Runner material

[DN5135]

Can some one comment on 304 or 316 stainless for runners. Would we need to resharpen every time out, or will we get a few uses out of them inbetween sharpening. Also shoud I do 90 or 100 degree.

 I know 440C is the material of choice, but it is harder to work with for the home builder. We are in a area that is predominatly snow ice (soft). Also based on other postings, we are making 3/16" plates at 26" and 30" lengths. We are also making 36" x 3/16 inserts. I realize the plates aren't legal, but the train of thought is even if we did race, we are not likely to win! And the thinner crossection will be better on snow covered ice. We do also have several sets of Sarns plates, 440C 1/4" inserts, and 316 angle runners to fall back on.
 

[Bob Rast DN1313]

I have a set of 304 plates I made years ago 304 or 316 not much difference in hardness, Ken or some one can provide data. .These are good snow blade but will need to be resharpened
after a a day of hard racing or sliding around the leeward mark.   Depending on your weight I would stick to 90 degrees unless you like doing 360s or 180s.I use one for a steering runner which holds up real well ,you dont have the sliding on front runner which dulls them , for light air or snow or optis they would make a nice runner. I made a poor runner selection at the worlds one year on the last day and showed up with the 304 plates anticipating light air. Wrong started blowing closer to 22, made it around without any stunts and finished in top ten,
Moral of the story, bring all your good stuff to the starting line in a major regatta.

I think the 304 are not really any harder or better than plain steel which you might harden the edge with a torch The main advantage , Cheap to build, low maintenance

The one problem with the 304 is keeping them straight, they will bend but you can straighten with arbor press or hammer. I don't think  the 3/16 will work to well if you sail them hard they will definitely need straightening  more often . Any way have fun experiment.

Good luck
Bob Rast
DN1313

[Bob Gray]

  I built 2 sets of 26", 3/16" snow plates last winter and we used them extensively in all types of snow and wind conditions (several 200# sailors used them in heavy air). They don't hold an edge like 440c but they held up great structurally and couldn't be beat in any  deep snow conditions. There is a problem though and that is 3/16" plates aren't legal. I submitted a proposal for consideration this year to make the minimum thickness for plates 3/16" that would change that.
                                                                                           Bob

[Bob Rast DN1313]

I had a set of 3/16 304 inserts that I couldnt keep straight probably not enough strenght in the insert steel,
Bob Gray did you bend any 3/16 plates 304 ? I thought it might be too soft for a plate, Ive bent 1/4 " 304 plates

Thanks
rasty 1313

[Bob Gray]

  The 3/16" plates are made from 304 stainless and I also have a set of 304  inserts.  I've never had a problem with them bending. A friend of mine has a set of 3/16", 304 inserts that he sailed all last season and he weighs about 190 an they never bent. I built the plates out of 304  because I believe it's less strong then most carbon steels an I believe about 25% as strong as 440c. I wanted to see how these thin, not particularly strong plates, would hold up to some serious abuse and they did great. As far as sharpening goes, I touched them up with a stone after each use and they held up for the season (they were used about 10 times last year). If I were to make more of these plate I'd probably get some 1060 steel and have them powder coated after flame hardening.
                                                                                                       Bob

[DN5135]

Thanks for the comments guys!  We haven’t bought the steel yet and could still change. A friend of mine has access to the Teflon type fry pan coatings as well.

How do you flame harden?  Is it just a matter of heating to cherry red with a torch and then quenching in water?  For that matter, I could heat the entire blades in a furnace at work. I'd stand them on edge in sand. Would that work?

I like this idea. What steel did Sarns use, is that what I should be making mine out of?

[Bob Rast DN1313]

I believe Sarns use to flame harden i think that quenching in old motor oil is one way due to high amount of carbon in old oil?? The trick with hardening is not to hard the edge can crack or the blades can get warped.You can straighten most steel by using ball peen hammer and anvil or other flat steel you need to be careful not to break blade I  broke a 440 insert steel once giving it that one more good hit.


Good luck
Bob Rast dn1313

[Geoff Sobering]

The good news is that 304 and 316 stainless cannot be hardened by heat treatment (a property common to all 300-series stainless steels).

Heat treating stainless (ex. 440C) is typically a two-stage process.  In the first, the material is heated to a very high temperature (ca. 1850F), typically in a two-step process, and quenched.  This leaves the material in a very hard (and brittle) state.  The next step is to temper it in an oven, typically following a specific temperature/time program, to reduce the hardness to the desired level.  Warping is common in both steps, typically requiring a final surface-grinding operation to flatten the piece.

There are some air-quenchable steels (typ. tool steels) that are nearly stainless and much easier to harden (a one step: heat, then air-cool process).  I forget the exact types. 

Cheers,

Geoff S. - US-5156