What about using an engine valve as milling cutter?

Suzuki4evr

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Not sure if this is the right section to post this,but here goes.

What do you think,can an engine valve be used to grind into some kind of milling cutter like a spline cutter for instance and if so,is it hard enough or should you still harden it? I am refuring to any engine valve but I am more thinking of truck engine valves wich are more robust and have thicker valve stems.

What do you think? Food for thought.

Michael
 

Mini Cooper S

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I wouldn't think it would be worth the effort, maybe in a pinch / emergency type situation. I also don't think that the stem would be up to the job, most are case hardened but bend easily. Another caution some valve stems (exhaust valves) are sodium filled to aid heat transfer, wouldn't be good to bust one of them open.

Just my $.02

Richard
 

lordbeezer

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Around 76-80 working at a ford dealership couple of us would pull the exhaust valves out of old 361,391 truck motors. Break them in half in vise with a hammer. Fill a glass jar with water. Dump the sodium in. Screw lid on then run like hell. Pretty Big Bang. Made a damn mess. Got in trouble couple times. Stupid but was fun.
 

Provincial

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A fellow I knew was in the government surplus business. After WWII, he bought worn-out engines from bombers and fighters that were not suitable for rebuild. He would make a pile of junk tires and put an engine on it, the light them on fire. This would melt the aluminum away from the steel in the engines so he could sell it for cleaner scrap. He said that they always stayed a long way from these fires because the sodium-cooled valves would overheat and explode. Apparently, they stayed cool enough from transferring heat to the valve seats, valve guides, and engine oil when running, but with the fire hot enough to melt aluminum, they would overheat and built up enough pressure to burst the (fairly thick) walls of the valve stem.
 

Suzuki4evr

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Ok I got my answer.....NOOOOOOOOOO!!!!!

I am actually a qualified automotive engineer by trade,but do machining from home after my bike accident in 09', but never thought of the composition of engine valves. Thank you all for the input. At least now I know.
 

kopcicle

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I am actually a qualified automotive engineer by trade,but
...metallurgical sciences are a different kind of animal. Far be it from me to contest anecdotal experience but I resort to science for the win.

As usual there is a TLDR at the end whenever I produce a wall of text.


The short version of those eight pages is intake vale steels possibly and exhaust steels not so much .
Exhaust steels are better suited to corrosion and high temperature resistance.
Intake valve steels differ in their carbon, nickel and chromium content. (yes , I know "other alloying elements")

So we're not going to be burning through our work so exhaust valves can be largely ignored.
We're not going to make a cutting tool out of any stainless related material because it won't hold and edge or take heat treat to any extent.
That leaves the higher carbon content intake valves.
This leads to time at temperature (heat soak times) and a decision to temper back or leave them as is.
It would then follow that most of the rough machining of the valve should be done in an annealed state.

Next we have the irregular wear on the valve stem. For accuracy a new valve should be used.

Finally we have the question, why? Here follows my anecdotal tale. I haven't always had access to proper tooling because of remote locations, lead times, or simply money. Instead I made what I could from what I had,
The first instance was re-cutting the pocket for a valve seat in an aluminum head after welding.
The next case was an involute gear cutter with the teeth form cut to 24DP 14 1/2PA the material was 12L14.
Later a multi tooth abortion of a fly cutter for surfacing small bits of 6061. This lasted only until the fly cutter arrived.
The list goes on but I think you get the idea. The important point is to experiment without reinventing the carbon atom. Simply put , all it took was a set of hardness testing files to determine if my heat soak and temper process was effective or if I was wasting my time. You have to have some indicator of hardness other than "did it hold an edge in the cut". I lost an identifiable amount of time educating myself in metallurgical properties as a result.

TLDR version
Exhaust valve, no.
Stainless valve, no.
Used valve, not the best idea.
Intake valves with identifiable carbon content.
Understand heat treat processes.
Have some way to test the heat treat.
Don't let anyone tell you it can't be done.
YMMV
 
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