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Thread: Hot engines


  1. #51
    combatpigg's Avatar
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    RE: Hot engines

    Vic, how would you open up the ID of the cranshaft tunnel with the tools that I have..?
    The lathe is a HF 9x13.
    WHO GUNNA FEED MAW KEEEIDS..???

  2. #52
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    RE: Hot engines

    Chuck up on the main journal, indicate it to make sure it runs true. Run around 900 RPM and a carbide tipped boreing bar. Easy feed, The chips will be red hot and stringy. I would rough it out up to the intake window since the interupted cut is likely to chip the tool. Once you get most of it out come back and work on the window area. Keep in mind a chipped tool will still cut for a while if the tool pressure is enough.

    I have done this on my little lathe at home to a TT.40 crank with cheap carbide tipped bars.

    This process is called hard turning. The idea is with the higher rpm and hard tool, carbide, you create a good bit of tool pressure. This in turn creates heat, when you get the sweet spot you are putting the right amount of heat in front of the tool to allow it to anneal and be cut. Even when you are in the sweet spot the tool will wear quickly, just keep sharpening it.

    We use coated inserts for small quick jobs but when we are serious and have a decent job we use a CBN insert. Most of the time we don't even need to grind the part, we just hard turn it.
    Pretty sure you won't want to spend the $ on CBN.
    A guy who used to live on this site and now is rarely here due to the "upgrade".
    Most likely fading away till the My Forums is fixed. Too bad.

  3. #53
    combatpigg's Avatar
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    RE: Hot engines

    Thanks Vic. From the rear edge of the window going forward I would be nervous about snagging the window with the boring bar.
    Do you make a split collar to hold the crank in the jaws of the chuck...?
    WHO GUNNA FEED MAW KEEEIDS..???

  4. #54
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    RE: Hot engines

    You aren't taking a deep cut like you could if it were soft. .015 or so a pass when you are at the window. If it's banging around to much you could slow the speed down some.

    I just chuck right on the crank. It's hard and less likely to spin or go askew than with a sleeve.
    A guy who used to live on this site and now is rarely here due to the "upgrade".
    Most likely fading away till the My Forums is fixed. Too bad.

  5. #55
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    RE: Hot engines

    The lathe jaws would be softer than the crank, wouldn't they? I recall a machinist cleaning up my lathe
    jaws by turning the whole chuck assembly, I think he drew the jaws out wards tight against a steel ring.
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

    Revver Bro #231

  6. #56
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    RE: Hot engines

    Hard to say which is harder. But yes, when boreing or turning chuck jaws you want to have them clamped.
    I doubt CP will need to re-cut his jaws for this job.
    A guy who used to live on this site and now is rarely here due to the "upgrade".
    Most likely fading away till the My Forums is fixed. Too bad.

  7. #57
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    RE: Hot engines

    Yeah I know, the point was it didn't dawn on me at the time that you could machine out the lathe jaws to true them, so I figured they must not be terribly hard, meaning that it sounds like a low risk deal chucking the crank directly.
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

    Revver Bro #231

  8. #58
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    RE: Hot engines

    How about using something like this? Only cost me a few dollars to make, but it works great for hard stuff like that especially if it doesn't require a super precise cut as far as exact dimension. I do wish I had a bigger compressor when using it, but I have a "auxiliary" air tank made from a water heater tank(not rusted and has a blowoff set at less than rated psi) when I need to do a grinding pass and if I let my little compressor fill it up it is enough constant supply to make a pass. I use the regulator on the end to spool the grinder up to a medium speed as the mount keeps the handle valve on the grinder depressed. As set up I can just pop it in and out of the quick-change. Make sure to cover the ways to keep the grit clean-up to a minimum. Todd
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    \"A guy told me the other day I must be very smart,......I told him \"No!, I\'\'m REALLY dumb, But learning from my mistakes!!\"\"

  9. #59
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    RE: Hot engines

    Todd, I was thinking that you could "power hone" your way through it. Do the whole operation under water, too.
    Years ago I opened up a few cranks with nothing more than a hand held electric drill, wood dowel with a slit at one end, sandpaper strips placed in the slit...and lots of patience.
    Compared to a prisoner cutting through steel bars with razor blades..it wasn't too bad though.
    I think you want to make a concentric cut for the best air flow..but I've got no real idea what the journey through the engine really looks like to those air/fuel molecules. The other consideration is the walls of the tunnel start to look kind of thin..but the crank pin location might limit how far you can open up the tunnel. The thing about converting a pattern engine to speed is you can do it in stages and see how the "limiting factors" shift from one area to another.
    WHO GUNNA FEED MAW KEEEIDS..???

  10. #60
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    RE: Hot engines

    Here some pictures to see some modifications on the OS speed engines.

    Have fun

    Best regards Michael
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  11. #61
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    RE: Hot engines

    Geeez, good work mate! Which one run the best ?
    Remember: Speed is life!

  12. #62
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    RE: Hot engines

    The best runner is the front intake

    24 700 rpm

    second is Zimmermann inlet

    24 500 rpm

    third drum intake

    23 500 rpm

    all use the same piston and cylinder, same prop, same fuel ....

    Best regards Michael


  13. #63
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    RE: Hot engines

    Michael,

    How do the modified OS engines compare in performance to the OPS VAE 10cc?
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

    Revver Bro #231

  14. #64
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    RE: Hot engines

    A very good performing OPS VAE is doing with the same prop max. 21000 rpm. Mostly it was not able to turn this ( my ) speed prop.

    Best regards

    Michae
    l

  15. #65
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    RE: Hot engines

    Michael, those are very impressive photos to compare a standard size crankshaft to a speed crank.
    You can not post photos like that without causing a lot of questions and a certain amount of jealousy though.....

    Did you have to make a custom bearing carrier for the front of the engine..?
    Who made the bigger crank..?
    The liner with the wide flange...does it delay expansion..? Stabilize the liner in the case..?
    How can you remove so much weight from the crank's counter balance and still have the engine run smoothly..?
    The bigger crank pin [and bigger rod] would need extra space for clearance inside the front housing. Were there any problems with making the extra room..?
    WHO GUNNA FEED MAW KEEEIDS..???

  16. #66
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    RE: Hot engines

    Folks, remind me - Zimmerman inlet = disc valve, right?
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

    Revver Bro #231

  17. #67
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    RE: Hot engines

    Hallo speedfreaks,

    the wholes in the counterbalance of the crank are for tungsten carbide pieces. This pieces are not in on the picture but will be in the running engine.

    The front end is made from a bar stock piece of aluminium.

    Yes you need more room for the bigger rod, but is is posible in the OS case.

    Here some details of the self made Zimmermann inlet.

    Best regards Michael
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  18. #68
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    RE: Hot engines

    That is a huge difference in rpm over the OPS Speed.60.
    I wonder how much extra air handling ability is required to go from 21,000 to 24,700..?
    Or from just 24,500 to 24,700..?
    Once you get into this realm of performance, imagine how difficult future gains will be to find..!
    WHO GUNNA FEED MAW KEEEIDS..???

  19. #69
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    RE: Hot engines

    CP, I think you are going to need a Bridgeport.
    A guy who used to live on this site and now is rarely here due to the "upgrade".
    Most likely fading away till the My Forums is fixed. Too bad.

  20. #70
    combatpigg's Avatar
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    RE: Hot engines


    ORIGINAL: vicman

    CP, I think you are going to need a Bridgeport.
    In the good old days the California junior colleges were almost free except for books and lab fees and sometimes a parking pass. A lot of old fogies took classes to pass the time or to help with a hobby.
    I would be surprised if it is that way today now that California's government is headed towards bankruptcy.
    I might still have a 1 time veteran's tuition grant available. That would be the ticket. Have some projects already lined up ahead of time then enroll in a machine shop class.
    WHO GUNNA FEED MAW KEEEIDS..???

  21. #71
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    RE: Hot engines

    There is a growing group of community workshops on Hackerspace. They basically are where a group of people from different backgrounds come together and build stuff. The one near me has a mill and lathe. They wanted a little too much for dues from a guy like me who has all the access to that I want. But it would be a great deal for someone wanting to do a project.
    A guy who used to live on this site and now is rarely here due to the "upgrade".
    Most likely fading away till the My Forums is fixed. Too bad.


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