Forrest, Give Us the Scoop on Honing

[BobWarfield]

Forrest, I've seen you post on several occassions about your use of hones for precision work. Is it possible you could give us the details or even a few pictures here?

Seems like it would be some valuable technique to capture. From what I understand it beats the heck out of toolpost grinding. It's something I've been curious about.

Best,

BW

[Mcgyver]

hones or laps?

i don't know much about hones, but depending on what you are trying to do consider lapping. imo hones are great for producing the desired finish, but they lack the control to make a bore round an parallel - not much precision control

here's some I've made and have used on various engines. in each case i held the casting in the lathe, covered the bed with paper towels. the laps float and hand held - you get a very sensitive feel on what parts of bore are tight. work your way up in grits expanding the lap every so slightly as you go. copper is the right material to use, the grit gets embedded in it. to save $$$ i solder thin copper onto a steel barrel.

http://i20.photobucket.com/albums/b201/michael0100/laps/collectionoflaps.jpg

http://i20.photobucket.com/albums/b201/michael0100/laps/lapcloseup.jpg

[BobWarfield]

McGyver, as always, your work is a pleasure to see and learn from. I love the idea of adjustable laps for working on cylinders. However, I did really mean "hones" not laps. Forrest has commented on Sunnen hones in a number of places, such as on this PM thread:

http://www.practicalmachinist.com/ubb/ultimatebb.php/topic/1/28023.html

Just bring up the page and search for "Forrest". I am just curious to hear more detail and perhaps see a picture or two of his hones. I understand there are benefits in maintain the proper cylindrical shape with hones versus some other methods.

Best,

BW

[Mcgyver]

sorry then for going off on the wrong tangent

[Optics Curmudgeon]

I've used brake cylinder hones to improve the finish on holes bored on the lathe and mill. In these cases the hole is straight and round, but perhaps a couple of temths small, and/or rougher than I would like. Typically where a sliding fit is required, such as a t&c grinder work spindle.

Joe

[lazlo]

here's some I've made and have used on various engines. to save $$$ i solder thin copper onto a steel barrel.

Mcgyver, I didn't realize that you're Michael Ward!

I downloaded your "Copper Laps, Really Ugly and Really Effective" article from rec.arts.metalworking a couple of years back -- outstanding article! I've made a couple of your laps with your directions, and they work great!

[lazlo]

Just bring up the page and search for "Forrest". I am just curious to hear more detail and perhaps see a picture or two of his hones.

In that thread I think Forrest is talking about actually using a Sunnen hone (machine). This isn't something a HSM'er can easily adapt to a home shop. This is a Sunnen hone head:



There are six honing stones arranged radially around the perimeter, and they're spring loaded so they press evenly against the bore when the head spins. It's basically a lap in reverse (the honing head rotates instead of the part). If you watch the engine rebuilding shows on Discovery channel, they often show the Sunnen hone being used to hone the engine cylinders -- it's a large machine.

Forrest has often recommended that HSM'ers can use brake hones as a poor-man's Sunnen, but that's only going to work for relatively large bores.
I get the impression that Zumba wants to build his own spindles, so making a lap like McGyver posted above, is probably a lot more suitable, especially for a Home Shop Machinist.

That's how Professor Chaddock recommended making the Quorn spindle, and how Phil Duclos made his air spindle -- bore it close to size on the lathe, and finish with a lap.

[tdmidget]

Lazlo I can't say that that is definitely not a Sunnen tool but I'v done quite a bit of honing with Sunnen equipment and I've never seen anything like that. If as you say the stones are spring loaded then all they will do is make a bad hole bigger. On every Sunnen tool I have used, both fixed machine and portable the stones are expanded in a positive controlled manner. Honing is as much a black art as science. However any piece of equipment that is spring loaded is only going to make a bad situation worse.

[dicks42000]

Sunnen hones....

Lazlo, tdmidget & others;
Regarding Sunnen hones...these can range from the CK 10 "Cylinder King" machine used for engine cylinders. (Yes, it can hone, grind & resize cylinder bores). The hone head is trued using a circular tool like a ring gauge.
Also, there are numerous Sunnen portable hones used for many things. I've got 2 sizes from about 2" bore to about 9". I use them once in a while, sometimes on engine blocks & hydraulic cylinders, driven with a 1/2 in. slow speed electric drill, sometimes in the drill press. I've used the small one in the lathe to size hub bores to fit on propellor shafts.
The stones are not spring loaded, they are expanded using a central pinion & rack on the stone or guide carrier. They can be trued using the ring gauge tool as I mentioned...These hones can correct for out-of-round & taper in a bore...just that measuring is a pain. The CK-10 & other honing machines can measure directly, iirc. I like the portability of these hones & sometimes you just can't afford to take the equipment apart to set the job up in a shop machine, or you just can't......
HTH.....Rick

[Yankee1]

Sunnen Hone

Hello
The sunnen hone that I have used had an adjustable dial and a foot pedal.
You would set the dial and this would take that amount off when the pedal was depressed all the way to the floor. It was used for fitting wrist pins for pistons. The difference between a good fit and a fit that was not acceptable was ,0002". The wrist pin was held in a fixture and after removing a tenth of a thousand we would try to fit the connecting rod on the pin. If it fit it was OK if not set the dial for another tenth and slip the bushing on the hone and while the hone was turning start depressing the pedal until the pedal bottoms out and try fit again.
Chuck

[Mcgyver]

Lazlo, that's funny, completely forget even doing that. man, now i sort of half pretend to know what I'm doing, half know....back then it more like 90/10 pretending

However any piece of equipment that is spring loaded is only going to make a bad situation worse.

I agree, despite a piece being bored in the lathe it can still be out enough to cause trouble with very fine fits. Why would it be out? Even if the bearings, headstock alignment, bed alignment (leveling) are perfect, things like a hard spot causing more deflection at one place, clamping pressure (you don't have to hold it as tightly when lapping) or subsequent machining ops releasing stresses and changing the shape. I can't speak with the authority of someone who's done millionth of an inch lab studies to prove the point, but when you use the laps on a workpiece cut in a lathe that you otherwise know to be well set up and accurate, and you feel the irregularity once the lap starts working...its fairly convincing. The cause for cartwheels and champagne is that these simple devices (either internal or external) produce bores and cylinders in the diy shop that would rival the best OD & ID grinding equipment, just takes more time. I'd consider using the spring loaded hone after lapping, lapping getting it perfectly round and parallel, the hone putting the scratches to hold the oil, if desired.

[wierdscience]

The type Sunnen hones I have used for portable honing/sizing are these-

http://www.mcmaster.com/ item# 7362A45


Micrometer adjustable and deadly accurate results are possible assuming proper technique is used.They are expensive,but it's one of those tools that nothing else will do.

[Ken_Shea]

McGyver,
Is the "Copper Laps, Really Ugly and Really Effective" atricle still available ?, I am unfamilliar with rec.arts.metalworking.

Did a search of course but did not locate any links to it.


Thanks Ken

[Bill Pace]

McGyver....
I would also like to see the original article. I have made up a couple similar to those pictured, but yours look to be---...er..a little more refined?? I always love to see another guys interpertation of going at a problem,--- one little change in a procedure can ease the whole process.

[Mcgyver]

found the link

http://metalworking.com/dropbox/_2002_retired_files/copper_laps.pdf

photography is poor - my early days of digital cameras, but description is accurate. hope it helps