Rivets or Machine Screws When Splicing a Mast?

[Dave_S]

Originally Posted by Chotu

Here’s a question. Do rivets pull both sheets together? I know they kind of clamp down when they install.

If you had a very small gap between a couple of sheets of metal, and you put a machine screw in there, you would retain the gap probably. That’s assuming both are threaded.

Wood rivets pull the sheets together?

You shouldn't thread both pieces. The outer material should have a very close fit clearance hole and not countersunk. The inner material should have the thread.

Most machine screws are undersized, we prep a clearance hole for a 5mm machine screw at 5mm.

[Wotname]

Left field observation -

If you want to know anything about rivets and aluminium - ask an airframe engineer. They use every known kind of rivet in every known structural application every time. Rivets work!

[Bruce K]

One from the left field! Assemble joint, drill required holes, disassemble, put flush head rivnuts in sleeve with tefgel, reassemble with machine screws. Screws can be tightened without fear of stripping.

[Chotu]

Originally Posted by Bruce K

One from the left field! Assemble joint, drill required holes, disassemble, put flush head rivnuts in sleeve with tefgel, reassemble with machine screws. Screws can be tightened without fear of stripping.

Pretty neat idea. I don’t think it would work because I’m not so sure you can get the thing back apart once it goes together.

Every video I see they use, come-a-longs to bring the parts together. I don’t know how you get them back apart without damaging them.

[Chotu]

I’m pretty stuck here. I can’t make up my mind.

Given that the internal piece might not be a perfect fit, should I use rivets or should I use machine screws?

That’s about the only factor here that I can think of that might affect the decision. Otherwise it’s a tossup.

The only other factors that I think machine screws will take a lot longer and cost a fortune at $90 an hour.

[Breaking Waves]

how thick is the tube wall and how thick is the sleeve?

If you are concerned with the fit of the sleeve, try to get the gap filled with thickened epoxy. Hopefully you will pull it tight and smoosh out most of that, but it will gap fill.

[neilpride]

Originally Posted by Chotu

I’m pretty stuck here. I can’t make up my mind.

Given that the internal piece might not be a perfect fit, should I use rivets or should I use machine screws?

That’s about the only factor here that I can think of that might affect the decision. Otherwise it’s a tossup.

The only other factors that I think machine screws will take a lot longer and cost a fortune at $90 an hour.

If the internal part dont match perfect the outer section then dont do it, sleeves fit evenly without gaps, let me know if im wrong ,but the whole question its to know if rivets or screws can help the sleeve to fit to the internal mast sidewalls?

Sleeves are sold on request.

Back to the question ,honestly try to fit a piece of small section in your current mast section its a risky bussines.

Just a accidental gybe its enough to see dislodged mast sections, imposible to drop the mainsail , not worth the saving...

[rslifkin]

Originally Posted by Chotu

I’m pretty stuck here. I can’t make up my mind.

Given that the internal piece might not be a perfect fit, should I use rivets or should I use machine screws?

That’s about the only factor here that I can think of that might affect the decision. Otherwise it’s a tossup.

The only other factors that I think machine screws will take a lot longer and cost a fortune at $90 an hour.

Have you asked the guy doing the work which method he's more comfortable or experienced with? That might be a factor in choosing.

[Chotu]

Originally Posted by rslifkin

Have you asked the guy doing the work which method he's more comfortable or experienced with? That might be a factor in choosing.

That’s a pretty good point. Maybe that is the deciding factor. Whatever he can do the best job with.

[Chotu]

Originally Posted by neilpride

If the internal part dont match perfect the outer section then dont do it, sleeves fit evenly without gaps, let me know if im wrong ,but the whole question its to know if rivets or screws can help the sleeve to fit to the internal mast sidewalls?

Sleeves are sold on request.

Back to the question ,honestly try to fit a piece of small section in your current mast section its a risky bussines.

Just a accidental gybe its enough to see dislodged mast sections, imposible to drop the mainsail , not worth the saving...

I’m just saying what if there’s like a minuscule little variance. Would the machine screws be better at keeping it in line? Or would the rivets be better at that?

The whole question was just to use rivets or machine screws. That’s it.

That was the whole question.

Not sure which of them is better. There have been a lot of different arguments on both sides here and no real conclusion.

[Chotu]

Originally Posted by Breaking Waves

how thick is the tube wall and how thick is the sleeve?

If you are concerned with the fit of the sleeve, try to get the gap filled with thickened epoxy. Hopefully you will pull it tight and smoosh out most of that, but it will gap fill.

The tube wall is 3/16” and the sleeve is 1/4”

[Celestialsailor]

Originally Posted by Chotu

I’m pretty stuck here. I can’t make up my mind.

Given that the internal piece might not be a perfect fit, should I use rivets or should I use machine screws?

That’s about the only factor here that I can think of that might affect the decision. Otherwise it’s a tossup.

The only other factors that I think machine screws will take a lot longer and cost a fortune at $90 an hour.

Maybe make a quick call to Buzz Ballenger of Ballenger spars. (831) 763-1196 He does this sort of thing all the time. Total custom guy.

[boatpoker]

Originally Posted by Celestialsailor

Maybe make a quick call to Buzz Ballenger of Ballenger spars. (831) 763-1196 He does this sort of thing all the time. Total custom guy.

What does the guy thats doing the job have to say ?

[MicHughV]

Chotu,

Tough to make a comment on this without knowing all the particulars.

There are a variety of topics concerning this issue online with proponents on each side, worthy of some time and effort on your part to read and digest.

I seem to recall you saying in a previous post, that the mast extension will be on the bottom of the mast. If this is correct, I'd favor the machine screws, for a variety of reasons, but in essence, you've already stated that the sleeve and mast are not a perfect fit, and for this reason alone, I'd favor the screws.

But they are really too many other variables here to properly ascertain with any degree of confidence on my part.

At the end of the day, I'd take the mast to a shop or have the shop come to you, as there will be likely a number of fasteners employed and number, spacing, etc, will be important, as well as fastener diameter, thread type, material type and so on.

I've noted this before, the compression and bending loads on a mast is quite enormous, as in tons enormous, so think twice and drill once.

This is not an area where saving a few bucks makes sense, so suck it in and get a pro to do the job for you.

[Chotu]

Originally Posted by boatpoker

What does the guy thats doing the job have to say ?

He says, “do you want me to use rivets or screws… I need to know soon so I can order them”