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Can rivnuts fix my mast?

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Wobble View Drop Down
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Post Options Post Options   Quote Wobble Quote  Post ReplyReply Direct Link To This Post Topic: Can rivnuts fix my mast?
    Posted: 04 Jul 14 at 1:12pm
Never thought- of that Ian. Brilliant suggestion and will give it a go next time, which hopefully will be a long way off!
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Ian29937 View Drop Down
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Post Options Post Options   Quote Ian29937 Quote  Post ReplyReply Direct Link To This Post Posted: 04 Jul 14 at 11:43am
Originally posted by Wobble

In reply to JimC...
No -- it's not just the rivet head but the rivet gun that won't go in there. This isn't such a problem for soft rivets but I have found that the harder ones (can't remember their name) are much more inclined to snap off before fully closed in. Also, the rivet size is limited by the hole in the fitting, smaller than that in the mast. 
Rivnuts would get around that problem as the rivnut size would  be bigger than that of the bolt going into them.



Have you tried putting a couple of small nuts on the shaft of the pop rivet. This moves the riveter away from the fitting and as long as the riveter still grips the shaft, it gets around the problem of interference from the fitting.

Cheers

Ian
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Post Options Post Options   Quote Wobble Quote  Post ReplyReply Direct Link To This Post Posted: 03 Jul 14 at 10:43am
Good idea on the scrap piece. If it all falls apart next week, I'll give that a go -- after my therapy sessions. 
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Post Options Post Options   Quote piglet Quote  Post ReplyReply Direct Link To This Post Posted: 02 Jul 14 at 5:18pm
Well done Wobble, I don't think the blood vessels in my Cerebral Cortex would have put up with that.
 
Your idea of pulling up a washer on adhesive for later pop riveting has some merit.
Though I would go for a scavanged piece of ally in place of the st.st. washer and epoxy or methacrylate in place of the superglue.
 
You realise it will break next week LOL
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Post Options Post Options   Quote Wobble Quote  Post ReplyReply Direct Link To This Post Posted: 02 Jul 14 at 5:02pm
Got the job done at last!

Incredibly fiddly, as predicted, and a little compromised.

In the end I  used the spreader hole to get inside with a lead mouse, stood the mast up and rattled like hell, exiting via the spinnaker uphaul sheave hole; then pulled in reverse so that I was able to pull the bolt out the hole and into place. Sounds easy but it took forever because I started with the wrong method -- trying to drop the bolt directly from the jib sheave above because I hadn't though it through properly and just went for the biggest entry point. Head-wrecker.

In the end, no ladders or platforms needed. But next time will definitely heed advice to use stronger fishing line, and also more highly coloured. Dull brown, lightweight line was the biggest cause of distress, with one bolt lost -- temporarily -- up the mast due to a break. (I am now doubly fluent in swearing and general crankiness.)

Bolts (6m) are a bit undersized for the hole due to the limit on the lug, and I could get only one nut on each bolt because of the shape of the lug and the need to leave room for space for the securing pin for the bottle adjuster, which still needed a bit of gentle hammer-persuasion to fit home.

Couldn't find nylon washers, but I did use Duralac and it got everywhere. Also used threadlock on the threads to help the nuts, now dead tight, stay in place. I'll need to monitor them carefully... here's hoping!

I hope this account helps anyone considering a similar operation. Thanks again to all for the very sensible advice.

PS: I was thinking when preparing at one point to fail with the bolt method (desperation being the mother of invention)... Would it make sense to pull a washer against the inside of the enlarged hole, then superglue it in place to give a new, smaller hole to fit the usual-size rivet? Also fiddly, but I think it could work generally where rivets are preferred but the hole has become too big.
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Post Options Post Options   Quote Wobble Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jun 14 at 5:15pm
Thanks sandgrounder for that excellent advice. Hadn't thought of using a nylon washer. 

Forced to wait a bit to do this job now, as I have discovered on taking it off that the spreader lug is cracked thanks to previous efforts with rivets, and I need to get a new one. Really want to get back on the water now but I'll have to be grown-up and deal with delayed gratification. 

Will post hopefully positive outcome here when done...
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Post Options Post Options   Quote sandgrounder Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jun 14 at 4:12pm
Originally posted by Wobble

I think that the cautions outlined above probably are pointing in the direction of Craiggo's bolts and a long-noser. Otherwise it looks as if I might be pioneering the use of rivnuts for this purpose, and I'd prefer someone else to do that experiment!
I can do fiddly stuff as I have been know to lose halyards etc up there before -- just resign to taking an afternoon to do it -- and I can do ffluent swearing too, so it seems I am well-armed to take on this task. I assume the bolt also takes a washer on the inside? 




I have done a lot of these over recent years, preferring the security of M5 A4 stainless steel bolts over pop rivets on every occasion. I use an A4 stainless washer on the inside, and also a nylon washer, with the nylon washer closest to the mast. To assist in pulling the bolt through the hole I find it helps to taper the end of the bolt using a Dremel and abrasive wheel, and I use 6lb fishing line.

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Post Options Post Options   Quote piglet Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jun 14 at 8:21pm
Monkey goo
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Post Options Post Options   Quote transient Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jun 14 at 1:18pm
....some Duralac might be good as well. It'll add the extra frustration of messiness.
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Post Options Post Options   Quote Wobble Quote  Post ReplyReply Direct Link To This Post Posted: 17 Jun 14 at 12:51pm
I think that the cautions outlined above probably are pointing in the direction of Craiggo's bolts and a long-noser. Otherwise it looks as if I might be pioneering the use of rivnuts for this purpose, and I'd prefer someone else to do that experiment!

I can do fiddly stuff as I have been know to lose halyards etc up there before -- just resign to taking an afternoon to do it -- and I can do ffluent swearing too, so it seems I am well-armed to take on this task. I assume the bolt also takes a washer on the inside? 
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