In this thread above I saw a comment suggesting that Zamak would be unsuitable for a water environment. That got me curious. What I found was that zinc in Zamak evidently enhances the already very good resistance to corrosion of aluminum. Here is a link discussing Zamak and corrosion resistance: https://www.totalmateria.com/page.aspx?ID=CheckArticle&site=ktn&NM=162 "All zinc-based alloys have excellent resistance to corrosion in a variety of environments. In general terms, the presence of aluminum in the alloys enhances the well-known corrosion resistance of zinc, which is the main constituent of the alloys." Denis
Make the core symmetrical in the plan view so you only need one core box. I use oil bonded cores and bake them on core plates so I have a dead flat surface to join the two halves. On larger cores I will hollow out as you show and add multiple vents.
Thanks Everyone! I found most of my missing mass, I used a ruler instead of a caliper to measure thickness, so I was under .031"(.8mm) on the measurement of the flat faces. Revised core print/box/core per ESC's suggestion below.
Well, let's get on with it! Just kidding. But, following with interest as others have mentioned. Denis
LOL, thanks Denis. In a perfect world I'd have the patterns done for this coming weekend's foundry get-together. In my world I am on 'light duty' due to surgery this weekend, busy at work, and behind on boat repairs so it may become an off-season project.
Have you definitely abandoned lost foam for this? After seeing Kelly's work I think that would be doable and not too hard.
Outstanding Kelly! I really appreciate the tutorial, thanks. It would be very informative to see how you would gate it in consideration of the thin sections.
While the scrap box was sitting next to the hot wire, I figured what the heck and just pieced together the feed system. Took 15 minutes, most of which was me scratching my head, the rest cutting and gluing. It will still have all the short comings of the original design you mentioned. I could add a few strengthening ribs. Best, Kelly
Amazing work in a more amazing time interval! Those ribs might damage the transom when the rudder is turned? It can go pretty much to 90 deg. I would keep them low profile. What do you say Tops? If they don's stick out past the spring pins that should be fine.
Running into a meeting, when I get out...I will try to assemble the existing to the boat and take some pics.
I’m gonna have to mess with some lost foam. Hey I assume it will not work for brasses due to the density far exceeding the sand?
Brasses and Bronzes are commonly done with LF. In fact, Iron may be the most common commercially. Patterns need to be burried at a reasonable depth and consideration to minimize the projected pattern area toward the flask surface. Are you thinking figures or machining blanks? Best, Kelly
Seems like the rig has a good amount of 'projection' from the transom. The motion is limited by the bridle that is the traveller for the mainsheet.
This was just for demonstration purposes for me, but assuming it casts successfully, you can have it if you want it. It would just take a couple minutes to make and stick on the Force 5 style reinforcing ribs. CrazyBillyBob is right though, it would cast much more easily at 3/16-1/4" thickness and naturally be stronger. If it was thicker, I would have just gated into the two bosses and called it a day. It may have cast as is that way. If you are going to make tooling, would you make it identical to a part with a known weakness? Best, Kelly
I'd be honored to have it. You'd have to sign it like ' Now stop watching YouTube shorts and go make something-KC ' The actual piece is about 1/32" (.8mm) thicker than what I first drew. There were about 160k boats made with the aluminum piece and it was replaced 24 years later with the plastic one. Remember when cars had all metal radiators? The change to plastic could have been a cost down measure and as a means to get them to hold up better in salt water. I would have to ask the old-timers if/what the real world failure modes were for these. I wish I had the chops to study it for forces and failure in CFD and FEA and then feed that info into something with an iterative or generative design function that would add and subtract materials to make an idealized part.
