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Radial engine build


ptwizz
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Still not much to see. Here is the beginnings of a rocker. You can see how little is left from the 3" diameter billet.

At the risk of repeating myself, I'd like to tell the story of the duck carving man:

I was at a local village fete some years ago, where there was a stall selling assorted carved wooden ducks. Behind the stall sat a man on a stool, beside him a pile of logs, each about a foot to 18" long and maybe 4" diameter. As I watched, he picked up a log and began carving it with a small knife. After about 20 minutes, he had produced another duck, which was waxed and added to the display on the stall.

As he picked up another log, I asked him "Do you have a design in mind when you start, or just make it up as you go along?"

He replied "I just pick up a log and cut off all the bits that don't look like a duck".

Since that day, I have described my approach to machined parts in the same way. Pick up a billet of Aluminium 2014A-T6 and cut off all the bits that don't look like a rocker.

I have been telling this story for years. Recently I overheard someone who I have never met telling the story to another.

2016-10-16 16.27.40sml.jpg

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Darius, it's not CNC. It's a manual milling machine with a manual rotary table. I have fitted a set of digital readouts to the three primary axes of the machine, but these are simply an easier-to-use version of the dials on the handwheels.

For complex parts like the rockers, my drawings have several sheets. The first one or two sheets simply define the part and tolerances. Other sheets show the angles to set the part for particular operations, the linear distance to move the cutter at that angle, etc.

When I design parts, I have to think of how I will make them, how I will hold the part to the machine at each stage, how I will cut a particular face with the tools I have in my workshop, etc. It makes sense to record all this information at the same time as I record the design of the part itself.

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  • 5 months later...

I now have a complete set of rockers, each fitted with bronze bushes and a roller tip running on a hardened pin. The cylinder heads require more modification to provide clearance to the new rockers. I had measured one head, made all the rockers and then found that the heads are all slightly different and the one I had measured was the only one which the rockers would fit. As a result, I've had to make another substantial fixture to support each head on it's side so I can machine them all to match.

Unfortunately, I still can't post pictures, despite clearing all cookies, history etc.

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  • 1 month later...

A little more progress.. The engine now has all it's rockers and pushrods assembled, so I can turn the crankshaft and all the valves open and close at the appropriate times. That's the valve timing phase of the project complete. I've just ordered some more large lumps of metal, most of which will end up in the bucket under my lathe. The first will be the 'seal plate' which closes the oil space at the front of the engine and houses the supercharger drive gears. The second will be the supercharger planet gear carrier, which also functions as the nut which pulls up against all the bearings and spacers on the timing end of the crankshaft.

I still can't post photos here.

Kiwi - I see Geoff about once a week. I believe he also designed, or had a hand in, the BRM H-16.

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On 5/9/2017 at 16:32, ptwizz said:

Kiwi - I see Geoff about once a week. I believe he also designed, or had a hand in, the BRM H-16.

Yes your right Pete but after that he also designed the V12 which was more powerful and had more success 

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  • 3 months later...

I still don't have the facility to post pictures.

If anyone is still following the slow progress of this project, there is a complete photo record of the build here https://groups.yahoo.com/neo/groups/R_and_R_engines/photos/albums/1849802645

Much time has recently been devoted to getting my microlight up to date with servicing etc, installing a new bathroom and a string of issues with my wife's bike. Winter should see more progress, provided I don't dragged too far into redecorating.

 

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  • 3 months later...

Simon, You can be assured that whatever this engine ends up in, it will be shown off to anyone who has expressed the slightest passing interest.

End of year progress report: I have now made the supercharger drive gear arrangement and its housing. The supercharger is driven through a planetary gear when 'engaged' and driven at low speed through a roller clutch when not engaged. The planetary gear has a floating ring gear, so that when a brake band is tightened the ring gear is stopped and the blower is driven at 4 X crankshaft speed. I have a few fiddly bits to do for the brake band actuation, then on to the supercharger impeller. The impeller looks exactly like a turbo impeller, but it's 5" diameter! Rather than try to machine it from a single billet, I will be fabricating it from a machined 'cone' and separate vanes. Each vane will have tabs which pass through slots in the cone, to be peened over and finally brazed in place. The impeller will run at 14,000 rpm max. At work, I have access to a 7.5kw pump test rig which I can use to spin it up and check for vibration, distortion and pressure / flow rates.

Still have no facility to post photos. I only have the 'Insert other media' button available.

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  • 2 weeks later...

Cheers Simon.

More photos added:

A large bearing is fitted to the cam front plate, concentric with its bearing on the crankshaft nose. This large bearing supports a ring gear which runs free except when the supercharger (S/C) is engaged.

A nut screws onto the nose of the crankshaft and locks the bearing inner races and cam drive gear in place. This nut also carried the planet gears for the S/C drive, each of which runs on a needle roller bearing.

A brake band will be mounted to the S/C gear housing. A cable will pull the brake band tight around the ring gear, holding it still so the S/C impeller is driven at 4x crankshaft speed. The arrangement is similar to that used in Model T Ford and automatic transmissions.

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  • 5 months later...

A few more photos added to the album. The supercharger (it'd be rude not to) impeller is fabricated around a cone, turned using my home made radius turning attachment. Nine of each of two sizes of impeller vane are cut from 2mm steel, with tabs which fit into the slots on the cone. Each vane is TIG welded at the back of the cone where the tab goes through, then the whole assembly is brazed, using the TIG torch at lower current to accurately heat and draw the Sifbronze material along the join (mostly) without forming blobs and puddles. The assembly is finally trued in the lathe.

PS I have now passed GST for the microlight, so look out for G-BZNP at an airfield near you (provided its not too far from me).

Edited by ptwizz
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