18 Cylinders Isotta Fraschini (straight six-cylinder x3 )

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Foketry

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Piston rings
To build these rings I did not follow the Trimble method because in previous experiences I had a lot of waste , after heating.
I wanted to try the method without heating of which I have seen videos on Youtube and I have read some explanations.
I used Nodular cast iron or Ductile cast iron (EN-GJS-400-15) ,the difference between traditional gray iron and ductile iron is the shape of the graphite. While cast iron has small flakes of graphite, ductile iron contains spherical graphite nodules.
The graphite spheres give it more resistance and elasticity than traditional gray iron which in my opinion is more suitable for making rings.

First step
Starting from a cast iron rod , I turned the OD leaving a 1 mm of stock allowance , the same for the ID

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Foketry

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Second step
I turned the piston rings leaving a small stock of 0.03mm on the thickness of the rings, necessary to polish the 2 sides with sandpaper and WD40.
I left the rings joined by a thin thickness on the internal diameter, so as not to leave burrs.




IMG_3413.JPG
 

Foketry

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Third step
internal turning to separate the rings
IMG_3415.JPG


Fourth step
Rings cut
I slipped the rings on an alignment pin and they were compressed in the vise

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Fifth step
Finishing turning of the outer diameter
by means of a tool fixed on the spindle, perfectly concentric with the rotation axis, a bushing with a conical hole and a fixing washer that holds the ring closed, with no space in the cut, I turned the outside diameter exactly equal to the honed diameter of the cylinder

IMG_3423.JPG

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sixth step
inside diameter finishing turning
I slipped all the rings into a tube that has the same diameter as the cylinder, through many small steps I turned the diameter of the rings up to the desired size.
IMG_3431.JPG
 
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Foketry

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Polishing of both sides of the rings and final inspection, more than 50 piston rings
with the known method of light I checked all the rings, it looks amazing, but zero rejects
The real final test will be the compression test once the pistons and heads are installed.
In the photo only some rings have been polished, it is a very boring job, smooth one side, measure, smooth, measure etc.
I will do it in the next few days, maybe ...


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IMG_3432.JPG
 
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ajoeiam

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Polishing of both sides of the rings and final inspection, more than 50 piston rings
with the known method of light I checked all the rings, it looks amazing, but zero rejects
The real final test will be the compression test once the pistons and heads are installed.
In the photo only some rings have been polished, it is a very boring job, smooth one side, measure, smooth, measure etc.
I will do it in the next few days, maybe ...

(Wacky beeg grin! ) - - - boring maybe - - - but just imagine if you had even more cylinders? (Chuckling)

A very nice job by the lookee see and an interesting method of getting things done - - - thanks for sharing!!

Wondering - - - - could you have turned an internal mandrel and then used a sleeve to compress all the rings onto it followed by the OD finish machining as a way to save time?

Given the quality of your machining - - - had you considered using a tool nose radius with speeds/feeds so that you would not have to polish the individual rings or is this final polishing quite needed?

TIA
 

ddmckee54

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Foketry:

In your Step 5 description you say that the ring is turned to the exact same OD as the honed ID of the cylinder - with no space in the cut. Does this mean you won't have any ring gap? If so, what's going to happen as the ring heats up?

Don
 

Foketry

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(Wacky beeg grin! ) - - - boring maybe - - - but just imagine if you had even more cylinders? (Chuckling)

A very nice job by the lookee see and an interesting method of getting things done - - - thanks for sharing!!

Wondering - - - - could you have turned an internal mandrel and then used a sleeve to compress all the rings onto it followed by the OD finish machining as a way to save time?

Given the quality of your machining - - - had you considered using a tool nose radius with speeds/feeds so that you would not have to polish the individual rings or is this final polishing quite needed?

TIA
yes , I could have compressed the rings to make them more locked, in reality I have slightly glued them on the outer diameter with cyanoacrylate, after having compressed them with a spacer and tailstock. After the internal turning some heat released the rings.

I believe that the rings must have the support surfaces (at least one of the 2) with a mirror surface. The compression seal takes place on this surface. Therefore a surface roughness and a flatness that only a polishing with 1000/1200 grit sandpaper can obtain.
 

Foketry

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Foketry:

In your Step 5 description you say that the ring is turned to the exact same OD as the honed ID of the cylinder - with no space in the cut. Does this mean you won't have any ring gap? If so, what's going to happen as the ring heats up?

Don
I will get a really small gap with a diamond file, in my humble experience after a few minutes that the motor is running this gap widens. Our cylinders and piston rings are not hardened :rolleyes:
 

ajoeiam

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yes , I could have compressed the rings to make them more locked, in reality I have slightly glued them on the outer diameter with cyanoacrylate, after having compressed them with a spacer and tailstock. After the internal turning some heat released the rings.

I believe that the rings must have the support surfaces (at least one of the 2) with a mirror surface. The compression seal takes place on this surface. Therefore a surface roughness and a flatness that only a polishing with 1000/1200 grit sandpaper can obtain.

That sounds like there is a use for a surface grinder - - - hmmmmmmmmmmm (re: polishing the rings and sizing accurately).
 

Foketry

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My surface grinder for piston rings

I built myself this little surface lapping machine , the rotating disc is a brake disc driven by an electric motor with worm gear , naturally the surface of the disc was made perfectly planar.
I can lap 9 rings at the same time, I put 320 grit silicon carbide powder at the first step then 1000 grit, seasoned with WD40 oil, I measure the thickness of the rings every 2-3 minutes with micrometer. Few minutes on each side is enough to finish the rings

IMG_3559.JPG

IMG_3560.JPG

 

ajoeiam

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My surface grinder for piston rings

I built myself this little surface lapping machine , the rotating disc is a brake disc driven by an electric motor with worm gear , naturally the surface of the disc was made perfectly planar.
I can lap 9 rings at the same time, I put 320 grit silicon carbide powder at the first step then 1000 grit, seasoned with WD40 oil, I measure the thickness of the rings every 2-3 minutes with micrometer. Few minutes on each side is enough to finish the rings


View attachment 139921
Would love to watch the movie but its format is not readable here - - - bummer!

Looks like you got to make tools to make tools to make the whatsits - - - - good on you!!!!!!!!
 

ddmckee54

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Many years ago when I worked at Sundstrand in Ames, I had to rewire the controls on one of the lapping tables in the "Seal Room". It was a just a LITTLE bit bigger than yours but it did the same type of work.

Did you use a new brake disc when you built yours, or just re-surface an old one?

Don
 

Foketry

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Many years ago when I worked at Sundstrand in Ames, I had to rewire the controls on one of the lapping tables in the "Seal Room". It was a just a LITTLE bit bigger than yours but it did the same type of work.

Did you use a new brake disc when you built yours, or just re-surface an old one?

Don
Using a new disc would be a waste, I used a worn disc from my car. I got it from the repair shop that does my car maintenance. A friend of mine made it perfectly flat by grinding the surface, at no cost .
Also the electric motor with worm gearbox is used, paid a few euros.
 

CFLBob

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It's a cool machine, with the three different sub turn tables to lap the rings. Clever design.

For what it's worth, I've ground mirrors for telescopes and it's a similar machine but we tend to do one at a time. Depending on what you're doing, lenses or large mirrors the tools change shape.
 

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