Metal fabrication advice

[drcoastline]

I am looing for advice on the best approach to have the port lights in my boat reproduced. Best approach=cheapest.

After speaking with several experts regarding my boat. it seems the port holes in my boat were custom made by the manufacturer. Also from speaking with the experts it seems the body of the part was cast. They are made of aluminum.

I am not sure if casting is the best approach today? Maybe CNC or some other method is better? It also doesn't make a difference to me if the part is aluminum. It can be brass, stainless steel, or some other material as they will most likely get painted as opposed to chromed.

In addition to the aluminum housing you will see a brass plate that sandwiches the glass in place and is secured by brass screws. I am not sure why they used dissimilar metals? But these will be replaced with like kind material or at least something that will not cause electrolysis. The plate and screws are easy. I need advice on how to have the main housing manufactured.

Thanks in advance for your help and suggestions.

[id10t]

How many are there ? If more than 1, are they all the same?

Don't think 3d printed plastic would work... can you draw it out for an online service like https://www.emachineshop.com/ ?

[ckelly78z]

Find someone with a CNC table that can mill it out of aluminum, should take longer to determine/enter the measurments than it will to produce the new part.

[asphaltgambler]

^^^^ This^^

[LWJ]

I used to sell aluminum parts by the semi truck load. That is a big casting! Big = costly.

Milling isn't cheap either.

I don't have a basis for cost estimate on this other than to say expensive!

Can you fill in the port light opening or expand it for a standard size? Probably cheapest.

Do you need opening portlights? If not, you can do custom pretty cheap. I supplied aluminum to a custom sized port light manufacturer long ago.

This is a sticky problem and takes creativity. Last thought is weirdest but may actually work. What about 3D printing?

Good luck! Show us more of the project.

[Porchdog]

Just Guessing 12" x 6" x 1" - is that about right?

We would most likely water jet the basic shape and finish mill - in 3 different axis. By the time that's done the material cost is probably minimal - machining is expensive.

As asked above - how many do you need and how quickly? With basic dimensions I can probably get you a quote.

They probably used aluminum because of the ease of casting. I would want to anodize aluminum for that application. I suspect stainless or bronze would be about the same price for finished parts.

[herr_oberst]

I'm wondering why you can't refurbish what you have, (unless you are showing a good part and others are broken or corroded to the point where they aren't usable anymore?)

[Porchdog]

The refurbish idea could be a good one - if your parts can be welded. Welding cast aluminum can be tricky.

Even getting castings might not be as expensive as you might think.

[VincentVega]

Have you talked with Port Townsend? I have some of their stuff and its dead on. Not the cheapest though.

[stomachmonkey]

Originally Posted by herr_oberst

I'm wondering why you can't refurbish what you have, (unless you are showing a good part and others are broken or corroded to the point where they aren't usable anymore?)

Was my thought as well.

Depending on quantity that could be a two weekend six pack job with the six pack being the biggest cost.

Or send them to Shaun.

[drcoastline]

Hey guys,

Thank you all for posting. Your input is greatly appreciated.

The port holes are roughly 8"(H) X 16"(L) X 1" (T). There are ten windows of this style all together. We are refurbing what we can. Soda blasting to bare metal, repairing with JB weld and painting. At some point all the port lights were removed and stored. They were replaced with one inch thick Lexan. The Lexan is beginning to deteriorate and crack and does not properly seal. Not to mention they look like crap. I removed the Lexan lights and reinstalled the old lights with new gaskets. Unfortunately two are missing. If the price were right I would replace the ones in the worst condition plus the two missing. As for time? The sooner the better but what choice do I have? So however long it takes, it takes.

I am not opposed to 3D printing if the material will hold up to being dogged down. Heck I have even thought about trying to press a mold in some clay and filling it with JB Weld.

I have not spoken to Port Townsend but I will. There is a foundry in NC that I spoke to. I'm waiting on an answer.

LWJ- you can see the boat here. GM 671N Marine Diesel

[john70t]

Originally Posted by LWJ

That is a big casting! Big = costly.

For milling, do they only sell castings in blocks, or are hollow squares or custom pours available from the foundry or whoever sell those?

For 3D aluminum printing, it looks like measuring/scanning/paying for a custom print over the internet will get you results..for a price.
And even home metal printers are getting to be less than $4k:
https://www.bing.com/search?q=custom+3d+printer+aluminum+&qs=n&form=QBRE&sp=-1&pq=custom+3d+printer+aluminum+&sc=0-27&sk=&cvid=EFA31714F9AC40A2A1ED8E6FD336EC5B

[red-beard]

If you are going to have one milled from plate, there are shops that can use an imager to make an exact duplicate, except for finish.

Maker sure you use 5052 Aluminum, which is one of the most marine resistant alloys. 6061 plate is a bit stronger, and nearly as marine resistant. Either should work fine.

[Baz]

Originally Posted by VincentVega

Have you talked with Port Townsend? I have some of their stuff and its dead on. Not the cheapest though.

[Porchdog]

Castings would be essentially to size, just requiring clean up and polishing. Pattern making for the casting would be the greatest cost. If you are supplying a sample they can probably cast a resin pattern from it, which could be a bunch cheaper.

Since they were originally cast the sample will already have draft - the pattern guys will just need to add a sprue and vents. For that matter they might just be able to use your part for a pattern. There are still small foundries out there doing custom work.

They might even lost-wax cast a part like that - for the size I expect that would be more expensive.

There are also casting houses out there 3-d printing patterns. Since you have a sample I suspect that wouldn't be a savings.

I can model one of those for you. The cheapest 3-d printing is likely by Shapeways or a similar company. We have found found good strength with their "Strong and tough" plastic. I wouldn't be surprised if they want $400. each for those - but you pretty much need to submit your model and get a quote.

3D metal printing is still pretty expensive especially for something that large.

[jcommin]

none of the options are cheap.

IMO refurbish where you can -
If a replacement is needed - CNC machine with 5052 Aluminum as Red suggests.

[nota]

boat scrap yards for used parts ?

[tevake]

https://www.marinedepotdirect.com/bronze-rectangular-portlights.html

This came up in a Google search. Not sure if your dimensions are cut out or finish.

I'd be concerned with reusing old aluminum, it can be hard to keep finish on it long term once it has had corrosion. Some cast aluminum is better than others.

Let your admiral know it's great seeing her involved with the restoration work!

Cheers Richard

[drcoastline]

Originally Posted by Porchdog

Just Guessing 12" x 6" x 1" - is that about right?

We would most likely water jet the basic shape and finish mill - in 3 different axis. By the time that's done the material cost is probably minimal - machining is expensive.

As asked above - how many do you need and how quickly? With basic dimensions I can probably get you a quote.

They probably used aluminum because of the ease of casting. I would want to anodize aluminum for that application. I suspect stainless or bronze would be about the same price for finished parts.

Porchdog can you get me an estimate? If aluminum I need at east two as they no longer exist. But some are worn enough that it may be better to just replace them rather than try and restore them. I do like the Stainless idea. If the price were right I would get all ten in stainless.

Thanks

DRC

[JeremyD]

This is one of my clients - they do a ton of custom stuff for the SF industry

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