Oxy acetylene?

[mattjeanes]

I am contemplating the removal of four very rusty screws from an aluminium housing. My agricultural and automotive experience of shifting rusty screws from steel and cast iron housings would incline me to heat the screw with the oxy-acet torch before attempting removal. Do you experienced boat guys do this or is it likely to end in molten aluminium tears? <br />Thanks to all you marine pros for sharing your experience on this great forum - it's much appreciated by us land lubbing engineers.

 

[WillyBWright]

Re: Oxy acetylene?

The aluminum will melt to the bolts before they get hot enough to do any good. Try a propane torch first, or mapp gas with a propane tip. Can't get it hot enough for that to happen. Heat the housing, not the bolts. If they don't break free from that, hit them with penetrating oil as everything cools. Contraction will help pull the penetrant into the threads. Gets real stinky and real smokey, so extinguish all flames and put a fan on it.

 

[R.Johnson]

Re: Oxy acetylene?

Using Oxy-acetylene could get away from you in a hurry. In most cases involving an outboard motor, propane would be a better choice. If you are an experienced welder, and oxy-acetylene is all you have, use it. Just be careful.

 

[rodbolt]

Re: Oxy acetylene?

hello<br /> how good are you? I only use oxy-acetylyne. I burn out the trim pins of old jonny rudes and such almost daily. oxy-acetylne is a must for us saltwater techs. if you are not profecient with smoke you cannot take anything apart. I would use oxy-acetylyne or grind them off flush and drill them out depending on what how and where.<br /> good luck and keep posting

 

[Joe Reeves]

Re: Oxy acetylene?

Matt..... A hand held propane torch with a blow torch tip would be the best route to go. Anything hotter than that could cause the destruction of the aluminum housing.

 

[Bobby D.]

Re: Oxy acetylene?

Hi Matt, "What is too hot" when heating aluminum. A good way to tell when you have applied enough heat on aluminum is to coat the aluminum piece with carbon. This is accomplished by using an oxy-acetylene torch. Light the torch and turn off the oxygen valve so you have pure acetylene coming from the torch. Cover the aluminum with the black carbon from the acetylene flame. Now using nuetral heating flame heat the alun. when the black (soot) carbon disappears from the alum. thats it.

 

[MadeCoolCom]

Re: Oxy acetylene?

Hi There you said<br /> am contemplating the removal of four very rusty screws from an aluminium housing. My agricultural and automotive experience of shifting rusty screws from steel and cast iron housings would incline me to heat the screw with the oxy-acet torch before attempting removal<br />####################################<br />If you want to remove the screws from aluminium housing then maybe you don't want to heat the screws if you do apply heat to the screws than the heat will make screws expand and harder to remove.

 

[G DANE]

Re: Oxy acetylene?

Screws and bolts are stuck due to corrosion. If you are able to heat screws red-hot, most of the time they will expand and when cooled down they will be removable. Thats what I get when I TIG weld a piece of a bolt or a nut to a broken bolt. Works almost every time. If you have, drill a hole in a piece of asbestos plate ( or similar since asbestos is illegal ), and mask off when you heat.

 

[jim dozier]

Re: Oxy acetylene?

MadeCoolcom the whole idea of heating stuck bolts is to make them expand, breaking the mineral corrosion bonding them and then, MOST IMPORTANTLY, let them cool back down and contract. This further breaks residual bonding. Also if you don't let it cool down you are more likely to snap the bolt if its still hot.

 

[mattjeanes]

Re: Oxy acetylene?

Thanks for the ideas guys.<br />Having considered everything I used the oxy-acet with a No. 2 nozzle and carefully heated the screws until the heads were approaching red hot. After they had cooled a little I poured on the penetrating oil and once it was all cold I was able to remove all 4 screws without too much trouble (despite them having badly corroded philips drive heads). <br />Having read the reply fro G Dane,I am quite taken with the idea of TIG welding on nuts and will certainly try that next time I get a broken screw. (It's nice to know that being an expert welder is some compensation for being a fairly clueless newcomer to marine engineering!)