I have made both of my cylinder sleeves, and of course the second one came out better than the first. I was targeting an ID of 1.000″ and I had to take the first one out to 1.005″ to get the ID consistent all the way through and to remove a scratch by honing. The technique I used to get the second near perfect included the following strategies:
- Used a four jaw chuck to give max clamping support on the blank cast iron work piece.
- Cut the ID before the OD to provide more material to stabilize the blank while cutting the ID.
- I used an oiled paint stick and applied constant, but slight, pressure on the outside of the sleeve, sort of a poor man’s following rest to counter act the pressure of the boring tool. without this I was getting about .002″ spring in the part from the start of the boring pass to the finish.
- When close to my final dimension, I used a bunch of spring passes where I did not advance the cross slide, just ran again and again
- I ran the lathe really slow so there was no chatter, I had to go down to 280 RPM, but got really clean cuts.
- I used the finest power feed setting. A single pass took about 6 minutes
All of this required extreme patience, but I got two sleeves that I am happy with. But more important I think I have a solid technique for future builds.
Wow did I learn a few things preparing my cylinder sleeve blanks. I attempted to cut the cast iron rod into two using a standard cut off wheel like I use to cut mild steel. That did not work. I cut and cut and cut and cut and all I ended up with was a chunk of really hot cast iron. Finally I stopped and did some research. I then switched to a diamond masonry blade and that made all the difference. It cut right through the cast iron. On the first blank I drilled the internal ID out to .5″ using the largest drill bit I own, then bored it out to close to the final 1″. That took forever. So I bought a set of drills sized 9/16 to 1″ and drilled the blank close to final dimension before I started boring. Much quicker.
Set up on the table saw for cutting cast iron blanks. Out of the frame is another large C clamp (G clamp) holding the wood to the miter slide.
Test fitting the first blank in the cylinder block. I turned the OD first on this one.
My drill bit set from Amazon, saved a bunch of time boring.
Second cylinder sleeve – nice finish on the ID, right on the numbers, no chatter at 280 RPM.
Honing went pretty quick on the second sleeve and I took off just under .001″ of material. the first sleeve took longer as I had a step of .002″ at the top end that I could feel with my finger. After taking this out and removing a scratch toward the bottom I ended up .005″ over my target internal diameter. This will complicate the manufacture of the rings as I will have to make two batches of differing sizes. The pistons will be different too, but in the big scheme of things pistons are nothing compared to making rings.
Sleeves test fit in the block. One cylinder I gave a cross hatch hone, the other I did not. I do not know if this matters. The sleeves are sitting slightly proud of the top of the block, these will be fly cut flat after the sleeves are secured in the block with loctite.