Bronze chain plates

[scherzoja]

I'm replacing the chain plates and am looking for a foundry to cast them.

Port Townsend Foundry is very slow at getting the quote to me and have more than 1 month back log.

Does anyone have a recommendation for a foundry to cast bronze chain plates in the US or Canada?

Thanks

[Orion Jim]

Just wondering why cast bronze rather than flat bar stock which is readily available and relatively easy to work with to produce your own.
Mystic River Foundry castings
These guys have vast experience working with small batch sailors needs.

[scherzoja]

Thanks for the referral to Mystic River.

All the shroud chain plates have two bends in them (6* and 5*) and backstay has a 26* bend. I can't bend 3/8 flat bar and don't know enough about bronze alloys to know how to bend it (and I don't have equipment to bend that thick of metal. If they were straight, I could get the flat stock. In addition, the holes are squared for carriage bolts and I've got too much on my plate. This is a job that is better to pay an expert to deliver.

Thanks again for the tip. I'll give them a call in the morning.

[Benz]

Any machine shop with a press brake can bend you some out of bar stock, and punch square holes in them. Probably lots cheaper than having them cast, esp. if patterns have to be made for each.
I made mine from 3/8" silicon bronze plate, cut with a plasma cutter at a local college, and bent on their press brake. The main ones have two bends: one out from the hull, the other around the chainwale. Not as elegant as a custom casting, but lots more affordable, and plenty strong.

[BillKny]

Seriously, you do NOT need to have something cast from scratch. That will cost oceans.

You need a machine shop to make these from bar stock. The square holes might be a challenge for home work (assuming they really are NEEDED), but even bending these isn't hard. Heat them red hot with a torch, and put them in a solid bench vise, and bend all in one go. It's not hard. I've done it.

[scherzoja]

Thanks y'all.

For bending, if the machine shop has a brake press capable of making the two < 10* bends and the one 26* bend, does the metal need to be heated before or after? Does making those kinds of bends in cold silicone bronze (3/8" x 1.75 or 2" wide) cause any stress cracks on the bend area? I can find a machine shop, but getting the silicon bronze is a little difficult here in lower Alabama. The carriage bolts are not needed, but wanted. I want to minimize outboard protrusions like with bolt heads because these are external chain plates.

Thanks for the advice. I'll check with machine shops for bending and square punching while I source the plate material.

[Benz]

Originally Posted by scherzoja

Thanks y'all.

For bending, if the machine shop has a brake press capable of making the two < 10* bends and the one 26* bend, does the metal need to be heated before or after? Does making those kinds of bends in cold silicone bronze (3/8" x 1.75 or 2" wide) cause any stress cracks on the bend area? I can find a machine shop, but getting the silicon bronze is a little difficult here in lower Alabama. The carriage bolts are not needed, but wanted. I want to minimize outboard protrusions like with bolt heads because these are external chain plates.

Thanks for the advice. I'll check with machine shops for bending and square punching while I source the plate material.

The material does does not need heating to press-brake bend it. You can work it several times before it fatigues, but a decent shop will make each bend right first go. It certainly can't hurt to torch it red-hot and let it cool afterward, but for one bend in each spot it's not necessary.
Alabama is no handicap to sourcing metal: you can get it shipped. I got my plate stock, 1/4" and 3/8" from a supplier in the midwest. Just google the key words.
After you see the price of bronze carriage bolts, you might change your mind and go with plain hex heads.....mine are such, and don't really offend the eye that much.

[scherzoja]

Thanks to y'all for steering me away from cast chain plates. It's been a while, but I found a supplier for 3/8" bronze plate (4 weeks for delivery), then found a place to cut and bend (7 weeks for them to finally get around to getting the job done, then another machine shop to cut the square holes (another 6 weeks).

Then it took me about a week to drill the round holes for clevis pins, round off the ends, and clean up the finished product. That's the way it is around here. If I can find someone to do the work, it takes weeks for them to get the job done. Sometimes, after delaying for weeks, they come back and say, they can't do the job after all.

Oh well. These are done and now I have to install them and watch them tarnish.

Thanks again for the tips.

[markxengineerin]

lookin good- do you know how they made the square holes? Hard to see but it looks like they might have a little radii in the corner, which would be a good thing, but probably doesn't matter either way.

[scherzoja]

I don't know what they used to make the square holes. The corners are round. I asked them to make rounded corners to decrease risk of stress fractures. It almost looks like a 1/32" drill bit in each corner, countersunk. When I approached them weeks ago and asked if they can punch square holes, their reply was that they don't punch, they cut square holes. Ok with me. the width of those square holes is ~0.52"

[AndyEss]

It looks like they used a milling machine to cut those square holes.

[VChild]

Curious to know who the bronze supplier was.

[scherzoja]

Bronze supplier is Atlas Bronze

C65500 HGH SILICON BRONZE "A" SPEC PLA
C65500 SILICON BRONZE PLATE 3/8" THICK
ASTM B96
061 TEMPER - ANNEALED
atlasbronze.com


Once done with the final round holes, I finished the surface with....

Angle grinder with abrasive disk to round the ends
Angle grinder with 50 grit disk to begin smoothing edges
Orbital sander with 80 grit to remove grinder marks
File rough edged and smooth our round ends
Hand sand with following grit sequence: 60, 80, 120, 220, 320, 360

I know they won't stay shiny, but at least it started out nice.

[Benz]

Good work: those will last beyond your lifetime now. They're gorgeous.
What boat are you putting them on?

[alaskanviking]

do you need a machine shop or a sheetmetal shop?

i am still waiting on PTF for a quote on aluminum bronze. it was the holidays so the emails kind of got sporadic. i was going to call them again. I'm not really worried about time right now as there is a lot more to do to the mast before i can focus on the chain plates. i had gotten a rough quote without specific dimensions several years before and we were talking ~$2000 - $2500 for 8 plates. i would prefer the aluminum bronze. the idea of having a local machine shop bend up silicone bronze really quick is becoming appealing.

i was going to use 5/8" silicon bronze, to keep the strength up, and to match the size of the turnbuckle toggle. spreads the load along the full toggle pin that way. I suspect that will require to be heat bent.

i have to run over to the machine shop for aluminum luff track this week, i think I'm going to draft up a quick rough drawing and see if they can do it. there is a metal worker/fabricator all the boatyards use and is very skilled but he doesn't do bronze, plates just stainless. didn't really think about the actual machine shop.