Custom rudder mock up
Printed From: CorrectCraftFan.com
Category: General Correct Craft Discussion
Forum Name: Off Topic
Forum Discription: Anything non-Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=18060
Printed Date: January-10-2025 at 10:44pm
Topic: Custom rudder mock up
Posted By: Luchog
Subject: Custom rudder mock up
Date Posted: June-14-2010 at 11:55pm
I need to make a mock up on this rudder so I can have one casted.
I need thoughts on materials and techniques to do it. thanks in advance. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique Commander 351W |
Replies:
Posted By: kapla
Date Posted: June-15-2010 at 1:02am
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first you need to grind off that MC script..then wait for more advice from the experts..LOL ------------- <a href="">1992 ski nautique |
Posted By: 79nautique
Date Posted: June-15-2010 at 12:15pm
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Doesn't seem to brite of an idea since they are pretty readily available to buy finished all ready.
------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: Luchog
Date Posted: June-15-2010 at 1:44pm
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It's not that simple Chris, it would end up costing around U$D700, and it has a big chance of not passing customs, in that case I shall travel 200milles to "talk" it through, and maybe it doesnt work.
Also I'm interested in doing the experience on the whole process of building the model, have it casted and fine tune it after. That way I learn, the other I just toss money around. If it takes time to have it done, I dont mind, I have plenty of it. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique Commander 351W |
Posted By: behindpropeller
Date Posted: June-15-2010 at 1:56pm
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How many are you making?
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Posted By: 8122pbrainard
Date Posted: June-15-2010 at 2:08pm
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Luch,
Use a closed grain wood and Bondo for the mock up then a couple coats of lacquer to seal it. Since it's a pretty simple casting and your not going high production, the foundry will be then able to hand form the parting line in the green sand. Figure on a shrinkage of 5%. Are you thinking of having the shaft cast as part of the rudder or doing a "overmold" onto a pre made shaft? The overmold gets tricky with casting and the pattern becomes more complicated. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: 79nautique
Date Posted: June-15-2010 at 2:55pm
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Pete it seems like starting from a forging would be the easier route, don't see where the casting is going to have enough strength in the shaft area or even overcasting it, doesn't leave much meat around it. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: kapla
Date Posted: June-15-2010 at 2:59pm
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buy a nautique style from guglieme..they sell for 300 dollars..they even come with the tunable plastic fin... ------------- <a href="">1992 ski nautique |
Posted By: Luchog
Date Posted: June-15-2010 at 9:16pm
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Pete, I think I was looking for your advice on this matter.
I'm yet to talk to the foundry guy to see how he wants the model to be made regarding the shaft, my idea is that he could cast it around a stainless steel shaft. Would that be overmolding it? I expected around 3% shrinkage. My plan is to cut 2 templates and fill them in between with some plaster like material, from there sand and grind as needed. What do you think? 79: what if the shaft has a few holes or patterns inside the rudder to "grab" on the casting? Behind the prop: One for starts, but if I get it right maybe I could sell some around here. Kapla: if my costs are too high I will consider it. As I just told on the phone, I feel this rudder will fit better the boat I plan on putting it on. thank you all for the input, keep it coming. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique Commander 351W |
Posted By: Luchog
Date Posted: June-16-2010 at 9:31pm
Based on this drawing I found on the internet...
I got this template  ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique Commander 351W |
Posted By: 8122pbrainard
Date Posted: June-17-2010 at 9:25am
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Luch,
Yes, the "overmold" is casting the blade over/around a stainless shaft. Talk to you foundry first because as mentioned, the process can be tricky with pour temps. If he does do it, it may take him a couple of tries/experimenting!!! The shaft may need some preheat. The stainless shaft would have small "wings" welded onto the shaft in the blades bossed area. They don't need to be very big. They transmit the torque better the a hole which doesn't allow for much shear. Talk to your foundry on how he wants the pattern made exactly. I've done some sand casting and on a short run it's easy to had cut the parting line so a split pattern isn't needed. If overmolding the shaft, you'd make the plus 5% pattern in the blade area but leave the shaft at the 1". He'd make the mold halves, open it up, drop the stainless shaft in and close up the mold. If you cast as one piece, then I'd give the shaft more than 5%. 10% extra will ensure there's plenty there to machine. Chris, I agree that a forginging sure would be stronger but they are all cast. The boss around the shaft to me looks like there's plenty of meat to do the job. EDIT: Luch, Have you considered just having one fabricated? CC was doing it on the 176's when they wanted to "detune" the hull because per Jody, the 176 was outperforming the 196!! CC couldn't find a small off the shelf rudder. Also, if cast in one piece, you'd better talk to your machine shop. There's going to be some fixturing needed to hold the rudder for machining the shaft. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: eric lavine
Date Posted: June-17-2010 at 10:01am
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i would think it would be as cheap machining a rudder out of a 2" piece, at the top bore a hole and clamp the shaft???? ------------- "the things you own will start to own you" |
Posted By: Luchog
Date Posted: June-17-2010 at 12:31pm
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Pete, phoned the foundry guy, he said to add or draw patterns into the shaft so it could grab better in the cast, he estimated shrinkcage by 1%!!!
The 2 issues holding me, we didnt discuss price yet, and, he told me something odd, that there's a need for a 3/8'' clearance on the thinnest part of the piece the cast can pour correctly. So, I might be taking another rudder so he has a better idea of what I want and can quote me accordingly. As 79 suggested looked for something already finished and found a U$D250 offer for a complete rudder assembly, which would end up costing U$D500 shipped home. Also called a local shop, they wanted U$D1000 for a complete stainless steel rudder assembly. Eric, I was wondering the same on the machining. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique Commander 351W |
Posted By: behindpropeller
Date Posted: June-17-2010 at 12:56pm
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I also think you could machine it for one piece less expensive.
1000 doesn't sound bad once you figure in the 100 hours of your time it will take to get the first part done. Tim ------------- |
Posted By: Luchog
Date Posted: June-17-2010 at 1:24pm
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Tim, dont take time in the acount, I wish I had U$D500 laying around to toss on a new rudder and not that much free time. Right now that money is for other more specific parts on the project.
I think I can have it correctly done for much less, that's what I pretend to find out. Costs wise, what's your thought? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique Commander 351W |
Posted By: behindpropeller
Date Posted: June-17-2010 at 2:01pm
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Hey....
Your drawing is missing a key dimension....shaft length(out of the rudder) or rudder height. ------------- |
Posted By: 8122pbrainard
Date Posted: June-17-2010 at 2:31pm
Luch, Ok, he's (and yourself) talking casting in Stainless reflecting the 1%. The 5% is for copper/brass alloys!! Machining flutes parallel to the length of the shaft would be another option for a "gripping" surface in the blades bossed area. Probably even better because I don't fell it would produce as much stress as the welded on tabs. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Luchog wrote:Posted By: 79nautique
Date Posted: June-17-2010 at 2:36pm
your going to have a hugh surprize when you talk price, think how much energy it will cost just to melt the alloy to pour in the green sand mold, Are they going to cast this under vaccum? you don't want any porousity around the shaft area or it will snap in two pieces, the 500 is looking much better than having a custom one poured and then machined. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: 79nautique
Date Posted: June-17-2010 at 2:38pm
you need a lesson on reading prints ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: behindpropeller
Date Posted: June-17-2010 at 2:41pm
Looked again, didn't have that portion in the screen since it was scrolled down. ------------- |
Posted By: Luchog
Date Posted: June-17-2010 at 3:23pm
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The shaft will be measured regarding the boat in question, which hopefully will be here to work on in 7-10 days. If going the all custom route, I have many options for the base and packing gland or not.
79, yes, those U$D500 are a big chance at this moment, but first I will ask around. That's still free. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique Commander 351W |
Posted By: kapla
Date Posted: June-17-2010 at 5:52pm
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Hey luch
so..you picked your boat? I planned an asado for you....let me know kapla ------------- <a href="">1992 ski nautique |
Posted By: Luchog
Date Posted: November-08-2010 at 10:59pm
Finally...
 ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=2095" rel="nofollow - 1980 Ski Nautique Commander 351W |