SS control cables

[svyolo]

I am trying to finish stuff up on the bottom of the fuselage. I noticed a couple of my little magnets that dropped to the floor had found a new home. Stuck to the control cables. I have some cable from both ACS and Wicks and it is all magnetic. SS shouldn't be, except for the absolute lowest grade which doesn't even really qualify as SS. I have a couple of 304 stainless (cheap) bits in my shop and they are non-magnetic. I am not sure if I have any 316 grade, which is better than 304. SS cables, control and structural, that I have used in the past were either 304 or 316.

Spruces catalog doesn't specificy grade.

[Archer39J]

The SS trim cable I have is magnetic. Stainless can become magnetic from cold working or machining, and probably from drawing out wire. I stuck with galvanized for the reports of SS cables wearing significantly.

[Battson]

There was a huge discussion about stainless steel vs galv. control cables for the Bearhawk. Try a search maybe, not sure where it was (maybe Yahoo)?

The conclusion was, IIRC:

- Stainless is only recommended for seaplanes, and suffers from accelerated wear.
- Galv was preferable most respects except corrosion performance.

I think I have stainless, I have had to replace several cables already.

[svyolo]

Spruce just references a MIL spec which I looked up and it just calls it "corrosion resistant steel". I stopped by a Marine store on the way home, magnet in hand. I knew they had some 316 SS. First couple of pieces were slightly magnetic. Next 2 or 3, zero. Slid down to some pieces labeled 304. Same deal. Some no magnetic, some strongly. I know for sure 304 isn't magnetic. Completely non-magnetic, as I recall.

I think this is what they call "Made in China, 2025".

[Mark Goldberg]

400 series stainless is magnetic. The 300 series stainless should not be. Mark

[rodsmith]

I have heard another disadvantage of stainless control cable is that it stretches more than galvanized. You can now buy pre-stretched galvanized cable from Spruce, which I did when I had to replace a too short cable.

[Battson]

The pre-stretched stuff is better, but it still gives a little eventually.

[zkelley2]

Spruce just references a MIL spec which I looked up and it just calls it "corrosion resistant steel". I stopped by a Marine store on the way home, magnet in hand. I knew they had some 316 SS. First couple of pieces were slightly magnetic. Next 2 or 3, zero. Slid down to some pieces labeled 304. Same deal. Some no magnetic, some strongly. I know for sure 304 isn't magnetic. Completely non-magnetic, as I recall.

I think this is what they call "Made in China, 2025".

Like Mark said, series 400 is magnetic. 200 is as well. 400 and 200 aren't necessarily "cheap" as in bad stainless. They have properties that can be desirable aside from being cheaper and are still corrosion resistant. Just less so. The 300 series is non magnetic in it's annealed state and slightly magnetic in it's hard state, something like cold rolling or work hardening will do that. 300 series knives are garbage for example of picking the wrong material for the job.
So you could pick up two different piece of 300 series and depending on how they were formed or used one could be slightly magnetic and one not at all.