Big s30v problem! Help!

B

bilinghm

Joined
Nov 10, 2005
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I just received my first order of s30v from Admiral. It is 1/8" X 1 1/2" and was delivered in mill finish oversized. I took it to my local machine shop for surface grinding. They put it on the magnetic chuck, turned on the flood coolant, and started doing clean-up cuts on the first side. To their horror,(and mine) the s30 v pulled off the chuck due to warpage. I warped enough that it will not stick back down on the chuck. Has this ever happened to anyone else!? Am I screwed? Suggestions?

Bill in Atlanta
 
Steel from the mill will often have a bend to it - and that can also happen with PG stock. The S30V in it's annealed state should be easy to put back pretty close to true. I'm not sure how long the piece is, but shortening it to something close to finished length might help it stick better.

Mete would be the guy to ask, but I suspect a stress relief cycle and cooling between Aluminum plates might leave it nicely flat also.

Let us know how it goes whatever you try.

Rob!
 
I have spoken with Crucible about the situation and they are going to have a company metalurgist give me a call. I asked about simply straightening it by bending and they seemed to recoil from the suggestion. I will post their suggested solution/remedy. The bars I received from Admiral were 72" long and i saw cut them to 18" pieces to fit on the magnetic chuck on the grinder. The shorter lengths were fairly straight, but a slight curve was detectable. After the first clean up passes, the 18" bar when placed on a flat was 1/8" off the table in the center.
 
Follow Crucible's suggestions ,but I would think it would have to be stress relieved ~1200 F and straightened in plates while still hot.
 
bilinghm said:
To their horror,(and mine) the s30 v pulled off the chuck due to warpage. I warped enough that it will not stick back down on the chuck. Has this ever happened to anyone else!? Am I screwed? Suggestions?
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Hi Bill, It sounds like you should maybe find someone with a little experience to do your grinding ;) Just kidding. Anyway, that does not make any sense. At 1/8" the magnet should suck that piece right down. It almost sounds like they did the first side with a chip or burr either on the magnet or workpiece (in the center)> That created a situation where there was a "hump" that was ground down to "clean-up". The piece was probably flipped and ground to clean-up on the other side. Now you probably have an hourglass rather than 2 flat & parallel sides. If this isn't for folders (where you need a particular size) just re-grind. This time though put shim under the gap before turning the magnet on. It might take a couple of flips, back & forth before you get it back to flat & parallel. BTW, did you know that you can grind a bar with parallel sides but still not have it flat :confused: :D Have you taken a micrometer and gone down the length to make sure you don't have the scenario I just described ( parallel but not flat ? ) If that is the case, & the steel is in the annealed state, and your blades aren't going to be 18" long, the bow, or warp will be less for 1/2 the length (as in a 9" blade). You might be able to just straighten by hand or in a vise.
 
Unless you're making 18" blades, cutting your blade blanks out then surface grinding them will cut down on warping and less grinding. When I surface grind, I take a little off each side at a time, lot a flipping but they come out flat and straight.
 
I'm pretty sure that the "won't stick to the chuck" comment was an exaggeration. The machine shop is a very modern CNC outfit with water jet machines, and a big hydraulic surface grinder. They were pretty surprised by the behavior of my steel. They said that they grind similar jobs everyday, but had never experienced warping like this before. They suspect stress caused by shearing the bar from a larger sheet. They thought stress relieving might be the best fix (1 hour@1000 degrees).

Assuming that they did everything right: no debris on the chuck or stock, sufficient coolant flow, etc. what went wrong? Has this happened to any of you?
 
It's annealed, why can't you straighten it? I guess I don't understand. I spend about half of every day straightening annealed steel.
 
Larrin said:
It's annealed, why can't you straighten it? I guess I don't understand. I spend about half of every day straightening annealed steel.
Click to expand...

My thoughts exactly, annealed steel is very easy to straighten. I have had high carbon steel warp on the surface grinder and I just staighten and go.
 
Straightening makes semse to me as well. I will share the advice from Crucible's metalurgist as soon as he calls.
 
Interesting. I my concern was a little premature. I just spoke to the metalurgist at Crucible. He said that the warp was fixable, flip it and grind the othere surface to final size. If it still is warped, straighten it over your knee! He did say that this material should never be sheared onless it is preheated, at Crucible they never shear it, only saw cut it. He said that cold shearing can occasionally cause the annealed sheet to crack and even fracture into a pile of pieces. He said that they have discussed the inadvisability of shearing s30v numerous times with retailers, but the practice remains. The 1.5" strip was sheared from a full sheet at Admiral. This caused stresses that probably contributed to the unusual degree of warping.

Thanks for all your good advice! You guys were right on target,
 
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