Rivets or Machine Screws When Splicing a Mast?

[Chotu]

Originally Posted by Dave_S

If the sleeve isn't a neat fit in the mast sections and the sleeve is thicker at 1/4" rather than 3/16" that I thought it was I will change my vote to screw fixings.

Again though, I would not use countersunk screws, I'd use pan head, torx drive 1/4". I like the sleeve length ratio in alanpride's images above rather than the shorter one shown previously. I would change the first row of fixings though to be staggered either side of the join line.

The mismatch you mentioned between inner and outer sections will require that the sleeve be progressively pulled into contact, matching the form of the outer sections of the mast. This will require you to spend some time re- tensioning the fixings in a cyclic pattern untill the mast and sleeve faces contact, then all fixing should tension the same. However as the surfaces are still moving and pulling together each screw tightened will relieve some of the load from adjoining fixings and these will need to be tightened again.....repeat untill no change is found.

I still worry about the standard of workmanship, but that seems to be just me.

P.S.
If you are going to use Loctite, first fit and tension all the screws, then remove them one at a time and Loctite.

Dave, I don’t know. I don’t know if the inner sleeve is going to be perfectly fitting. So why not assume that it isn’t? It’s really up to the skill of the person making it isn’t it?

I’d rather assume there are slight variations wouldn’t you?

I might get lucky and it’s perfect, but maybe it’s not. I don’t know.

I also like the long sleeve. Makes a lot more sense to me as well.

Why do you worry about the standard of workmanship? Further, why are you trying to give me another heart attack? Lol

How can I help the standard of workmanship? If I had you do this, could I still be worrying about the standard of workmanship? Yes. I could. If Neil pride did it, could I still worry about the standard of workmanship? Yes. I could.

But why should I?

Should I not trust the professionals know what they are doing?


I already have enough things to worry about without ruminating on this.

This forum sometimes seems to just increase anxiety.
Sometimes, I think you have to just stop worrying and just make a move. Otherwise I will never have a boat.

[team karst]

The chances of finding an extruded inner full splice with a close slip fit is about zero, correct?
So, the job consists of making a two piece internal section? Did I miss this?

[Chotu]

Originally Posted by team karst

The chances of finding an extruded inner full splice with a close slip fit is about zero, correct?
So, the job consists of making a two piece internal section? Did I miss this?

My Mast is a perfect ellipse.

So in AutoCAD, they developed a profile for it and they are making this internal piece as one section. Custom fabricated. There is no pre-existing piece. Correct.


So the internal piece is one fabricated single piece. Not multiple pieces screwed on.

I suggested the bump up to 1/4 inch. It will help the machine screws get a better bite, it can’t hurt because all it does is lineup the two pieces, and it will do that very securely.

[neilpride]

Originally Posted by team karst

The chances of finding an extruded inner full splice with a close slip fit is about zero, correct?
So, the job consists of making a two piece internal section? Did I miss this?

Zero, in older masts its a challenge to found a sleeve that fit perfect, if the spar maker its still in bussines and have the strussions plans , then there is a chance.

If the mast maker its in bussines , they make sleeves for the whole list of profiles on request.

Some folks under a tight budget try to get as close as posible with a profile and then try to machine that profile, sometimes work , others dont.

[Chotu]

Originally Posted by neilpride

Zero, in older masts its a challenge to found a sleeve that fit perfect, if the spar maker its still in bussines and have the strussions plans , then there is a chance.

If the mast maker its in bussines , they make sleeves for the whole list of profiles on request.

Some folks under a tight budget try to get as close as posible with a profile and then try to machine that profile, sometimes work , others dont.

And in this case I’m really lucky. Because my mast is a perfect ellipse. So they can fabricate that.

[neilpride]

Exactly, a ellipse profile its a easy way to make a sleeve , a cut in the back removing some material and voila...

[team karst]

OK, so this would be a sheet metal job (forming, seam weld, and grinding).
I had imagined some more complex shape; clearly, investing in an extrusion die is not an option.

[thinwater]

Possibly a dumb question.


If you cannot remove the plug once pressed into place, how do you drill the holes for the machine screws? The threaded portion is drilled tap-size. The mast portion is drilled clearance size. If you drill the tap size first, and then try to drill the clearance part, in aluminum, with the plug in place, the drill will really try to pull right through the full depth. Fast. You will end up with the holes drill clearance diameter, clear through. A good drill stop could work. Is that the plan?

With a rivet there is only one hole size.

I like the machine screw idea fine, but unless I can remove the plug, it's a little tricky. You could give up on the machine screws pulling the two parts together. But that is not desirable.

[Celestialsailor]

Originally Posted by Chotu

I don’t feel comfortable just calling someone and using them like that. That guy is in business.

Maybe folks in Northern Ca. are a little more receptive and friendly than where you are. Buzz has helped me a few times and when rebuilding a project boat has let me pick through is spar bone yard. Bill Lee (Former owner of Santa Cruz Yachts) and designer has helped me out when I needed a rudder for another project boat. Gery Mull (Renowned Yacht designer) openly gave me design advise while I was rebuilding at Ron Moore's(Builder, designer of the Moore 24) boat yard. As long as they feel you are not wasting their time going on and on and on, they are usually happy to help out. Funny thing, you're totally comfortable talking to strangers here. They are no different than anyone else. By the way...A shout out to Neil Pride. Great post.

[MicHughV]

Here's the big difference in my humble opinion.

A rivet requires a hole to be drilled thru' the mast and sleeve which will have a diameter slightly larger than the rivet to enable to rivet to be pushed thru'.
The rivet then gets tensioned, drawing the ball back to the rivet head.
You can't see the inside of the sleeve, so you can't tell if the tail end of the rivet is cracked, properly splayed open, etc...it's a toss of the dice.

A machine screw on the other hand will have a threaded hole, exactly matching the thread of the screw. ie, a tight fit. You will end up threading both the mast and sleeve as the thread tap must pass thru' the mast before getting to the sleeve.
This, imo, makes for a better and tighter fit.

A suggested above, you can use rivets to align and hold in place the sleeve and then finish off the job with machine screws.

I like to place a small dab of 5200 on the machine screw before screwing it in. This helps to lubricate the screw as it goes in, and also provides an additional barrier against corrosion between screw and mast. Finally, the dap will squeeze out under the screw head, sealing that connection as well.

[neilpride]

Originally Posted by thinwater

Possibly a dumb question.


If you cannot remove the plug once pressed into place, how do you drill the holes for the machine screws? The threaded portion is drilled tap-size. The mast portion is drilled clearance size. If you drill the tap size first, and then try to drill the clearance part, in aluminum, with the plug in place, the drill will really try to pull right through the full depth. Fast. You will end up with the holes drill clearance diameter, clear through. A good drill stop could work. Is that the plan?

With a rivet there is only one hole size.

I like the machine screw idea fine, but unless I can remove the plug, it's a little tricky. You could give up on the machine screws pulling the two parts together. But that is not desirable.

Thats why its important that the sleeve fit perfect but also posible to pull out.

[Chotu]

Originally Posted by Celestialsailor

Maybe folks in Northern Ca. are a little more receptive and friendly than where you are. Buzz has helped me a few times and when rebuilding a project boat has let me pick through is spar bone yard. Bill Lee (Former owner of Santa Cruz Yachts) and designer has helped me out when I needed a rudder for another project boat. Gery Mull (Renowned Yacht designer) openly gave me design advise while I was rebuilding at Ron Moore's(Builder, designer of the Moore 24) boat yard. As long as they feel you are not wasting their time going on and on and on, they are usually happy to help out. Funny thing, you're totally comfortable talking to strangers here. They are no different than anyone else. By the way...A shout out to Neil Pride. Great post.

I would say a lot more. Ha ha ha. I’m pretty familiar with the cultural differences.

Out here on the East Coast, people are very direct and will tell you to go F off if they don’t like you. Scares the crap out of Californians who visit. Lol

On the West Coast, they will be nice and pleasant to your face no matter what, but then behind your back they will tell everyone what a jerk you are, “forget” to invite you to the party or dinner. Etc.

That’s essentially the difference between the East Coast and the West Coast.

But I guess we have it all wrapped up now. I sent the instructions to the fabricator to go with the machine screws. I’m going to trust that’s the right way to do it. Seems a little more thorough.

[MicHughV]

Yep...machine screws is the way I'd do it.

[Dave_S]

Originally Posted by Chotu

Dave, I don’t know. I don’t know if the inner sleeve is going to be perfectly fitting. So why not assume that it isn’t? It’s really up to the skill of the person making it isn’t it?

I’d rather assume there are slight variations wouldn’t you?

I might get lucky and it’s perfect, but maybe it’s not. I don’t know.

I also like the long sleeve. Makes a lot more sense to me as well.

Why do you worry about the standard of workmanship? Further, why are you trying to give me another heart attack? Lol

How can I help the standard of workmanship? If I had you do this, could I still be worrying about the standard of workmanship? Yes. I could. If Neil pride did it, could I still worry about the standard of workmanship? Yes. I could.

But why should I?

Should I not trust the professionals know what they are doing?


I already have enough things to worry about without ruminating on this.

This forum sometimes seems to just increase anxiety.
Sometimes, I think you have to just stop worrying and just make a move. Otherwise I will never have a boat.

Sorry to worry you, I'm worried about it too.

I'm not a mast guy and have no experience here but I'm worried about the stresses you might see on this joint so I then worry about who's going to be doing this for you because I'm sure there is potential for significant loads on the fixings and I have a reasonable understanding of fixings.

The reason I worry about workmanship is we regularly sub-contract "tradesman" to do our installs and mostly the workmanship is poor. I spend a fair amount of time coming up with idiot proof designs rather than best for application designs just to minimise or account for the poor standards of workmanship that most people think is acceptable or all they are capable of.

That's why I suggested structural rivets first time around, because it is less likely for the installer to screw it up. Drill a hole through both sheets perpendicular to the face at that point, stick the correct rivet in and set it. I changed my mind when you mentioned that the sleeves shape was not a good match, and made of a thicker wall. I imagined a mast profile that had a different arc profile than the mast and that you would need to pull it in with the fixings, in a progressive way. You can do this with rivets but it is difficult to feel how they are pulling in and is better suited to screws. Now I believe you are not talking about large gaps, but small irregularities which would be ok for rivets.

[Benz]

Originally Posted by thinwater

Possibly a dumb question.


If you cannot remove the plug once pressed into place, how do you drill the holes for the machine screws? The threaded portion is drilled tap-size. The mast portion is drilled clearance size. If you drill the tap size first, and then try to drill the clearance part, in aluminum, with the plug in place, the drill will really try to pull right through the full depth. Fast. You will end up with the holes drill clearance diameter, clear through. A good drill stop could work. Is that the plan?

With a rivet there is only one hole size.

I like the machine screw idea fine, but unless I can remove the plug, it's a little tricky. You could give up on the machine screws pulling the two parts together. But that is not desirable.

The exterior part could be drilled and countersunk before the inner sleeve is put in, then the sleeve drilled at each hole to the right tapping diameter.