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hand honing tips for cylinders needed

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  • hand honing tips for cylinders needed

    I rebuild 2 stroke outboards for a hobby and hopefully a little profit eventually
    and was wondering if any of you guys have any tips or recommended reading
    regarding the subject of honing cylinders by hand. I use a goodson copy of
    the sunnen an-112 hone and a dewalt spade drill. After some reading I realized
    I needed to use keyway style stones for ported cylinders and roughing 70 grit
    stones for oversizing a bore. I read using them dry speeds this up.

    I have the keyway stones and truing sleeves for 2 of the most common bore
    sizes on the outboards I'll be targeting. I know reversing the stones and
    running the drill in reverse can help battle taper.

    Any tips on setup, dressing stones, when and how to use the truing sleeves,
    methods of setting bottom and top limit of stone stickout, how to prep blocks
    for dry honing, honing fluid used. How to prevent and correct bellmouth,
    barrel and taper.

    Most of the blocks i will buy will only need to be oversized .010-.015. I over
    sized one .030 and it took a very long time but the stones I had were
    previously used with oil so I couldn't use them dry. Can you oversize a 3-3.5"
    bore .010-.015 rough and finish within an hour and hold .0005 taper and
    out of round or is this being overly optimistic?

  • #2
    Originally posted by wes5.7
    Can you oversize a 3-3.5"
    bore .010-.015 rough and finish within an hour and hold .0005 taper and
    out of round or is this being overly optimistic?
    I sure wouldn't try it. I don't hone cylinders, but it seems to me trying to hit 5% metal removal accuracy with spring loaded abrasives in a hand drill is guaranteed to fail.

    I would use a boring bar, lathe or mill to get it to 0.001"~ oversize, round and ideally not tapered, then use the 'rough' hones to take out the last 0.0007" and the finish hones to take out the last 0.0003 and smooth the surface finish. Some taper could be removed by very tedious repeated measurement, but you would be much better off correcting the taper before then. I don't think hones are going to correct 'out of round' and would likely make it worse, and very hard to correct that via measurement and focused grinding.
    Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.


    • #3
      I'm not quite sure what you mean by hand honing but you have the right tool for the job.......

      Hopefully vpt sees this and can offer some advice........
      Opportunity knocks once, temptation leans on the doorbell.....


      • #4
        *googles some more on that type of hone after reading vpt's post*

        Ahhh. Thats a better looking device then I thought. I was thinking of these things:

        Don't think those could hold any accuracy.. but that sunnen is clearly a different beast.
        Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.


        • #5
          With the "deglazers", the TOOL doesn't "hold accuracy", the user does.

          I have used that type to *remove* taper in bores, not for cylinders, but for other items. Very much like filing a workpiece on the lathe, you spend more time where the measurement shows the bore needs to open up.

          Removing 15 thou that way sounds like a bit less than fun.
          CNC machines only go through the motions.

          Ideas expressed may be mine, or from anyone else in the universe.
          Not responsible for clerical errors. Or those made by lay people either.
          Number formats and units may be chosen at random depending on what day it is.
          I reserve the right to use a number system with any integer base without prior notice.
          Generalizations are understood to be "often" true, but not true in every case.


          • #6
            Many of the outboard blocks have the crankcase area designed so that you can not stroke through the end of the cylinder. In effect it's a blind hole. Impossible to hone these to .010" to .030" without excessive taper at the bottom. I would leave these to the professionals with a good boring bar that will take it very close to finish size with just enough left to allow for finish honing. The old rule of thumb was to leave .003" to hone but the guys with a good Kwik-Way, Van Norman, or other and a properly sharpened bit get by with .001" to .002".
            If you can stroke completely through cylinder a Sunnen hone with dry roughing stones will do a great job of taking it oversize. Sunnen is a RIGID type hone that will produce round straight bores unlike the spring loaded glaze breakers. AN100 stones DRY in a big Sioux 5/8" drill will take a worn out cast iron Kohler 1 cylinder to almost .010" in a couple minutes, finish wet hone with fine stones and you're done. You need a big slow drill with lots of torque and some way to hold everything down. Maybe your DeWalt will run slow enough to allow for stroking to get proper crosshatch angle but I question if you have enough hp to to remove a lot of iron with it.
            Generally, when honing cylinders the cylinder itself is your truing sleeve. If stones are over stroked equally 1/4 to 1/3 of their length they will wear evenly. There is no way to reverse the stones in a Sunnen hone and if you try running drill in reverse I believe it will lock up and not function at all.
            In any case you need to radius port edges a little by hand and watch out for tight spots at the bottom of those blind holes.


            • #7
              2X on what johnd said. Most people confuse glaze breakers with honing tools. While glaze breakers have their purposes they will only follow the existing hole and cannot true up an out of round hole, True hones such as the Sunnen or Superior Hone can true up out of round holes, but the equipment is fairly expensive.

              When I taught at the vo-tech we had a small engine program and they had a specialized boring mill similar to this one: I have set up small engines in a lathe on a face plate and angle plate combination, but it sure was time consuming.

              If you're doing this part time I recommend finding a small engine shop with one of these machines and have them bore the hole. If you go full time then I would look into one of the machines.


              • #8
                Needs a micrometer adjustable hone such as this-

                I just need one more tool,just one!


                • #9
                  And what of piston wear? How much is tolerable? Will it/they need re-sizing/replacing - especially after a bore enlargement?

                  Why not "farm out" the bore and piston to the "pros" and stick with the rest of it?


                  • #10
                    I would just pay someone, if I could find someone in town. The hone I use is
                    a micrometer adjustable hone. You can reverse the stones then it adjusts in
                    the opposite direction. I have honed blind bore cylinders to .0005 taper and
                    yes there's no room to overstroke the bottom. I would not attempt this with
                    a spring loaded hone. I realize a kwikway, rottler, van norman, or other boring
                    bar would be the best way to do this and if I were doing this as a full time
                    business I would buy one but a decent one with the table I need is ~$5000.
                    I've found one for $1000 but with no table it's pretty useless to me. I called
                    about a dozen shops and every marine service that had an ad in the phone
                    book and neither they nor the people they referred me to would touch a blind
                    bore. I would have to ship it out and with shipping cost these days it's really
                    not worth it.

                    I appreciate you guys trying to help but I know the best way to do this would
                    be to farm it out or buy a bar. I worked as a machinist for 8 yrs, 4yrs in a job
                    shop and we rarely had the best tools and equipment for the job unless it
                    was something we did on a regular basis. Example hexing 6ft shafts on a VMC
                    with 40" x travel and no indexing head for this diameter. I learned more in
                    6mos. at that shop than I did in the previous 4 at another shop

                    I'm sure most people, if they figured out some tricks to do this type of work
                    with equipment that costs the same as paying to have it done are going
                    to be pretty tight lipped about it. I already know how to do it I was just
                    hoping for some tips to make it faster and easier.

                    Johnd you seem to have some experience in this area. What rpm did the sioux
                    drill run. My dewalt is a 500rpm 9 amp spade drill. More rpms than I want, I would
                    prefer 250-300rpm. I've found some tricks to keeping the taper to .001 or less in
                    blind bores. I can oversize a blind bore +.015 in about 1 1/2hour, this was before I
                    got my truing sleeves and dial bore gauges. Johnd how much pressure did you
                    apply to the stones when you oversized bores with a hone? Does it create a lot of
                    dust running dry, like needing a respirator amount of dust? Did you use something
                    to limit overstroke? What oil did you use for finishing? I use pencil grinders and
                    a ball style hone to chamfer and smooth my ports. To the other guys I use a
                    hone identical to Sunnen an-112 that has a stronger yoke more like an an-815.
                    It uses sunnen an type stones. I would never try to use a brake cylinder hone
                    or ball hone to open up a cylinder for an oversize piston. Oldtiffe I mic every
                    wear item in the powerhead, if anything is worn or out of spec, usually .001
                    for pistons, it's replaced. Specs for cylinders is -.0005 and usually spec +.003 wear,
                    taper, or out of round. 2 stroke outboards have pretty loose tolerances, that's
                    why I considered doing this this way. I wouldn't try this for close tolerance
                    liquid cooled 4 stroke engines such as motorcycles with piston to cylinder clearances
                    as tight as .0005-.001. Some outboard makers set clearances up to .010 piston
                    to cylinder on some motors with piston tolerances +/- .002 and they run for decades
                    like this. In fact one of mercury's most reliable engines has these clearances, the 2.0L
                    V6. So according to spec sheets this engine can run .0075-.015 piston to cylinder
                    clearance. I would never build an engine .015 loose, too afraid it would break a piston
                    skirt, but according to specs it's within tolerance.
                    Last edited by wes5.7; 03-21-2012, 05:56 AM.


                    • #11
                      I've been out of engine rebuilding for 20 years. A couple places I worked had a Rottler boring bar on the table fixture so that was used for any blind hole work and multi cylinder boring jobs. For a while we did a lot of 2 cylinder outboard blocks for a marina, most common were a little over 3" bore I think and blind at the bottom. Congrats if you can hone those to an oversize and not get tight at the bottom. Something to be said for your keyway stones & truing sleeves. I could never have done it with what we had to work with.
                      The only time honing to an oversize seemed practical was on the 1 cylinder Kohler & other small engines with open bores at the bottom. First oversize available was .010" and they usually had almost that much wear by the time they needed rebuilding. We had a big old Sioux 5/8" drill that I'm guessing was in the 250-300 rpm range rigged to a home made swinging support attached to the wall to take the torque and weight. It had so much power it would break the hone if you caught a main web with it, or your arm, if you were trying to hold it. We used the Sunnen AN110? hone which is a little different than your 112 which I think they used to call the "Junior" for smaller bores. With the AN100 rough stones DRY you could really load up the pressure to pull the drill speed down. Fixture to hold block was a piece of board stuck in the side of crankcase that you would stand on. The slower rpm also means you don't have to stroke so fast to get a decent crosshatch. There is a lot of dust and grinding debris but it must be heavy. It was all in a 2 foot grey patch on the floor and never seemed to be in the air at all. We had an adjustable depth stop rigged to drill handle that bumped the top of block to prevent stroking too deep and just eyeballed it at top of stroke. Had a fixture with a pump and catch basin to circulate a little honing oil / parts washer solvent when finish honing automotive blocks with AN500 stones but just slopped a little of the same mix from a can on the 1 cylinders. My recollection is that the rough honing almost to .010" oversize took only a couple minutes. Faster than you could get it set up in the boring bar and the hone would produce a perfect bore at .010" when you would likely have to bore to .020" or .030" to get the same amount of ring wear out. Just didn't seem like you could center the bar accurately enough in a badly worn cylinder to clean at .010".


                      • #12
                        Thanks for the Info johnd. It was really tedious holding the taper that low,
                        it was a constant battle dressing the stones by hand and miking the cylinders
                        every couple of minutes. If I could find anyone nearby that would do blind
                        bores I would gladly pay them $40-50/hole. The only reason I decided to do
                        this is because the cost of shipping my block out and having it bored over
                        was about the same as buying my hone and drill. I already had measuring
                        equipment. I never sold my machinist tools.