Cylinder crosshatch general purpose vs. race

[modok]

One fact that has amazed me for many years is that many engine builders have discussed and even used plateau honing but do not know what the finished surface actually looks like. Nor can they draw a picture of it.

I'd have to take a sample of a good hone job, and look at that under a microscope, and then I'd know what it looks like, but what good it would do me? I don't know. Appearances are sometimes counter-intuitive and deceiving.

One would expect a microscopically flat metal surface to be smooth and brightly reflective, but it isn't smooth nor bright.
One would expect the smoothest surface to have the lowest friction, but it usually does not.
The surfaces of all metals you actually SEE are covered in oxide. When the cylinder and ring are operating as usual, they are covered in oxide.
Does a smooth surface aid in the formation of a smooth oxide film? That could be a good research project for somebody's intern.


Operators look at the color of the cylinder, and listen to the sound of the stones. If that is what they are looking at, then if I was employed to research it, I'd look at what they are paying attention to.
There is much that can be observed and the scientific method applied, but it's sometimes best done "blind".

[MotionMachine]

Aaron, does your profilometer read Rz? It'd be interesting to see what your Rz is before you hone some more. I always look at the Ra in relation to the Rz, not just the Ra number by itself, that only tells half the story. In general terms, the Rz should be 10 times the Ra. If you get an Ra of 12, and an Rz of 150, that might be an oil burner.

[jed]

With regard to piston deformation, the most informed source is Mahle. While piston skirts will expand and collapse, depending on axis and engine stroke, the ring lands are relatively unaffected. However
, the rings can and do twist in their grooves, presenting a distorted sealing surface and pressure leakage.
[/quote

the lands do not stay flat under load, fortunately the ring is most flexible in the direction of deformation being it is their thinnest diection and thus lowest second moment of area so conformance is good profoivided the piston is designed to not have abrupt changes in stiffness which cant be conformed to

Just thinking of the top of the piston or the combustion chamber side of the piston and it being
under combustion pressure and the the heat generated the top of the piston base to be
in a concave shape which would affect how the rings contact the oxide film

[createaaron]

[quote="David Redszus"

The acetone will dissolve the acetate and will form a casting of the honed surface which can be viewed under a microscope using a side light. The shapes of the plateaued islands, the grooves and the micro grooves on top of the islands will be clearly visible. I call it the poor man's (that includes virtually all racers) profilometer and its a great way to visually compare various honed surfaces.[/quote]

Ive heard of this process as well. All i can say is, if someone is serious about their efforts whether it be oem or race building, they should own a profilometer. Oem to aftermarket and material changes so much its hard to apply the EXACT same procedures to each block. I feel like they all have some variance.

[createaaron]

Aaron, does your profilometer read Rz? It'd be interesting to see what your Rz is before you hone some more. I always look at the Ra in relation to the Rz, not just the Ra number by itself, that only tells half the story. In general terms, the Rz should be 10 times the Ra. If you get an Ra of 12, and an Rz of 150, that might be an oil burner.

I believe so. Its a really nice mititoyo. Ill check it out once i get to the shop.

[jed]

When I was sorting out my honing procedure I used the same film but at that time I got mine
From MSC and it was called replicating tape or replicating film.
I was able to pick up a 500 power magnifying glass that hooked to my lap top and used
It to view the results of replicating tape of the cylinder surface.

I will try to make this short it is in regards to the Summen style honing brushes.
Back in the late 90s circle track magazine ran a story on the Brushes.. At that time they were called
Soft honing brushes.
Peterson manufacturing a automotive machine co who was wanting to promote there HP--- something
AN style honing machine got Smokey Yunick and the brush inventors together for this brand new
Way of finishing cylinder bores.
I think the company that engineered the brushes, no doubt with Sunnens help, name was
If I rember was Osborn Co.
They were a design and consulting firm for the honing industrie. They consulted and helped solve honing problems
It is my understand and recollection major car companies got them involved because the EPA had put
Pollution requirements on cars requiring them to pass certain standards at 25K 50k 75k and 100k.
The major car manifactures blamed the rings the ring manafactures said its not the rings it is the
Way u finish the cylinders. U are wearing out the rings seating them in. As we all know that is
The way we used to do it.
Hence the brushes were born. I don't know why they were called soft honing brushed I assume because
They don't make the cylinder bigger they clean the torn, folded, ripped metal from the cylinder wall.
At that time the pitch was the cylinders after soft honing replicate a cylinder that had 3000 to 5000
miles running on them.
U are not wearing the rings out trying
I got to get to that point of cylinder finish.
The head engineer presented a paper at a honing conference that had a 25 or so page hand out
With exactly what David wants as far as surface profiles and replicating tape 500 power magnifying
Pictures.
Any one could write for the hand out and I got one. It had every thing u want David but I trashed it
Several years ago when I went into retirement.
I tried to sell my collection of circle trach magazine and all the other years and years of hot rod, car craft
I couldent even give them away. So all ot it was recycled. Probably in someone's attic as insulation.
John

[createaaron]

Aaron, does your profilometer read Rz? It'd be interesting to see what your Rz is before you hone some more. I always look at the Ra in relation to the Rz, not just the Ra number by itself, that only tells half the story. In general terms, the Rz should be 10 times the Ra. If you get an Ra of 12, and an Rz of 150, that might be an oil burner.

Came out to about 20 RA and 160 RZ

[createaaron]

When I was sorting out my honing procedure I used the same film but at that time I got mine
From MSC and it was called replicating tape or replicating film.
I was able to pick up a 500 power magnifying glass that hooked to my lap top and used
It to view the results of replicating tape of the cylinder surface.

I will try to make this short it is in regards to the Summen style honing brushes.
Back in the late 90s circle track magazine ran a story on the Brushes.. At that time they were called
Soft honing brushes.
Peterson manufacturing a automotive machine co who was wanting to promote there HP--- something
AN style honing machine got Smokey Yunick and the brush inventors together for this brand new
Way of finishing cylinder bores.
I think the company that engineered the brushes, no doubt with Sunnens help, name was
If I rember was Osborn Co.
They were a design and consulting firm for the honing industrie. They consulted and helped solve honing problems
It is my understand and recollection major car companies got them involved because the EPA had put
Pollution requirements on cars requiring them to pass certain standards at 25K 50k 75k and 100k.
The major car manifactures blamed the rings the ring manafactures said its not the rings it is the
Way u finish the cylinders. U are wearing out the rings seating them in. As we all know that is
The way we used to do it.
Hence the brushes were born. I don't know why they were called soft honing brushed I assume because
They don't make the cylinder bigger they clean the torn, folded, ripped metal from the cylinder wall.
At that time the pitch was the cylinders after soft honing replicate a cylinder that had 3000 to 5000
miles running on them.
U are not wearing the rings out trying
I got to get to that point of cylinder finish.
The head engineer presented a paper at a honing conference that had a 25 or so page hand out
With exactly what David wants as far as surface profiles and replicating tape 500 power magnifying
Pictures.
Any one could write for the hand out and I got one. It had every thing u want David but I trashed it
Several years ago when I went into retirement.
I tried to sell my collection of circle trach magazine and all the other years and years of hot rod, car craft
I couldent even give them away. So all ot it was recycled. Probably in someone's attic as insulation.
John

It seems like the machinists are almost 50/50 on this subject of brushes. Maybe 60/40 the majority using brushes.. Its apparent that the technique of using ball hones and the brushes work but now that ring material is improved so much and some guys using compression rings that look like oil scrapers the bores are getting smoother and smoother. This is atleast what I've been reading and seeing from fellow machinists that have far more many years under there belt. I have been using brushes the entire time ive been a machinist.

edit: Our teacher originally taught us to use the rough, medium then brush and skip the fine because the bore was too smooth. Now I have been seeing many many guys using rough (70-120) medium (220-280) then the fine (400) and no brush.

[David Redszus]

edit: Our teacher originally taught us to use the rough, medium then brush and skip the fine because the bore was too smooth. Now I have been seeing many many guys using rough (70-120) medium (220-280) then the fine (400) and no brush.

The purpose of a plateau is to produce a deep valley to contain oil and smoother flat tops to support the ring.

A rough stone (100-180 grit) will cut deep valleys with peaks of about the same height. The fine stone (400 grit) will trim the peaks to produce a flat plateau.

What purpose does the medium grit stone serve?

[createaaron]

What purpose does the medium grit stone serve?

We only have 70 grit, 220 grit and 400 grit at school. Thats all I have available to use. Our program is being cut and there is no budget so I just use whats available and try to make it work.

[modok]

edit: Our teacher originally taught us to use the rough, medium then brush and skip the fine because the bore was too smooth. Now I have been seeing many many guys using rough (70-120) medium (220-280) then the fine (400) and no brush.

The purpose of a plateau is to produce a deep valley to contain oil and smoother flat tops to support the ring.

A rough stone (100-180 grit) will cut deep valleys with peaks of about the same height. The fine stone (400 grit) will trim the peaks to produce a flat plateau.

What purpose does the medium grit stone serve?

It makes the 400 cut cleaner.

[machinedave]

What purpose does the medium grit stone serve?

We only have 70 grit, 220 grit and 400 grit at school. Thats all I have available to use. Our program is being cut and there is no budget so I just use whats available and try to make it work.

What school is it if you don't mind me asking?

[createaaron]

What school is it if you don't mind me asking?

Northwest Tech in Bemidji, MN

[jed]

David are the ball hones u use or do u just recommend them aluminum oxide silicone carbide.
The aluminum oxidewhich are not supposed to be as aggressive.
Also can u explain the oxidation process that is taking place in a running engine.

[machinedave]

What school is it if you don't mind me asking?

Northwest Tech in Bemidji, MN

I thought you might have Paul's class. Not many automotive machine shop courses these days. I run into him a few times a year. Good guy.