Filling aluminium.

[stevebaby]

I cut the v brake posts off my aluminium framed mtb and installed discs. It was a rough job so I need to fill it so I can get the frame powder coated. Not sure whether to get a torch and have a go at brazing it myself (and learn a useful skill) or get someone else to do it.
If it's cheaper to get someone else to do it than buy a torch that would probably be the way to go as I'm unlikely to do much brazing in the near future, but you never know.
Any suggestions?

[OnTrackZeD]

If you have cut them off it's too late because they screw out from aluminum frames, metal frames there brazed on.

[RonK]

Don't try it at home. Aluminium is extremely difficult to weld. An amateur welder would almost certainly ruin the frame.

[outnabike]

Hi stevebaby ,
If you are going to join things to aluminium, it can be tough for a beginner.But soldering is one way. Temp control is everything and one error will blow away your project.



http://www.ebay.com.au/itm/Aluminium-We ... 0865171345" onclick="window.open(this.href);return false;

"Durafix aluminium welding rods are used to repair Aluminium, Al-alloys, Zinc, Pot metals, Die-cast and Kirksite dies. In fact you can use it on almost any non-ferrous metal, except stainless steel. You can use Durafix on dissimiliar metals (copper to aluminium) and even galvanized steel.
This revolutionary product designed specifically for aluminium welding, uses no flux, making it easy to use and environmentally safe. A low working temperature of 732° F (392° C).

Durafix is the easiest method of welding aluminium and is ideal for use on all types of repairs. Large or small the rod can help you make a professional, inexpensive and durable weld.
The Advantages of Durafix!
* There is no need for expensive equipment.
* No need for years of welding experience.
* It's convenient and can be used by both novice and professional alike.
* Welds are clean and free from slag, and stronger than the parent metal.
* You can now repair aluminium, previously too difficult or uneconomic.
* Durafix can be applied with any handheld torch - Oxyacetylene, Mapp, Map/Pro or Propane.
* Durafix works on most aluminium, zinc, copper, brass, pot-metal and die-cast aluminium.
Available in 1, 5, 10, 20, 50, 60 and 100 Packet sizes"
Some of these things are available on the internet, from the USA.

in my opinion tig is the way to g and get a person with experience to do it.

[ldrcycles]

Any suggestions?

Yep, if it's just cosmetic use automotive filler, otherwise sell the frame for scrap. I used to be a welder (only steel though) and can say from personal experience that unless you find someone who is a very good welder and has experience in welding the sort of heat treated aly normally used for frames it isn't going to end well. I would not expect that sort of talent to be had cheaply.

That Durafix stuff could be worth a shot, but as outnabike said, it would be very easy to destroy it.

[mitchy_]

where abouts are you? i can recommend a fantastic welder in WA.

[stevebaby]

If you have cut them off it's too late because they screw out from aluminum frames, metal frames there brazed on.

They were definitely welded to the frame.

[stevebaby]

where abouts are you? i can recommend a fantastic welder in WA.

Sydney unfortunately.

[stevebaby]

Hi stevebaby ,
If you are going to join things to aluminium, it can be tough for a beginner.But soldering is one way. Temp control is everything and one error will blow away your project.



http://www.ebay.com.au/itm/Aluminium-We ... 0865171345" onclick="window.open(this.href);return false;

"Durafix aluminium welding rods are used to repair Aluminium, Al-alloys, Zinc, Pot metals, Die-cast and Kirksite dies. In fact you can use it on almost any non-ferrous metal, except stainless steel. You can use Durafix on dissimiliar metals (copper to aluminium) and even galvanized steel.
This revolutionary product designed specifically for aluminium welding, uses no flux, making it easy to use and environmentally safe. A low working temperature of 732° F (392° C).

Durafix is the easiest method of welding aluminium and is ideal for use on all types of repairs. Large or small the rod can help you make a professional, inexpensive and durable weld.
The Advantages of Durafix!
* There is no need for expensive equipment.
* No need for years of welding experience.
* It's convenient and can be used by both novice and professional alike.
* Welds are clean and free from slag, and stronger than the parent metal.
* You can now repair aluminium, previously too difficult or uneconomic.
* Durafix can be applied with any handheld torch - Oxyacetylene, Mapp, Map/Pro or Propane.
* Durafix works on most aluminium, zinc, copper, brass, pot-metal and die-cast aluminium.
Available in 1, 5, 10, 20, 50, 60 and 100 Packet sizes"
Some of these things are available on the internet, from the USA.

in my opinion tig is the way to g and get a person with experience to do it.

That looks pretty good, but they want 25 quid to post 5 rods! So I don't think so.
I'll probably just use some hi temp filler..just mix it, chuck it in and sand it. The powder coaters should know what to use so I'll give them a ring and see what they recommend..

[Dragster1]

Ally frames are hard to weld without a Tig,the heat will distort everything . you could use Devcon or another epoxy resin for Aluminium only.

[stevebaby]

Any suggestions?

Yep, if it's just cosmetic use automotive filler, otherwise sell the frame for scrap. I used to be a welder (only steel though) and can say from personal experience that unless you find someone who is a very good welder and has experience in welding the sort of heat treated aly normally used for frames it isn't going to end well. I would not expect that sort of talent to be had cheaply.

That Durafix stuff could be worth a shot, but as outnabike said, it would be very easy to destroy it.

Automotive filler will melt in the powder coating oven unfortunately. There are a few hi temp fillers for powder coating but they only come in large containers and I only need enough to cover my thumb nail.

[outnabike]

Another way is to drill a hole into the centre of the problem,(assuming it is not to large here)and tap the hole with a suitable thread.
Then screw in an ally thread and carefully cut it off,then file it up. All this takes time and a bit of skill though.
I reckon a bit of care you did not use originally is now paying you back. We have all done it.....

[KGB]

What temps are powder coating ovens run at? And for how long?

I've heard PCing aluminium bike frames is not a good idea as it can mess with the heat treatment of the frame (namely artificial age hardening). I realise other aluminium bits like car wheels and windows are PCed day in day out but a bike frame can be a bit more delicate than most items.

Just what I've heard and read, thought I'd toss it in there. Is a normal spray job an option?

[OnTrackZeD]

If you have cut them off it's too late because they screw out from aluminum frames, metal frames there brazed on.

They were definitely welded to the frame.

Thats OK I've never come across aluminum and steel welded together.

You can get metal filler from auto shops like Repco that you knead and push into to hole, shape and wait for it to set like steel.

[toolonglegs]

Thats OK I've never come across aluminum and steel welded together.

And I doubt you ever will on a bicycle frame.

[Dragster1]

Thats OK I've never come across aluminum and steel welded together.

And I doubt you ever will on a bicycle frame.

LOL! its impossible to weld steel to aluminium, he would of cut the studs and nuts off if it is an ally frame. filling it with anything other than metal isn't going to work either because you need electricity to run through it for the powder coat to stick

[ball bearing]

Is a normal spray job an option?

That's what I would do.

[stevebaby]

If you have cut them off it's too late because they screw out from aluminum frames, metal frames there brazed on.

They were definitely welded to the frame.

Thats OK I've never come across aluminum and steel welded together.

You can get metal filler from auto shops like Repco that you knead and push into to hole, shape and wait for it to set like steel.

The posts were made from aluminium.

[stevebaby]

What temps are powder coating ovens run at? And for how long?

I've heard PCing aluminium bike frames is not a good idea as it can mess with the heat treatment of the frame (namely artificial age hardening). I realise other aluminium bits like car wheels and windows are PCed day in day out but a bike frame can be a bit more delicate than most items.

Just what I've heard and read, thought I'd toss it in there. Is a normal spray job an option?

Powder coating ovens are around 200C, usually for about 20 minutes.

[stevebaby]

Thats OK I've never come across aluminum and steel welded together.

And I doubt you ever will on a bicycle frame.

LOL! its impossible to weld steel to aluminium, he would of cut the studs and nuts off if it is an ally frame. filling it with anything other than metal isn't going to work either because you need electricity to run through it for the powder coat to stick

Exactly. there are hi temp fillers which are conductive enough for coating, but on re-examination, I have an area about half the size of my little fingernail to fill. The high temp fillers don't come in small quantities unfortunately and they're hard to come by in Australia anyway. The one's I've seen advertized in the US also come with a solvent for cleaning and that might be a problem to ship.
All I really need is a small blob of molten metal on it and I can file and sand it fair.

[stevebaby]

What temps are powder coating ovens run at? And for how long?

I've heard PCing aluminium bike frames is not a good idea as it can mess with the heat treatment of the frame (namely artificial age hardening). I realise other aluminium bits like car wheels and windows are PCed day in day out but a bike frame can be a bit more delicate than most items.

Just what I've heard and read, thought I'd toss it in there. Is a normal spray job an option?

A spray job is looking more and more likely, but I've had half a dozen frames powder coated and they've all stood up pretty well. A two pack finish would be pretty good as far as durability goes, but a good two pack job isn't cheap either.

[stevebaby]

Another way is to drill a hole into the centre of the problem,(assuming it is not to large here)and tap the hole with a suitable thread.
Then screw in an ally thread and carefully cut it off,then file it up. All this takes time and a bit of skill though.
I reckon a bit of care you did not use originally is now paying you back. We have all done it.....

Yeah, I hacksawed them off and instead of clogging my files up with aluminium dust, I thought I'd just give them a touch with an angle grinder. Der.

[Dragster1]

Can you put a pic up so it gives more of an understanding and of the post you cut off. If the hole is quite substantial compared to the diameter of your seat stays it may weaken the frame some what. Im sure some engineering shop or Fence fabricating guys would be able to put a plug in there and zip around with the tig, just throw some cash or a carton their way

[OnTrackZeD]

"The posts were made from aluminium."

I've being thinking about this statement and I think I've work it out.

The post or Brake Bosses where screwed into their holder which is aluminum and welded onto the bike frame. So you cut off the welded brake boss mount.

Normally the best thing IMO would of been to undo the brake boss and insert a brake boss plug into the hole, job done.

[KGB]

Correct. That was my understanding.
You'd be left with the small "lumps" that the posts thread into but they're pretty slim and low profile anyway.

Doesn't help much now. Need pics.