Brass vs Silicon Bronze

T

Tom Widney

LOVES Wooden Canoes
Another basic question. Marine fasteners seem to be available in three basic types, Stainless Steel, Brass and Silicon Bronze.

I realize that Stainless is not typically used in WC canoes and that Brass and Silicon Bronze seem to be the fasteners of choice, but the SB is about twice the price of brass... are the benefits of Silicon Bronze worth the added cost?

Could someone expound on the merits vs drawbacks of all three types of fasteners so I can spend my hard earned $'s wisely?

Thanks for the basic lessons in boat building guys, I couldn't do near as well at this hobby with out it.
Tom
 
Silicon bronze is significantly stronger than brass, and is the better choice for structural fasteners. Brass will also undergo dezincification if the boat is used in salt or brackish water, resulting in rotten fasteners. I only use brass screws when fastening stem bands. Old Town's diamond head bolts are brass, but are a size larger than the bronze carriage bolts many builders use.

Stainless steel can be used, but it just looks wrong on a traditionally built canoe, and really wrong on a restoration.
 
In a nut shell:

SS is ugly, can, and will rust.

Brass is softer than silicon bronze and corrodes when exposed to salt.

Silicon Bronze resists salt corrosion. It’s stronger than brass, and does not rust. Yes a little more money for some sizes but its’ benefits are worth it.

There are a few suppliers of cut thread which are superior to the rolled version.
 
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A minor correction,

Rolled threads are superior to cut threats, as they are stronger and much better able to withstand stresses in fatigue due to the smooth surfaces. The cold working and grain flow also help.

Dan


"of cut thread which are superior to the rolled version"
 
Whichever one you believe to be stronger, buy the proper tapered drill bit, like a Fuller countersink/counterbore for that particular screw size and things will usually go quite well. Straight-sided pilot holes don't compare well to those made by tapered bits.

The most important real-life thing you can know about the brass vs. bronze screw question is that an alarmingly high percentage of brass screws will usually shear off during installation into hardwood. Bronze is far less likely to do this and once you have had to dig out a couple broken screws while trying not to tear-up the wood around it, you'll be done with brass screws.

If you do have to use one, drive a steel screw of the same size into the hole first, then remove it and screw in the brass one. You may also find that a little bit of soap on the threads makes them drive easier and makes breaking screws less likely.
 
Todd Bradshaw said:
Whichever one you believe to be stronger, buy the proper tapered drill bit, like a Fuller countersink/counterbore for that particular screw size and things will usually go quite well. Straight-sided pilot holes don't compare well to those made by tapered bits.

The most important real-life thing you can know about the brass vs. bronze screw question is that an alarmingly high percentage of brass screws will usually shear off during installation into hardwood. Bronze is far less likely to do this and once you have had to dig out a couple broken screws while trying not to tear-up the wood around it, you'll be done with brass screws.

If you do have to use one, drive a steel screw of the same size into the hole first, then remove it and screw in the brass one. You may also find that a little bit of soap on the threads makes them drive easier and makes breaking screws less likely.
Click to expand...

+1. But we prefer beeswax to the soap for corrosion resistance.

Rolled threads are usually work-hardened by the process. whether brass or bronze, but bronze has a greater toughness.
 
My statement about cut threads being superior is directed toward silicon bronze wood screws.

I have started a new thread titled cut vs rolled thread that begins to explore this topic.
 
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