Glueing alumium

This topic has 25 replies, 14 voices, and was last updated 5 July 2015 at 15:14 by Neil Wyatt.

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2 July 2015 at 11:25 #195557
David Brown 9
Participant
@davidbrown9
I need to glue 2 small pieces of aluminium square tube together. Can anyone recommend a good glue?

David
Advert

2 July 2015 at 11:25 #7687
David Brown 9
Participant
@davidbrown9
2 July 2015 at 12:12 #195571
Gordon Tarling
Participant
@gordontarling37126
JB Weld – not the 1/2 hour stuff though.
2 July 2015 at 12:44 #195575
Ajohnw
Participant
@ajohnw51620
Aircraft have been held together with epoxy but they also tend to use rivets because the peel strength isn't too good.

You might do better to find a cheaper source of something like this

**LINK**

I've never tried it but solders for aluminium have been around for some time.

John

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2 July 2015 at 12:53 #195576
paul 1950
Participant
@paul1950
I have used solder on alloy by covering it in oil then scratch a clean surface through the oil then solder through the oil. this keeps the air away from the clean surface.
2 July 2015 at 12:55 #195577
Ian S C
Participant
@iansc
Another two are, Araldite Super Strength, and Loctite Epoxy Weld.

Ian S C
2 July 2015 at 17:02 #195604
john carruthers
Participant
@johncarruthers46255
To hold the front screen in a Lightning we used a 2 part polysulphide, it would bond glass/ally and ally/ally, not cheap though.
2 July 2015 at 17:35 #195608
OuBallie
Participant
@ouballie
Posted by paul 1950 on 02/07/2015 12:53:28:

I have used solder on alloy by covering it in oil then scratch a clean surface through the oil then solder through the oil. this keeps the air away from the clean surface.

Oil?

What am I missing?

Geoff – Melting
2 July 2015 at 17:39 #195609
paul 1950
Participant
@paul1950
oil stops it oxidizing
2 July 2015 at 19:19 #195617
Roderick Jenkins
Participant
@roderickjenkins93242
David,

My old company has considerable expertise in adhesive technology. When I was looking to glue hooks onto some metallic tensile test pieces I was advised that the sort of epoxy of which slow setting (blue packaging) Araldite is an example, is as good as you will get without complex surface pre-treatment and subsequent heat regimes.

If you feel like going down the solder route then I can recommend this stuff **LINK** .

HTH

Rod
2 July 2015 at 20:27 #195623
Ajohnw
Participant
@ajohnw51620
It's about on Ebay as well in a couple of forms. Seems the one from the link already posted is friction braising – the brush and the end of the rod is dislodging the oxide layer. See ebay 280619538986.

There are also some fluxed rods on there which I suspect would be better for butt joining tube etc.

John

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2 July 2015 at 22:55 #195644
Michael Gilligan
Participant
@michaelgilligan61133
David,

The recommendations to use Epoxy are good … but it is VERY important to get a clean, fresh, metal surface; and then apply the adhesive within a couple of minutes.

To make a microscopically 'keyed' surface, which is better for bonding, you can etch it with Phosphoric Acid [available as Jenolite, etc.], wash it clean and blow-dry.

MichaelG.
2 July 2015 at 23:11 #195647
Anonymous
I use Bernzomatic fluxed rods, butted thick walled tube to plate with no problem and it took some good whacks with a lump hammer to break the joint when I finished with it. Recently repaired a motorcycle thermostat housing which is it's real forte along with filling stripped thread holes, fine for joining pieces as long as it isn't a stressed joint. wouldn't like to rely on it.
3 July 2015 at 09:18 #195666
Muzzer
Participant
@muzzer
Use a small stainless steel wire brush to clean up the surfaces. You can get these from a welding shop. They are used to clean up aluminium before welding – similar mechanical de-oxidising requirement.

Murray
3 July 2015 at 10:24 #195671
maurice bennie
Participant
@mauricebennie99556
Hi All What kind of oil please.? Can ally be hot welded ,with hammer blows, like iron .?

Thanks Maurice.
3 July 2015 at 11:42 #195674
Anonymous
Posted by maurice bennie on 03/07/2015 10:24:41:

Can ally be hot welded ,with hammer blows, like iron .?

Thanks Maurice.

Very much doubt it, It goes from solid to liquid in an instant when you reach the right temperature.. Time honoured method for annealing is to coat it in soap and it's at the right temperature when it goes black, you don't see the metal change colour and it's so close to the melting point you can end up with a puddle of metal if you go a touch past it.
3 July 2015 at 14:27 #195682
Ian P
Participant
@ianp
Posted by Mick Berrisford on 03/07/2015 11:42:12:

Posted by maurice bennie on 03/07/2015 10:24:41:

Can ally be hot welded ,with hammer blows, like iron .?

Thanks Maurice.

Very much doubt it, It goes from solid to liquid in an instant when you reach the right temperature.. Time honoured method for annealing is to coat it in soap and it's at the right temperature when it goes black, you don't see the metal change colour and it's so close to the melting point you can end up with a puddle of metal if you go a touch past it.

I heard about this soap thing a long time ago but never used it because I did not know what kind of soap had to be used.

With modern products nowadays only bearing a name with products of yesteryear (Nitromors for example) it may be that modern soap is not up top the task?

Ian P
3 July 2015 at 14:52 #195684
Ian P
Participant
@ianp
After posting my reply a few moments ago I had a thought….

There have now been 15 responses ( from 14 different contributors) containing numerous suggestions to solve the original question about gluing two small bits of square aluminium tube together. I'm as guilty as (some of) the rest in not adding anything of relevance to the subject.

Without David posting more details about what he is trying to do the odds are that even our best suggestions will be irrelevant. One persons small square tube might be 3mm or it might be 20mm, we dont even know if it is a butt joint, lap joint, or a joint between nesting tubes. Without knowing how strong the joint needs to be its very difficult to give any meaningful help.

With research its sometimes possible to glean some facts from the enquirers forum profile (none in this case) or by looking at their photo albums (but the forum software make that a pain) but whilst I would be glad to offer any answers I could I realise that all I am doing really is adding to the forum background 'noise'.

Hopefully the OP will respond soon as the subject is only a little over one day old.

Ian P
4 July 2015 at 11:27 #195739
Neil Wyatt
Moderator
@neilwyatt
I tried the Alutight solder wire I got at harrogate and found it really effective and easy to use. Beware very cheap 'aluminium solder' that is basically just zinc or tin (not sure which).

Neil
4 July 2015 at 13:58 #195750
OuBallie
Participant
@ouballie
Posted by paul 1950 on 02/07/2015 17:39:10:

oil stops it oxidizing

Paul,

Yes understood, but.

Always a but isn't there

Putting oil onto a surface you want to weld goes against the grain, as well as everything I've been taugh and methods used.

Geoff – Hence my 'What am I missing?"

PS:

Too hot/humid to think straight
4 July 2015 at 20:22 #195780
David Brown 9
Participant
@davidbrown9
Thanks for all the replies. I bought some Araldite rapid steel two part epoxy adhesive from Halfords and this seems to have worked fine. Despite the name it appears to work on most metals. The 2 aluminium square tubes are small, 20mm wide and quite short

This is for my Bath intereferometer for testing telescope mirrors, which I am trying to improve. It has nothing to do with a bath you wash in! It is named after the German scientis who invented it.

One of the square tubes will hold a small laser diode and the other one will support it. The joint has to be fairly strong but not incredibly so, I will not be applying any force to the joint.

The interferometer isn't actually that complicated to make, but I tend to be in a bit of a rush and not plan things out properly, so end up having to improve/modify them. I still have some way to go to get it working right.

David
4 July 2015 at 20:25 #195781
john carruthers
Participant
@johncarruthers46255
are you buying or making the beam splitter?
5 July 2015 at 09:48 #195790
David Brown 9
Participant
@davidbrown9
I bought it quite a long time ago from Galvoptics in Basildon, Essex, I can't remember how much it was, but it wasn't cheap! You can also use two right angle prisms (for example from an old binocular). I tried this but didn't have much success.

I have been making and improving the intereferometer for quite a long time, I will hopefully get there eventually! There is a Bath Intereferometer yahoo group, I have posted on there once and will again once I have made some more progress.
5 July 2015 at 11:41 #195807
Neil Wyatt
Moderator
@neilwyatt
Are you making a mirror, David?

If so you may find THIS saga of interest.

Neil
5 July 2015 at 12:22 #195811
David Brown 9
Participant
@davidbrown9
I have nearly finished a 14 inch mirror (it just needs aluminising).

Next is a 20 inch mirror (I already have the glass blank). I have already seen the thread on Stargazer's Lounge. I think it likely that making the 20 inch will turn out to be a saga for me as well! One thing making mirrors is teaching me is patience!

The 14 inch mirror took around a year and a half, and the mount still isn't finished to my satisfaction-it works-but not very well-another of my projects that needs improving!

So who knows how long the 20 inch will take!

David
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