Aluminum fixed triangular made Mast steps.

[Cheechako]

They used to be available, had them on my 30 footer. and hate the damn things! The ones I had were tubular aluminum with flattened ends. It was the mid 80's though. You would want to use SS rivets anyway for strength, so maybe it doesnt matter that the steps are stainless and less crack prone than alum.....?

[delmarrey]

And they do make all aluminum rivets.

And BTW, that outer corner, with aluminum needs to have a large radius to keep from cracking. Your Dad should have access to a radius chart for what ever thickness the material is. Which he should know I'm sure, but forum members may not.

[boatsail]

Originally Posted by Cheechako

They used to be available, had them on my 30 footer. and hate the damn things! The ones I had were tubular aluminum with flattened ends. It was the mid 80's though. You would want to use SS rivets anyway for strength, so maybe it doesnt matter that the steps are stainless and less crack prone than alum.....?

If it's good enough for a space shuttle.....

We are actually going to be using aluminum rivets. 6 per step. He went over the different types of aluminum and the properties that they have. some types crack, some types wont bend (thye want to go back to original), some types bend and hold. I don't remember the type that he got from his friend (at the shop), but he said it was the kind I would want to use for the properties it had.

he made a template for bending and a template for the holes. So much more accurate than I would have made them had I tried them on my own.

[Charlie]

If you could give us the type of aluminum that would be a great help.

[boatsail]

Originally Posted by Charlie

If you could give us the type of aluminum that would be a great help.

I will ask him and let you know.

[boatsail]

Originally Posted by Charlie

If you could give us the type of aluminum that would be a great help.

ok, here is the best way I can explain it. He went into more detail with all kinds of nomenclature, here goes. Basicall you want some 5052.

5052 can bend real easy, wont crack
6061 can crack (he has tricks to bend it he was telling me about with heat or taking corners off to avoid cracking, but basically, he said we would not want to use it if we could help it and we happen to be able to help it)
7075 you will see they make a lot of canoes and things out of it. doesnt weld really easy and you will even notice it has properties almost like tearing if you take it to destruction.

Started going into even more, but I kinda got lost.
H34 most common
H32 is softer

He even went into ways you can make brittle aluminum bendable by rounding all edges, taking a tortch, turn down oxygen, go over your line...black it, then turn up oxygen burns off the sooty stuff, that way you know its hot enough once that black burns away (with steel it would be cherry red, aluminum does not get that color, so they use the blacken trick). then you bend.

He said even at goddars, they would have some 6061 come in and the jigs from the last job worked fine....new 6061 would break over and over again (differnet batch) so they would use the tricks.

Bottom line is if you got a choice, get some 5052. Bends easier and holds the bend, does not crack as easy and is not brittle.

[boatsail]

I'm thinking of making a nice jig up and fabricating these things. There really is nobody in the marketplace that makes the aluminum mast steps. West sells stainless and I searched far and wide, could not find it. That was the reason I started this thread.

[GaryMayo]

My fear in all of this, is how much strength have you taken out of your mast with all the holes you are adding?

I would not drill my mast full of holes, and I would not to purchase a sailboat with a mast so modified.

This mod will weaken the mast to some degree, just how much, who can tell?

[stillbuilding]

Originally Posted by GaryMayo

My fear in all of this, is how much strength have you taken out of your mast with all the holes you are adding?

I would not drill my mast full of holes, and I would not to purchase a sailboat with a mast so modified.

This mod will weaken the mast to some degree, just how much, who can tell?

Depending on the design of the steps, it is just possible that the steps could stiffen the mast significantly.

[delmarrey]

Originally Posted by GaryMayo

My fear in all of this, is how much strength have you taken out of your mast with all the holes you are adding?

I would not drill my mast full of holes, and I would not to purchase a sailboat with a mast so modified.

This mod will weaken the mast to some degree, just how much, who can tell?

I did some research on this years ago in the process of building some davit type arms that needed to be lighten up but still strong.

It all comes down to where holes are placed and how far they are from critical edges and stress points. As well, as how far they are from each other.

Also, if the holes are filled then some of the strength is gained back. As for the little holes in a mast, when one puts a pop/blind rivet into the hole, it retains some of that strength.

The object is not to put holes in critical places where stress is an obvious factor and if they are large holes that the edges are rounded off. Radius and polishing does wonders to help avoid stress cracking.

A lot of the air craft parts I built for Air Research had to be put into tumblers to polish off all the sharp edges/scratches, after they were de-burred.

If you look at mast failures you will see most are at one of the spreader arms.

[S/V Alchemy]

Originally Posted by boatsail

I'm thinking of making a nice jig up and fabricating these things. There really is nobody in the marketplace that makes the aluminum mast steps. West sells stainless and I searched far and wide, could not find it. That was the reason I started this thread.

That's saving me some time. My feet are NBA-style long and wide (good for keeping upright on a canting deck, I suppose) and I have despaired of finding mast steps capable of fitting in the preferred "triangular" style.

So I wonder if 5052 bar stock affixed to a 6061 mast would call for 5052 or 6061 rivets?

Great thread, btw.

[boatsail]

Originally Posted by S/V Alchemy

That's saving me some time. My feet are NBA-style long and wide (good for keeping upright on a canting deck, I suppose) and I have despaired of finding mast steps capable of fitting in the preferred "triangular" style.

So I wonder if 5052 bar stock affixed to a 6061 mast would call for 5052 or 6061 rivets?

Great thread, btw.

interestingly enough, just by playing with the bar at home depot, I would guess it to be 6061 aluminum (I test bent a couple of pieces, no science behind it, just a guess). ON their website, they do not state the type of aluminum it is on their spec sheet. The rivets you buy at the store dont state the type of aluminum it is.

I honestly don't know if 2 different types of aluminum will corrode one another, but if I had to do an unscientific guess, I would guess the level of corrosion would be less than 2 totally different metals.

Talking to my father about differnt types of aluminums they use on projects, they do mix the different types on the same job and this is for space shuttle operations, so I would have to guess that if there were corrosion, it would be minimal. please note, this is my guess, not fact. Once again, if it's good enough for a space shuttle.....it's good enought for my 78 cal!

[delmarrey]

Aluminum pop rivets are 5052 or 5056 material.