Making a knob
 

Warning: metal content.

I made an aluminum knob to replace a plastic knob I didn't like on a
machine I otherwise like a lot. Then I black anodized it.

Details at
http://users.goldengate.net/~dforeman/knob/

Don Foreman wrote:
Warning: metal content.

I made an aluminum knob to replace a plastic knob I didn't like on a
machine I otherwise like a lot. Then I black anodized it.

Details at
http://users.goldengate.net/~dforeman/knob/


That's right purty, Don.

--Winston

I made an aluminum knob to replace a plastic knob I didn't like on a
machine I otherwise like a lot. Then I black anodized it.

Hey Don,

Please discuss that anodizing a bit. Does it have a hard surface like the
commercial Job? Is this an easy to do thing like nickel chrome, or really
involved like triple chrome?

Karl

On Sun, 22 May 2005 12:12:24 GMT, "Karl Townsend"
remove .NOT to reply wrote:

I made an aluminum knob to replace a plastic knob I didn't like on a
machine I otherwise like a lot. Then I black anodized it.

Hey Don,

Please discuss that anodizing a bit. Does it have a hard surface like the
commercial Job? Is this an easy to do thing like nickel chrome, or really
involved like triple chrome?

Disclaimer: I'm no expert on anodizing.

My understanding is that "hard" anodize has smaller pores that don't
accept dye as well. The process is the same, and it's easy to do; I
think the difference is that "hard" anodizing is done with more
concentrated acid at higher current and lower temperature.

The electrolyte is just battery acid from NAPA, diluted 2:1 with
distilled water for hard anodizing or 3:1 for a film that is to be
dyed. I do it at room temperature. Cooling the electrolyte might
result in a harder film. I really don't know how hard the film I get
is. I used a current of about 0.1 amp per square inch. I've read
that lower current will result in better dye saturation but I haven't
tried that yet. My knob isn't really a deep black, more of a
gunmetal color. A matte finish (beadblasted) might also result in a
darker black.

My "secret weapon" is using Ted Edwards' electrocleaning soup to get
the aluminum waterbreak clean. It's in the dropbox somewhere. I
don't use any electricity for that, just dip the work in the soup for
a few seconds and scrub it with a rag. It really does the job!

After anodizing, the work is typically sealed by immersing it in
boiling distilled water, perhaps with a sealant chemical added.

There are some good websites about anodizing, though I don't have the
URL's at hand. Google on anodize and telescope.

Caswell's plating manual has a good section on anodizing, and he sells
the dyes and some other chemicals like de-oxidizer and sealant.

Don Foreman wrote:
Warning: metal content.

I made an aluminum knob to replace a plastic knob I didn't like on a
machine I otherwise like a lot. Then I black anodized it.

Details at
http://users.goldengate.net/~dforeman/knob/

a FINE knob. We're very proud :)

In article et,
Rex wrote:
Don Foreman wrote:
Warning: metal content.

I made an aluminum knob to replace a plastic knob I didn't like on a
machine I otherwise like a lot. Then I black anodized it.

Details at
http://users.goldengate.net/~dforeman/knob/

a FINE knob. We're very proud :)

Now you will discover whether the torque-limiting grip on the
original knob was because the part in which it worked could not take any
more force than you could put through the wimpy knob. I hope that is
not the reason for the original knob being as it is.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 22 May 2005 22:24:34 -0400, (DoN. Nichols)
wrote:

Now you will discover whether the torque-limiting grip on the
original knob was because the part in which it worked could not take any
more force than you could put through the wimpy knob. I hope that is
not the reason for the original knob being as it is.

What a sorry excuse for a functional design that would be.
Fortunately, I don't think that's the case here.

There's about 3/4" of 3/8-16 threadlength in the aluminum or
magnesium casting, so I don't think I'll jack the threads out
barehanded. If that happened, then I'd drill it out and fit a
knurled stainless threaded bushing. I want the damned clamp tight.

It won't happen. Some good and thoughtful engineering clearly went
into the design of this motor and mount, other than the silly knob.
Bow-mount trolling motors see hard use, this one can take it -- has
done for 7 years now. Running into submerged stumps and rocks and
chewing thru thick weeds are just part of a day's work for such a
motor. Chasing bass rquires it. It gets the job done with a shrug.

Don Foreman wrote:

Some good and thoughtful engineering clearly went
into the design of this motor and mount, other than the silly knob.

The engineering team assigned that part to the New Guy and spent their
time on the critical parts.

Don Foreman wrote:
There's about 3/4" of 3/8-16 threadlength in the aluminum or
magnesium casting, so I don't think I'll jack the threads out
barehanded.

Even if you tried, you'd likely break the bolt. From MH, length of
thread engagement required to break the screw instead of stripping for a
"screw" of 50Ksi yield in a "nut" of 10Ksi yield is
50E3 10E3 thread_SLe .375
0.7745714499
and I would expect your Al alloy to be better than 10Ksi.

Ted