What grit stone for honing used liner?

[Jon Pike <jhpike@domain.elided>]

> This is a follow up to a message sent last week.   I've decided to purchase 
> a ball-type "flex-hone".  What grit should I purchase: 120, 180, 240 or 
> 320?  I thought the common hone for preparing cylinders for new rings was 
> 240.  Since my liners are used and have some wear, should I use a 320 to 
> minimize taking additional material off?
>
> I'm using stock Borgo rings.  Would honing grit make a difference in if I 
> was using Hastings or Deves rings?  Are there general recommendations for a 
> particular grit for different ring materials?
>
> Thanks,  //kct
Hi Kevin..

Well, let me say I have no direct experience with Flex Hones.. though I 
probably will soon.

I have been reading up on them.. and just got their info booklets in the 
mail the other day. Rather interesting stuff! I'm wondering if 
independent testing backs up the fairly compelling case they make in 
their studies.

So, looking in their documentation, they seem to reccomend 120 to 180 
grit, for 30 - 60 seconds, sometimes using both in two steps.  They also 
seem to be reccomending a finer surface for Moly coated rings, and a 
coarser one for chrome, but I'd ask the ring manufacturer as well.

The finer ones seem to be more for brake cylinders and other hydraulic 
systems.

Also it seems that a newly turned liner has a rougher surface, and might 
take more time honing than a used one,  though for a glazed surface they 
mentioned using 120 grit and running for 60 sec.. maybe in that case you 
want coarse and a longer time.  The graphs showed a pretty fine surface 
even after that.

But overall they say you will remove only a small amount.. perhaps 
.0005"  At one point they said with a rough liner and 60 sec on the 120, 
and another 60 sec on the 180, that .001" was removed, and only because 
it was a new liner with a lot to wear down.  Glazed ones wouldn't loose 
as much, since you are recreating a grooved surface, instead of wearing 
down the mountain range of a newly turned liner.

Anyway, take it with a grain of salt.. I'm just condensing what they say 
in their brochures. Getting them and reading for yourself (and looking 
at those nice surface graphs and electron microscope pics) would be an idea.

I'm also interested in the opinion of the more professional of us out 
there, if these are all they're cracked up to be?

And, anyone try these for surfacing valve guides?

Last point.. shop around for a good price..  Just doing a bit of 
searching on the web today, I found a HUGE variance on how much places 
will charge you!  The hone may not gouge you, but wach out for those 
resellers!!  ;-)

Jon
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