ESE's works engine tuner

[Condyn]

Re knee mill cutting. Thank you for the extra details. Very nice way to visualize it.

[Myron]

Thanks for reply wob

[Flettner]

cutting hemispheres on a knee mill

the best way i can come up with to visualize why this process works is to think of taking a large glass and placing the open end on a globe and note that the rim of the glass is in contact with the globe at all points. If the rim of the glass is the cutting tip of the tool and the globe is rotated, then it will cut the surface of the globe.

If the edge of the cutter touches the axis of the hemisphere then the cut is controlled by a combination of the radius of the cutter and the angle of the spindle. CAD makes quick work of fixing one and calculating the other.

Attachment 349859
Here we are cutting the squish with a 1.25" end mill and using the CAD to tell us the angle needed is 5.0°.

Attachment 349860
Here we are cutting a hemispherical combustion chamber, fixing the spindle at 45° and adjusting a boring bar to the needed 28.3mm diameter.

Attachment 349862
After setting the angle of the spindle and the diameter of the cutter, the rotary table is positioned so that the lowest pass of the cutter is on center with the work in the rotary table. Once aligned the knee can be raised or lowered to control the depth of cut but everything else should be held in position.

Spooky, just what Ive been doing.

[Flettner]

Steel pistons? Or a screw together composite piston? How well does steel wear against Nikasil? Should a steel piston be hard chromed and ground after? Or Nitrided?
This is what keeps me up at night.
With CNC it could be machined out to a similar weight as aluminium, certainly similar as a forged alloy piston.

[Muhr]

cutting hemispheres on a knee mill

the best way i can come up with to visualize why this process works is to think of taking a large glass and placing the open end on a globe and note that the rim of the glass is in contact with the globe at all points. If the rim of the glass is the cutting tip of the tool and the globe is rotated, then it will cut the surface of the globe.

If the edge of the cutter touches the axis of the hemisphere then the cut is controlled by a combination of the radius of the cutter and the angle of the spindle. CAD makes quick work of fixing one and calculating the other.

Attachment 349859
Here we are cutting the squish with a 1.25" end mill and using the CAD to tell us the angle needed is 5.0°.

Attachment 349860
Here we are cutting a hemispherical combustion chamber, fixing the spindle at 45° and adjusting a boring bar to the needed 28.3mm diameter.

Attachment 349862
After setting the angle of the spindle and the diameter of the cutter, the rotary table is positioned so that the lowest pass of the cutter is on center with the work in the rotary table. Once aligned the knee can be raised or lowered to control the depth of cut but everything else should be held in position.

For those who do not have the tools to do so, it should be possible to transfer the desired shape to a piece of HSS and just dive into the head in a lathe

Or

[F5 Dave]

Can you put some concentric ridges in there? Or perhaps some 4 leaf clover indentations?

[wobbly]

Why concentric ridges , they could be a continuous thread form - this would generate chamber swirl just like a 4T port. Could be Rh/Lh for above and below the equator, or clock/anticlockwise tracks.

[Grumph]

Steel pistons? Or a screw together composite piston? How well does steel wear against Nikasil? Should a steel piston be hard chromed and ground after? Or Nitrided?
This is what keeps me up at night.
With CNC it could be machined out to a similar weight as aluminium, certainly similar as a forged alloy piston.

Didn't Frits post a pic of a Ducati piston some time back which was a beautifully delicate steel piece ? Memory says that in those bore sizes and RPM the strength/weight calculation favoured steel

I'd suspect that a coating of something like tin - or flash plated aluminium - would work well enough in nicasil.

I recommend a warm drink at night for you Neil. And of course dreams which feature working schematics of uniflow engines.....

[Flettner]

Yes, the uniflow exhaust piston gets a thermal hiding.

[husaberg]

Didn't Frits post a pic of a Ducati piston some time back which was a beautifully delicate steel piece ? Memory says that in those bore sizes and RPM the strength/weight calculation favoured steel

I'd suspect that a coating of something like tin - or flash plated aluminium - would work well enough in nicasil.

I recommend a warm drink at night for you Neil. And of course dreams which feature working schematics of uniflow engines.....

https://www.cycleworld.com/2016/01/1...ology-feature/

[wobbly]

Kentastic had designed something very similar ( in aluminium ) for KZ2 some time ago , sadly having a business that makes money is strangely more important.
Cant believe how cool that tiny small end pin is.

[Norman]

Steel pistons? Or a screw together composite piston? How well does steel wear against Nikasil? Should a steel piston be hard chromed and ground after? Or Nitrided?
This is what keeps me up at night.
With CNC it could be machined out to a similar weight as aluminium, certainly similar as a forged alloy piston.

Here is a link to a sae pre-view for a two stroke steel aluminium hybrid piston

https://www.sae.org/publications/tec...-0508/preview/

[Suzuki nut]

Yes Niels, I do have pictures of the 50cc triple and a lot of other Suzuki racers, about 200 in total. But it is rather impractical for me to post them one by one.
I would gladly ZIP the whole lot but I forgot how to upload zipfiles to Kiwibiker. Anybody?

Do you have any photos of the Suzuki RK67? I am after a photo of the underside, which shows all the cooling fins

[OopsClunkThud]

Can you put some concentric ridges in there? Or perhaps some 4 leaf clover indentations?

The lettering in the squish area balances the heat between the exhaust and transfers, and the 4 leaf clover combustion chamber creates counter rotating vortices eliminating the gyroscopic effects...

[F5 Dave]

Aie, may T luck of T Irish be wit ya.