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jonbuoy
14th March 2007, 09:52
Couldn't find anything on here about these:

http://www.durafix.co.nz/index.php?content=demonstrations.htm


Has anybody had any luck or experience with these rods? Looks quite handy, I've got a couple of cosmetic cast aluminium holes to fill and I'm also thinking about using it to make a gearshift lever for my clip ons - butt welding aluminum together. How strong is this stuff?

imdying
14th March 2007, 10:08
A friend of mine imports them... they're bloody impressive. Go watch the demo videos... it really is that easy!

jonbuoy
14th March 2007, 10:25
Yeah I saw the demos - it looks a little too easy! If they are that good I might go for a kit. My only worry is how much of the stuff I can get between the two joints, it looks quite runny.

imdying
14th March 2007, 10:31
It is disturbingly easy to use... even I can manage it. I was a bit skeptical when I say the video of the coke can getting welded up, but yep, that easy. Definitely get a kit, it's cheap enough to have some good fun with. Buy another stainless steel brush though, the ones that come with them are ok, but not a long life item.

jonbuoy
14th March 2007, 10:33
Ok thanks.

Macktheknife
14th March 2007, 10:54
Now that is a cool product! Cheers guys

The Pastor
14th March 2007, 11:23
thats what I was after, very cool dude!

What?
15th March 2007, 09:03
Wot imdying said - it's good gear.

imdying
15th March 2007, 09:19
Just Chillin
021-1442139 - Phil

He has plenty in stock, go nuts!

The Pastor
15th March 2007, 09:21
what about brazing steel?

imdying
15th March 2007, 09:48
Wouldn't you just use a brazing rod??

Motu
15th March 2007, 11:30
How strong is the joint? It looked more like brazing than welding,definatly a lower temp than normal alloy welding.But I liked his technique...the swishing/wiping motion,I must try that next time I try alloy welding.

imdying
15th March 2007, 11:50
Now that I'm not sure about. It seems very strong... you can cut/drill/tap/beat crap out of, all you like, so in that respect, very strong.

I'm drumming up a couple of bits of alloy tube to do some tests with. I've a press at work that should be able to wrench the two pieces from each other with a little mucking about.

I'd quite like to build some front fairing stays, and a rear subframe, so I'm quite keen to see just how strong it really is. First impressions, hella strong :yes:

jonbuoy
15th March 2007, 11:56
One of those videos shows a straight butt joint between two bits of alloy plate - then he puts a wrench on the top of the plate and bends it right over - the plate bends but the joint doesn't give way. Pretty impressive.

imdying
15th March 2007, 12:35
Yeah, I saw that... seems too good to be true!

Fooman
15th March 2007, 13:19
How strong is the joint? It looked more like brazing than welding,definatly a lower temp than normal alloy welding.But I liked his technique...the swishing/wiping motion,I must try that next time I try alloy welding.

The US webpage (www.durafix.com) states that it welds zinc alloys and brazes aluminium alloys. This suggests that it is a zinc alloy. Somebody has stated the composition at 94% Al, 6% Zn, but that doesn't work with the quoted temperature (solidus for that composition at ~ 600 deg C). 94% Zn and 6% Al gives a eutectic at 381 deg C according the Al-Zn phase diagram in front of me.

If the connection is design such that there is plenty of area and is nice and smooth as per a brazed joint (e.g. lap joint), then it should be no problem. Corrosion may be an issue (e.g. galvanic corrosion) with the difference in compositions.

There are aluminium alloys out there for brazing aluminium, but they are at a higher temp (~570 deg C for Al-Si brazing alloys) which is closer to the melting point of the major aluminium alloys (~595 to 650 deg C), so temperature control has to be greater, especially if you want to avoid incipient melting or unwanted age hardening.

Another thing to note about brazing, is that it is not just low temperature applications. Gas turbine blades are repaired using brazing (especially single crystal blades) and the melting point of the brazes (~1100 deg C) is not much higher than the operational temperature (900-1000 deg C) of those blades. It's expensive to do, but at ~ $5000 to $10000 per blade, there is plenty of incentive to do a expensive repair rather than a more expensive replace.

Cheers,
FM

Brian d marge
15th March 2007, 13:30
The US webpage (www.durafix.com (http://www.durafix.com)) states that it welds zinc alloys and brazes aluminium alloys. This suggests that it is a zinc alloy. Somebody has stated the composition at 94% Al, 6% Zn, but that doesn't work with the quoted temperature (solidus for that composition at ~ 600 deg C). 94% Zn and 6% Al gives a eutectic at 381 deg C according the Al-Zn phase diagram in front of me.

If the connection is design such that there is plenty of area and is nice and smooth as per a brazed joint (e.g. lap joint), then it should be no problem. Corrosion may be an issue (e.g. galvanic corrosion) with the difference in compositions.

There are aluminium alloys out there for brazing aluminium, but they are at a higher temp (~570 deg C for Al-Si brazing alloys) which is closer to the melting point of the major aluminium alloys (~595 to 650 deg C), so temperature control has to be greater, especially if you want to avoid incipient melting or unwanted age hardening.

Another thing to note about brazing, is that it is not just low temperature applications. Gas turbine blades are repaired using brazing (especially single crystal blades) and the melting point of the brazes (~1100 deg C) is not much higher than the operational temperature (900-1000 deg C) of those blades. It's expensive to do, but at ~ $5000 to $10000 per blade, there is plenty of incentive to do a expensive repair rather than a more expensive replace.

Cheers,
FM

Agreed the key is design the Joint , for large area , keep the loads low .. ie non critical areas and it would be fine and one assume that the area should be clean !

Me I trundle round to the local welder and put on my sad face ......

Stephen

Motu
15th March 2007, 14:25
Yes,brazing is a stronger joint than many realise - all the British frames were brazed.And even Rickman brazed their Reynolds 531 frames rather than welding,they said welding damaged the metal.

A lot is opperator experiance.I have a Henrob welding torch,and have seen the demos live - pretty impressive welding coke cans and unheated unprepped cast iron with a piston ring,hard facing with a hacksaw blade.I have attempted all those,and yes it can be done....but I'd need a shit load of practice behind closed doors before I could pull it off.

imdying
15th March 2007, 14:49
Coke can looked a bit too easy to me... took Phil 3 goes before he could do a mint job :yes: So yeah, pretty darn easy!

Should give him some cast iron, that'll mess him up :D

pete376403
15th March 2007, 20:45
Yes,brazing is a stronger joint than many realise - all the British frames were brazed.And even Rickman brazed their Reynolds 531 frames rather than welding,they said welding damaged the metal..

Most (if not all) of those brazed joints were spigot (?) type, where the tube is inserted into a socket, which gives a very large contact area compared to a butt join. If you had to join steel with a butt joint, arc welding would be preferable (and far more suited to mass production using robot welders)

laRIKin
16th March 2007, 17:11
The way I was trained.
All brazing joints must be lapped. (to get a good surface area, a thick material butt joint maybe OK)
And to me it is brazing and not welding.
I'm not saying that is a bad product, but the terms they are using are misleading.

imdying
16th March 2007, 19:42
Most (if not all) of those brazed joints were spigot (?) type, where the tube is inserted into a socket, which gives a very large contact area compared to a butt join.That's how I plan to make my subframe. Good mechanical join, less reliance on the braze.


And to me it is brazing and not welding.
I'm not saying that is a bad product, but the terms they are using are misleading.Agreed.

jonbuoy
2nd April 2007, 12:02
Got some of these in the post today - even having a quick go with scrap ally I'm impressed by how strong lap joints are with this stuff. I did get it to break but only by flexing the ally 3-4 times first.

Macktheknife
2nd April 2007, 12:33
Got some of these in the post today - even having a quick go with scrap ally I'm impressed by how strong lap joints are with this stuff. I did get it to break but only by flexing the ally 3-4 times first.

Be good to know how you feel about it in a couple of weeks when you have had a good play with it.