The Atkinson Differential Debacle, maybe

[jimsshop1]

Hi All,

So after building three different, (successful by the way) IC engines, I got interested in Mr. Gingery's odd but fascinating differential machine. After doing a lot of reading about casting aluminum and ordering a book about that, I decided to also order Mr. Gingery's book on How to Build the Atkinson Differential Engine. Well now let me tell you my friends this has so far been the most intensive and expensive model engine build yet for me! So far I have built three of the cope and drag boxes for the sand castings and speaking of casting patterns, have you ever carved a split wooden 6 spoke flywheel? Many hours in that piece, but the other patterns weren't so bad. That's all I'm going to tell you for now. Next time I will have some pictures of all the other parts I have made including the cylinder assembly which so far has been the most challenging and frustrating part of all to assemble.:fan: Until next time you all have a great day!

Jim in Pa

 

[Gordon]

I am also in the process of building this engine. I made all of the patterns and a local shop said that they would cast them for me. I have no interest in building a furnace and doing the casting myself and they said that it would be easy for them to do it. After waiting two months I finally gave up and just started making the engine from bar stock. At this point I am mostly done. I found a couple of problems in the drawings. See my posts

http://www.homemodelenginemachinist.com/showthread.php?t=27487

I have been doing 2D CAD drawings as I go along and making corrections as I go along. If it would help you I can send you my in process CAD drawings as long as you understand that you are on your own.

 

[jimsshop1]

Hi Gordon,

That looks very nice so far. Too bad about the casting place not coming through. Yes I would appreciate your updated drawings if you don't mind as I'm sure it will help me later. I too find it interesting that more builders are not interested in this engine. I am getting close the casting stage and since I have never cast before it could be another challenge to perfect. Today I melted and poured around 30 cupcake size pucks to get some of the impurities out of the aluminum as I am melting cutoffs and there is a lot of junk on the pieces. I cut some in half and machined one and they look good inside and machine well.

How did you fare making the cylinder? Did you have good luck with the brazing process? I had to make 2 as the first one was a piece of pipe and looked terrible.

Thanks again for your reply.

Jim in Pa

 

[jimsshop1]

I see what you mean with the valve body being too close to the shaft. If I have to move that valve body, I quit:redface2:

My email is [email protected] if you want to send the drawings and I appreciate your help very much. BTW, nice job on the flywheel, it looks cast.

Jim

 

[Gordon]

Drawings sent. Good luck.

 

[jimsshop1]

As promised here are some photos of my progress. I hope to melt and pour the castings tomorrow. I have built a flask large enough to melt 7 pounds of aluminum from the ingots I cast last week.I know this is enough to do all the parts except the flywheel. That will be last with a full flask and I hope it will be enough. Wish me luck.

Jim

Note: The cylinder on the left was a failure as I made it from 1" gas pipe. It was so out of round it would never work. At work I found a length of 4140 DOM, honed and polished. It turned out well so I just used a brake hone to break the glaze inside so the rings would seat better. Ordered rings from Otto today. I may just get this thing together sometime soon. Whether or not I ever get it running is another hurdle.

 

[jimsshop1]

I kind of moved this discussion over to casting and forging section and have posted more pictures and comments if any one thought I gave up

Jim

 

[jimsshop1]

It seems (not) a lot of the regular builders are into casting and I don't blame anyone for that! The whole process is very time consuming, labor intensive and dangerous to say the least especially when one is getting along in their "golden" years. So with that said, I'm back here to post a pic of where I'm at with this project after the casting experience. Thank you for looking.

Jim in Pa.