Repairing diecast, aluminium, pot metal and cast iron

Advice and guidance on repair and restoration techniques.
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daveslot
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Repairing diecast, aluminium, pot metal and cast iron

Post by daveslot »

Has anybody been successful repairing holes in aluminium castings, the type of repair which will be on show, i.e. in a polished section? Seen ally rods, non flux type on ebay and wondered if anybody had used 'em.
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Re: Repairing ally castings

Post by johnnyo57 »

I had a crack in a Sega mad money front casting welded up using TIG method it worked very well, aluminium is not very easy, nigh on impossible to weld with any other method.
Holes can be filled but you will need to dress and polish it up afterwards obviously. I would suggest you find a company that can do this for you should not be expensive
as it would only take about 5 mins to do.

regards john
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Re: Repairing ally castings

Post by pennymachines »

Having recently experimented with the fluxless aluminium "welding" rods, I'm inclined to agree with John. It's probably more sensible to hand it to a professional. I just repaired an internal aluminium casting using the rods, but it took quite a bit of practice on other bits first, and I don't feel ready to try it on my Bradley Challenger casting until my technique improves.

It's fun learning how to do it yourself, but not such fun if you ruin a vital part. I'll report back when I've tried a few more pieces.
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JC
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Re: Repairing ally castings

Post by JC »

Although not a 'welder', I have done a bit of welding in the past (although only on steel) but I do understand the science to a fair degree. Aluminium welding was traditionally very much a black art, to be performed only by a select few experienced welders, with a unique skill. Aluminium could only be welded with oxy-acetylene, using a sulphur-based flux. I recall hydrogen was often used as an alternative to acetylene, although I don't know for what reason. Aluminium welding was one of those skills that you could either do or not - and most couldn't.
In more recent times, TIG welding has become the norm, using tungsten wire and an argon gas shield (unlike steel, where more or less any inert gas will work - CO2 being the norm, aluminium needs argon).
TIG welders are expensive - really expensive! OK you can get cheaper TIG welders (although nowhere near as cheap as MIG welders), but a decent TIG rig will cost several thousand pounds. Now, I've heard a little about these 'aluminium rod' gimmicks, although I admit it is only a little. But I have to question whether they can be a serious alternative to ' doing it properly' - I would certainly question whether this method can offer any reliable strength. They may well be OK for 'patching up' but I am inclined to put them in the same league as spray 'chrome' paint.
My advice - if you want to weld aluminium, pay someone who knows what he's doing.
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Re: Repairing ally castings

Post by youngerap »

JC wrote:My advice - if you want to weld aluminium, pay someone who knows what he's doing.
I tend to agree. In a past life my brother was a specialist aluminium welder for the USAF at Mildenhall, so I asked his advice on welding cast aluminium. His view was that it should be relatively easy with the repair being strong and invisible, but qualified this view with the assumption that the welder knows his stuff! Otherwise, it would be the easiest thing in the world to go from minor repair required to disaster in the matter of seconds. His advice is to do your homework to ensure that the guy you are commissioning is qualified to weld aluminium and can prove it.
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Re: Repairing ally castings

Post by pennymachines »

Yes, that's the point, a specialist aluminium welder has countless hours experience. That's where the advertising of these fluxless rods is not 100% honest. You really can't just pick them up for the first time and expect success. It takes a bit of practice to get a feel, for example, of how to distribute the heat around the casting (without flux, you don't get much visual indication of temperature).

Before dismissing them as a gimmick, I thought it worth experimenting a bit. As I said, I've now successfully repaired a casting, but, like JC, my main concern was whether the joins have "any reliable strength". According to the advertising, it will produce a join stronger than the original material. This is how they describe the bonding:
... a grain boundary reaction takes place that causes Aluminium ions from the bodies being welded and Zinc, Copper and Manganese ions from the Techno-Weld to diffuse across the weld boundary to a depth of several microns, producing a genuine weld.
Whether this should really be called welding, brazing or soldering needn't concern us here. What matters is - will it make a clean, strong, long-lasting join?

Techno-Weld has been thoroughly evaluated by the Technical Welding Institute (TWI) and been recognised as "Opening the door to a revolution in the process of Aluminium joining technology" ... it has also been given full approval and support from the British Aluminium Plate Research Centre in Birmingham (I found nothing about such a body on the internet) ... endorsed by BOC LTD and Reynolds Metal Corporation (presumably Reynolds Metal Company - now merged with ALCOA) ... for use in welding Aluminium as a valuable alternative to conventional welding.
Techno-Weld - the Product

So much for the blurb. Here's how I tested it:
I sawed through a piece of flat aluminium stock, roughly 2.5cm wide and 2mm thick, ground and cleaned the edges with a spinning wire brush, then joined them together again using the rod.
join1.jpg

I then ground flat and polished over the join.
join2.jpg

Finally, I put the piece in a vice and walloped it with a rubber mallet to see if the join would break.



Here's a close-up, after bending. There was no opening or cracking along the join. I'm sure no glue would stand this test.
join3.jpg

My conclusion is that this is a useful addition to the slot restorer's armoury, suited to the kind of repairs we tackle, particular when professional welding would be too expensive.
It would not do for safety critical items like bike frames, where the process would destroy the aluminium's heat treated strength.

The Technique
As I said, you will not get a good join until you master the technique. I used HTS-2000 rods (similar to a number of other brands) which came with some basic instructions.
My first efforts were not encouraging. I tried fixing a broken mazak pinball plunger surround (surplus to requirements), but the casting wanted to melt before the rod. Subsequently, I found there's a method of dealing with this, but it seems quite difficult to master.
broken-casting.jpg

For now, I'm working with aluminium castings. After initial frustration, I searched the internet for guidance and found these videos created by Technoweld, which convey what you have to do much better than written instructions.





1. Grind the edges to be joined to clean metal, then clean with a stainless steel brush reserved for the purpose. This removes the oxide layer which quickly forms on the surface and would be a barrier to joining.
2. Apply heat. Butane/Propane is fine for weights up to 1/4". On my first attempts, in order to avoid melting the castings, I used a fine tipped butane/propane torch, but soon discovered a broader heat source was needed. It is essential to spread the heat around the piece, not just at the join.
3. Rub the rod along the edge. When the temperature is something above 380°C, it will melt and you run a bead of it along the edge.
4. Maintaining the heat, scrape the molten metal with the steel brush or any sharp stainless steel implement. This removes the layer of oxidation that has formed beneath the molten rod and allows it to penetrate the aluminium, preventing further oxidation.
5. Repeat this process on the other piece, if you're joining two separate pieces.
6. Position the join using clamps or sandbox.
7. Bring both pieces back up to the melting point of the rod and push together. You may then add more rod and finish by stroking a small stainless steel screwdriver blade along the join.

A strong join will only be achieved if the rod remains molten for at least 6 seconds during cooling (longer on larger castings). This allows it to form a large, strong crystalline structure. So you must ensure there is enough heat applied in a general area around the repair. For small items, the heat could be progressively reduced to slow cooling.

A few things you can do with HTS-2000:

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Pot Metal / Die Cast welding repair rods

Post by gameswat »

Topic merged - Site Admin.

Nobody seems to have talked about this product, so figured I should pass on the lead. https://muggyweld.com/super-alloy-1
Have been using this stuff for at least 5 years and has helped me out of countless tough situations with parts made of Unobtanium! In fact, I can honestly say that this stuff has made me thou$and$ in sales of otherwise useless machines. Here's the instuction sheet https://muggyweld.com/packets/superalloy1postsale.pdf
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gameswat
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Cast Iron welding rods

Post by gameswat »

Topic merged - Site Admin.

These rods are just amazing!! Imagine welding cast iron with just an arc welder and no pre-heating of the iron!!!! http://muggyweld.com/72-electrode
Apparently the weld stretches as it cools so as not to stress the very delicate cast iron. I have used these to repair some delicate antique machine and other castings (well over 100 years old) that once ground down looked and worked as good as new!
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Re: Cast Iron welding rods

Post by coppinpr »

These rods look to be answer to a lot problems - thanks for sharing the info.
I was recently in Lidl supermarket, always on the look out for stuff in their non-food dept and saw an arc welding kit for 39 pounds! It looked OK to my untrained eye, complete with mask and gloves! Anyone know if it's any good before I splash out? !PUZZLED!
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Example of pot metal welding repairs

Post by gameswat »

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Here's a restoration job i just did a few nights ago showing what can be done using the the Muggy Weld Super Alloy (S/A) welding rods. This was for a 1959 Williams "Ten Strike" bowling arcade game. The figure was badly cracked where the gears mesh to swing the arm, and the bronze bearings were loose and sloppy due to worn pot metal. The wear was so bad that the gears had unmeshed during use and worn the teeth away. So as well as welding the body I also replaced both gears and both bearings.

1st problem: The three mounting holes into the main body casting were stripped, these hold the top casting which keeps the bearings tight. I imagine this is what caused all the problems in the fist place! Since the bowling arm is cast iron, each time it swings this creates a lot of momentum. Once the threads weakened in the lower casting, the top casting (head and shoulders) was loose and the arm movement quickly wore away the bearing holes and stripped the gears!! To repair I filled both front holes and re-tapped for original threads. But the rear hole had very little thickness to the metal so i welded a brass nut underneath so as not to have this problem ever again. The S/A sticks to brass like shite to a blanket!

2nd problem: These castings were both made using a centrifugal mold so they're not solid castings. They do this to cut down on metal usage, like a thick Easter egg. There were voids underneath three of the four bearing holes - two on the top casting and one on the bottom. These all showed signs of fatigue and missing pot metal causing some of the looseness with the bronze bushings. To say the arm was sloppy is an understatement! To repair first I laid each casting on it's side and carefully filled the three voids using gravity to assist with the flowing S/A. Then i added S/A to all the four surfaces of the bearing mounts. It was a fiddly job to machine those bearing mount holes again but I got there in the end. Next time i would tackle this issue differently though to speed up the process. I'd machine brass tubing first to the correct inner diameter, then machine/file out the worn bearing holes to take the thin sleeves of brass. Then weld the four brass halves it in place to hold the bearings, meaning very little maching, instead of welding the old worn holes and having to machine the rough surface. The repaired voids are now solid as a rock!

3rd problem: The lower main body casting had cracking and missing pot metal around where the lower gear fits, front and back. So in use this would allow the gear that fits in a brass tube to flex away from meshing with the upper gear. I welded the cracks and filled the missing areas and also added extra thickness since the original was so thin in some places.

Luckily with this job I wasn't dealing with pot metal cancer. This is where the castings crack internally and expand and warp all over the place due to a poor quality metal mixture I'm told. I've tried welding partly cancerous parts but usually even light heat applied caused the parts to literally explode! So always wear goggles if you try. These rods really work best on broken or worn parts. As I said earlier these rods really stick to brass, so on occasion I've added brass internally to strengthen a break and then welded with Super Alloy, so no brass is showing, and now stronger than new!
Attachments
Lower casting showing cracked and missing metal just below where the lower gear fits inside.
Lower casting showing cracked and missing metal just below where the lower gear fits inside.
Upper casting showing voids and missing pot metal around bearing holes.
Upper casting showing voids and missing pot metal around bearing holes.
Upper casting showing filled voids and repaired wear to bearing holes.
Upper casting showing filled voids and repaired wear to bearing holes.
Lower body casting showing void and missing metal.
Lower body casting showing void and missing metal.
Lowwer casting showing welds to all damaged areas.
Lowwer casting showing welds to all damaged areas.
Lower casting showing outer welded repair.
Lower casting showing outer welded repair.
Lower casting showing outer sanded weld.
Lower casting showing outer sanded weld.
Both upper and lower casting fully machined and ready to be fitted with gears.
Both upper and lower casting fully machined and ready to be fitted with gears.
New gears and bushings installed.
New gears and bushings installed.
Fully restored and bowling like a champ again!
Fully restored and bowling like a champ again!
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Re: Pot Metal / Die Cast welding repair rods

Post by tazmantic »

Yeah, I have seen this stuff but not sure if it's available in the UK !PUZZLED! but you can get Durafix. I think it might be similar.
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Re: Pot Metal / Die Cast welding repair rods

Post by pennymachines »

It's very similar to the zinc alloy HTS-2000 I've been experimenting with (topic merged above).

It claims a slightly lower working temperature of 350º versus HTS-2000's 380°C - 408°C, which could be helpful.
Unlike my rods, it comes with a pot of flux. This offers several advantages. The flux "turns from powder to liquid at the exact moment when the rod should be applied" helping you to judge temperature - particularly important on aluminium which doesn't glow red before melting. It prevents re-oxidation of the aluminium during the braze (obviating the fiddly wire brushing of the molten join), and it helps the molten rod flow.

Price-wise however, it doesn't compare favourably in the UK.
5 x 24cm HTS-2000 rods for £12 (from ebay or http://www.aluminiumrods.co.uk/)
5 x 18" Muggy Weld rods plus flux for £66.10 (from Caswell).
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Re: Pot Metal / Die Cast welding repair rods

Post by gameswat »

These rods work great because it's so important to keep the pot metal as cool as possible to stop it cracking or exploding. As for price, no other product has worked for me, so not an issue. Previously I would either glue, and/or bolt together the breaks. I was so happy with these rods I eventually tried all the other products made by Muggy Weld and have had great success with them all. Have used a hell of a lot of their Silver Solder to restore small cast iron breaks and stainless steel repairs. But PM, I do also use a different brand of rod for alloy welding.
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Re: Pot Metal / Die Cast welding repair rods

Post by pennymachines »

Agreed - if it does the job, it's well worth it.
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gameswat
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Re: Pot Metal / Die Cast welding repair rods

Post by gameswat »

I just looked into the other alloy rods I've been using for the last 3 years and they're actually HTS 2000. They seem to work very well.
tazmantic wrote:Yeah have seen this stuff but not sure if its available in the uk but you can get durafix think it might be similar
No agent in Aust either, I just buy online from the states.
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Re: Pot Metal / Die Cast welding repair rods

Post by tazmantic »

Bought some HTS2000 rods off evil bay, well think they are as listing has now been changed lol and have been having a try to see what happens, managed to weld 2 bits of ally no problem and the weld was really strong gave it the hammer test and the ally just bent and weld stayed intact :)
So thought I'd have a go on some scraps of pot metal well ain't that a different story as said the pot metal and rods melt at about the same temp so before you know it these a big blob lol. It says in the instructions with pot metal to actually melt the rod with the flame then heat it all and try to like mix it together with a piece of steel !OMFG! I sort of had some success but its tricky as think my blow torch flame is too big really need a fine flame.
I did successfully fix a lever off an air rifle, the boss was quite hefty so didn't melt quickly but lever did :( so I made a new lever out of ally and welded it on to the pot metal boss worked a treat !!THUMBSX2!!
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Re: Repairing diecast, aluminium, pot metal and cast iron

Post by treefrog »

Digging up old topic, I was interested whether anyone had attempted to have a go on a precious part other than Gameswat great resto of that figure. Especially what the original poster mentioned and a common issue in our world, cracked rather than broken castings.

The Muggy Weld product sounded excellent with the use of flux and lower temperature, but I could find no supplier in the U.K., they use to sell on Amazon Uk, but saw this on their website
Contains cadmium. Super Alloy 1 cannot be imported to countries in the EU due to import regulations
, maybe that will change in 3 days time, but I doubt.

They have great advice sheet though on how to use and mention that a crack needs to be thoroughly prepared and rubbed down inside, which means making the crack larger to get a file in. Also the products are not suitable for cast aluminium, except
For castings thicker than 1/8″ we recommend beveling the base metal with a grinder prior to soldering
https://www.muggyweld.com/wp-content/up ... ctions.pdf

Before I destroy a poinsettia casting, thought I would check any results |/XX\|
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gameswat
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Re: Repairing diecast, aluminium, pot metal and cast iron

Post by gameswat »

Tree, the Super Alloy 1 isn't what you want for this job I think. Fine if you are painting or plating the repair, but the colour of the product will not match cast aluminium when polished or burnished, it darkens the way pot metal does. You'd need to either use the Muggy Weld 5 alloy rods. But those need much higher temperature, a little lower than the cast aluminium melting point. I've done it but you need an oxy torch to get enough heat to something the size of a slot casting. And with that much heat you 'll often cause some kind of warping with such old castings. Alloy Tig welding would likely be a much safer option, but I'm not sure how that colour matches to old cast alloy?
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gameswat
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Re: Repairing diecast, aluminium, pot metal and cast iron

Post by gameswat »

Tree, the HTS2000 rods are good for repairing aluminium damage and making things, but again a terrible match colour wise for cast alloy. I would never try and use these on the exterior of any castings that are to be left raw. I recently had to fill some drill holes in an almost 100 year old cast alloy panel and chose to make my own plugs from old castings to fill the voids. I slightly chamfered the holes both sides and then gently rivetted the plugs into place, then ground back the detail with a die grinder. Effect is pretty much invisible. And no heat placed in the middle of delicate castings which would definitely have caused warping and possibly cracking.
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Re: Repairing diecast, aluminium, pot metal and cast iron

Post by treefrog »

Thanks GM, it has answered the question as around delicate castings as this would probably have been my main concern given how thin some are and of course colour matching.

I guess the alloy 1 would be good for pot metal parts, not that we can get here
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