HONING precedure

[headflow]

I have decided to do the block work by myself instead of farming it out.
And I got the boring and honing riggs up an running but I would like all the tips and info on how to best do it...

I have a manual honing cabinet with sunnen AN-head, and a BIG mill that I use for boring and I can bore to within 0.01mm (0.4 thou)

How close to the finnished bore diameter should I bore = how much to leave for honing?

Can I Hone right up to finished dimension with a AN-300 stone and then just platau with a Flex-Hone?

Or should I go throu a sequence of honing stones lets say (AN-100 to AN-200 to AN300) ?

All inputs are greatfully apriciated
/Lars

[larrycoyle]

Lars,

Have you ever opened up a can of worms. In my opinion .004" is not even close to enough material to hone a cylinder and make it straight and round. You have to consider several things. If you could take a section of the cylinder after you finish boring it and put under a microscope you would be amazed. Unless you are the exception to the rule, boring is akin to ripping metal away from the side of the cylinder and you have to leave enough material to remove these excess "rip marks" I will call them and get to the actual surface of the cylinder wall. I will leave the actual process for others as it has changed since I built race engines but I used to leave .010" in a block to hone.

Larry

[headflow]

Thanks Larry but what I mean is that I can bore with 0.4 thou diameter precision.

My first test was to leave 0.004" for honing but I was thinking that maybe I could bore closer (0.002" ?) and have save some time on the honing process...

/Lars

[larrycoyle]

That is not enough material to leave for the honing process. The honing process is the absolute last place to save/cut time or corners.

[Alan Roehrich]

Larry is correct. You need a least 0.004 hone stock, at a minimum. the reason is that the fractures from the boring operation go about 0.002 to 0.003 deep, and deeper depending on the boring tool, the load, and the feed rate.

We have an older Axe cabinet that we converted to air power stroke. It took a lot of experimenting and learing to get a reliably good finish that seated rings quickly and reliably. Until you are really good at getting a good finish with no taper, you should leave at least 0.005 hone stock, maybe a little more. Otherwise, you could risk "losing" a cylinder by not getting a good finish before it gets too big.

I understand completely that using an older, manual hone cabinet is difficult and tiring, leading you to want to leave less hone stock, but it is the wrong thing to do.

You should start with 150 grit, or you can go as low as 70 grit, if you want to take out more material.

You should NOT skip from roughing (70 to 150) to finish stones. The intermediate steps are important too. So do not skip the 220 grit. Going straight to the 280 grit from the 150 grit will not work. The best example I can give you is what happens when you skip steps in color sanding and buffing paint. Honing works much the same way, you get rid of big deep scratches by making a lot more smaller scratches, and each step makes more smaller scratches until you get the right finish.

Go through the full range of stones, taking out at least 0.001 with each grit before moving on. Then take out a little under 0.001 with your finish stones (to prevent glazing), and if you are using 400 grit or finer, then take out 0.0005 or less on the last step.

You should be flooding the bore with hone oil. The more the better.

Be careful not to use too hard a stone, as it they will not break down while cutting, and the cylinder will glaze.

I never use hard stones to finish, but instead use the softer grey stones. The green, red, or yellow stones are very hard. To me, they are too hard to use to finish. You especially should not use them on a manual/assist hone cabinet, because you cannot load the stones enough and still stroke the machine.

If you can find it, the Federal Mogul/Speed Pro catalog has a really good little article on rings and honing.

[PackardV8]

When dealing with precision machining, terminology is everything.

Just asking, but is there any chance when headflow is writing .4 thou he means four-tenths of a thousandth of an inch, i.e. .0004"?

Looking at it another way, 25.4mm in an inch times .0004" = .01mm

Of course, it has been a long, hard day and my last math class was 40 years ago . . .

jv.

[Alan Roehrich]

In his second post, he actually typed out 0.004, so I think he means four thousandths. And from previous experience, that's not much when using a manual cabinet with some sort of assist, especially when you haven't been doing it long.

[Cobra]

The amount of material left for honing after boring is dependent on the boring procedure, and subsequent finish. As others have posted, this is typically 0.003"-0.005". Automatic boring machines index cylinders to crankshaft centerline and maintain proper spacing. This would be difficult to duplicate on a mill. Manual honing is an artform requiring a good teacher and much practice. If you have not been taught this procedure find a good teacher and learn the art. Soft stones act like hard stones, hard stones act like soft stones, spindle speeds must be changed to compensate. Honing speeds and pressure must match stones. Too little pressure and stones glaze, too much pressure and roundness and straightness goes out the window along with stone life. I am old and will leave this task to the trusty Sunnen CK-21!

[rolan nix]

you need a mim.of .005 to hone if you have the correct plates,and use the proper methods of installing them. i thank about everone has it right.it takes a lot of work and knowhow

[Dave Koehler]

There is some good news in your desire to hand hone. I did a lot of hand honing before the CK10 machines arrived. After you have successfully done some by hand it becomes a snap to adjust or trim the automatic or semi automatic machines to get a "perfect" job because you now understand how metal moves around (or doesn't) when honing. You will learn how to deal with bellmouth, flare, out of round, dwell, over or understroke,etc.
Despite the pita that it is It's actually a good thing to know and will benefit your work down the road.

Yup, you need .004 -.005 to finish. I have done it with a little less but you better have one hell of a "smooth" finish with the boring bar first. When you hear the "whine" of the stones passing the boring bar marks on the first few strokes you will understand what rough means.

Dave Koehler
www.koehlerinjection.com

[CRE2004]

What's your (meaning anyone who cares to share the information) floor to floor cycle times for honing a V-8 with torque plate that has .005" left in it?

[PackardV8]

Better state what block you are asking about. A big block Mopar has about 25% longer cylinders than a small block Ford.

[larrycoyle]

Jack forgot to mention the metal content of the blocks that impact the time as well. I.E. If a block has a lot of nickel in the metal, the process changes.

[CRE2004]

True enough. For anyone responding to my post, please note what block the data is for. It doesn't have to be a Mopar block to be relevant.
Thanks,
Mike

[PackardV8]

Most of us won't be honing one any time soon, but my sources tell me the compacted graphite iron used in the recent Cup blocks presents a high level of difficulty for every machining operation, but especially requires a whole new and different honing technique and stones.