Rotary broaching question

Are you talking about a knob going over the straight splines on a pot shaft? You do not need a rotary broach. And are you just machining brass? No big deal. Just make a broach out of any high carbon steel and arbor press the job…DONE. You could even use 1144 and heat treat it. Have used that steel MANY a times on such!
 
OR, just buy cheap overseas brass knobs with the spline hole and modify the knob. OR, just salvage the spline hole and use it in your knob…Done
 
T Bredehoft said:
Yeah, make it your self.
get some 5/16 (or what ever is needed) drill rod, with your rotary table machine 18 tiny groves in it after turning it to the proper diameter and taper, Heat it cherry red, quench in oil, soak it for 1/2 an hour in the oven at 500º and let it cool down. go to town, make enough to sell to your competitors.
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What kind of oil can you use for quenching? I wanna learn how to do heat treating for the future. I have nothing planned with O1 steel but its nice to know. Im open for projects.
 
We always used fish oil in the shop, but I imagine most oils would work.
 
You can use water or oil. Also brine. Many types of oil will work, vegetable oil is common with hobbyists. O1 and other O series steel is commonly quenched in oil, but it can be quenched in water. Same but opposite with W1, which is commonly quenched in water. It depends on your setup, and on what you are trying to achieve. Generally, water cools quicker and harsher, oil cools slower and gentler. Still air is also a coolant. If you are doing multiple parts, or even single parts, you need enough coolant to let all the pieces get below the critical temperature at the correct pace. Too much oil or water will not cause problems. Oil can and does catch on fire, have a lid handy to quench the fire. There are lots of processes and different ideas to achieve what is needed.
 
Thanks, Bob, I didn't realize you could quench O1 in water or A1 in Oil, figured it wouldn't work right. I use non-detergent engine oil, but sure, any oil should work.
 
T Bredehoft said:
Thanks, Bob, I didn't realize you could quench O1 in water or A1 in Oil, figured it wouldn't work right. I use non-detergent engine oil, but sure, any oil should work.
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If you have a poor setup where you are not quite reaching the temperature of O1 you want for the time you want, then you might want to quench it quickly in water to keep it as hard as possible. OTOH, you can quench W1 steel in oil to make it not quite as hard. It depends on the properties you are looking for. I have done just a little of this, but have read about how to modify the process to change the results. Knife makers seem to understand some of these practices. It can also go wrong. Be ready to waste some steel and heat and time to find out what happens.
 
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