I've seen many more pictures of cylinder cross-hatching than I have done myself but almost all the ones I've seen OR done were weak efforts in comparison to the Cummins factory x-hatch in the photo. I opened this 1300 hour 12-valve to investigate rough off-idle behavior and came upon an example of x-hatching that far outdoes even the ones I've seen done by my favorite machine-shop pros! The x-hatching in this image is so aggressive that when I took the picture I could actually feel it with my fingernails. I have no idea what tool they used to do it with but obviously if the idea was to have reserve oil on (or rather IN) the cylinder wall there it was loud and clear. I'd want to adopt this practice. I thought of uploading this image because I'm in the middle of a Deutz air-cooled engine stripdown that involves among other things a badly scuffed piston probably caused by low-oil-pressure leading to inadequate cylinder-wall under-piston cooling oil leading to overheat and piston expansion. This particular F6L912 engine has absolutely no x-hatching marks left so I'd like to know what the consensus is on the x-hatching in the photo: is this an exceptionally zealous x-hatch or is it the kind I should try to achieve if I keep the old cylinders? (they're in the machine-shop being evaluated). I remember installing a new Deutz jug in an F4L912 many years ago and IT NEVER SHOWED such x-hatching either. Am I missing something? I think this Cummins 12-valve was a firepump engine designed for a short life and immediate off-start acceleration to spec rpm.
Cylinder was honed on a purpose built machine, possibly a Micromatic or Nagel. The honing head typically has two sets of stones, a rough and a finish set. They were probably trying for a "plateau" finish, where some of the coarser grooves from the rougher stones can still be found under the finish stones. The rougher stones will cut to a set diameter, and then the stones retract. The spindle will reverse direction and the finish stones will extend. The finish stones will stroke for a specific length of time. See the sharp reversal in the direction at the top of the stroke? You can't get that from a Sunnen. Old school would have been hydraulic drive, now its probably electric drive with a ballscrew. My guess is the size of the coarser marks is beyond design intent.
I haven't had to hone a liner or cylinder in years so can only speak from an old time view. The honing looks rough if they were just breaking the glaze. I'm guessing that from looking at the top of the cylinder and lack of machining there and the black showing through at the ring lines that terex herder is correct about a machine hone and not a glaze breaker in a drill.
All automotive bores are done for the last 50 plus years on a wet tank hone. Rottler is the most common. The idea of honing is to hone to parent metal to remove edge from cutting tool of bore bar plus provide a retaining hatch for oil. Torque plates are used to simulate the stress of a cylinder head torqued in-place. Cast rings are the hardest on a cylinder bore for wear, but cast rings will also seat on a glazed un-honed bore where moly or chrome won't. When I worked auto machine the best bore bar I ever ran was a 1938 Storm. It had a very slow feed compared to any other bar. Which created less heat at the cutting tool tip for less distortion. Plus after a final pass the bores had a shine from a very fine slow feed that other bars didn't produce. It makes for a true round cylinder, not to mention it took half as much time to hone, although the bar was slow. Grow a beard in the time it took. It wasn't a high production machine, I looked at it as you want the best or second best, I'll take the Storm.
Machine honed for sure, I took the pictuire myself and that's the factory x-hatch you see there. The engine was almost new. I always thought that oil-retention was the purpose of x-hatching but apparently it never was, x-hatching is there to prevent ring-rotation until the rings get seated although according to some gurus ring-rotation is impossible to prevent even if the x-hatching is still visible. I haven't done many engines but I have never seen still properly stagered ring-gaps in the ones I that have taken apart. What got me in the subject engine was the DEPTH of x-hatching, like I said one could easily feel it with fingernails, those are not your everyday honing hatch marks there, those are gouged cylinder walls! So is there something in terrex herder's remark about "beyond design intent"? Is that possible in a computer run engine factory? Whatever the case, I understand that any plateau-honing that nowadays comes after x-hatching is there for moly rings to seat with less wear but the fundamental purpose for the x-hatch itself is still unclear and the amazing depth of the one in the image is still a mystery to me. Finally if it was not a 'design foobar' and I both knew it's pupose and wanted to reproduce it on a hand-held drill then what tool would cut like that? That engine BTW is still exactly the same way, I gave it to one of my sons who parked it in the warehouse while scouting for a K10 to host it. Another particularity it also has in all cylinders (off-topic) is that the pistons with the rings in them are aboout 1/16" loose in the cylinder at TDC, like in some racing engines although this is a diesel. I have a viodeo of it but don't know if video uploads work in this forum.
You have to host the video to YouTube first then link it.
I have seen so many strange things i should have kept a diary and took pictures . I cant remember evey seeing a GM inline 6 that the rings gapes were not lined up. I have honed or tryed to break the glaze on engines with sand paper on a 1/4 all thread in a drill and they didnt use oil but i have had more than one bored and new pistons that did use a little oil. If a engine didnt use oil and it burnt a piston a new piston and rings could be put in it with out any honing and it wouldnt use oil. There is alot i wish i know about rings.
If that is how it looks in real time, the stones used were way too coarse, and can cause more problems than not.
https://www.sciencedirect.com/science/article/abs/pii/S0301679X21005570
45654340, the engine that is ) Putting it up on the tube isn't worth the effort. I gave the engine to my son and he's seen that kind of looseness before though not in diesel pistons
Those more rarified groves are actually much harsher than they look, and it's a 1300 hour factory engine.
Interesting, thanks! I would have thought that ring contact surface being so much less than cylinder wall surface, ring preservation would dominate. When cylinder wall preservation is claimed it does also imply less ring wear of course. My very first impression upon seeing this 'gouging' was that an attempt was being made to keep some of the upstroke wall oil sprayed behind the piston for the down stroke but I'm nowhere near qualified enough to have an opinion as well as an impression
I once spent 2 days on my back under a '75 Pinto v6 because someone had convinced me that it had a glazed cylinder that absolutely HAD to be fixed. I forget what the underlying issue was but we fixed only the glazing, NOTHING else changed! About ring gaps, my theory is that x-hatching does not move rings OR stop them from moving, but any pressure snuk past a gap will work the next ring in one direction or another. This effect cancels itself out when the next ring gap is lined up because at that point less pressure gets to that ring. This explains lined-up gaps but not gaps that ether remain or return to stagered. Upon hearing this an old hand with immigrant english once asked me "how many schools do you have?". I told him only one but I might buy a few more )
I've torn down a few engines in my time and don't ever recall seeing the ring gaps lined up. I've seen lots of deep cylinder ridges, lots of taper and oval, pulled lots of liners with plenty of bubble implosion. I guess I haven't looked for it because of the use on the engines but I suspect I would have noticed something like that just with general observation. I have a glaze buster hone I've used on a few gas engines. I used it once on a diesel with low hours that was torn down for other reasons. I have a rough set of stones and a fine set plus the tool has a spring with a thumb screw so the pressure on the stones can be changed. Engine work became a lot less of a thing when new and exchange engines with a warranty became common. The cost of mistakes also became an issue that could put a single guy out of business in a hurry. The other issue was customers wanting to cut corners on cost and blaming their bad decisions on the rebuilders.
I rebuilt a lot of engines at one time and had great luck with every one but mine . I had a jeep that i rebuilt a 250 chevy for. I had the block board i had hard seats and valves put in the head. I got it running but the valve train made noise they didnt get the seats at the wright height got that fixed and it drank oil. If you changed the oil it would use the first quart in around 400 miles then it would use a quart in less than 200 miles. I had it apart 2 times trying to figure it out it never fouled a plug and ran good . I put a used engine in the jeep and sold it. I know i steal have that engine maybe i will take it apart agin someday .