CriCri MC-15 in NZ

Discussion in 'The light stuff area' started by MadRocketScientist, Jun 19, 2009.

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  1. May 16, 2019 #1461

    proppastie

    proppastie

    proppastie

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    So turned hardened bolt into special tapped nut? Or is that a sleeve?
     
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  2. May 16, 2019 #1462

    MadRocketScientist

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    I will turn and tap the centers of the M10 bolts for 1/4-28 aircraft bolts to hold the prop on.
     
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  3. May 17, 2019 #1463

    MadRocketScientist

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    And still making good progress, I continued on with the prop bolt stubs today.
    DSC08002 (Medium).JPG
    First I marked out the bolts with some 18mm masking tape.
    DSC08004 (Medium).JPG
    Then cut them off with the cordless angle grinder, the cutoff wheel has seen better days!
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    As long as I didn't cut too close to the masking tape there was plenty to finish up in the lathe.
    DSC08008 (Medium).JPG
    Not shown but I drilled out the centers to 5.5mm in the lathe. I started the internal thread of each hole before removing it from the lathe...
    DSC08011 (Medium).JPG
    Then set up a vice and collet holder on the CNC bed and hand tapped each hole. The high tensile steel is really hard to tap and work hardens easily. I would have preferred to have drilled the hole out to 5.7mm (75% of the thread) to make the tapping go smoother, but since I couldn't find a drill bit around, 5.5mm had to do. Eventually got them all threaded 1/4-28.
    DSC08015 (Medium).JPG
    I put them on a threaded fixture in the lathe and turned them to length. I also set up a 1/4" drill in the tail stock and counterbored the front.
    DSC08017 (Medium).JPG
    The bolts fit!
     
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  4. May 17, 2019 #1464

    proppastie

    proppastie

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    Break any taps?
     
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  5. May 17, 2019 #1465

    blane.c

    blane.c

    blane.c

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    That's just mean.
     
  6. May 17, 2019 #1466

    proppastie

    proppastie

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    Sorry but others might want to be aware of potential problems. I am highly impressed ......
     
  7. May 18, 2019 #1467

    MadRocketScientist

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    Very surprisingly, no. Has to be close to some of the worst material I have tried to tap. Even stainless cuts a lot smoother.;)
     
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  8. May 18, 2019 #1468

    MadRocketScientist

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    You haven't broken any taps yet? :p:p:D
     
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  9. May 18, 2019 #1469

    proppastie

    proppastie

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    I break them in aluminum
     
  10. May 18, 2019 #1470

    blane.c

    blane.c

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    quit buying them at harbor freight.
     
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  11. May 18, 2019 #1471

    MadRocketScientist

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    Aluminium is nasty, especially the lower grades because they are so gummy! I have broken a few quality taps in aluminium, mostly after using them in steel. I try to keep a set dedicated to aluminium so they stay nice and sharp.
     
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  12. May 18, 2019 #1472

    MadRocketScientist

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    I continued making the prop hub stubs today and almost got them finished. I made them a press fit in a hole I had reamed with a 3/8" reamer as a test. Even doing that they are bit tight in the actual parts. I think I may turn them down slightly more.

    DSC08020 (Medium).JPG
    I also set up the two prop hubs and spinner mounts in the CNC and milled the holes out to 9.4mm ready for reaming.
    DSC08022 (Medium).JPG
    Once I had the holes CNC'ed I shifted the whole mdf jig over to the drill press and ran the 3/8" machine reamer through all the holes,
    DSC08030 (Medium).JPG
    Very happy with results.
    DSC08032 (Medium).JPG
    DSC08035 (Medium).JPG
    I haven't pressed the stubs into place yet. I think they need to be reduced in size ever so slightly and I also want to alodine the hub. I might do a trial fit of the hub onto the crankshaft first, before alodining anything.
    DSC08024 (Medium).JPG
    While I had the CNC running I cut a couple of bits of 10mm acrylic,
    DSC08026 (Medium).JPG
    And stuck them together with superglue. some 1/8" drill bits kept everything lined up while the glue set (really fast)
    DSC08029 (Medium).JPG
    And I have a jig for drilling the holes for bolting this onto the front of the crankcase.
     
  13. May 19, 2019 #1473

    MadRocketScientist

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    I decided to fit the prop bolt stubs into their hubs ;) and fitted a hub onto a crankshaft. I will have to take them out again sometime to alodine everything but checking that everything fits is important.
    DSC08038 (Medium).JPG
    Looking good
    DSC08039 (Medium).JPG
    I also drilled and tapped the retaining bolts on the starter/ignition mounting brackets.
    DSC08040 (Medium).JPG
    Stubs come through the spinner mount nicely.
    DSC08042 (Medium).JPG
    And moving into the realm of 3D printing, A friend printed the ignition sensor holders on his 3D printer. Thanks Mark!
    DSC08044 (Medium).JPG
    And with some hall effect sensors sitting in place, eventually they will be epoxied in place. Which reminds me, I need to check how well epoxy bonds to PLA and ABS plastics!
    DSC08046 (Medium).JPG
    Three versions (so far) of the ignition sensor holders, it is taking some time to get these exactly right, and I'm still not on the final version :eek::D
     
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  14. May 22, 2019 #1474

    MadRocketScientist

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    Just a couple of pictures of the engines in place. Still waiting for bolts for the music wire clamps
    DSC08047 (Medium).JPG DSC08049 (Medium).JPG
     
  15. May 26, 2019 #1475

    MadRocketScientist

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    More slow progress...
    DSC08064 (Medium).JPG
    First up, a test fitting of another updated version of the ignition sensor bracket on the engine. Looking good but the bad news is that I might have to make these from phenolic rather than PLA. The 3D printed plastic gets soft at a far to low temperature to be much practical use. I may test an engine with PLA brackets but I don't count on them lasting.
    DSC08067 (Medium).JPG
    I have been thinking about this next little job for quite some time. The flapperon bearings have a 4mm internal hole but I really wanted to use aircraft hardware to hold these on. Most of the M4 metric bolts I have been able to source have been closer to 3.9mm, leaving a lot of play when inserted into the bearings. When things are clamped up tight it might not have been so much of a problem, but still..
    There is also the unknown quality issue.
    DSC08069 (Medium).JPG
    I made this fixture in the lathe for reaming the 4mm hole in the bearings out to 4.15-4.20mm. I started by turning up a cap (in the previous and next pictures) and then making this externally threaded holder with a counterbore for locating the bearing. I had machined the bore to 12mm to fit the bearing but when I used a milling cutter in the tailstock to flatten the bottom of the bore, things went wrong. The hole ended up 0.7mm oversize!:confused::confused: I had the use a piece of heatshrink on the outside of bearing to center it for reaming. Turned out okay in the end.
    DSC08071 (Medium).JPG
    With the cap screwed tightly in place, the ball part of the bearing was clamped from each side and I could ream the hole. The reamer is made from a broken 3/16" solid carbide router cutter that I ground the diameter down to slightly under 4.2mm. I used the diamond wheel the grind a bevel on the end to act as the cutting edge. The holes in the first few bearings came out a little bigger than I wanted at around 4.2mm, but after a few tweaks to the homemade reamer, I got the fit much closer to the bolt size. Having a few spare bearings helps.
    DSC08074 (Medium).JPG
    DSC08076 (Medium).JPG
    I pressed out the previous bearings from the flap levers ready for installing the new resized bearings. I have some polishing to do first.
     
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  16. May 26, 2019 #1476

    proppastie

    proppastie

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    You have both CNC mill and 3d printing. ...Why this vs that ?
     
  17. May 26, 2019 #1477

    BJC

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    Mad:

    When you complete your airplane, please do not fly it; it deserves to be in a museum devoted to individual craftsmanship.


    BJC
     
  18. May 26, 2019 #1478

    blane.c

    blane.c

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    What? Do not listen to him. Not to fly it is a sin with everlasting Hell as a punishment.
     
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  19. May 26, 2019 #1479

    TFF

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    For sure fly it. Some of me always hates that a plane will not fly again in a museum. Just not allowed to tear it up!
     
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  20. May 27, 2019 #1480

    MadRocketScientist

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    The 3D printer isn't actually mine, but 3D printing and routing can complement each other. I prefer the CNC router though.
     
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