M14 Forum

Bamban

To the Poly owners,

Have you guys actually had the surface hardness tested on the receiver and op rod?

The reason I am asking, I did a crude hardness test on the parts I sent to Losok for Black Nitride coating. I used a sharp metal file to see if the file bites the metal. The FS, gas cylinder and the bolt passed, the file just slid past the metal.

I ran the file on the gas lock that I did not send, it bit it big time. I am afraid to test the receiver for I am afraid what I will find. Chicken.

The file to test hardness was not my own idea. I remember when I was working a mechanical engineer who used to work for me was a Timken applications enginner before he moved on to the semiconductor industry. We were talking about QA/QC one time, he mentioned that at the Timken factory they employed some blind people and their jobs were to sample pieces from production lots. Their only tool was a sharp metal file and they ran the file on the sample piece to make sure the file did not bite the bearing. I could not remember now what he said the equivalent minimum hardness for the file not to bite the metal.

nez

Hamstrosity

Would it be out of line to get the receiver treated as well?

Bamban

Losok did not want to do it back when I had the other parts done. He wants to research more about the metal used on the receiver and op rod. Most people posted before that the two items were good to go. I am curious though, I might go ahead and do the file test on them.

Gus Fisher

SEI has been doing their melonite process on suspect Chinese receivers for some time. If there was any doubt in my mind, off it would go to SEI for that process.

Bamban

Thanks, Gus.

lowell66dart

These look cool. Gotta find a price.

http://www.google.com/url?sa=t&rct=j...vAxG07YAWjb3UQ

Found it, $85 on Amazon.

Bamban

Good info. Are you buying a set?

Bamban

Well, I could not resist.

I ran the file on the receiver and op rod, they are NOT as hard as the Melonited parts from Losok. They are not as soft as the gas lock though, but I am putting marks on the receiver at three different places I ran the file on and the same on the op rod. I have no idea how hard the surface on these parts are, will not know till I get the hardness testing files with different hardness or have the parts tested locally. Just the fact that the receiver appears to be softer than the bolt surface, at this point I don't have any conclusion what these mean.

The Melonited parts are tough, the file just glides through the surface. Good job Losok!

The Poly file test bugged me so I file tested the 762MM receiver, 4 digit older SEI, 5 digit SAI, another 5 digit SAI, and the 4 digit SAI. The 4 digit SAI feels about the same as the Poly and the rest the file just glides over the surfaces. Just so happen my 4 digit SAI has been my number 1 gun and who knows how many barrels have been through that receiver, I am on the 2nd one, and I suppose the previous owner went through at least 3. This current barrels has about 4700 rounds and still going.

Again, this is just a home job and subjective at that, and may not mean anything.

mikebaker1129

It sounds like the Nitride finish helped the parts out that you sent !
How much does this guy charge to do this coating?

Bamban

You have to PM Losok for unit pricing. I sent him a few parts and he quoted me a package price.

MemphisMachinists

There are special files made for this. I don't know if this is what you are using. I have a set somewhere. I think they have different color handles to indicate different levels of hardness. I never had a lot of faith in them, but I will try to find them if you want and post pics or even mail them to you to try.

Seventh Fleet

I drilled out the connector lock hole to fit a GI connector in my two heel stamped Polys and I noted that it was some very hard metal.

This was before I figured out to chuck the GI connector pin into my drill and use emory paper to make the GI connector pin fit the hole in the receiver which was much easier to do. Which is what I did on my latest IDE Mich imports Poly.

7th

jmoore

Regular files usually run about 60 Rc. They quit cutting well generally somewhere in the mid to high 40 Rc range. But they will still do a little cutting before dulling in the 50s.

IIRC carbo nitrided finishes can run in the high 60s to mybe the low 70s, but the Rc scale isn't usually run up that high.

Bamban

MM,

Thank you.

I realize the subjective nature of the file test, I was bored last night. I would to borrow your file set if I could. At least I can establish the rough relative surface hardness of the Poly against the others.

Nez

Dave P

Grizzly tools: http://www.grizzly.com/products/6-Pi...ile-Set/T10277


$40