Hello one and all!

[Mr Fro]

Hello ladies and gents,

I'm starting to get in to welding a bit nowadays (just Arc at the mo) and have been dipping in to the tutorials to help me along adapting an old caravan base to a motorbike trailer. :-)

I found the tutorials very helpful to dial in my settings and help fix some of the bad habits I picked up.

I spent most of this weekend chopping up and welding my trailer which I really enjoyed and for the most part my welds aren't that bad. :-) I got a bit frustrated that my buzz box kept cutting out and I doubt the fact that the wire worked lose and fell out of the earth clamp several times helped my weld quality very much...

Anyway, that's enough of my drivel for now - I'm looking forward to soaking up some knowledge!

 

[eSCHEn]

Hi Mr Fro, welcome

 

[cumbriasteve]

Welcome to the forum:

Is your buzz box a 'turbo' model, they give them that fancy name when they have a cooling fan inside them, if not it can be beneficial and cheap enough to fix a fan into it, even on the outside of the vent can make a big difference to cut out times.

 

[Mr Fro]

Oh yeah, I've got the Turbo daddio machine... Last all for about 90 seconds before needing 10 minutes to recover. I've got a few fan units I've been thinking of cutting in to the casing but I've not "got round to it" yet... :-)

 

[PTvor]

You might find a 240V box fan fits on the inside, there may even be holes ready drilled for it for the deluxe model, or you can out a hole and drill holes for the mounting screws and fit it inside or outside. Put on a wire finger guard.

It won't make a lot of difference to the number of rods you can burn in succession but it will make a difference to the reset time.

The cable falling out of the earth clamp is an unacceptable nuisance. This might be a particularly rubbishy pressed steel earth clamp which you can't do much with. Much better ones can be had for £4 or so and the tags 50p or a quid. You could even make your own tag from a couple of inches of copper pipe, squeeze half flat so that you can drill it to be bolted and then squeeze the other end over the stripped cable using a bench vice. There are proper crimping tools for doing all this but must needs when the Devil drives.

 

[Mr Fro]

I ended up using an old earth ring terminal and soldering it VERY solidly in place before crimping the whole lot to the clamp - getting much more consistent welds now. :-)

There's a fan at the back of the box already and I have another 240V (which I "borrowed" from another bit of kit...) and I've been pondering where to site it - blowing in from the side or sucking out from the top... Answers on a postcard!

 

[cumbriasteve]

blowing in from the side or sucking out from the top?

That's one of those things I have never been able to decide which is best, if it is sucking out then it must be sucking it in to suck it out, that appears to equate to the same thing.

Then of course if it is blowing in, it must also be blowing out, which is the same as sucking out...sort of ish.

I am getting dizzy now but think the answer lies with the strength of the air flow at a certain point.

My totally inexperienced view is probably that I would have as much air blowing at the unit rather than sucked at and over it.

 

[PTvor]

Air being taken into a fan comes from a general direction and has smooth flow. Air blown out of a fan is turbulent and more directed.

Turbulent air is better for cooling than smooth flowing air, because more of the air comes into contact with the hot surfaces. The fact it's directed has advantages and disadvantages, depending on how things are laid out. One disadvantage with fans blowing in is that you can find a lot of dust and rubbish building up where the air hits.

That's why you usually see fans blowing air over heatsinks in electronics, rather than sucking air over them - not always.

I've tried it both ways with a buzz box and a 240V 30W box fan. I thought it worked better extracting air from the case but there wasn't much difference. There's already a lot of turbulence because the air flows in through louvres and holes in the bottom and it's a very powerful fan.

It's a case of diminishing returns with fans. A 2W fan is massively better than letting the heat find its own way out. A 20W fan would be a useful improvement but not a fantastic improvement over the 2W fan. The problem you are stuck with is the rate heat is conducted out of the transformer core and to the outside of the transformer where it can be taken away.

You might not see a vast improvement by fitting an extra fan, if there's one already there.