Author Topic: 917 180 degree V 12  (Read 84906 times)

Online Vixen

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Re: Momentary lapses of reason......
« Reply #60 on: July 08, 2016, 07:23:41 PM »
Dave,
OK, so you are going for the bore and stroke dimensions you prefer rather than an exact 1/3 scale.
What CAD package do you use? With AutoCAD there is a neat way to import a bit map image, stretch the image to the required size, you can then trace/ draw over the image to produce accurate CAD drawings to your chosen size. Saves a lot of ruler and divider work.

Tell me more about 3D printing in aluminium.

Mike
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Re: Momentary lapses of reason......
« Reply #61 on: July 08, 2016, 07:32:47 PM »
Exact 1/3 size is 1.13 bore x 0.93

At 29.4% we get 1" x 0.823"

0.823 is a pretty odd ball dimension....even in Infernal....and the strokes varied a bit from engine to engine.

Don't mind cutting gears or making gear cutters.....not that hard, so what ever the spacing comes out to, we can do it.

One supplier of DMLS parts...just give them a 3D cad model.    Bulk tolerance is about +/-.005"....and about 80% billet strength.....Prices would be comparable with custom castings......

https://www.protolabs.com/documents/united-states/alsi10mg.pdf

Dave
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Re: Momentary lapses of reason......
« Reply #62 on: July 08, 2016, 07:38:33 PM »
Dave,
OK, so you are going for the bore and stroke dimensions you prefer rather than an exact 1/3 scale.
What CAD package do you use? With AutoCAD there is a neat way to import a bit map image, stretch the image to the required size, you can then trace/ draw over the image to produce accurate CAD drawings to your chosen size. Saves a lot of ruler and divider work.

Tell me more about 3D printing in aluminium.

Mike

Besides, If I go down the EXACT size route...then if we're going to have some intellectual integrity, I should work from original parts or original drawings and not reverse engineering it from two section drawings that may or may not be accurate.....

Dave
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Re: Momentary lapses of reason......
« Reply #63 on: July 08, 2016, 07:57:25 PM »
For instance, that cross over duct on your supercharger could have been 3D printed hollow and then post machined.   The downside would be the alloy might have a different color than the rest of the supercharger....
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Re: Momentary lapses of reason......
« Reply #64 on: July 08, 2016, 08:21:11 PM »
Solidworks
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Online Jasonb

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Re: Momentary lapses of reason......
« Reply #65 on: July 08, 2016, 08:24:33 PM »
1/3rd scale does work out quite close to 1 1/8" x 15/16"

But 3/10 is not a bad ratio either, if its good enough for John Deere models its good enough for this ;)

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Re: Momentary lapses of reason......
« Reply #66 on: July 08, 2016, 08:30:17 PM »
If I go the 3D printed "casting" route, the part has to stay under 10.5" long, and at 3/10 scale that works....

Additionally, I'd like to keep with standard sizes if possible as It minimizes how many custom reamers and such I need to make.

Dave
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Re: Momentary lapses of reason......
« Reply #67 on: July 08, 2016, 08:33:03 PM »
I think that gear pump would be the scariest part of the job for the most part....guess I'd start with that      That and the crankshaft.

Dave
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Re: Momentary lapses of reason......
« Reply #68 on: July 08, 2016, 08:35:27 PM »
I suppose I could go to 1" x 0.8125 and have better "Fidelity"....

Dave
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Re: Momentary lapses of reason......
« Reply #69 on: July 08, 2016, 08:41:57 PM »
A six throw crankshaft, some ten inches long with a precision cut output gear in middle, looks pretty scary to me. If you can achieve that then everything else would be plain sailing.
Mike
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Re: Momentary lapses of reason......
« Reply #70 on: July 08, 2016, 08:47:29 PM »
Yeah it does look scary doesn't it Mike!     I wonder about a lap joint in the center half round-half round held together with the gear.     Would need some layout to figure that out....and some damn tight tolerances to make work...but can't be as bad as a scale Hirth joint!

Dave

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Re: Momentary lapses of reason......
« Reply #71 on: July 08, 2016, 08:56:04 PM »
you could also put two ball bearings there ....perhaps.....on the crank

The alternative would be to lay out the crank and see if a say 3/4" OD cutter could make it in there....you would need a roughing cutter and finish cutter.

This is a good dialog....work out the problems, or at least shine some light on them!...



Dave
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Online Vixen

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Re: Momentary lapses of reason......
« Reply #72 on: July 08, 2016, 09:00:01 PM »
A Hirth coupling may not be that scary, it may be considered as two well made bevel gears. Once you have a set-up with all the angles etc. you can repeat as many times as needed. A Hirth coupling may be easier and more precise than a half round joint.

When you do the layout, check the size of the gear teeth. If you find a convenient DP or CP or Module gear size, this may have an influence on the model scale.

Mike
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Re: Momentary lapses of reason......
« Reply #73 on: July 08, 2016, 09:02:25 PM »
Coupling concept, obviously it would need a key on the gear of some sort
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Online Vixen

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Re: Momentary lapses of reason......
« Reply #74 on: July 08, 2016, 09:08:17 PM »
Na ..... Hirth coupling in place of the half rounds.

Is this still a "momentary lapse of reason"? It seems to be taking on permanent roots.

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Sometimes, it can be a long and winding road

 

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