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Post by Johansson on Nov 3, 2012 2:05:20 GMT -5
You should see my "shed" at the moment, it is filled with three motorcycles in different stages of completion, the rocket engine test bench, furnace, foam cutter, an old dish washer used as small part cleaner etc etc so I have finally settled in so to speak. To get more stuff in there I have to throw out something else. I will measure the shafts next time I have time, today my mother-in-law is visiting and will take care of the kids so me and my feancee can get some quality time on our own. It feels like ages since just we two went to a restaurant and ate in peace and quiet.
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Post by Johansson on Nov 3, 2012 16:33:00 GMT -5
I assembled the gearbox tonight, no shims used or anything since I only need it to mock up the drive line at this point. Primary gear in place. Pressing a bearing onto the outgoing shaft. Both shafts in place! Aaaaaand....done! Here is the complete drive line mocked up, it will be a pretty compact unit. Closer. From the front. Cheers! /Anders
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Post by racket on Nov 3, 2012 22:19:12 GMT -5
Hi Anders
Scaling off the gas producer , thats a solid gearbox..............fine german engineering ;-)
Cheers John
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sven
Veteran Member
Joined: February 2012
Posts: 102
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Post by sven on Nov 4, 2012 15:56:26 GMT -5
Looks good, really solid gearbox indeed.
Sven
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Post by Johansson on Nov 4, 2012 16:50:39 GMT -5
A very nice gearbox indeed, I need it to be solidly built since it will take up all force from the chain drive.
The gas producer will be freely moving axially on the lower frame tubes so the freepower duct can expand from the heat without anything buckling or cracking so the gearbox will be the only fixed part in the driveline.
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nersut
Veteran Member
Joined: September 2012
Posts: 223
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Post by nersut on Nov 4, 2012 17:16:16 GMT -5
Hi Anders That gearbox looks strong & solid! The gear set looks like a "super-sized" angle grinder reduction drive. Will the gearbox be further back to accommodate a exhaust gas duct/deflector? Cheers Erik
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Post by Richard OConnell on Nov 6, 2012 3:58:32 GMT -5
Haha Erik, I think each of your 3 comments matched mine in the same order Great work Anders!
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Post by Johansson on Nov 6, 2012 13:43:25 GMT -5
Hi Anders That gearbox looks strong & solid! The gear set looks like a "super-sized" angle grinder reduction drive. Will the gearbox be further back to accommodate a exhaust gas duct/deflector? Cheers Erik Thanks Erik! (and Richard The gearbox will be slightly further back but I will try to use the standard gearbox shaft tunnel which leaves little space for a large volume exhaust duct, it will work since the duct lenght is so short. Cheers! /Anders
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Post by Johansson on Nov 7, 2012 14:08:01 GMT -5
During the last two evenings I have been busy figuring out a way to couple the Allison C20 turbine wheel to the angle drive shaft, it needs to have a tight fit to both the shaft and the turbine wheel, a curvic coupling that matches the one on the C20 wheel and a internal keyway to secure the part to the shaft. I need to get the fit perfect to avoid any wobble, the damn thing will rotate at over 30.000rpm so a sloppy fit won´t do. A decently sized chunk of steel was dug out of the metal pile and fitted in the lathe, the first step was to make the hole for the gearbox shaft. I opened up the hole to slightly less than 24mm and used an adjustable reamer to take away the last tenths. Taking the last cut in the lathe, notice the use of the dial test indicator. An old machinist in the nearby village taught me that trick, great when you don´t have digital scales and need to take 0.01mm cuts. Test fitting the turbine wheel, snug fit baby! With that bridge crossed I made the keyway slot, since I have decided to use the standard shaft it looks a little bit funny with the long slot and the short key but you won´t see it once the part is fitted to the shaft. Milling the keyway, I was careful not to make the cut too deep and weaken the wall overly much. It will only transfer 50Nm so it should be ok. After testing the fit I started with the trickiest part, namely the curvic coupling. The painted marks were made during a test I made to make sure that the 21th and 1th slot would allign, I used dividing plates to get the slots at the exact angles. This is what it turned out like, now I just had to find out of it actually would fit the turbine wheel... ;D Sweet! With everything put together it looks like this, this part is just one small piece among many in the engine but still one of the ones I am most proud of since it turned out so well. Left to do is to make a spacer washer to secure the turbine wheel to the shaft and figure out a way to lock it securely in place. Cheers! /Anders
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dennis
Member
Joined: May 2012
Posts: 15
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Post by dennis on Nov 7, 2012 16:07:47 GMT -5
That is a very beautiful shaft indeed ! If you have to deal with making key slots in holes more often you might want to invest in some broaching tools for your press to avoid unnecessary weakening of your parts... cheers, Dennis
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Post by Johansson on Nov 7, 2012 16:22:05 GMT -5
Thanks!
I know where to borrow a broaching tool but in this case I couldn´t use one since the slot ends 30mm in, if I had made it any longer it would have broken through the surface where the turbine wheel sits...
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Post by ernie wrenn on Nov 7, 2012 16:55:20 GMT -5
Nice job!! I keep learning new ideas from you...
ernie
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Post by racket on Nov 7, 2012 17:30:01 GMT -5
Hi Anders
Nice coupling , I'm envious of your machining skills :-)
One thing I might have recommended would have been to grind off one of the male curvic "teeth" on the turb wheel and make the coupling with one less female curvic recesses so that the turbine wheel is indexed , this way it will always go back in the same position to maintain balance .
Otherwise , she's looking like she's ready to start powering the bike .
Cheers John
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joolsned
Member
Joined: October 2012
Posts: 36
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Post by joolsned on Nov 8, 2012 4:19:18 GMT -5
Some fine engineering there, looking good
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Post by stoffe64 on Nov 8, 2012 4:31:11 GMT -5
fantastic work Anders, as always! now i know who i should ask for help if i would like to build a freepower one day cheers/stephan
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