hello John.
Congrat on the runner. I am in to making rings and I like to know what method you where using. you know this is my first attempt of making CI-rings.
Only been using Viton rings on my engine(s)
best Regards
CS
Hi CS,
I'll try to take a stab at the method I used... Sounds hard but it actually was fairly easy to do.
1) Cut a tube of cast iron with the ID the desired ID of the rings. Turn the OD 0.005 oversize.
2) Part off rings.
3) Lap or grind them to thickness. I used my surface grinder to make them all exactly square and the right thickness.
4) Snap the rings to create the gap. Just lay the ring over the edge of a sharp corner and press down... Snap!
5) Gently file the ends square. No need to try and gap them now. Just square up the ends.
6) Make a mandrel out of mild steel that will be used to heat treat the rings. The diameter needs to be computed to give the desired spring. Many sources say 4 times the thickness is the right value.
The diameter of the mandrel is:
D = ((ID x pi) + (4 x T)) / pi.
7) Gently open the rings and slide them over the mandrel.
8) Heat the mandrel and the rings until all is cherry red. Hold it at this temperature for several minutes. Now allow to air cool. Remove the rings from the mandrel. They should now be sprung open.
9) Turn a dummy cylinder tube from aluminum long enough to hold all the rings. Take light cuts on the ID until the rings fit in snugly and have the desired end gaps.
10) Now, set the tube and rings aside. The next steps will be to make a mandrel for turning the rings to the right OD and making them dead round.
11) Make a cap per the drawing. Make the cap first!
12) Turn a stepped mandrel with a tapped hold in the end. It should be turned to an OD where the tube with the rings inside just slides on. Do not remove the mandrel from the lathe to keep everything running true.
13) Slide the tube with the rings inside over the mandrel with all the rings up against the step. Install the cap and tighten the screw.
14) It is not likely you'll be able to slide off the tube to machine the rings. That's why it's made from aluminum: easy to turn sacrificial tube.
15) Take light cuts and machine the tube away to expose the rings.
16) Turn the rings to the ID of your cylinder +0.0002 to 0.0005
17) Using 400 grit sandpaper or Scotchbrite give the rings a fine finish. Tweak the OD while polishing to be within 0.0002 of the cylinder ID.
18) Remove the cap and slide off the rings.
19) Deburr them.
They should fit your cylinder nearly perfectly!
Cheers,
John
