Riv-nuts vs pop rivets

[oldbilbo]

I've been securing a couple of fittings to the mast wall and have found it convenient, for one such, to insert some M6 s/s rivnuts. FWIW, here's a pic...

That exercise got me wondering. Other fittings are secured using pop rivets, and some by self-tapping screws. I'm likely to want to attach some robust fittings for runners, for an inner forestay, and also a steaming/deck floodlight.

Given that the cost of my time is modest, but I can afford non-professional but reasonable-quality DIY-type tools, what, to the riggers and engineers amongst us, are the pros and cons of each type of fastener and process....?

 

[David2452]

Not a rigger or even close but I use rivnuts a lot and their major, if not only advantage and the reason I use them is ease of removal for serviceability and tightening if they become loose, a pop rivet is a once only chance and if it becomes loose for any reason must be replaced, same goes for any service or replacement removal of the secured component.

 

[BERT T]

+1 For rivnuts, I used them a lot when building electrical control panels. As David points out serviceability is a big issue, do you climb the mast carrying a battery drill and a pop riveter or a 10mm spanner.

 

[Jcorstorphine]

Again, not a rigger but I have used monel pop rivets over the years to build a couple of masts and modify another using a heavy duty lazy tong tool. However I do get a bit twitchy setting the larger size rivets as the lazy tongs tend to skite as the rivet sets. I recall the story recanted here by another formite who damaged his face while up a mast using lazytongs which slipped and dug into his cheek. If I were to buy another tool I would buy one of the lever type which don not require substantial inward force to set the rivets.

As to Rivnuts, I wanted to use a couple of 6 mm SS for a mod on a mast and tried to make various setting tools but gave up and ended up using Pop Rivets.

There was one product I used back in the 70's which did not require any special tools and that was an aluminium alloy insert which had thin flange and a split boss. You basically drilled a 8 mm hole, fitted in this insert and when the fitting was screwed in, it flared the insert and secured the screw. Much better that self tappers. Trouble is I have never seen them since.

 

[TradewindSailor]

I would have thought that monel rivnuts would be vastly superior to stainless steel.

I have s/s rivnuts in my mast ... or rather I assume they were once stainless steel, probably A2 or worse. The rivnuts themselves are corroded, as is the aluminium around them .... that they are seized in well. Now I don't have the fitting on the mast it all looks pretty ugly!

 

[West Coast]

I have used rivnuts in our FRP structures we supply industrially, but not often as we have only been able to get A2 grade stainless

 

[NormanS]

For permanent fittings, you won't get much better than monel rivets. If it's for something removable, use rivnuts. Self-tappers on masts are really only suitable for things with little load on them, and generally mast wall thickness is not enough for reliable thread tapping.

 

[Norman_E]

..........
As to Rivnuts, I wanted to use a couple of 6 mm SS for a mod on a mast and tried to make various setting tools but gave up and ended up using Pop Rivets.................

The problem is that the wall of the mast was probably as thick as the thin part of the rivnut that has to deform outwards to set it. Most rivnuts are intended to be set into quite thin sheet metal parts.

 

[lw395]

I've used these people
http://www.memfast.co.uk/shop/Vprod2.asp?cat=2254005218
Generally you can use these rivnuts with metal a bit thicker than the quoted grip range.
I find it's fairly easy to set them with a long allen screw a few washers and a nut.
Put the nut on the allen screw, then the washers, then the rivnut.
Insert in hole, hold allen still with T-driver, then tighten the nut down.

Lightly loaded fittings on thick ali, I would just drill and tap though.

 

[doug748]

I should use 6mm monel pop rivets for the runners and inner forestay.

Having to put a few in myself, earlier in the year, I bought a "Faithfull" long handle type gun on 'tinternet. It was hopeless and failed to accept the rivet mandrel. I understand others have had more luck with these tools so it obviously had a defect, nevertheless I sent it back.

In the end I bought an Eclipse lazy tong, which was grand. Take care because only the latest models can cope with 6mm. I see you are in the West Country? The good news is that Trago Mills stock the Eclipse for about £40, a great bargain.

As already mentioned, lazy tongs are not the thing to take up a mast but I guess you will be operating at ground level.

 

[paul-essex]

http://www.bollhoff.co.uk/en/uk.php I have used these before at work

 

[NormanS]

I should use 6mm monel pop rivets for the runners and inner forestay.

Having to put a few in myself, earlier in the year, I bought a "Faithfull" long handle type gun on 'tinternet. It was hopeless and failed to accept the rivet mandrel. I understand others have had more luck with these tools so it obviously had a defect, nevertheless I sent it back.

In the end I bought an Eclipse lazy tong, which was grand. Take care because only the latest models can cope with 6mm. I see you are in the West Country? The good news is that Trago Mills stock the Eclipse for about £40, a great bargain.

As already mentioned, lazy tongs are not the thing to take up a mast but I guess you will be operating at ground level.

My Faithfull, long handled one works fine with 6.4mm monel rivets.