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Old 13-01-2018, 19:13   #1
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Silicon Bronze chainplate reassurance....

My old chain plates were ss 1/4 inch thick by 1 1/2 wide by 26 inches long. I made bronze ones from silicon bronze from online metals. They’re the same size but instead of 1/4 inch they’re 3/8 inch thick. I know I’m “supposed” to use forged bronze, I assume the 3/8 bronze sheet I got is not forged. So am I gonna be ok with these?i checked the specs for it it’s pretty close to 304 , other then the elongation I think was 13% vs 30%. After drilling the holes and bending it I was supprised how easily it bent and drilled and had me second guessing it. Any one care to weigh in?
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Old 13-01-2018, 19:57   #2
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Re: Silicon Bronze chainplate reassurance....

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Originally Posted by Eastward ho 24 View Post
My old chain plates were ss 1/4 inch thick by 1 1/2 wide by 26 inches long. I made bronze ones from silicon bronze from online metals. They’re the same size but instead of 1/4 inch they’re 3/8 inch thick. I know I’m “supposed” to use forged bronze, I assume the 3/8 bronze sheet I got is not forged. So am I gonna be ok with these?i checked the specs for it it’s pretty close to 304 , other then the elongation I think was 13% vs 30%. After drilling the holes and bending it I was supprised how easily it bent and drilled and had me second guessing it. Any one care to weigh in?
Should be good to go for hundreds of years. For all practical purposes it has a near infinite fatigue life. It has stood the test of time so I like it even better than titanium.
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Old 13-01-2018, 20:22   #3
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Re: Silicon Bronze chainplate reassurance....

If I were to survey your boat, I would find no fault with those.
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Old 14-01-2018, 06:03   #4
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Re: Silicon Bronze chainplate reassurance....

Well that’s good to hear.the ease of which it’s machined , cleaned , and bent had me nervous. Can’t see why any one would want to messs with ss compared to bronze. I wasn’t sure if it would cut on a plasma cutter , but it cut it nice and straight with no problems and it drills easily with a cobalt bit. I drilled 24 holes with one bit . The ss killed my 20$ bit after 2 holes.
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Old 14-01-2018, 08:50   #5
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Re: Silicon Bronze chainplate reassurance....

My experience drilling Stainless has taught me that a sharp bit, oil and steady consistent pressure are needed to keep the drill bit cutting and prevent the Stainless from work hardening.
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Old 14-01-2018, 08:59   #6
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Re: Silicon Bronze chainplate reassurance....

They don't need to be forged. BTW, 3/8" isnt sheet, it's called plate. Good job, I wold have went to 3/8 also. More bearing area for the pins.
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Old 14-01-2018, 12:25   #7
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Re: Silicon Bronze chainplate reassurance....

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My experience drilling Stainless has taught me that a sharp bit, oil and steady consistent pressure are needed to keep the drill bit cutting and prevent the Stainless from work hardening.


And slow speed, trick is to not generate heat.
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Old 14-01-2018, 17:21   #8
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Re: Silicon Bronze chainplate reassurance....

Thanks I’ll sleep better now. They sure are pretty
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Old 14-01-2018, 17:44   #9
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Re: Silicon Bronze chainplate reassurance....

I forgot to mention the carriage bolts that were there were facing inward so the squares are actually in the hull. I wouldn’t know any better but that doesn’t seem a sensible option in my head. So that leaves me with bronze hex cap bolts for mounting options. As much as I want to just put them in and sloop some caulk in there I’m thinking these holes need to be filled and re drilled or they’ll leak and creep up. Is this something I should be definitely concerned about?
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Old 14-01-2018, 18:19   #10
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Re: Silicon Bronze chainplate reassurance....

Put a round hole in the chainplate and a round bolt in it. DON'T make square holes in the chainplate. Carriage bolts are not suitable.
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Old 14-01-2018, 18:47   #11
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Re: Silicon Bronze chainplate reassurance....

Yes I’ve done that I’ve made the round holes and they line up and I’ve dry fitted the chainplates. But the hull has the square holes in it from where they used carriage bolts. I guess I shave to fill these in?
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Old 31-01-2018, 23:27   #12
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Re: Silicon Bronze chainplate reassurance....

How big are the square holes and what size holes do you anticipate in your new chainplates?

Iam confused a bit whether the existing carriage bolts are thru and thru or somehow embedded in the hull. Your new chain plates will be better off thru bolted clean thru the hull, with a backing plate on the inside for optimal strength. If you can find bronze bolts and nuts, all the better for a lifetime of service, to reduce possibility of galvanic (or crevice) corrosion because of dissimilar metals e.g. bronze chainplates & SS bolts.

With the square holes, if the fit is to sloppy for your taste, you can always close up,the existing holes with an epoxy or resin putty and drill them out when cured, using your new chain plates as a drill guide.

If you bed everything well with Dolphinite bedding compound, they won’t leak for 40 + years afterwards.
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