Need Help!- Hardening 4140 with Butane torch?

[PEU]

Im making some straight gear hobs out of 4140 rod (3/4"), I would like to know if I can take them to cherry red for hardening with a butane torch (I can't find mapp or propane at local shops)

My plan if this is possible is:

Slowly heat to cherry red with the butane torch
Use a magnet to see if the part sticks to it
if its non magnetic keep it hot for a minute
dip in water (is salt water better?)

should I repeat for better hardening?

Please comment. Thanks!

[dertsap]

you may want to check the machinists handbook (if you have one) to see what is the best color to quench at after heating it red hot

[PEU]

Im googling as I write this, but first I need to know if the butane torch can heat the part to the temperature needed.

This is the torch:
http://articulo.mercadolibre.com.ar/...rramientas-_JM

Thanks!

[Geof]

I don't think your butane torch will get hot enough but surely if you like ribs you must have a barbeque. Get a vacuum cleaner, put the hose in the outlet and use it as a blower on the barbie; that will get hot enough just like a good old fashioned blacksmith's fire.

[diecutter]

I would keep looking for a Mapp gas outfit. I bought one at Lowes for under $30 and a 16 oz. cylinder (yellow) for under $8. This setup will quickly and easily heat a 3/4" steel bar to red and beyond. It also allows for excellent control of the heating.

I initially tried propane, and it did not even begin to get things hot enough no matter how long the heat was applied. You might want to consider tempering the parts in a toaster oven after quenching to reduce brittleness.

[PEU]

Originally Posted by diecutter I would keep looking for a Mapp gas outfit. I bought one at Lowes for under $30 and a 16 oz. cylinder (yellow) for under $8. This setup will quickly and easily heat a 3/4" steel bar to red and beyond. It also allows for excellent control of the heating. I initially tried propane, and it did not even begin to get things hot enough no matter how long the heat was applied. You might want to consider tempering the parts in a toaster oven after quenching to reduce brittleness.

You probably transmitted your toughts over 8000 miles straight to my head

I kept looking and after calling an industrial supply store they pointed me in the right direction: air conditioning shops as they use mapp for joining copper pipes.

I purchased a bottle and the torch for pesos 176 (u$d48) then to my well ventilated kitchen I went, filled the sink with water, clamped the 4140 piece (a gear hob) in a self locking plier and slowly heated it to red, also had a neodimium magnet in another self locking plier to test for magnetism. Once the magnet didn't stuck, I heated it a little more and dipped it in the water.

Used a diamond disk to sharpen the tool a little more and I just finished my first gear in ALU !! a success!!

Will start a thread about the gear themselves.

Thanks Guys!

Pablo

[djr76]

Where would you get your welding supplies? they should be full of different types gas's, get yourself an oxy/acetylene setup.

[diecutter]

I have a welding torch setup as well as three electric heat treat ovens, but find it more convenient to grab the Mapp gas torch for small one off jobs since it works so well.

The reason hvac shops use Mapp gas for soldering (besides being convenient and economical) is that they do silver soldering which requires a much higher temperature than lead solder.

peu, looking forward to your thread on gear making.