How many amps for a cast manifold?

[200T]

Hi!

I'm looking into buying an arc welder to repair some cast manifolds. What I don't know is; how many amps should the welder have? At a guess, 150 amps won't be sufficient?

Don't ask me, how thick the material is, at a guess 6-7mm? Maybe 10 at places?

Thanks!

Regards,
Jan

 

[backpurge]

It will depend on what size electrodes you want to use.

 

[200T]

Mhmm. Ok. Well - actually - I don't know. What would be a sensible size? 2.5 to 3mm? Thanks!

Jan

 

[backpurge]

You don't really want to go any smaller than 3.2mm, for this a 150 amp machine will be perfectly OK, the only problem you may come across is, if you are doing a lot of continuous welding the machine may cut out due to the duty cycle but this is just a case of letting it cool down for bit

 

[200T]

Ok! Thanks for the advice! Appreciate it

Regards,
Jan

 

[HOUNDMAGNET]

you will also need a substantial propane torch aka roofers type or oxy/propane and heating nozzle to preheat the manifold before welding

 

[200T]

you will also need a substantial propane torch aka roofers type or oxy/propane and heating nozzle to preheat the manifold before welding

I've planed to put it on a substancial coal fire / forge Heating, welding, put it back into the fire and let both cool down slowly, then a skim and it should be ready for use again.

Does this sound like it could work?

Regards,
Jan

 

[TechnicAl]

cast iron rods are designed to run on low current, about 30 amps per mm as a general rule

 

[dannyp]

I don't seem to get on with welding cast hot. cooler seems to work better for me.

i go for about 50 degrees C or so, weld and inch or so and peen it with hammer then weld and inch or so somewhere else and do the same, then leave it allone for a while and come back to it when some of the heat has gone.

also find it's a lot easer with an inverter

 

[TechnicAl]

I don't seem to get on with welding cast hot. cooler seems to work better for me.

i go for about 50 degrees C or so, weld and inch or so and peen it with hammer then weld and inch or so somewhere else and do the same, then leave it allone for a while and come back to it when some of the heat has gone.

also find it's a lot easer with an inverter

Thats the correct technique

 

[Tigman]

I wouldnt pre heat at all , drill cracks at both ends if possible , then the crack doesnt get longer and V out the crack , so you can fill it in !

 

[PTvor]

Hi!

I'm looking into buying an arc welder to repair some cast manifolds. What I don't know is; how many amps should the welder have? At a guess, 150 amps won't be sufficient?

Don't ask me, how thick the material is, at a guess 6-7mm? Maybe 10 at places?

Thanks!

Regards,
Jan

Just at first glance you are attempting something difficult and you know it, and you are looking into buying an arc welder to do it, which suggests you don't have much experience using one. CI rods aren't cheap and are not the place to learn.

It could be easier and cheaper to pay someone to do it, especially if arc welding isn't a technique you are familiar with and you are only now considering buying an arc welder. It sort of depends what these manifolds are worth, how many quids you can write off and so on.

I can't help thinking that the way to approach it is to be good with arc on mild steel first, then mess about welding cast manifolds that don't matter and which it would be cheaper to get from a junkyard anyway, and then to tackle manifolds which matter.

I do believe you should look into getting this work done by someone who does it on a routine basis and failing that, practice on some rubbish first.

 

[200T]

Hi!

Your observation is correct! What you suggest is what I plan to do; I've collected a good pile of scrap metall and scrap cast manifolds to practice first! I would buy a 2nd hand welder or borrow one - but I'd need to know what I have to look for, hence the question I've done a little bit of arc welding in the past, it's not 100% new to me. But like you said - without praticing first I will not succeed

The manifold in question is rare and even cracked 2nd hand ones are expensive - and 99% of them are cracked anyway (construction flaw).

You are right - paying someone to do it is the safe & easy way. But then I'll never learn it...

Thanks all for your suggestion!

Regards,
Jan

 

[PTvor]

So it's advice on buying an arc welder.

See

http://www.mig-welding.co.uk/buying-arc-welder.htm

http://www.mig-welding.co.uk/arc-welder-types.htm

There are basically three choices.

An air-cooled buzz-box, cheap, even new, but overheat easily.

A secondhand oil-cooled welder. Big and very heavy but far better duty cycle than a buzz-box. Usually a high voltage range for rods which need it. Prices vary a lot but £100 to £150 about the mark.

A new inverter. £200 to £300 and upwards to get one with a decent max output current and duty cycles and a guarantee and backup likely to be worth something.

They've all got advantages and disadvantages. If you are not in the UK, things will be slightly different, e.g. 16A sockets being normal, rather than 13A sockets. The market might be different, e.g. old oil cooled welders being sought after and more expensive than inverters.