Thread: Best welded joint type for novice?

On the subject of metal cutting. Please do not be tempted to put one of those awful toothed metal cutting blades on your angle grinder. I know that they are sold as suitable, but they are highly dangerous due to vicious kickback coupled with unguarded teeth. Would any of us use a circular saw with no guard?
BobL summed it up really well before. Any tool for wood can generally be used for Ally.
I am interested to see how the Ultrabond sticks work out. I will be surprised if they are particularly successful in this application, last time I looked they were damn expensive too. If they are the ones I think they are they are very high in Zinc which will mean anyone using them to repair a boat will be in for a rude shock.

The rods seem to be an aluminium/copper/magnesium alloy.

Well, if nothing else Robsons has got the price down on these from what they were being sold for at agricultural field days.
I will be interested to hear how they perform for the bench building job.

Originally Posted by mugget

So when talking about a "good weld" that would mean no voids, contamination etc.? As well as good/correct penetration?
Exactly

From what I've read it seems that a steel weld should actually be stronger than the surrounding material? Correct.

Is that true of aluminium also? Can't say for sure ,but it would seem logical.

And what is the general opinion on grinding welds? Is that a definite no-no on structural jobs (just for reference)? My take on it ,if you grind (to excess) there is something to hide. Seriously there are some genuine reasons to grind.
Its common place that there are welds that are blended at the toes -as in heavy mining equipment. In general, grinding all the the weld face, in industry it says its something to hide.

How about adding extra weld to fill a section that had a concave weld finish? Is that type of thing considered okay for home/DIY stuff? A concave (fillet) can be tolerated under non critical conditions in a home situations.

Interesting info about just tacking the right spots Grahame. Is that type of thing just temporary? Tacks normally form part of the finished weld.
Or it can be permanent depending on the usage? Tacks can also can stand alone ( again for a light loading) in some instances.

Does this help?

Originally Posted by mugget

Ah yes, I forgot some details... let's say aluminium square box (2mm - I was considering 1.5mm but thought that would be trickier to weld?), angle and sheet (3mm). The welder is a 140amp MIG. This little project will be a light duty work bench.

Whoa there!

I just re read your post and realized I missed the above .

Sorry! My comment was written with welding of steel in mind. I am sorry to rain on your parade, but 140 amps ,while ok for steel but just won't do for welding aluminium.

The ability of your Mig to weld aluminium depends on it being of adequate power to be able to go into spray mode.Your thin wall steel will weld just fine in the short arc mode as delivered by your little mig, but needs extra grunt to deliver a spray on the wire diameter that you will need. I would suggest that 180 amps may be the very base minimum.Some may say 200 amps. Even then suspect some machines ( of this rated amps) may be quite capable but others similar rated machines may not.

Any way I don't think 180 amps on sub 2mm sheet is a good idea.



I can almost hear some saying ,thats ok I will get smaller diameter wire.

If your had the power needed there is still a problem if you do not have a spool gun.Any thing over a 2metre gun cable is going to give you problems.You might be able to get a cheap one and cut it down to a shorter length

The soft aluminium wire does not like being pushed up the mig cable. Yes even a straight mig gun cable.Small diameter steel wire does this with no problems but the ali will kink and result in many birds nests at the drive wheel to untangle.Then there is the contact tip ,its not size for size as the aluminium expands in cross section and needs an over size tip.

Thats a lot of problems to overcome.Lots traps for new players. Someone with a top end machine may have might do it but I really dont the little mig is an option on light stuff.

Are the aluminium soldering sticks looking good at this point?

Grahame

Originally Posted by Grahame Collins

Whoa there!

I just re read your post and realized I missed the above .

Sorry! My comment was written with welding of steel in mind. I am sorry to rain on your parade, but 140 amps ,while ok for steel but just won't do for welding aluminium.

The ability of your Mig to weld aluminium depends on it being of adequate power to be able to go into spray mode.Your thin wall steel will weld just fine in the short arc mode as delivered by your little mig, but needs extra grunt to deliver a spray on the wire diameter that you will need. I would suggest that 180 amps may be the very base minimum.Some may say 200 amps. Even then suspect some machines ( of this rated amps) may be quite capable but others similar rated machines may not.

Any way I don't think 180 amps on sub 2mm sheet is a good idea.



I can almost hear some saying ,thats ok I will get smaller diameter wire.

If your had the power needed there is still a problem if you do not have a spool gun.Any thing over a 2metre gun cable is going to give you problems.You might be able to get a cheap one and cut it down to a shorter length

The soft aluminium wire does not like being pushed up the mig cable. Yes even a straight mig gun cable.Small diameter steel wire does this with no problems but the ali will kink and result in many birds nests at the drive wheel to untangle.Then there is the contact tip ,its not size for size as the aluminium expands in cross section and needs an over size tip.

Thats a lot of problems to overcome.Lots traps for new players. Someone with a top end machine may have might do it but I really dont the little mig is an option on light stuff.

Are the aluminium soldering sticks looking good at this point?

Grahame

Plus you will need the correct shielding gas which will be different to your MIG gas.

This is a great thread. Lots of information in a short time and space and no negatives(yet). On the subject of buying your own shield gas cylinders, can anyone give me an idea of size and cost of cylinder and contents. The small cylinders sold on EBay work out, at a quick estimate $93.00 per refill on top of $200 for the cylinder itself. As they are said to be equal to 3 disposable cylinders (tho probably a bit less) that works out to be $31.00 equivalent. Still vastly too expensive for me considering I manage just fine now with the flux cored mig wire, especially considering where I do my welding has open ends to the weather. Think wind tunnel.

Speed Gas is still too far away from me. I am waiting for them to extend their tentacles much further South but still interested in cost.

With regards to learning to weld with aluminium, when I last visited Arthur at his scrap yard off Prospect Road Adelaide, I saw an attempt to ali weld fence panels set up near the driveway just past the shed. An oxy set was in attendance. The results looked like a dogs breakfast.

From Karl

On the subject of metal cutting. Please do not be tempted to put one of those awful toothed metal cutting blades on your angle grinder. I know that they are sold as suitable, but they are highly dangerous due to vicious kickback coupled with unguarded teeth. Would any of us use a circular saw with no guard?

Scares the carp out of me just thinking about it. It is this sort of thing combined with the lowest common denominator type of individual that creates all those safety rules that most of us find so pathetic. I totally agree with you.

Timless Timber

What about if I am welding case hardened plasticine out of China made from recycled sardine cans?

Where can I get some of this? In regard to your welding class just remember that

such that the tutor later couldn't get it off even with the grinder...and had to break out a gas axe to fix my stuff up!

this indicates a good weld!!!!!!

I need to look into some of the products mentioned here.

Dean

Originally Posted by Karl Robbers

On the subject of metal cutting. Please do not be tempted to put one of those awful toothed metal cutting blades on your angle grinder.

What I am interested in trying are the counter-rotating tungsten-tipped "cut anything" saws everyones seems to be putting out. Essentially a cold saw with no kickback in an angle grinder format.

Originally Posted by RustyArc

What I am interested in trying are the counter-rotating tungsten-tipped "cut anything" saws everyones seems to be putting out. Essentially a cold saw with no kickback in an angle grinder format.

Heard some good things about them, but not used one. Makita make a metal cutting circular saw, it cuts to 3mm steel quite well and would probably handle 50X50 box section on a good day, (I used one extensively cutting 100X100X4 SHS and it didn't like it one bit - don't blame me, it was the bosses idea!), but I always found them to be a poor design as far as cut visibility - there is none and they are a bugger to set up with a straight guide. Hilti make a 22 volt metal cutting saw that is supposed to be the ducks guts, single blade circular saw style. As with all things Hilti, I should imagine it will work really well. Did I mention my Hilti fetish? I am going to get a demo of this saw at some stage when my bank balance recovers from my recent purchases.
Obviously, if ally is the target metal then a circular saw with a negative rake triple chip blade will do really well, just use crc or metho for lubricant.

Originally Posted by Karl Robbers

Makita make a metal cutting circular saw, it cuts to 3mm steel quite well and would probably handle 50X50 box section on a good day

I have a GMC (don't laugh) metal-cutting circular saw which I use once in a while, and it's a remarkably decent unit. It's a bit scary to use, but it cuts clean and doesn't put heat into the work, unlike an angle grinder.

The trickiest cut I've done was ripping a 800mm long bit of 65x20mm bar down to 60mm - I fabricated a guide that clamped to the base plate with cap head screws, set the blade depth such that it only just penetrated the 20mm section (very important) and went for it. It took a while, but ended up with an 800 long 20mm x ~2-3mm offcut that sits perfectly flat, indicating no distortion from heat.

Originally Posted by RustyArc

I have a GMC (don't laugh) metal-cutting circular saw which I use once in a while, and it's a remarkably decent unit. It's a bit scary to use, but it cuts clean and doesn't put heat into the work, unlike an angle grinder.

The trickiest cut I've done was ripping a 800mm long bit of 65x20mm bar down to 60mm - I fabricated a guide that clamped to the base plate with cap head screws, set the blade depth such that it only just penetrated the 20mm section (very important) and went for it. It took a while, but ended up with an 800 long 20mm x ~2-3mm offcut that sits perfectly flat, indicating no distortion from heat.

I didn't realise that GMC made them. Actually GMC gear punches well above its weight.

Cheers Grahame for that extra info.
And yes, the ally repair rods are looking like quite an attractive option at this point!!

I have the repair rods and will pick up my ally order tomorrow if it's all ready to go (got it all trimmed to size, I can't transport 6.5m lengths anyway). I'll get some scraps or use my offcuts to do tests with the repair rods. Tests will involve butt joined square box sections and a large hammer... I'll post results when I get done! (Hopefully by Wednesday at least.)

Originally Posted by RustyArc

What I am interested in trying are the counter-rotating tungsten-tipped "cut anything" saws everyones seems to be putting out. Essentially a cold saw with no kickback in an angle grinder format.

Hi Rusty, Ive got the one off TV that u can get from Big W. I find its no precision tool with its wide kerth. Abit scary at first use with its noise but does what its supposed to. Ive had no kick backs so far from plunge cuts, back and forth ect....I mainly use it for ripping 3mm plate alloy into smaller manageable bits.

Looking forward to hear the results mugget.

Okay, first results are in:



I brushed over the join areas with a stainless steel brush, then just sat the pieces in place and went about heating it, applied the repair rod. In the 2nd attempt I used a screwdriver to spread around a build up of filler that was already on the piece. Not sure if that would contaminate it at all? But that's what the instructions say to do in order to break the surface tension and join two puddles etc. I did that on the top edge. The bottom edge looked pretty tidy, I managed that one with the rod only and I didn't have to touch it again aside from re-heating it when I bonded the piece again for the 2nd attempt.

I didn't brush the sides, which I think I will do on the final, or maybe I'll have a bit more of a play around tomorrow. But even as it sits now I'm fairly impressed with it, ought to be fine for my purposes (no way I'll be beating on it like this). It seems like it works better if a larger area extending away from the join is tinned.

It seemed like I could work on one side of the join without affecting others, so that makes things a bit easier. I'll probably have to work on one side to kind of "tack" it together, and rotate the job to get at each side.

I'm not sure how to hold the pieces in place, hoping that gravity will do that for me (by working on a join only when there's a tube directly beneath it, rotating the job to achieve that).

Well that's it for now, I'll post back if I make any more discoveries.