Rust in valves.
I make my bodies in brass, but with all of my valves so far I’ve used mild steel for the stems, being that they’re prototypes. I’ve always intended to use stainless on production items. I’ve had a very mild amount of rust appear on the MS items even within a day. And that’s having given the stems a good coat of silicone grease before assembly.
Then it occured to me that Blod’s stems look like they’re made from MS, but I figured “surely not…” Then I rememembered that the bodies of the Blod valve are MS, and logic dictated that the stems probably are too. So what’s the deal with that? Is rust not an issue? Because I’d love to kick SS into touch if possible. Has anyone had a Blod apart after some period of use? If so, how did it look?
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With a 16mm bar I take 0.5mm deep cuts. So 1mm reduction on diameter. Speed for turning 304 would in the mid 700rpm. Even at a 1000rpm I can machine a complete stem without cooling or resharpening.
Things get different with aisi 316 though thats much thoughfer.
Regards,
Marc
Mild steel is to soft for stems imho, you could use a steel bolt in 12,9 quality. That’s pretty though and offers plenty rust resistence!
regards,
Marc
I don’t know why MS would be too soft, the only issue I’ve had with it is the fine surface of rust it develops very quickly. I even used alum in my earliest prototypes and that held up pretty well too, though it was for very short-term testing only.
The deepest I go with MS is 1mm. I guess that would be fine for 303 too, but with much lower speeds, maybe around 150/200rpm on 14mm OD and lower (with plenty of coolant)?
aisi 304 is pretty easy to machine with hss. Just don’t do overboard with your lathe speed. SS needs pretty hefty cuts as to let the swarf and chips flow heat from your work.
Mild steel is to soft for stems imho, you could use a steel bolt in 12,9 quality. That’s pretty though and offers plenty rust resistence!
regards,
Marc
“Free-cutting” meaning it doesn’t need coolant and doesn’t destroy tools? SS with the ease of MS and none of the drawbacks of SS? And rust-proof too. Sounds good if that’s the case. Cheers Blod! 😀
Hey dude.
The stems n tophats are (were) 303 free cutting stainless and the body’s are EN1A BDMS but i chemically black them.
Ive had bodys outside for days on end, even in the rain and although the blacking isn’t a total rust proof, it certainly slows it down.
If ive still got it in August, i have about a mtr of the EN metal i used left.
You can have it as it dont look like i need it any more.
Later cray boy.
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700rpm? Jesus! 😯 I get smoke off MS at 300rpm when I take the coolant flow off the piece of work. I don’t think my carbide tips would last very long at that kind of speed.