Aluminum vs Stainless

[Marc]

I am getting ready to "clean" up my mast.  I need to change out the cheek block at the top and was wondering if it was okay to use stainless rivets to mount the new block on an aluminum mast.  Do the two materials get along with one another?  I'm also thinking of strength betwenn stainless and aluminum rivets.  Marc

[AdriftAtSea]

I would use stainless steel or monel pop rivets, since they have far more strength and fatigue resistance than aluminum pop rivets do.  I would also coat them with TefGel or Lanocote before putting them in place, to help prevent galvanic corrosion between them and the aluminum. :)  Being that it is the block at the top of the mast, salt water is going to be less of a problem than it would lower down, so I would imagine it will last a good long while. 

[Marc]

Thank you for your reply Adrift, can I hire you to finish the rest of my boat?  LOL

[AdriftAtSea]

Depends... what 'cha offering... :) and where's the boat located?

[Fortis]

I woudl choose Monel over stainless for the rivets, but also consider going over to stainbless threads and tapping the holes in the mast so that the cheeck plates can be machine screwed into place. It takes hardly any time at all, the tap costs less then a good sized bag of pop-rivets (let alone the hefty pop rivetter you want to cope with monel or stainless rivets). DO USE A BARRIER SURFACE BETWEEN THE STAINLESS CHEEK BLOCK BASE AND THE SIDE OF THE MAST. I used to use various paint-on poop formulas...Now I cut up a PET drink bottle to the right size and just use it as a shim in between the two materials!

If you go for machine threads to hold the blocks on, then do not forget to use something like Loctitie to secure the threads, a spring washer on each bolt is also workable.


Alex.

[AdriftAtSea]

Fortis does have a good point.  What material are the cheek plates on the block?  If they are stainless steel, you really do want a galvanic separator between the two.  Milk bottles make good barriers, and are easily available. 

The problem with tapping a mast is that some masts are too thin to safely tap and expect the threads to hold any significant load. 

A better option, since this is presumably near the end of the spar, is to through bolt the cheek block to the mast. 

Also, how curved is the mast compared to the mounting surface of the cheek block.  If they're significantly different, you will need a base for the block to sit on.  One good solution, if you do need a base, is to pop rivet the base to the mast, and then screw or bolt the cheekblock to the plate.  That is how the line clutches on my friend's boat were done. 

BTW, the tools for the stainless steel pop rivets aren't all that expensive.  I bought mine down at Sears for about $20.  A good tap set costs just as much.

[Fortis]

Why would you buy a set of tap and die tools? You only need one tap. About $4. I drill the pilot holes, then mount the tap in the cordless drill on very lowest speed, lube it up and use it to run the threads. Then swap the tap out and mount the driver of choice for the bolts....Attach hardware and all is good.


I love my metabo cordless drill!


Alex.

[CharlieJ]

All good points, and certainly nothing wrong with rivets  but remember- you have no need for a whole tap set. That's one reason I've heard for people shying away from tapping machine screws- the cost of the tap set.

Just buy the ones you need, as you NEED them.  You'll more than likely end up with  4 or 5  different taps, which should cover 99 % of all work you do on the boat. I have a full tap and die set and there are a dozen in there I've never used ( in boat work)

The ones I use the very most are the 10-32 and 10-24 taps, and the 14-20.

[CharlieJ]

 ;D ;D

I see Alex and I were less than a minute apart on our posts

;D  ;D

[Marc]

This website is the greatest!!!  Thanks to everyone!  I cannot tap the mast for it is to thin for me to be comfortable to hold the bolts.  So, since the base of the shaeffer cheek block is stainless I'm going to use the milkjug idea and probably bolt it through with 10-32 bolts, nuts and washers, since it is at the top of the mast.  Can't do it the weekend though,  I'm in Nebraska with family for Easter :( :(

[CapnK]

To add some emphasis to a part of what's been posted:

When tapping threads, use PLENTY of lube - makes the job better, faster, easier, and will keep you from having to try and pick a mangled, broken tap out of the side of your mast.

[AdriftAtSea]

How do you know??? :)  And when you break the tap, it will be the only one of that size...and the store will be out of stock on that size. :)

To add some emphasis to a part of what's been posted:

When tapping threads, use PLENTY of lube - makes the job better, faster, easier, and will keep you from having to try and pick a mangled, broken tap out of the side of your mast.

[Banshi]

I would disagree with a couple of points on this old but useful thread.

1)Don't piece meal your tap collection, buy a set you'll save a ton of money and time in the long run. You can get them at the flea market for a 1/4 of the retail cost. The same goes for drill bits.

2) Never tap a hole by putting a tap in an electric drill. It can be done but you'll break more bits than you will save time and you can cause a serious injury to yourself. Taps are very brittle and the slightest bind can break one. The thicker the material the more important a good lubricant and the correct tool becomes. Use the tool designed for this task.

[CharlieJ]

I'm forced to disagree with your first disagreement ;D But I do mostly agree with your second.

I build, rebuild and repair boats for a living. I have a complete set of taps and dies in my shop. I've had that set for 30 years and MOST of the set has never seen use. There just isn't that much of a variance of thread sizes and pitch in use ( or needed) on most boats. I really see no reason at all for someone working on just the one boat, to invest in a whole set.

As I said earlier, buy the few you need, get decent quality and use them, buying new sizes as you need them. Most folks will wind up with 4, or maybe 5 taps.

And while I agree with not using power tools to tap with for the most part, I HAVE used a battery drill set slow to tap mast track screws when setting track on several masts at once. When you are drilling and tapping 300 or 400 screws while  rigging a mast ( or two) that battery drill is a real lifesaver. I would not however use it as a matter of course.

[TJim]

Coupla other things, when taping aluminum (or drilling) use wd40...and I always use a drill press if it's something I can get there.  You can probably do 10 or 15 to one with a drill press. TJim

[TJim]

P.S.  A mill is even better and faster...especially if you have digital counters on it. (I think everyone does now) TJim

[Banshi]

    I can purchase a set of taps and dies retail for between 30 and 60 bucks (you can probably get a large set for less at the flea market), you'll spend probably 20 for the 5 seperate and this does not include the fuel to go there, wear and tear on your vehicle not to mention the lost time and speeding ticket you got on one of the trips that cost you 75 extra bucks................................now why is it better to buy the 5 individually again? I get at least as much use if not more from my taps for cleaned corroded gummed up threads.....shall we add 5 more trips for those and another ticket for running a stop sign  ;) Even for the DIY it pays to buy a basic set.

    Pinch a penny and spend a dollar is all to common in todays world, I should know I am a Carpenter who has "graduated" to Commercial Construction Superintendent building multi million dollars jobs and I am still amazed, after 28 years, at how much money and effort people will expend to save a buck. Numbers on a piece pf paper never tell the whole story, in fact they rarely tell half the story.

[CharlieJ]

I guess we'll have to agree to disagree.

And I haven't had a ticket of any sort in 30 years, since I grew up enough to start obeying traffic laws ;D I can't afford them so I don't do things to GET them.

Now my stepson on the other hand----------- ::)

[CapnK]

I think that there are pro's and con's to both ways of obtaining/having taps/dies, and other 'complete sets' of tools...

Sure is nice to have a full set, working around the boatyard. It seems manufacturers delight in using odd or different hardware in odd places, and you always run across that odd stuff at the worst or most inconvenient time. It is nice to have 'sets' of hardware then, so that you don't need to make that run to the store for a 5/176th socket, or a 8/17 thread... ;D

But for me, on my boat, I am trying to use an absolute minimum of different bits-n-pieces, so that I can get by just carrying those few sizes of hardware needed to deal with what I have.

BTW - Welcome aboard, Banshi!

Edited to add: I do keep 2 of the most common taps, because like Dan/Adrift pointed out above, I know from experience that things break/go missing right when they are needed most.  ::) :D

And like CJ - I don't speed too much either - can't afford the time, ticket, and insurance increase that speeding will get you! ;D

[Auspicious]

Some or maybe even most sets also come with a case of some sort. Particularly for tools with cutting edges like taps, dies, wood chisels, and drill bits the case serves to protect those edges as well as keep things organized.

As an old motorcycle racer I still have dozens of 1/16" drill bits left over from drilling for safety wire. Those I just keep in small envelopes.

sail fast, dave