Welding Tips and Tricks

Just a quick point that's likely already been mentioned - but with the number of people posting here with issues learning aluminum Tig it's a common theme of using a flap wheel to clean the metal - my experience is that while a great tool for general post weld blending / removing burrs / taking off sharp corners etc they are not good for pre-weld use as it's very easy to get the glue that bonds the emery leaves to melt & leave a residue on / in the surface of aluminum - trying to weld over this is a pain - it may not look much or even be visible but it will contaminate & once stuck on does not easily come off with wire brushing or solvents - if you need to sand I use regular metal sanding discs on a backing pad - if all you need is clean then a wire brush is usually enough - if it's a casting or oil soaked piece then use O/A torch & cook it - then wire brush - if you really have to use a flap disc use a course grit with very light pressure holding it as flat as possible & only use a new one or nearly new - hope this helps - I learned the hard way !

It is to be avoided, but I often use reclaimed metals. I use Norton Blaze Orange discs. They are like a Scotchbrite in wheel form. I think they are even better on steel, or to remove paint

It is to be avoided, but I often use reclaimed metals. I use Norton Blaze Orange discs. They are like a Scotchbrite in wheel form. I think they are even better on steel, or to remove paint

I must try some blaze - seen a few in video's - I believe they are ceramic so very sharp long lasting grit - do you think the performance / lifespan justifies the extra cost ? I currently only have ceramic grit on one belt sander & the little 2" Roloc discs - for such a small disc they do well - I often use them to re-profile axes without overheating the edge along with other random blending / finishing jobs.

That is a tough question to answer. They are a better quality, but Home Depot has a similar product at less than half the cost. If I'm very careful with the norton, it lasts more than twice as long, and leaves a cleaner finish. Approach a corner at the wrong angle, it ruins a disc. I'd rather lose a cheap disc than an expensive one. One aluminum project that required a finish as though no weld had been made, the customer wanted to help. He destroyed three in an hour. I wore away 1/3 of mine in a side by side.

Willie

That is a tough question to answer. They are a better quality, but Home Depot has a similar product at less than half the cost. If I'm very careful with the norton, it lasts more than twice as long, and leaves a cleaner finish. Approach a corner at the wrong angle, it ruins a disc. I'd rather lose a cheap disc than an expensive one. One aluminum project that required a finish as though no weld had been made, the customer wanted to help. He destroyed three in an hour. I wore away 1/3 of mine in a side by side.

Willie

Thanks for the reply - I figured as much - guess I should get one just for special occasions without sharp edges ! - there is a similar product if it's the one I think you mean made by " Smith & arrow " but I don't think they sell in the UK currently - shame they had some really good slitting discs @ sensible prices that I bought previously.

It comes down to laying a pad at shallow angle. It can run off a cliff all day. Turn around, and try to climb on, it won't go well.

There are flap wheels for use on aluminum and non ferrous metals, makes a big difference in performance. Listen to episode 80 of the WTT podcast for some great info on choosing and using abrasives, as well as cheap vs expensive grades.

Somewhere along the line I heard that you should avoid using (some? all?) abrasives on aluminum that you plan to weld because the abrasive grit can contaminate the aluminum, and since some abrasives are aluminum oxide (the same stuff that's in anodizing and in the layer of oxidation that you normally remove with a wire brush before welding), they can cause problems.

Don't know whether it's true or not, but it makes sense as one explanation for why abrasives can muck things up.

It's true.But sometimes metal is so heavily oxidized, a hand brush won't remove it. I have had some success with a power stainless brush, use only if it'll take all day by hand.

Lightning wrote:Somewhere along the line I heard that you should avoid using (some? all?) abrasives on aluminum that you plan to weld because the abrasive grit can contaminate the aluminum, and since some abrasives are aluminum oxide (the same stuff that's in anodizing and in the layer of oxidation that you normally remove with a wire brush before welding), they can cause problems.

Don't know whether it's true or not, but it makes sense as one explanation for why abrasives can muck things up.

The podcast I referenced has a gentleman from Walter Abrasives as a guest, this and other good information is available to anyone who can spare the time to listen.

There is (was) a member that worked for NASA and he reported that they (NASA) used abrasives on aluminum that was to be welded

Correct me as needed. I have the sense that I can sand, grind, power brush steel because A. it is less sensitive to contaminants than aluminum, and B. it has less tendency to gall. The heat of friction tends to soften alum, and contamination is wiped in. The goal is to minimize heat input. Hand brushing, filing, (my favorite is a file made for ski tuning, made of stainless.) One expert I am aware of uses a stainless tooth brush, and acetone as though it was tooth paste.

Correct me as needed. I have the sense that I can sand, grind, power brush steel because A. it is less sensitive to contaminants than aluminum, and B. it has less tendency to gall. The heat of friction tends to soften alum, and contamination is wiped in. The goal is to minimize heat input. Hand brushing, filing, (my favorite is a file made for ski tuning, made of stainless.) One expert I am aware of uses a stainless tooth brush, and acetone as though it was tooth paste.

This is what I have

I'll have to give those a try Richard, Funny that we use aluminum oxide coated products to remove the aluminum oxide layer that cause so many issues.

I found that a flat 36 grit disk with a backer pad is the way to go with aluminum. It's coarse enough that it doesn't "clog" the aluminum substrate. Of course you have to use some finesse as the 36 grit will really move some material. Let's say you are patching in or joining two pieces of tube and want a smooth transition. I hit the weld with the 36 grit pad and get it close then do the finish work with stick on scotch rite pads down to finish grades. Can make it look like the tube was never modified.

I’m a huge fan of Red ScothBrite pads on my angle grinder. Coarse enough to remove heavy oxidation, but not so coarse that it tears up the surface. And there’s no glue residue. A quick wipe afterwards with Acetone or equivalent, and weld away.