Re: bending brass grab irons


Michael Watnoski
 

Hi Rob,

I always bend my own grab irons. It seems that the commercial never match exactly. Many of them use too heavy wire or a material that is too hard to clip without chipping my good wire cutters. Also drop grabs have the wrong dimensions or wide radius bends.

I use a pair of needle nose pliers with a piece of tape on the inside of the jaws. Just set the wire against the tape and roll the jaws on a hard surface for a sharp bend. bend with fingers for a slightly larger radius.

You have found the main problem with Detail Associates wire. It develops a temper in the wire making process. Bending it adds work hardening which makes it brittle. It can be annealed by heating it slightly with a butane lighter at the bend point. Unfortunately, there is very little control of the amount of softening. You also don't want to soften the whole grab as it won't hold its shape when handling.

My suggestion is to skip the DA brass wire and use the Tichy phosphor bronze wire. This has a consistent hardness that will not change if heated. It can be bent multiple times without cracking. It holds a straight line well and bends easily. The springiness is handy for making electrical pick ups.

Michael

On 3/20/2012 2:00 AM, Rob Kirkham wrote:
I'm working on a Speedwitch model of an Erie 70000 series boxcar. The
ladders have relatively shorter rungs, so I am bending my own (about scale
16" length). Using DA .008" brass wire, I find some of them break at the
bends as a result of metal fatigue. While I can bend plenty, so will
eventually get enough for the model, I'm wondering if heating the brass wire
before bending will do anything to make it take the bend with less
brittleness?

If you have experience on this topic, I'd like to hear about it.

Rob Kirkham





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