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Engine Turning--Seeking your expert advice on methods

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  • Engine Turning--Seeking your expert advice on methods

    Gentlemen--I have a few projects that I would like to decorate using engine turning, specifically an aluminum plate that I fab'd for the controls of my Harig Surface Grinder. I have tried in the past using a Cratex Round 1/2" Dia on my mill with a three second contact time, cleaning (resanding the end every five or so circles), and WD-40 as a lubricant. The results have OK but not great, see the latest example.





    Here are my specs:

    One to three-quarter inch diameter circles
    Overlap each circle by about one-quater to one half inch
    Overlap each row by about the same
    Aluminum material
    Will use Mill and DRO for spacing
    Needs to POP and look $hit hot

    My research has shown that there are several methods:

    1) Cratex

    2) Wire brush used by gun makers and available from Brownell's (too small for my application) or larger wire brush (fine wire) with zip tie and tape to avoid stray strands

    3) Felt Bob flat end with a lapping compound

    4) Scotchbrite

    5) Dowel with some form of end using leather, wet/dry paper, or plain and lapping compound in a slurry of grease/oil

    I would like to seek your experience and what's worked best for you. In advance, thank you, your suggestions and recommendations are alway appreciated.

  • #2
    I'm no expert, But anything I've read about it says your work needs to start out pretty well mirror polished first and be spotlessly clean before you even start. Looking close at your pictures, You can see some heavy scores within some of the circles. I'd guess that was from chips or dirt hiding in the tool marks. And I've found consistant application pressure was real important along with the exact time used for each circle.

    When the job is done, You flush the grinding compound off till it's again totally grit free, Wipeing it off tends to blur everything you've just spent so much time doing. The grit size used has a great deal to do with just how the light reflects off of each swirl. Hardwood dowels work well as long as their faced off true after inserting them in a collet or drill chuck, Just use fine sandpaper streached out tight and fastened down with tape. Then bring the dowel down onto the sandpaper till its faced off truely flat. You might try 3 or 4 jewels on scrap material first just to get the dowel fully embedded with all the grit it's going to accept. Being consistant with everything and that high polish to start are the most important items that I've found.

    There's multiple engine turning designs depending on how you set up the work, It's orientation, Spacing, Overlap, ect. Your imagination is about the only limit.

    Oh yeah, Almost forgot. You cover the work with a pretty consistant layer of whatever your grinding with, Then just move the work over how much you've decided on and do each one in turn. The grinding material should never be played with till the job is 100% complete. Some trials on scrap stock of the same type as your part will give you the pressures and times needed.

    One more thought, Usually there's a direct relationship between the parts size and the circles, Yours may look better 30-50% smaller. But it all depends on the viewer anyway.

    I hope some of this helps.

    Pete
    Last edited by uncle pete; 05-13-2012, 07:42 PM.

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    • #3
      eye candy
      the forum for answers
      one of the better references with all the assorted names for it.
      Nuff said
      Glen
      Been there, probably broke it, doing that!
      I am not a lawyer, and never played one on TV!
      All the usual and standard disclaimers apply. Do not try this at home, use only as directed, No warranties express or implied, for the intended use or the suggested uses, Wear safety glasses, closed course, professionals only

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      • #4
        Pete--thanks for your reply and words of wisdom, there are much appreciated and very helpful and you're correct it never dawned on me to go with smaller circles, probably because 1/2 cratex was all I had.

        My I impose on you for one additional question--lapping compound grit size and secret formula for a carrier agent? Recommendation?

        I believe I will experiment with the dowel.

        Again, many thanks!

        Comment


        • #5
          Originally posted by PTSideshow
          OMG! That's the most amazing engine turning I've seen!

          "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

          Comment


          • #6
            Hammerfest,
            Nope, I really shouldn't be thanked, As I said, I'm no expert. The main problem about recommending any specific grinding compound is, It's one of those stupid answers that falls into the "It all depends" pile. Your work hardness, Material type, Just how reflective you'd like it, Yada,Yada,Yada. I'm not all that sure there's any one grinding material that would produce really nice work on every material every time. The coarser old school valve grinding pastes were I thought just too coarse for nice work. I didn't seem to get very good, Or real reflective results with it. Maybe on something like a real hard grade of stainless or hardened steel it might have worked better? With all the different grades of lapping powders, Grinding pastes, polishing compounds, And even a few kitchen cleaning powders around you could probably spend endless hours just trying various items and materials. I've read about, But haven't tried it yet, That Comet or Ajax kitchen powder mixed with oil till it's about like peanut butter in consistancy is "supposed" to work pretty good on the softer materials like aluminum and brass. Leather glued to the end of the hardwood dowel is supposed to be pretty good also for jewelling. Brand new pencils, Or at least the brand new eraser at the other end of the pencil works pretty good for small jeweling. But for both of them your needing to think about just how much heat can be produced just due to the friction. So that weight/dwell time is again important.

            About the only rough rule of thumb I figured out was, The finer the compound the longer but lighter weight you dwell at each spot, But that can be a problem with the softer materials too. You can end up with pretty deep divots dwelling too long in something like 6061 T-6 aluminum or brass especially with a coarse grit. So again your needing to think about just how much your leaning on the spider handle for downforce. I'll bet there's a few others on this forum that could add a lot more than my limited experience can. Jeweling or engine turning depending on what you call it is probably easier to screw up than it is to do it right IMO. It does take some experience with playing around on scrap material first. The guys who do it proffessionaly have paid their dues and have earned everything they charge.

            PTSideshow's last link was the one I was trying to remember. That guy really is an artist. I've been amazed everytime I see that website.

            I happen to really like engine turning. But there's more than a few around that despise it's use at least on on rifle bolts.

            But for sure post your results no matter what you get. There's 99.9% about this I still don't know.

            Pete

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            • #7
              I've had good results using scotchbriite. I punch circles with an arch punch and attach them with Velcro onto the head of a modified bolt as an arbor. I use a drill press and eyeball the spacing. Not as exact as yours,but looks pretty good. Bob

              Comment


              • #8
                Originally posted by lazlo
                OMG! That's the most amazing engine turning I've seen!

                If my memory hasn't totally failed? I recall seeing that guitar on one of the Ornamental Turning forms. I really wish I could remember where. Depending on your own personal defination. That wasn't done by jeweling or engine turning. It was done using a rotary table and a boreing head. What your looking at are individual facets cut into the guitar body using various offsets on the boring head and dividing with the rotary table, And also various offsets of the guitar body on the rotary table. It's a remarkable work of art for sure. It's mostly a series of circles cut with a V form of boring bar would be the best way I can describe it. But a few areas were also cut with the spindle on a slight tilt so the tool sweeps in and out of the cut in the designated area. It's a mind bending job not to make any mistakes. Good 3d visulisation skills really help.

                I highly reccommend you never ever Google or go onto any sites that have anything to do with Ornamental Turning if items like that interest you. There's no turning back from that pit of madness once started

                "Guilloche" would be another term to use on Youtube, But I refuse all responsibility should you ignore my warning. I've got a few recommended book titles though.

                Pete
                Last edited by uncle pete; 05-13-2012, 08:38 PM.

                Comment


                • #9
                  Here's a guy who makes his living at it:

                  http://www.cs.ucr.edu/~eamonn/et/et.htm

                  Laz, I think the work on that guitar is more appropriately called "damascening", which is a sub set of engine turning.


                  oops! I see someone beat me to that link! Still, amazing stuff. That Prop Spinner is just crazy. How did he do it!
                  Last edited by Thruthefence; 05-13-2012, 09:13 PM.

                  Comment


                  • #10
                    Originally posted by uncle pete
                    What your looking at are individual facets cut into the guitar body using various offsets on the boring head and dividing with the rotary table,

                    It's mostly a series of circles cut with a V form of boring bar would be the best way I can describe it. But a few areas were also cut with the spindle on a slight tilt so the tool sweeps in and out of the cut in the designated area.
                    Oh, so it's basically radial V-cuts, and not overlapping scratch patterns like engine turning?

                    I'm intrigued -- the URL for that picture indicates it's a thumbnail -- I need to hunt down the full-size image...

                    By the way, from my amateurish experiments with wood or aluminum and lapping compound, a major difficulty in engine turning is getting the circular scratches uniform (depth, mostly). Has anyone tried it with a Cratex cylinder? Seems like that would eliminate a lot of operator error.
                    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                    Comment


                    • #11
                      Here is a quick and simple video on rifle bolt engine turning.

                      http://www.youtube.com/watch?v=vfOLo...ure=plpp_video


                      THANX RICH
                      Last edited by v860rich; 05-14-2012, 12:13 AM.
                      People say I'm getting crankier as I get older. That's not it. I just find I enjoy annoying people a lot more now. Especially younger people!!!

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                      • #12
                        Lazlo,
                        Yep you've got it nailed. The tough part with items like this is just figureing out what method was used. Going just by internet pictures doesn't make it all that easy sometimes. You could almost say that guitar is like radial checkering on a flat surface but in a circle once it's finished. A boring head is a really powerful tool for the Ornamental Turners. But very, very few are willing to work in metal.

                        If I had to bet? I'm thinking that design was pre done on CAD just to finalise exact tool depth settings and offsets. I'm not sure it could be done any other way at least semi easily anyway. Since you can't do any polishing afterwards due to the designs complexity, Your tooling has to be razor sharp, And Ultra finely finished on each cutting edge so it leaves a reflective surface condition after each cut. But if I remember the thread correctly, That guitar was done on manual equipment.

                        I sure wish I could remember exactly what forum I saw this on. It was about 2 years ago when I saw the thread.

                        One mistake towards the end of that guitar project? For sure you'd want to blow your brains out. It's probably the finest modern type of work that falls under the Ornamental Turning classification that I've seen so far.

                        Pete

                        Comment


                        • #13
                          I'm intrigued -- the URL for that picture indicates it's a thumbnail -- I need to hunt down the full-size image...
                          Not much hunting required... the clue's in the words "www.metalcarver.com" in the bottom left of the picture !

                          Lots more pictures here:- http://www.metalcarver.com/guitar/alp1-1.htm e.g.:-


                          Cheers

                          .

                          Comment


                          • #14
                            I've played around with this a little. I've used a wine cork with sandpaper and a simple drilling cycle, worked out OK. Tried a pencil eraser and some lapping compound, I didn't like that very much.

                            Did this little project a few months back(a gift). I wanted something that looked pretty cool. 1/8" endmill running .200 circles, helix in and helix out.
                            I think it came out pretty sweet, it came out incredibly smooth, and throws light around like crazy.

                            Comment


                            • #15
                              Looking at the second picture in post 1, it looks like you started at the bottom right and worked right to left. Then went up one row and worked left to right, alternating as you went up. To me, the pattern would be more symetrical if all the rows started at the same end working your way up. Also, there seems to be a small area in row 2, just above the first two spots in row 1, that was not touched. It would be more even or consistent if all the surface was affected even if its only part of a spot. I would also use a smaller tool so you get more than one spot on those thinner ends at the bottom. I've never done any of this, but that is what I would try.
                              Ernie

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