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Thread: Cowl fasteners

  1. #1
    Junior Member
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    Cowl fasteners

    Right ladies and Gents
    I realise this was discussed in 2010,
    in the very near future I will receive my Nynja kit ( no pressure PD) This will be ranger no 5 for me. This time I want to add cowl fastenings to a professional standard. Some one must have worked out the definitive make and model of fastener to use by now???
    Please help....
    Regards
    Damian

  2. #2

    Cowl fasteners

    I have used The Southco 1/4 turn screws from Zygology for 10 years now and they have never let me down, easy to release and lift off the lid, easy to put back on, but a bugger to get the fixing right first time round. If I were to build another SkyRanger I would definitely go for the Southco solution.
    Adrian.

  3. #3

    Cowl fasteners

    There are a few problems to overcome to use quick release fastners.

    Most require some pressure to engage - and can flex the composite to cracking point doing so - so reinforcing the sides of the lower cowling is needed for these. A strip of Ali or similar.

    Most when undone protrude to some extent. On a cowling with curved sides ( Nynja is more curved still than SKR) this tends to result in the cowling still locked in place 'pegged' in position and resisting being pulled off. This in turn gives rise to ripping the fastners out of the cowling when trying to wrestle it off. Two ways to get around this - use fastners that come out when undone - (but then be careful not to lose them) or one solution used by the Israelli dealer is to make a hinged 'trap door' section on the lower cowling where it curves around the front - which falls backwards when fastner released.

    Ther are all a bit of a bugger to fit - they need accurate drilling and hole matching between parts, and may need different depths of fastner for different areas - deeper for instance where the firewall laps under thickening the material. It's important they clamp the cowling parts together solidly othwise all will jiggle in operation and wear. That can be a double headache if you use fastners that come out when released - you need to make sure you put them back in the right holes. Dzeus type fastners if not quite right can distort and grab. I spent half a day recently trying to get the bonnet of an Escapade that had used these - in the end we had to saw through several fastners which would not come out - whilst trying not to scratch the paint!

    I still prefer using screws. In the kits these days we use flanged panhead stainless screws, which with a hex screwdriver spin out really quickly. On our last demonstrator I experimented grommetting the holes in the top cowling to stop them wearing from contact with the threads during insertion and removal. I used Dzus grommets and their flanging tool which I modified by grinding down the lip so it fully flattened and clamped the grommets in position. So far 100 hours in the holes are good and system is working well, and looks neat and professional. Holes are around 6mm so nice and easy for alignment using the 5mm screws - no nasty out of alignment holes to grab the screws and cause cross threading etc. tool not super cheap, but I might be persuaded to lend ours out to builders.

    I also have started using rivnuts in place of the lug nuts - for now just on the rear edge where there is the firewall top to fix them Through as well as the glass fibre. These provide a solid fixing and resist the holes pulling. The rivnuts tool is not expensive and rivnuts can be used in lots of other places - like the centre console and instrument panel - where they are neat and work well. So a good tool to buy for a build.

    Paul

    Links to Dzus grommets and tool and rivnuts tool:
    http://www.lasaero.com/site/products...e?id=V01AHJ5JZ http://www.lasaero.com/site/products...e?id=V01XC83F9
    http://www.pvrdirect.co.uk/productin...FTDJtAodFiUAlQ

  4. #4
    Junior Member
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    Cowl fasteners

    Thanks Adrian & Paul,
    I have seen some poor attempts at faster fitting, hence why I asked the question.
    On my swift build I used lots of rivnuts where I could.
    When I had a C42 the camlocks just seemed to work , but I think the receivers are too large for the lip on the skyranger lower cowls?
    I'll have to find something else to occupy idle hands until the kit arrives!
    Best regards
    And have a happy Christmas

  5. #5
    not real name 500 Club
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    Jun 2008
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    Cowl fasteners

    Damian,

    I've used Camlocs on my Swift and my current Nynja: I'm quite happy with the results and consider them well up to the job. You say you've used them before, so I'm sure you don't need me to describe them. The important thing to get right, of course, is the length: those too long WILL fit, but stand proud when secured.

    Maybe I'm lazy, but I would find the prospect of unscrewing perhaps a dozen screws, possibly dropping one or two into the grass, just to do a daily inspection a disincentive; I'd still (reluctantly) still do it, since I'm an engine freak, but lesser men might not bother..... :-)

    I AM a big fan of rivnuts, about which I knew not, until Paul introduced them in the course of the Nynja build. I've used them to great success on the binnacle and other places, but far and away the best are those used to secure the front spat. The first attempt, at tapping threads in the front oleo legs was simply awful, with the spat wobbling about like a spare wotsit. Using rivnuts, it's really secure.

    Paul: I think the cause of your frustration was with 'Dzus' fasteners, although I concede you WERE probably cursing the Greek gods at the time!

  6. #6

    Cowl fasteners

    Camlocs are ok, but fall out after a few hundred hours as they only need the holes to elongate a touch to fall through. We tried them on one of our demo SKRs and they were disapointing after quite a short time.

    I have also flown a fair few school C42's doing instructor tests and they are quite fiddly and fall out. Also the pins in the. Wear and fall out or go asymmetric over time which can cause problems.

    I reckon it is quite a bit quicker using the screws well set up and with a hex head screwdriver so they can be spun out.

    After the post this morning I spent a bit of time looking at the fastners on the southco site. I quite like thesehttp://www.southco.com/en-us/09-12-17 they are threaded but with fast lead and captive so won't fall out. And I reckon the sadle receptacle used on the curved bits and with a slot cut upwards in the glass fibre, might just solve the 'Jacking out' needed to remove the panel which tends to lock it in position. Not sure how hideously expensive they are but I might get some samples to play with.

    Paul

  7. #7
    Junior Member
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    Cowl fasteners

    Thanks for the input guys...

    These look like they will pop out of the way to allow cowl removal, but would they cope with the curvature?
    Damian

  8. #8
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    Cowl fasteners

    Dohhttp://www.ebay.co.uk/itm/DZUS-type-1-4-Turn-Self-Ejecting-Fastener-Complete-with-Spring-4-4-5-2mm-Panel/141331976169?_trksid=p2047675.c100005.m1851&_trkpa rms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3 D28111%26meid%3Df831a17801044720a1c98bee31c4fc06%2 6pid%3D100005%26prg%3D11472%26rk%3D2%26rkt%3D6%26m ehot%3Dag%26sd%3D111309986291&rt=nc
    try attaching the link !!!

    http://www.ebay.co.uk/itm/DZUS-type-...09986291&rt=nc

    Tried making the link live for you Damien but doesnt seem to work - maybe the gap which i closed has something missing?

  9. #9
    Senior Member 500 Club
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    Norwich, Norfolk
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    Cowl fasteners

    Damian Perkins wrote:
    in the very near future I will receive my Nynja kit
    We've got a kit on order too Damien, here's hoping for a Jan 2015 double-delivery?

    Some interesting products on this site;

    http://rhf.co.uk/quick-access-fasten...Ot4aAvUr8P8HAQ

  10. #10
    Senior Member 500 Club
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    Cowl fasteners

    All these links are a bit bewildering
    is there anything on this PDF worth trying out?

    http://www.southco.com/static/Litera...9-12-17.en.pdf

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