Stainless self-tappers into aluminium?

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KAL

KAL

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I have a table bracket to fit to my aluminium steering pedestal, but don't want to risk galvanic corrosion by using unprotected stainless self tappers. Can anyone suggest an alternative (or a way of achieving this safely)?
 
Screwwing into Aluminium

I would suggest tapping a thread for suitable sized screws. ie 3mm. Put Duralac on thread. or use monel pop rivets.
You may be unduly worried if you consider the number of rivets and screws set into your aluminium mast. Much more critical. good luck olewill
 
Aluminium is a very grabby metal which means that it is very likely that the screw will seize half way in and break.It is much better to drill and tap for a machine screw.Always use plenty of Duralac or ,if you don't have any,Loctite.
 
Rivnuts... Helicoil...

If the thickness of the pedestal is suitable then how about using stinless Rivnuts.. Then your machine screw will be stainless against stainless.

Another option (that I user last year on my pedestal) was to use stainless helicoil thread inserts. Now the m5 stainless machine screws screw into a stainless threaded hole so should remove easily in future.
 
For fixing anything to Aluminium we use Aluminium rivets. If we have to do stainless bolts to Aluminium we coat the stainless in Duralac. As said above screws are not good in Aluminium, if possible the table bracket should be Aluminium with lots of screws coated in Duralac into the wood to spread the load and then rivet to the pedestal. That should give you strongest attachment.
 
I suppose an advantage of stainless screws/bolts is the table can be removed when winter sets in. Our garden table was treated with lasure wood varnish maybe 10 years ago and is still in near pristine condition, having wintered indoors.
 
snooks said:
As a slight diversion from the thread, anyone know of somewhere to get a set of good quality taps and dies from?

I've used google, but you never know the quality of the tools until they arrive.
Click to expand...

RS can generally be relied upon to supply half-decent stuff. Not the cheapest, but convenient. Make sure that you buy High Speed Steel taps (HSS). Forget about all the other terminoligy cheap suppliers use like "hardened" and "titanium coated", just buy HSS (although if you want, you can get HSS with added coatings and treatments).
 
snooks said:
As a slight diversion from the thread, anyone know of somewhere to get a set of good quality taps and dies from?
Click to expand...

JL Industrial sell reasonable quality tools IME. Their current sales flyer has some tap and die sets on page 12, there may be more further on.

snooks said:
I've used google, but you never know the quality of the tools until they arrive.
Click to expand...
I've bought quite a few taps and dies from JLI when they've been on special offer and they've been fine for my use. I asked a similar question once on uk.rec.models.engineering and was told to always buy High Speed Steel (HSS) taps and dies because they have a ground finish and are higher quality than carbon steel ones.

Hth,

Boo2
 
Duralac

William_H said:
I would suggest tapping a thread for suitable sized screws. ie 3mm. Put Duralac on thread. or use monel pop rivets.
You may be unduly worried if you consider the number of rivets and screws set into your aluminium mast. Much more critical. good luck olewill
Click to expand...

+1 on Duralac - used it to isolate the aluminium and steel bits on my windlass on the foredeck - gets a good soaking in salt every trip - works fine
 
I have a set of taps and dies from MachineMart - they've proven up to every job , so far. Most sets don't include a plug tap, so are no use for blind holes.

Rob.
 
Wow - thanks for a wealth of advice. Haven't come across Duralac before. Will look it up and get hold of some.

The bracket is aluminium as well as the pedestal. I will certainly avoid self-tappers based on opinions voiced here.

Are monel rivets widely available and will they avoid the corrosion issue? I haven't got any taps and it seems silly to buy a whole set for 4 screws.
 
Hoolie said:
I suppose an advantage of stainless screws/bolts is the table can be removed when winter sets in. Our garden table was treated with lasure wood varnish maybe 10 years ago and is still in near pristine condition, having wintered indoors.
Click to expand...

That's the beauty of this bracket. It fits onto the pedestal permanently and you simply remove a split ring to mount/dismount the teak table.:)
 
KAL said:
Wow - thanks for a wealth of advice. Haven't come across Duralac before. Will look it up and get hold of some.

The bracket is aluminium as well as the pedestal. I will certainly avoid self-tappers based on opinions voiced here.

Are monel rivets widely available and will they avoid the corrosion issue? I haven't got any taps and it seems silly to buy a whole set for 4 screws.
Click to expand...
If you do a google you can easily find Monel rivets suppliers.I'd use them in preference to screws in your case.Duralac is messy stuff.Make sure you clean afterwards because once dried it is very hard to remove.
 
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