Thermal Chamber Aluminum To Wood Fastener (?OT?)

316 Stainless or titanium hardware. Both will pit aluminum, so perhaps a insulating shoulder washer between the fastener and aluminum. 5000 series aluminum (5052, 5083, 5086 are used for boat hulls) have high corrosion resistance and are weldable. I think McMaster Carr carries 5086 sheet if you don't mind paying a premium.

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Mark

Can you use nylon screws and nuts, larger to compensate for weaker? You'd have less possibilities for galvanic corrosion.

As long as it's green, you're being good...

--
John

. . We use 5052H32 for the kids to make chassis out of at the college, so I've got scrap coming out my ears. That's not a bad idea; I can use the turret punch to stamp out dime size washers and then punch a clearance hole for the stainless wood screw.

Thanks...

Jim

I use small zinc screws (from ACE Hardware) for my BBQ handles so they don't rust outdoors. I don't know if the come in larger sizes.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave

Sorry for asking a dumb question, but why do you want to strap aluminum to a material that snacks on aluminum?

John

Sorry...the comment was MEANT to say that it eats aluminum that is in intimate contact and dries slowly (like an aluminum screw an inch or so into the pressure-treated) much more rapidly than the aluminum frame of the greenhouse that has pretty much of an air gap (however miniscule) all the way around.

The alternative is to use untreated wood and watch it decay in a few years.

Jim

her,

Hot/cold will make condensation inside, and rain will wet the outside. The corrosion problem is that wet wood attacks the metal by electrolytic attack.

So two solutions are: keep the wet wood from contact with the metal (use plastic washers or even just Tyvek housewrap where the two meet), or change the materials (a stained stick of cedar might last a long time even when wet).

There are coated 'deck screw' fasteners that tolerate treated lumber, which are less expensive than stainless. This suggests a layer of (for instance) epoxy paint on the aluminum where it contacts the wood.

A layer of sheet rubber, or roofing felt will keep the two apart. Vinyl tubing to protect the threads where they pass through the pressure treated material, and a little silicon grease to keep the fumes from the threads.

--
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Make sure all the parts that touch each other are the same metal eq

316. Put plastic washers between the screws and the aluminum.

Paint all the parts before you assemble the thing.

Use nuts and bolts and grease them before you put it together.

Use the special fasteners for use with the lumber.

Don't use the aluminum parts.

I vaguely remember "shouldered washers" to keep power transistor mounting screws from shorting the case to the heatsink.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave

Jim Thompson wrote in news: snipped-for-privacy@4ax.com:

I suspect that spray-on plastic truck bed liner stuff would work well for insulating and protecting the aluminum from corrosion.It's made to be out in weather and sunlight.

--
Jim Yanik
jyanik
at
kua.net

Better to use Aqua Lube as a grease. Silicon grease washes out pretty quickly in a wet environment.

Thanks for the thoughts, gang. What worked best were:

(a) Duct tape to "insulate" the bottom of the aluminum greenhouse frame from the pressure treated foundation ... and

(b) Home Depot "Deckmate" steel screws with a coating that I couldn't peel off or cut through with an exacto knife ... guaranteed not to corrode for life. (Couldn't get them to say my life or theirs, but what the hell {;-)) ... and

(c) The old standby dishwashing detergent as lube to make the screw want to go into the wood easily.

Thanks again for getting my thinking cap to make it happen.

Jim

--
"If you think you can, or think you can\'t, you\'re right."
        --Henry Ford


>>
>>   A layer of sheet rubber, or roofing felt will keep the two apart.
>>Vinyl tubing to protect the threads where they pass through the pressure
>>treated material, and a little silicon grease to keep the fumes from the
>>threads.
>
> Better to use Aqua Lube as a grease. Silicon grease washes out pretty
> quickly in a wet environment.