Cylinder Honing

[stihltech]

OK, you are not HONING the cylinder (as in increasing size). You are cleaning and deglazing the cylinder to make it usable again.
I know, even the sellers of these tools call them hones. It would take hours to hone a cylinder to an actual oversize with a ball or 3 shoe deglazer. And then it would be garbage.
Here come the haters.

 

[bwalker]

OK, you are not HONING the cylinder (as in increasing size). You are cleaning and deglazing the cylinder to make it usable again.
I know, even the sellers of these tools call them hones. It would take hours to hone a cylinder to an actual oversize with a ball or 3 shoe deglazer. And then it would be garbage.
Here come the haters.

If you tried to resize with a ball hone you would just wear out the abrasive. Nicisil is that hard.
The haters in this particular case don't have a clue what they are talking about.

 

[muddy42]

If you tried to resize with a ball hone you woukd just wear out the abrasive. Nicisil is that hard.
The haters in this particular case don't have a clue what they are talking about.

I once messed up Nikasil with a 80grit sandpaper on a drill. I was unexperienced and the cylinder was actually beyond repair anyway - with deep scoring through the plating. Don't do this!

 

[bwalker]

I once messed up Nikasil with a 80grit sandpaper on a drill. I was unexperienced and the cylinder was actually beyond repair anyway - with deep scoring through the plating. Don't do this!

You did not remove nicisil with 80 grit. Physically not possible.

 

[huskihl]

You did not remove nicisil with 80 grit. Physically not possible.

I’ve gone through 3 rolls of 80 grit emery or utility cloth. It’s actually the only grit I use.

 

[bwalker]

I’ve gone through 3 rolls of 80 grit emery or utility cloth. It’s actually the only grit I use.

For removing aluminum transfer?

 

[muddy42]

You did not remove nicisil with 80 grit. Physically not possible.

Thats what I thought before I managed it. Did you understand the fact that the sandpaper was glued to a 1 inch dowel and being spun by a drill? After this abuse, you could see id changed the shape pf the cylinder with a bare piston fitted for reference.

This was a 1981 husky with multiple scores close together. Maybe that affects the integrity of the coating? Ive thrown it away otherwise I’d take a photo for you.

 

[bwalker]

Thats what I thought before I managed it. Did you understand the fact that the sandpaper was glued to a 1 inch dowel and being spun by a drill? After this abuse, you could see id changed the shape pf the cylinder with a bare piston fitted for reference.

This was a 1981 husky with multiple scores close together. Maybe that affects the integrity of the coating? Ive thrown it away otherwise I’d take a photo for you.

If you did the coating was already worn through.
Nicisil has a Rockwell C hardness of 90 and Aluminum oxide as found on sandpaper is 70 best case. As such it's just not possible, which is why diamond hones are used to hone to size nicisil cylinders.

 

[huskihl]

For removing aluminum transfer?

Yes

 

[muddy42]

If you did the coating was already worn through.
Nicisil has a Rockwell C hardness of 90 and Aluminum oxide as found on sandpaper is 70 best case. As such it's just not possible, which is why diamond hones are used to hone to size nicisil cylinders.

Surely it can't just be a rockwell hardness numbers game? Won't a steel drill bit, bastard file or hacksaw (google says tools steel is rockwell 64) cut nikasil just fine? Thanks

 

[stihltech]

I agree with not going through the nickasil with the ball hone. If you go through, it was done before you started.

 

[huskihl]

The damage I’ve seen from ball hones was removing all the Nikasil from the edges of the ports

 

[nedsim]

Surely it can't just be a rockwell hardness numbers game? Won't a steel drill bit, bastard file or hacksaw (google says tools steel is rockwell 64) cut nikasil just fine? Thanks

Of course it's not. Keep in mind that Nikasil is silicon carbide grains embedded in a nickel matrix. The SiC is very hard, the nickel not so much. Diamond grinding wheels are similarly made up of diamond crystals embedded in a plated coating or bonding material. If it was just a matter of which-is-harder diamond wheels would never wear out. I can assure you they do.

BTW, applying Rockwell C numbers to thin coatings or brittle materials (SiC or aluminum oxide) is near to meaningless. If you look at the Mohs numbers for SiC and aluminum oxide they're not that far apart. Depending on where you look, 9.0 for aluminum oxide, 9.0-9.5 for SiC.

 

[nedsim]

The damage I’ve seen from ball hones was removing all the Nikasil from the edges of the ports

Makes sense to me. I can imagine the balls springing into the ports and whacking the far edge as they climb out, and turning up the edge of the soft underlying aluminum. This leaves a fragile point that gets knocked off. Repeat thousands of times.

Not saying ball hones are the devils work, but I also don't believe it's not possible to cause damage if they're misused.

 

[ZeroJunk]

The damage I’ve seen from ball hones was removing all the Nikasil from the edges of the ports

I have done it. The first saw I ever rebuilt. Stihl 046. I bought a big bore kit and broke a ring trying to slip it on. Baileys gave me my money back and said they had some brittle rings. So, I bought a new piston.
To say I ball honed the hell out of it would be an understatement . Didn't know any better.
I probably took 15 thousandths of the nikasil off the edges of the ports. But, sure slicked it up.
Gave it to a friend of mine who thought it was greatest saw ever. He moved and gave it to a friend of his who wanted to know what I had done to that saw. Ran rings around his Husky 61.
Of course, neither had ever ran a sort of big saw.
That was probably 2008 ??? He's still cutting firewood with it. Usual maintenance and replaceable things periodically.
So, I'm thinking if plating doesn't flake off it's not the end of the world.
Not sure it matters when you are going to give it to somebody anyway.

 

[huskihl]

Makes sense to me. I can imagine the balls springing into the ports and whacking the far edge as they climb out, and turning up the edge of the soft underlying aluminum. This leaves a fragile point that gets knocked off. Repeat thousands of times.

Not saying ball hones are the devils work, but I also don't believe it's not possible to cause damage if they're misused.

Exactly that

 

[bwalker]

The damage I’ve seen from ball hones was removing all the Nikasil from the edges of the ports

I've never had that happen, but I have always sized the hones per Brush Research recommendations and only hone for a few seconds, which is plenty to do the job.

 

[bwalker]

Surely it can't just be a rockwell hardness numbers game? Won't a steel drill bit, bastard file or hacksaw (google says tools steel is rockwell 64) cut nikasil just fine? Thanks

No, they won't. When porting you get into the aluminum beneath the plating at the port edge and peal it back. If the piece your working on was a solid block of nicisil good luck.

 

[bwalker]

Of course it's not. Keep in mind that Nikasil is silicon carbide grains embedded in a nickel matrix. The SiC is very hard, the nickel not so much. Diamond grinding wheels are similarly made up of diamond crystals embedded in a plated coating or bonding material. If it was just a matter of which-is-harder diamond wheels would never wear out. I can assure you they do.

BTW, applying Rockwell C numbers to thin coatings or brittle materials (SiC or aluminum oxide) is near to meaningless. If you look at the Mohs numbers for SiC and aluminum oxide they're not that far apart. Depending on where you look, 9.0 for aluminum oxide, 9.0-9.5 for SiC.

Synthetic aluminum Oxide as used in sand paper is much softer than the numbers you quoted.

 

[nedsim]

Synthetic aluminum Oxide as used in sand paper is much softer than the numbers you quoted.

There are various synthetic aluminum oxide abrasives that differ in their friability (toughness), but as far as I know their hardness doesn't vary much.

Corundum on this page refers to natural aluminum oxide, alumina to synthetic.
https://universalium.en-academic.com/294862/Hardness_of_prominent_abrasive_materials