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Post by Johansson on Sept 24, 2012 0:05:07 GMT -5
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sven
Veteran Member
Joined: February 2012
Posts: 102
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Post by sven on Sept 24, 2012 10:11:37 GMT -5
Nice video, but dont see pics:/
Sven
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Post by Johansson on Sept 24, 2012 14:11:31 GMT -5
I know, I have no clue why the damn pics won´t show. They show just fine on a swedish motorcycle forum and if you click the links you will see them.
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Post by racket on Sept 24, 2012 15:40:32 GMT -5
Hi Anders
Looks good :-)
You'll be getting orders for those .
Cheers John
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Post by Johansson on Sept 25, 2012 0:05:56 GMT -5
Hi John, At least no one can accuse me of buying all parts for my bike. As soon as I sort out the lost foam casting I will be able to make heaps of stuff, right now I am considering to skip the plaster coating since the gasses have nowhere to go but up through the pouring sprue which causes lots of smoke and bubbling. Without the plaster shell the gasses vent out into the sand and the result is a much less violent pour, the downside is a slightly rougher surface but since I can machine the surfaces that needs to be within specs it only gives a nice texture to the surface. Another option is to give the pattern a thick layer of plaster coating and then use acetone to melt the styrofoam inside it, this leaves an empty shell which later can be burned to remove every bit of plastic. This procedure is similar to the lost wax method and leaves very fine looking castings. Cheers! /Anders
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wolfdragon
Senior Member
Joined: April 2011
Posts: 287
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Post by wolfdragon on Sept 25, 2012 6:50:14 GMT -5
I would go the acetone route simply because it only alters your current procedure by a small amount. The only issue with going the no plaster route is getting the sand packed well enough to hold up during the pour, a feat that I have seen turn out quite horribly...
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Post by Johansson on Sept 25, 2012 11:49:09 GMT -5
Won´t the acetone damage the plaster shell?
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wolfdragon
Senior Member
Joined: April 2011
Posts: 287
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Post by wolfdragon on Sept 25, 2012 16:43:35 GMT -5
that warrants an experiment to see...
I have seen 50/50 plaster and silica flour work in a lost foam with acetone melt before
Provided that the plaster when completely dry can candle the exposure to acetone, there shouldn't be any problems...
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Post by Johansson on Sept 26, 2012 0:24:22 GMT -5
I have made three identical styrofoam parts to see which method that works the best, the first one will be put directly in the sand, the second will be coated with plaster just like the gearbox was and the third one will be coated and then have the styrofoam melted away with acetone.
Should be interesting to see the difference between the cast parts.
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Post by Johansson on Oct 7, 2012 14:37:55 GMT -5
I did the casting test today and to my surprise the pure styrofoam part turned out best while the plaster covered one with acetone poured into it was a complete mess. The pure styrofoam pour (the one to the left) didn´t burn or smoke at all leaving me to believe that it went bad somehow, the other two pours burned and smoked and had lots of gasses coming up the sprues while pouring. Here is the pure styrofoam casting, best result with sharp corners and a perfect looking sprue. Here is the plaster coated styrofoam casting, almost as good as the uncoated one but the sprue didn´t look nearly as good. Most likely caused by the escaping gasses during the pour. And finally the part that I had the highest expectations for, I don´t know what happened but it bubbled and smoked like mad while pouring and the result is a complete disaster. The part had been left to dry for an hour in front of a heating fan after the acetone pour and after that it has been sitting on a shelf inside my house for over a week so it couldn´t have been wet. The result is very good since the easiest and by far quickest way to do lost foam casting turned out to be the best, it takes only a couple of minutes to cut out a styrofoam pattern and several days of coating and drying to get a thick plaster shell around it. Can´t complain about the details either, the corners are just as sharp as they were on the styrofoam pattern. Cheers! /Anders
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wolfdragon
Senior Member
Joined: April 2011
Posts: 287
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Post by wolfdragon on Oct 7, 2012 19:08:59 GMT -5
That's quite surprising... At least now you know which one works best for you
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Post by Johansson on Oct 7, 2012 23:55:05 GMT -5
Surprising indeed, at least now I have tried all three methods at the same time so no difference in pouring temp that could mess up the result.
The question is how a larger styrofoam pattern will turn out, but the only way to find out is to try I guess.
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Post by Johansson on Oct 13, 2012 14:20:34 GMT -5
Finally some progress on the JU-01 build! My friend Lars-E donated a chunk of SS2343 which I need to finish the power turbine housing. And I finally got the order confirmation for the angle drive, it cost me 1100 euro but if it works it is worth every cent. Cheers! /Anders
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nersut
Veteran Member
Joined: September 2012
Posts: 223
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Post by nersut on Oct 28, 2012 3:00:37 GMT -5
Hi Anders How far are you with the power turbine part? I bought a Allison Rolls Royce 250 3rd turbine wheel too from eBay for 78$ in auction & a am very interested how in you are going to build yours. And I am still searching for a cheap 3rd nozzle guide for the turbine. I don't have all the cool tools & machines you have & not to mention skills to fabricate my own. Looking forward to see your power turbine build. Cheers Erik
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Post by racket on Oct 28, 2012 4:01:11 GMT -5
Hi Erik You'll probably find that your 3rd stage wheel will require a much larger gas producer than your current DIY engine if you wish to use full annulus entry into the turbine wheel , you'll only be needing ~half the annulus if using a ready made NGV stator , stators don't come up for sale very often as they're not a "stressed" part that needs to be time expired like a turbine wheel . Theres pics of what I made for my 3rd stage wheel here www.ivcity.com/john/index.html , you might only need to fabricate a semicircular scroll duct to feed half of the turb wheel . Cheers John
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