Dry spray paint in 20 minutes.

[mr_modify1]

Great for smaller pieces of metal.

[nova_robotics]

I hate to be that guy, but I hear this repeated on jobsites all the time. The moisture isn't coming out of the metal. Craft guys will swear up and down there's water in steel, and that a torch makes it come out. There is no water in steel.

I have a cheapo digital heat gun. You can just set the temperature on a little LCD display on the back. It's pretty handy. I've used it to cure JB Weld and paint super fast many times. I'm sure the NACE inspector would have something to say about it though.

[Beserkleyboy]

Yup...I think he was absent that day when the physics class studied humidity and condensation...and EVERY tin of paint, anywhere in the world has min & max temps specified, based on not just ambient temperature, but accepting that the substrate to be painted is at equilibrium with the ambient temp...good thing he's probably not guaranteeing his hobby work...

[sossol]

I hate to be that guy, but I hear this repeated on jobsites all the time. The moisture isn't coming out of the metal. Craft guys will swear up and down there's water in steel, and that a torch makes it come out. There is no water in steel.

I have a cheapo digital heat gun. You can just set the temperature on a little LCD display on the back. It's pretty handy. I've used it to cure JB Weld and paint super fast many times. I'm sure the NACE inspector would have something to say about it though.

This is the first I've heard the notion that water is *in* the metal. Maybe he meant on, but misspoke.

I'll admit that it's pedantic, but my pet peeve is usage of the term "drying". Except water-based paints (tempura, gauche, etc.), paint doesn't dry - it cures. In most cases heat accelerates the chemical process.

A quartz heat lamp would give the same results as far as a faster curing time after painting, but I've used this pre-heat trick. It does work. Letting parts sit on a heater that's in use anyhow works a treat.


Neil

[nova_robotics]

This is the first I've heard the notion that water is *in* the metal. Maybe he meant on, but misspoke.

It's a very common myth all across Canada and the US with tradesmen. They call it "sweating out" the steel. They will swear up and down that there's water in steel, and that a torch makes the water come out. I've gotten into a number of arguments about this.

Also extremely common:

Gasses don't weigh anything. For example, a full bottle of argon will weigh the same as an empty one.

If you put an extension on a socket it will somehow make the torque "go away," and you need to increase the setting on your torque wrench. This one really gets me because guys overtorque bolts ALL THE TIME, sometimes to the point of snapping the heads off because the torque "disappears" inside the extension for some reason. If a bolt needs 100 lbs-ft of torque, you can be guaranteed that the tradesmen will tack on at least another 25-30 lbs-ft if they're using an extension. This isn't just common it's basically a rule among the trades. Drives me nuts.

[sossol]

It's a very common myth all across Canada and the US with tradesmen. They call it "sweating out" the steel. They will swear up and down that there's water in steel, and that a torch makes the water come out. I've gotten into a number of arguments about this.

I'd always assumed that sweating the steel was rhetorical, since it resembles sweat.


Neil

[Rangi]

Are you using the term "trades" loosely.

[nova_robotics]

Are you using the term "trades" loosely.

Well it doesn't apply to the sparkies or tin bashers. It definitely applies to the iron workers, welders and millwrights though.

[mwmkravchenko]

It's a very common myth all across Canada and the US with tradesmen. They call it "sweating out" the steel. They will swear up and down that there's water in steel, and that a torch makes the water come out. I've gotten into a number of arguments about this.

Also extremely common:

Gasses don't weigh anything. For example, a full bottle of argon will weigh the same as an empty one.

If you put an extension on a socket it will somehow make the torque "go away," and you need to increase the setting on your torque wrench. This one really gets me because guys overtorque bolts ALL THE TIME, sometimes to the point of snapping the heads off because the torque "disappears" inside the extension for some reason. If a bolt needs 100 lbs-ft of torque, you can be guaranteed that the tradesmen will tack on at least another 25-30 lbs-ft if they're using an extension. This isn't just common it's basically a rule among the trades. Drives me nuts.

One of Propane's by products as it burns is water vapour. You are actually condensing the water onto the cool steel.

I hear you on the misapplication of torque wrenches as well. I have had those conversations. Go to where? Now there is a little loss in the sockets between the extension and the socket end. But not that much. A few percent at the most. Actually thinking this through that may be erroneous as well. If the rotation is blocked where in the ratchet - extension - and then socket is the torque disappearing to? Potential twist in the extension shaft. That is about it as far as I can think through.

[nova_robotics]

Now there is a little loss in the sockets between the extension and the socket end. But not that much. A few percent at the most. Actually thinking this through that may be erroneous as well. If the rotation is blocked where in the ratchet - extension - and then socket is the torque disappearing to? Potential twist in the extension shaft. That is about it as far as I can think through.

I actually worked this out one day and it's pretty interesting.

If you're using an impact then the "springiness" of the extension will limit the torque at the bolt. The extension is essentially a torsion rod and the impact is energy (or impulse?) limited. So some of that energy will go into doing work on the torsion rod instead of being transferred to the bolt. Somebody has already noticed this and turned it into a product. You can buy torque limiting extensions off the shelf.

BUT! If you look at what happens at the extension when you have a conventional torque wrench on there, the extension is sloppy at both end connections. It will bend over a few degrees in the direction of the force applied. That actually increases the effective lever arm distance between the point load (your hand) and the bolt. So if your torque wrench is set to exactly 100 lbs-ft, the fastener will experience a slightly greater torque, say 102 lbs-ft. The effect is small, only a few percent. But still. Opposite to what everyone assumes will happen.