
If you go this route, and have more questions, feel free to send me
some mail directly. I skim this list in digest, so I might miss a
reply sent there.
-detrick
KI4STU
On 7/31/07, [EMAIL PROTECTED]
[EMAIL PROTECTED] wrote:
Date: Tue, 31 Jul 2007 04:42:32 +0100
From: Andy - GM0NWI [EMAIL PROTECTED]
Subject: [Elecraft] Project Knobs
To: 'Elecraft Discussion List' elecraft@mailman.qth.net,'Flying
Pigs' [EMAIL PROTECTED], [EMAIL PROTECTED],
[EMAIL PROTECTED]
Hello to everyone in the group from Bonnie Scotland..
I am currently tryin' to source some 2 inch - 2 1/4 inch diameter knobs for
a project that will be gettin' undertaken in
The near future..
I am in need of 3 sets of 3 (9 knobs in total) I think.. although this may
not be case as I progress
But better I think to plan ahead..
Can anyone on the list give any details of a supplier, ..or possibly some
ideas from a what type of older
Radio's in the past might have had this sort of diameter of knobs
included..?
Think VFO -Tuning Dial sort of diameter.. and you'de near a ball-part
figure/size..
Has anyone in the past home-brewed this size and diameter of knob for a past
project..? If so, care to share how you
Did it..?
I've looked around the internet are lots of places, and there just does'nt
seem to be anyone out there who stocks
This sort of thing, both here in the UK and the US and further afield..
Really would appreciate help or ideas on this one folks..
TIA..
72's 73's[EMAIL PROTECTED]
Andy
GM0NWI
Elecraft K2 Fully Loaded QRP S/n 01432
Elecraft K2 Fully Loaded QRO S/n 05469
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