I need to hone this cylinder and while looking online for a hone of that size (which I found much to my disbelief)
I wish that would happen more often when I need something that "shouldn't" exist....
they mentioned a finish of 35-50 Microinch(.9-1.4 Micrometer)
Nothing to do with steam engines, but that's in the range you'd find called out for older gasoline engines with high tension rings. (Normal tension rings, no descriptor needed prior to low tension rings...) Back before they started calling out not only the profile of the ridges and valleys contained within the surface finish.
(is this 0.9-1.4 thousands of an inch?)
No. That is 35 to 50 microinch. A microinch is one millionth of an inch. So what you're looking at there is one third to one half of a "tenth". A micrometer is one thousandth of a millimeter. That surface finish inside the boor will "look" like you just absolutely ruined it with the hone, but (if the bore were bigger) you could drag your fingernail on it and it'd feel dead smooth and with moderate pressure and a long attention span, you would not be able to file your fingernail with it.
and this made me think that I might need to bore the cylinder undersize to allow for material removal.
I doubt you're going to find performance profiles for any stone in a proper hone that size, and the ball hones don't take much out of the middle diameter at all. (They're sure good at opening up the ends though).
Ok, enough picking on those little heaps of crap, as you might actually be able to pull it off with a ball hone in a bore this small, simply due to the practicality of having a reamer to put it on size and true, and then you would be literally just scratching up the surface, instead of actually sizing with the ball hone. (Don't size with a ball hone...) You'd want to keep it inside the bore though, pulling those ball stones out and back in is brutal on the precision of your bore. You'll get picture clearly when you first insert it.
Honing a cylinder is new to me and I have only one shot to get it right so please let me know if I'm understanding this correctly.
Thank you,
Michael
That means you've got no practical option but to do some testing. And if you're ball honing (I'd give it a go, as you're gonna be a LONG time finding a hard hone and figuring out the pressure and removal rate that generates a finish like you're looking for with any given grit of stone. They're usually rated at "full cut", which means max material removal rate, and you will NOT be doing that in this size range. So the ball hone might, in your case, have an advantage there. (Dam that was hard to say. I hate those things....) But you need test holes for two reasons. First, you need to know how fast you're removing material, how fast to spin the thing and oscillate it (They're looking for cross hatches, even if they didn't specify), and VERY, VERY importantly. Crazy stupidly important- You NEVER, EVER make a final finish with a brand new stone. On a hard hone, the stones would have in theory removed material before they ever came close to final dimension. With the ball hone, you want it used some before you can expect any consistancy, as right out of the box, the grit will be very uneven, and there will be some deep scratches until the high spots wear down to the low spots to "equalize" how much pressure is being applied at each contact point within each little ball on the ball hone.
So yeah... That's how I'd go about it. Practice. Make three or six holes in the same material. Or as close as you can come to it. See what it does, and react. Then make your "good" hole accordingly, and go from there.