Chainplate Fabrication

Sep 29, 2016
72
Lord Nelson Lord Nelson 35 3 Full time cruiser
After paying almost $400 to have 2 chainplates made I decided I was doing the other 4 myself. I ordered 6 feet of 316L from www.onlinemetals.com for $76.98. That price included the shipping.
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Careful measurements of the old chainplates were taken.
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The metal was cut to size and the tops were rounded with a flap disc on a grinder. I was actually surprised how well it worked using a flap disc.
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The cut to size pieces were then marked for drilling.
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They were drilled (slowly) on a drill press using carbide bits and cutting oil.
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After all the holes were drilled the process of polishing began. I started with 80 grit flap discs on a grinder to remove the mill scale then moved on to a 120 grit flap disc. I couldn't find any flap discs finer than 120 grit so the next step was done with 220 on a random orbital sander then 320 then by hand using progressively finer grits wet sanding through 2200. A final polishing was done using barkeepers friend powder mixed with water to a paste consistency on a microfiber rag. The old backing plates were still serviceable so they were polished and reused.
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Tedd

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Jul 25, 2013
745
TES 246 Versus near Vancouver, BC
Nice work!

If you have a bench grinder, you might try a Scotchbrite wheel for medium polishing and jeweler's rouge with a cloth polishing wheel for final polishing. I think you can get all of that at Harbor Freight.

Tedd
 
Apr 5, 2009
2,774
Catalina '88 C30 tr/bs Oak Harbor, WA
When you get all done with fabrication, make sure that you passivate the surface. Any stainless steel that has been in contact with mild steel will begin to get surface rust from the active steel on the surface. I use Wichinox but there are other choices. Here is a good technical article
 
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dLj

.
Mar 23, 2017
3,373
Belliure 41 Sailing back to the Chesapeake
When you get all done with fabrication, make sure that you passivate the surface. Any stainless steel that has been in contact with mild steel will begin to get surface rust from the active steel on the surface. I use Wichinox but there are other choices. Here is a good technical article
Nice to see someone actually posting a useful link on this subject. The standard that passivation is done to is ASTM A967. The article referenced skims that standard to a degree. But also adds in some of the cleaning steps that should be followed not explicitly covered in the standard. Those cleaning steps can be proprietary, in fact they mostly all are. A couple things not covered in that article - water used with solvents needs to be deionized or distilled water, tap water won't cut it. Using citric acid baths are really easy, but there are some caveats. If going that route I'd recommend using a commercially available product rather than trying to concoct your own formula. For small parts they make a paste that you could use, really simple and easy to use.

For what's it worth....

dj
 
Sep 29, 2016
72
Lord Nelson Lord Nelson 35 3 Full time cruiser
The only other metal it was in contact with was the carbide bit, however the barkeeper's friend used to polish in the last step contains oxalic acid which helps the stainless to passivate.
 

dLj

.
Mar 23, 2017
3,373
Belliure 41 Sailing back to the Chesapeake
The only other metal it was in contact with was the carbide bit, however the barkeeper's friend used to polish in the last step contains oxalic acid which helps the stainless to passivate.
Nope. You clamped it down on your bench with C clamps visible in your original photos. It's actually amazing where contact with iron based materials happens throughout the whole process.

dj
 
Sep 29, 2016
72
Lord Nelson Lord Nelson 35 3 Full time cruiser
Nope. You clamped it down on your bench with C clamps visible in your original photos. It's actually amazing where contact with iron based materials happens throughout the whole process.

dj
I suppose that is true.
 
Apr 5, 2009
2,774
Catalina '88 C30 tr/bs Oak Harbor, WA
Nope. You clamped it down on your bench with C clamps visible in your original photos. It's actually amazing where contact with iron based materials happens throughout the whole process.

dj
That photo was the reason I posted. When I bought new standing rigging for my C30, all of my new shinny swedges started turning red after the first rain. I called the rigger and he said that it was completely normal but that didn't work so well for me. I did some research and found out about the Passivate thing. I got a tube of Wichinox and wiped it on the swedges, waited 15 minutes and washed it off. Now 5 years later it is still as shinny as when it came out of the box. I have attached some photos of my dodger hardware before and after treating. This was wipe on with terry cloth and hose off with no rubbing or polishing.
 

Attachments

Jun 5, 2010
1,107
Hunter 25 Burlington NJ
Wipe the stainless down very very well with solvents and rinse with water, then blot/air dry. Any residue from the metal in the grinding discs will encourage rust later - yes; even with 316 stainless.

Factory spec for nearly every production boat I can think of is typically 304 stainless for chainplates, due to cost and ease of working the material. 316 is overkill - EXCEPT if your 304 is coming from Asia, from which really bad 304/18-8 SS is noted, in which case 316 (if material must come from Asia) is the only option.

Good US-made 316 can be had from Metals Depot and US Metals; but caveat emptor, so always ask specifically and get certification documents.
 
Sep 29, 2016
72
Lord Nelson Lord Nelson 35 3 Full time cruiser
All good advice Diana. The discs used were non metallic. 36 grit zirconia flap discs actually and the source for the metal did in fact supply the mill test report.
 
Apr 5, 2009
2,774
Catalina '88 C30 tr/bs Oak Harbor, WA
Ever wonder why you start to see a light redness on your brand new SS screws within a few weeks of installing them? :banghead:
My understanding is that rubbing any carbon steel item against stainless can cause the steel to become active and get surface rust. That is the red blush you often see on SS. I was told that a long time ago by another boater who suggested the Wichnox to me. Since then, when is see some of the red on SS, I hit it with the Wichinox and the problem goes away so does not come back any time soon. I have since heard of another "Passivation paste" that also seems to work and if my stock runs out I might look there.
 

dLj

.
Mar 23, 2017
3,373
Belliure 41 Sailing back to the Chesapeake
@Hayden Watson said it well above. The passive oxide layer is disrupted and you can get a tiny amount of iron transfer between your carbon steel tool and your stainless. Those don't allow the passive oxide layer to form in those areas, and these particles themselves rust easily making for more problems.

The paste alluded to above, at least the one I know of, is great stuff! It's a citric acid based paste, very easy to work with and quite effective.

All this said, who uses plain carbon steel wrenches anymore? You find it more in clamps, vises and those kinds of tooling in today's world.

You still should work clean and passivation cleaning is often overlooked. But if you just tightened up some nuts with modern tools, you probably don't have much to worry about.

dj
 

dLj

.
Mar 23, 2017
3,373
Belliure 41 Sailing back to the Chesapeake
@DianaOfBurlington the concerns expressed about Asian supplies no longer really applies in today's manufacturing of stainless steels. Some years ago, they were having problems in producing stainless. But with the new technologies in refining stainless steels those problems are really a thing is the past. It used to be difficult to produce the L type 304 and 316. In fact you had to specify you wanted either 304/326 or 304L/316L. And the L variety would cost more due to the difficulties in producing that version. However that is no longer the case. New technologies have made both quite controllable to produce.

If you are getting stainless steel for sure get certifications with the material. But I really wonder how many people actually understand how to read them. Not armed with that knowledge, they are pretty useless. I guess they do make the supplier think a bit more but that's about all I can think of that it does for you if you personally don't know what the values are that the material needs to meet.

dj
 
Apr 5, 2009
2,774
Catalina '88 C30 tr/bs Oak Harbor, WA
...
All this said, who uses plain carbon steel wrenches anymore? You find it more in clamps, vises and those kinds of tooling in today's world.

You still should work clean and passivation cleaning is often overlooked. But if you just tightened up some nuts with modern tools, you probably don't have much to worry about.

dj
I find that the #1 culprit is those darn driver bits that are used for everything. They are all carbon steel and most hardware attachments use either phillips, allen, star or torx. I have just tried to get into the habit of a quick passivation after any install.
 

dLj

.
Mar 23, 2017
3,373
Belliure 41 Sailing back to the Chesapeake
I find that the #1 culprit is those darn driver bits that are used for everything. They are all carbon steel and most hardware attachments use either phillips, allen, star or torx. I have just tried to get into the habit of a quick passivation after any install.
Excellent point - as I hardly ever use these - they slipped my mind. Spot on! (pun intended)

dj