Buzzbox conversion to oil cooled..

[SiPMerlin150]

I'll scrap the idea of oil bathing the transformer and try to increase the volume of forced air flow through the welder, I might go as far as making another housing for the transformer set to allow more air flow to pass around it.

I dont want a fire ball or even electricution problem to arise.

Thanks for all your input and views guys!

 

[rich r]

You might be able to improve matters by adding some baffles and guides to direct the cooling air where it's actually needed, and avoiding turbulence. Maybe even add a finned heatsink to the transformer (and anything else that's getting hot) which will help draw the heat out, and the fins will help smooth airflow.

I think revising the fan arrangement is probably the way to go. There are some air cooled buzzboxes out there with decent duty cycles, it's all just down to how well you can get the heat out of the box really...

 

[madkayaker]

I carnt remember who but someone used a fan from a tumble dryer (I think) and bolted it to the side. Apparently it would move so much air it tried to take off! The photos might be in the photo albums

 

[PhillipM]

Pulling air out with a fan is generally a lot more efficient than trying to blow it in where you want it.

 

[madkayaker]

This is the fan I used http://www.maplin.co.uk/230v-main-axial-fans-1810 the 120mm one it fits into the back to one side of the sliding piece of transformer. It has to go in at a bit of angle and I might have cut a lug off but it works a treat. Think it blows air onto the thermal cut out.

 

[SiPMerlin150]

This is the fan I used http://www.maplin.co.uk/230v-main-axial-fans-1810 the 120mm one it fits into the back to one side of the sliding piece of transformer. It has to go in at a bit of angle and I might have cut a lug off but it works a treat. Think it blows air onto the thermal cut out.

Thats the exact one i have stuffed inside, so i will have a go at moving it around tonight, are the fan body's made from alu? Might mig tack it in position if its steel...

 

[madkayaker]

I used two long bolts top tight bottom with a bolt behind to space off. Will take a photo if you like when I'm next at my workshop

 

[SiPMerlin150]

I used two long bolts top tight bottom with a bolt behind to space off. Will take a photo if you like when I'm next at my workshop

That will help lots! I'm looking at the internals of my welder right now and trying to position this fan is a head scratcher!

 

[Wallace]

Can you not fit the fan on the outside of the box with a finger guard like this:

 

[SiPMerlin150]

I did think of that wallace, I even have the finger guard, but due to the power connections being two spade connections that are on the body of the fan, they are exposed live parts that could be accidently touched.

I've mounted the fan diagonal inside the unit at an angle where it blows cool are onto the transformer windings, and the wiring and switches.

I can use it on full power now (125 amps!) I can burn 2 x 4mm rods before the thermal cutout kicks in. Not much, but hey, I can use bigger electrodes again.

 

[Justme]

Think it blows air onto the thermal cut out.

Thats exactly what you dont want. You will be cooling the sensor & keeping it from tripping.

Better to cool the coils & shield the sensor so its still senses the actual transformer cores temperature.

 

[Lawnmowerboy]

Are you sure the insulation on the transformer is oil resistant?

 

[madkayaker]

Thats exactly what you dont want. You will be cooling the sensor & keeping it from tripping.

Better to cool the coils & shield the sensor so its still senses the actual transformer cores temperature.

Never had any problem in the 5 years I have used it since modifying

 

[SiPMerlin150]

Are you sure the insulation on the transformer is oil resistant?

Nope! Its looking like some kind of paper twist with a laquer lamination painted on...