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gidon

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I've recently been toying with idea of getting some equipment to do some basic metalworking - for jigs etc - but maybe for "enhancing" some projects at a later stage.

I can't get me head around the difference between welding and brazing - mainly with regard to the strength of joint. And also what I need for either? Brazing appears a cheaper setup - is that right? What do you actually need for both if that's not a stupid question? Any suggestions / explanations greatly appreciated?

Also considering a small metalworking lathe. Something like the micro from Axminster. I know as little about turning - so please advise - could I also use this for turning small wooden knobs for woodworking projects too. Would help justify the cost! Anyone recommend a cheaper alternative to the micro?

I just discovered the delights of permanent threadlock - which if I had discovered a while back would have saved a lot of messing around with epoxy (with limited success). But this has resparked my interest in this lot.

Many thanks,

Gidon
 

Noel

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Gidon, me too. If I could also add a further question about welding -arc , mig or gasless and just how stong is brazing? Think Chris has a MW lathe.


Noel
 

jasonB

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One of my other hobbies is model engineering, am currently making a 1/12th scale coal fired traction engine so I have a reasonable set up.

The main difference between welding & brazing is that welding uses a filler of the same material and is used for joining like materials together. Brazing uses a metal of a lower melting point ( a bit like brass) to join metals together.

There are several types of welding kit available, electric arc, TIG, Mig and gas(oxy-acetalyne). Brazing is bone either with Oxy-acetalyne or carbon arc rods which can be fitter to an arc welder.

There is also silver soldering which uses a much stronger solder than that used for plumbing and is as strong as brazing but it is not good for gap filling, on small areas this can be done with a propane torch.

I have an EMCO lathe which is upto toolmaking spec and would cost about £3k to replace but there are a number of imported lathes that would be quite capable from companies like Warco, Chester, Engineers Toolroom etc

A good online source for engineering materials & equipment is http://www.chronos.ltd.uk/

Yes you can use it for wood as well as making your own hardware like hinges and handles

Jason
 

jasonB

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Noel the metal will usually bend before the braze or silversolder joint fails if you have done a good job.

Jason
 
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Anonymous

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Ahh Gidon, metal working :D

You may have noticed that I play a fair bit - being an engineer, my first love was always metal :wink:

Brazing is a missunderstood art. What most people call brazing is in fact bronze welding - I used to make motorcyle frames in my garage using this very technique. Most top class steel frames (harris magnum etc.) were bronze welded as it does not melt the parent metal and so you don't get stress fractures around the joint during use - pretty important :wink: [-X

OK.

Brazing is a process where one actually heats up ALL of the material and flows a bronze filler around a joint. The ajoining pieces of steel must be tightly butted, i.e. joint well formed. Difficult to heat the entire object with a home setup :p

Bronze welding uses an oxy-acetelene welding (oxygen and mapp gas in small sets) set to locally heat the are of the joint and then flow the bronze filler around it - often the rod has flux coating on it but you can get bare rod and paint flux on first. No melting of the parent metal. You will get 60,000 PSI tensile strength. Brazing is very good for repairing cast iron.
Bronze welding is VERY strong but takes a bit of skill (practice) to do well. My favourite technique and strong enough for most things (including racing motorbike frames !!)

Gas welding uses the same kit but you actually melt the parent metals into a pool and then feed in a steel filler rod to weld the joint. Higher temps. and requires a fair bit of skill. Stronger than bronze welding but quite a bit harder. You could get stress fractures around the joint if it were subject to a lot of vibrations. I love gas welding :wink:
Best for thinish materials below 4-6mm

MIG welding is basically a glue gun approach. A filler is automatically fed into a weld pool which is surrounded by an inert gas. NO skill what-so-ever required. Weld is not as strong as gas welding or any others for that matter. Melting of parent material is generally not as complete as with gas welding. Good for welding plates on cars etc. I hate MIG welding!!!!!!
Best for thinnish materials due to lack of penetration

TIG is expensivbe and difficult - but you can weld aluminium with it!


Electric arc welding is a very violent approach. One basically has a stick of filler connected to a DC supply and the material to be welded connected to the other terminal. Loads of current flows, melts the parent metals and the filler and one gets a pool. The rod is fluxed and so one gets a coat of slag on top of the weld that mush be chipped off with a hammer.
Very difficult to weld thin material this way as one blows holes in it very easily. For big stuff, this is the one. Used to weld ship hulls, lorry chassis, bridges etc.

I now use a small cheap gas set set I got from B&Q as I sold my main gas set and lathe about 10 years ago - and regretted it ever since :cry:
Bronze welding is likely to be more than strong enough for most tasks but steel thicker than 6mm takes a LOT of gas to heat up adequately

I have been looking around for a cheap metal working lathe but they are rare as hen's teeth. Look at £400+ for the lathe and then you need tools etc.
 

Chris Knight

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Gidon,

As Noel mentioned I have a MW lathe ( a Myford Super Seven). However, it is apparent from their replies that Jason and Tony are much more expert in the field.

I would say that for me, and my skills, MIG welding is great. It is very easy and if you don't want to make mission critical frameworks, it is quite strong enough - MIG welders are cheap too! It is great to be able to get a few bits of angle iron or whatever from your local metals merchant (B&Q even have some thin walled stuff) and knock up some handy stands, brackets or whatnot - in very short time.

My tests have involved me jumping up and down on simple right angle brackets that have held together perfectly and I am not particularly svelte).

I have made several workshop benches, shelving brackets and other odds and sods in this way with angle iron and quarter inch plate and they are extremely useful.

I use my lathe for all sorts of minor jobs - furniture fittings like hinges and stuff involving odd sized screw threads mostly
 

gidon

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This is so strange! I sent a long reply to this asking yet more questions. I was thinking today that it was funny no one had replied - dug up the post and found out my reply is no where to be seen? I'm sure I saw the post with the latest reply intact? All very weird.

Anyhow - I'll try again:

Thanks a lot for all your very informative posts! There really are experts in all areas on this group. Right so let me see if I get it. I think it's between MIG welding and brazing? Both are as strong as each other - perhaps brazing more so if done well? You can't join aluminium - or can you with brazing? All I would need for brazing is something like this from Axminster, and some solder. So the cheaper option? If I go down the MIG welding route what sort of amperage do I need? Machinemart have a their Pro 90 at £140 - would that handle most likely tasks?

I really like the idea I could use a metalworking lathe for wood - nice ebony feet Jason. I'll look into this seperately - it really is major bucks as far as I can see.

Thanks again,

Gidon
 

Chris Knight

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Gidon,

You might want to go up a notch or so if you go for the MIG welder. I have the 160EN http://www.machinemart.co.uk/product.as ... 2030&g=105 and it will handle thicker material at not too great a cost difference. It will also handle gas free welding if you want to do that - however, I always use it in gassy mode.

You can certainly weld aluminium - I don't know if you can braze it as such but I have seen some sort of flame driven alumium joining process at a couple of model engineering exhibitions - I never paid any real attention to it however.
 

jasonB

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The axminster link will not get the work hot enough for brazing unless you are joining VERY small bits of metal, it will be OK for silver soldering reasonable size items as SS requires around 600 deg to melt.

You cannot braze aluminium, it can be welded or there are some "solders" available but they are not that sucessful.

Jason
 
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Gidon

The axminster kit will NOT braize (bronze weld - you clearly did not read my post [-( )

You need some sort of oxy/acetalene kit. Some B&Q stores and Halfords sell a small oxygen and mapp gas cylinder kit for about £40 complete with gun. You will NEED welding goggles too. I use one and it is really useful for small jobs

You don't want solder. You use bonze welding (might be called braizing) rods and I would recommend the typoe that comes with flux on.

It is possible but difficult to gas weld aluminium with special welding rods and flux. I am a very skilled gas welder with 20+ years of experience and I struggle to gas weld ali. You cannot MIG weld aluminium. Most people TIG weld aluminium - very expensive kit and difficult to do well.

As an aside, I do a lot of metal work (evident from my posts :wink: ) and the single most useful tool is an angle grinder which can actually be a very precise piec eof kit with a bit pof practice
 

gidon

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Jason - thanks. But I'm still unclear what silver soldering is? Same as silver brazing in Axminster catalogue? Is is strong enough for workshop jigs etc?

Tony - I did read your post - honest! Doesn't mean I understood everything though! I find this all pretty confusing. Especially the brazing - and variations of. I think I'm going to look into getting a MIG welder - I like the glue gun comparison :oops:! Sounds nice and easy.

I have got an angle grinder - bought it to cut up some slate slabs. Boy was that messy. I've not had much success cutting metal with it - tried it on some long iron rods I had in the garden I was trying to fit in the car for the dump. Ended up cutting them more quickly (and safely) with a hacksaw. Most likely cheapo diamond discs and bad tecnique!

Thanks again.


Gidon
 

Chris Knight

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Gidon,
Tony is dead on re the angle grinder, I have used one a lot for various tasks and it can be wielded with surprising delicacy. For cutting steel rods you shouldn't be using diamond disks, you need a straightforward carborundum type abrasive disk - in all probability marked "For cutting only" as opposed to grinding. These will munch through steel rods before you can say "hacksaw"
 

jasonB

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Gidon

Silver solder is definatly strong enough for jigs & small tools. It is used a lot for the boilers of model steam engines which are tested to at least 200psi, it was also the traditional way of joining the tubes of bicycle frames with lugs before TIG welded frames from the far east took over the mass production market. It is still used for handmade frames though I prefer the look of smooth fillet brazing which is what my custom made mountain bike has(uncle is a frame builder and can work steel, alloy and titanium)

Here is a link that explains silver soldering better than I can

http://easyweb.easynet.co.uk/~chrish/t-solder.htm

Jason
 
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I once tried to weld ali, no success. It was when I was in Cyprus in the army and we had a river crossing boat with a big outboard motor. The exhaust box broke and as it was WW11 issue we couldn't get parts. After trying to weld the ali box I finished up having to take the motor back to the central stores.We weren't supposed to have the boat, it had been acquired as things are in the army and I was expecting trouble at the stores. I found the C.O of the stores and told him I had damaged the outboard. "Throw it on that pile of scrap over there"He pointed"If you want another help yourself from that pile there" There was a stack of cases as high as a house ,turned out they had all arrived without any paper work. I'd spent about a week trying to do a repair for nothing.
 

aldel

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Sorry Tony

You can MIG weld alloy and I have successfully done it a number of times.
All you require is a Mig welder alloy Mig wire and a small cylinder of Argon gas plus very clean work. Also weld stainless with the correct wire and Argon
I also find gasless MIG on steel easy. Requires a gasless capable MIG welder and Gasless wire. Only proviso is that you get a smaller gas shield and so is not really suitable for outdoors on a windy day. Saves on CO2 cylinders though.
I use a Clarke 150 TE

Regards Aldel
 
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Anonymous

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I take it all back on the ali welding with MIG. In all companies I have worked at we used TIG and i had heard that one could not MIG ali. Clearly incorrect!!


Id o believe that TIG is better suited although Chris's link suggests that MIG is better for thick material

BTW, silver soldering is quite strong
 

gidon

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Chris - that would explain it - I had thought diamond discs was the ultimate general purpose disc - it seems not.

Jason - perfect - thanks for the explanation and link. That may just do me ...

I'll let you know what I go for if I ever make up my mind.

Cheers

Gidon
 
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