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Technical "How Do I" Engine Turn inside an entire hood?

Discussion in 'The Hokey Ass Message Board' started by FlatHead Deuce, Sep 30, 2014.

  1. FlatHead Deuce
    Joined: Dec 1, 2008
    Posts: 21

    FlatHead Deuce
    from Ipswich MA

    I 'm in search of tips, techniques on engine-turning the inside of my aluminum hood. Currently just a sheet of formed aluminum, I'd like to engine turn the entire inside, then mate it to the inner reinforcement/frame. 20140618_114305.jpg 20140618_114305.jpg
  2. What part don't you understand ?
  3. loudbang likes this.
  4. T Fritz
    Joined: Jul 1, 2010
    Posts: 175

    T Fritz

    Well, most smaller items are done on a Bridgeport. I think on something that large a Styrofoam backer to hold the panel firmly mounted on some saw horses or the work bench t start with. laying out a grid pattern or using some sort of straight edge to locate yourself for each application of the abrasive. One goo thing is the hood inner structure will rake up any long line and help with any error you may create.


  5. fatkoop
    Joined: Nov 17, 2009
    Posts: 712


    I think you would have been better off to do the engine-turning before it got formed into shape. On a flat surface, the swirls are more uniform and much easier to get to. Also, engine-turning a sheet with square edges is better so you can maintain uniform spacing. After that, you can trim the edges and form the curved surfaces.
    falcongeorge and need louvers ? like this.
  6. Damn.....what is it for ? Austin Healy? Cobra? Interesting shape, that's for sure.
  7. Fatkoop is right but plan on a longer process to engine turn a completed bonnet.
  8. The37Kid
    Joined: Apr 30, 2004
    Posts: 27,946


    I wonder if this Delage GP car had the underside done as well? Bob [​IMG]
    kiwijeff likes this.
  9. Yeah, I was wondering what the english wheel would do to the engine turning after the fact too. This car is fukn' crazy. What do you think? Before curves or after ?
  10. redo32
    Joined: Jul 16, 2008
    Posts: 1,799


    The Delage was engine turned on the completed body. Built & owned by George Wingard, the body was built by Chuck Foster. George said Chuck did it all by hand. 3037-6.jpg 3037-12.jpg 3037-12.jpg
    Last edited: Oct 1, 2014
    kiwijeff, FlynBrian and loudbang like this.
  11. It can be done on a curved surface, but you're going to have to use a very small mandril. Small mandril is going to equal thousands of small turnings, and countless hours of applying those turnings. You're going to have to design some sort of cradle which can be indexed side to side and back to front. Engine turnings need to be very accurately spaced, or else you'll just end up with a mess. Best bet in your case would be to polish and clear coat the inside.
  12. The37Kid
    Joined: Apr 30, 2004
    Posts: 27,946


    Redo32, thank you for the additional photos of the George Wingard Delage GP car. One of the highlights of the Hershey meet is seeing what is on display from the Wingard collection every year. Really nice guy with a fine collection of Vintage race cars. Bob
  13. How about getting a sheet of thin aluminium (0.3mm), do your engine swirlies on that, then the thin sheet can be attached (glued?) to your panel.The edges can be "hidden " by the moulding or beading which can be seen in the photos. The only problem is the thin aluminum may crease trying to get it to form to the curve of your panel.
  14. The Old Crow belly tank was done freehand. So was the Spirit of St Louis[​IMG]
    kidcampbell71 and kiwijeff like this.
  15. [​IMG]
    Looks like he just had a fixture line to follow. Straight line all the way to the cowl fairing. This would take a hell of a lot longer then a little hood. Screw it, all you have to do is try. Straight line, and a few of those Eastwood abrasive tips.....would be a great start.

    A couple of threads here on the subject. Search engine turning or jeweling.
  16. It needs to have some waviness in the line of swirls. If it is arrow straight and evenly spaced it looks "dead" - like the photo-etched stuff you can buy.

    A flexible straight edge and a sharpie will give you a straight line on the panel, then overlap the swirls by eye. As the previous poster says, give it a go. Try it with some scotchbrite glued to an old valve and put it in a cordless drill on a slow speed.
    need louvers ? and Ben38 like this.
  17. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547


    all my grandpa did was use a wooden dowel rod that was cut to fit the old drill press and some clover valve grinding compound on the tip , he laid the lines out with a pencil and went at it , for something that big a radial drill press would be a nice thing to have
  18. oldolds
    Joined: Oct 18, 2010
    Posts: 3,138


    Take something flexible, like a cheap wooden yardstick, to give you a straight edge to work with. The rest is going to have to be free hand. Some things there is no easy way.
  19. The37Kid
    Joined: Apr 30, 2004
    Posts: 27,946


    When we did Bugatti dash and firewalls we had a fixture. picture a yard stick with evenly spaced holes drilled down the center, then cut it in half. Thous half holes were the guide for the shank of the pad holder that was in a hand drill. Back then we used to cover the sheet in a special mix og heavy valce grinding compound and just grind away, remembering to shift the guide after every pass gave the proper look to things. Bob
  20. alchemy
    Joined: Sep 27, 2002
    Posts: 16,727


    I like the Kid's plan the best. Or maybe you could use an articulating arm mechanism to hold the drill, like a flamecutting table or somesuch.
  21. need louvers ?
    Joined: Nov 20, 2008
    Posts: 12,906

    need louvers ?

    If I were you, I'd do these in a fairly large swirl as has been suggested, so it is a bit more like the cowl on the Spirit of St. Louis. It'll take far less time that way, and the larger turns will have a tendency to look less erratic if you get a little off course, too. I have used the 1 1/2" Scotchbrite rollock style pads in a rollock holder to do the same thing you are contemplating. Personally, I've done a bunch of turning on my drill press with a guide, so I would be very comfortable doing this free hand. I would suggest you practice for a bit, and do the same.

    If there ever is a "next time", turn the material first, then cover the whole deal with low tack masking tape and form away. Pull the tape when you are done...
    kidcampbell71 likes this.
  22. The37Kid
    Joined: Apr 30, 2004
    Posts: 27,946


    Do louvers that get punched in steel use the same dies as aluminum? Could you punch louvers in a sheet of engine turned alunimum without scratches? Bob
  23. lippy
    Joined: Sep 27, 2006
    Posts: 5,470

    from Ks

    I wonder if you could use a laser beam to follow. Lippy
  24. The funny thing is I never noticed the difference. There is some very pretty flourishes in that plane cowling huh? I'll be damned. Another stupid question, by me to follow, there....literally a recognized variety of engine turning methods out there....or is it the look of whatever the hell one chooses to abrade their surface with to achieve said engine turning slash jeweling ? I've always seen the smaller stuff....even though my eyes probably totally missed the differences.
    Joined: Jan 18, 2011
    Posts: 1,273

    from alabama

    Somewhere on the HAMB is a reference to where you can guy sheets already done...I don't remember where it was..........may need to start a thread asking where it can be bought......just a suggestion
  26. DC43
    Joined: Sep 20, 2014
    Posts: 17


    Lay out your pattern carefully, then use a VERY soft pencil (art supply store) for guidelines, then use electrical tape for a guide, then select whether you would like "softer" of "coarser" swirls and select the material to create your swirls, and go at it. Experiment on a scrap piece of aluminum with the same finish you are starting with, as it will truly affect your final product. I have done it this way for a lot of years. My Grandfather taught me this method, and it leaves enough "error" in the final product to make it look correct, but is precise enough to look like the craftsmanship that it is.
    Good luck, and take your time, you will not regret the preparation it takes to get it right!
    (Would love to see photos posted of the final product!)
    Ben38 likes this.
  27. KLM Metals ? Ryan had a thread on his dash truck project. Pretty cool stuff......but for that hood, I would follow whatever the most insightful post here is on the real deal stuff. Be bad ass to pop a hood and see what ya' did.......without a bond adhesive letting go.....on a curved engine heated hood panel right? With my luck I would have an engine turned fan blade pattern on my hanging jeweled sheet. Ouch, yep....that's my shit right there. How'd I do?
    Last edited: Oct 4, 2014
  28. need louvers ?
    Joined: Nov 20, 2008
    Posts: 12,906

    need louvers ?

    Absolutely! I would however, as I said before do a layer of masking tape or even better the plastic wrap that comes on some pre-finished aluminums to protect things and allow me to lay out the pattern without marking the metal directly. Sharpies do wash off with a bit of lacquer thinner, but when there is a texture involved, I've had some want to stay down in the swirls.

    Actually, yes. The most common pattern that you see is each swirl overlapped by about 50%, with the next row overlapped 50% and advanced 50%. It takes FOREVER to do, especially when you are doing something small like a gauge panel and using a 1/2 Craytex stick, but it "fills in" the pattern the most. The Spirit's cowl is a much rougher free hand kinda deal that would cover a large surface like that a lot quicker. I'd say that it's over lapped by more like 1/3 or maybe even 25% per swirl, and the same on the next row. I looser pattern like that is far more forgiving on a compound curved surface visually.
  29. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    from BC

    My thoughts exactly.
  30. FlatHead Deuce
    Joined: Dec 1, 2008
    Posts: 21

    FlatHead Deuce
    from Ipswich MA

    Wow, thanks guys! I got a bunch of good ideas here, much appreciated!
    In hindsight, we should have turned, then formed the hood...

    Hood is for my '67 Volvo 1800s racecar/street car. Inner brace will cover quite a bit of it, so some mistakes may be "hidden".

    I know it is not a "Hot Rod", but it is very much hot-rodded with Posi, ARE rims, Watts link, full roll-cage, Competition head Isky cam, Stahl header, Mallory ignition etc.

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