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Need some info on carbide strips


C Craft

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I am in the process of making up a couple of new file guides. So I am looking for carbide strips to put on them as a wear surface. These strips were suggested, 

https://www.mcmaster.com/#tungsten-carbide-strips/=17vrvvn

Given that I need at  least 2 of the 6" strips, and WOW, now I am looking at 2ea. 1/2" X 6" @ $39.47. So at 2ea. this is $78.94 plus shipping so I am looking at about $80.00 or more for two strips!! 

 

So in the process of trying to find a cheaper but still a good carbide strip I ran across these. 

Can anyone explain this to me??? I was looking for a cheaper source of carbide blanks and came across this page. Not sure what all the designations mean????

http://www.ebay.com/rcm/v1/STB-66L-3-16-x-3-16-x-12-C-2-Carbide-Blank-Rectangular-Strip-/?itm=191802938222&_trksid=p2045573.c100033.m1843

What does the designation STB designation mean?????

Also what does the -612L, -212L, 316L, designations mean???

What does the C-2 designation mean???

I understand they are cheaper for a reason and I am trying to understand, what I am buying, if I decide to buy them!!!!

C Craft Customs ~~~ With every custom knife I build I try to accomplish three things. I want that knife to look so good you just have to pick it up, feel so good in your hand you can't wait to try it, and once you use it, you never want to put it down ! If I capture those three factors in each knife I build, I am assured the knife will become a piece that is used and treasured by its owner! ~~~ C Craft

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Yep, that is the only designation I understood! The ones from McMaster-Carr are also tungsten carbide. That is better but what I am asking about is the STB designation and the   -612L, -212L, 316, etc. as well as the C-2 designation! 

I realize I am not comparing apples to oranges, what I want to know is how to read the oranges!! LOL :D

Like I said, "I   understand they are cheaper for a reason and I am trying to understand, what I am buying, if I decide to buy them"!!!! I am not familiar with those designations. 

I am guessing the C-2 is probably about grade but not sure! So can anyone read one of the designations and explain what the accompanying numbers and letters mean!! 

C Craft Customs ~~~ With every custom knife I build I try to accomplish three things. I want that knife to look so good you just have to pick it up, feel so good in your hand you can't wait to try it, and once you use it, you never want to put it down ! If I capture those three factors in each knife I build, I am assured the knife will become a piece that is used and treasured by its owner! ~~~ C Craft

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STB = Standard Tool Blank.  The lower the C number, the softer and tougher it is (this is relative as all carbides are pretty hard).  As far as I can tell, and I may be wrong, the other numbers are just part numbers for inventory/ordering purposes.  

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Thanks Jerrod! Exactly what I was looking for! I forgot you were a metal specialist!! 

OK picked this up on a machinist forum;            http://bbs.homeshopmachinist.net/threads/20472-C2-and-C6-carbide

C2 for cast iron, brass, aluminum, etc. Also, use C2 on steels if you have an interupted cut. C5/C6 for pretty much everything else. C2 is on the soft end of the carbide scale. It's needed for cast iron and brass because of the way the material "breaks" instead of shears. The harder carbides will chip or crack on cast iron.

This is also from that same thread,

You can get some idea by holding the carbide to an ordinary grey grinding stone such as is supplied with the $1.99 chinese grinders. The harder and more brittle the grade the easier it is to grind, generally. The "softer" carbides such as C2 or C1 are usually the toughest and most abrasion resistant and are much harder to grind. I have a handfull of C1 carbide pieces and an ordinary stone merely polishes off the dirt. C6 will take a slight grind although too slowly to be useful.

So if I am reading this correctly, the guy says; C2 or C1 are usually the toughest and most abrasion resistant and are much harder to grind

So I would think that would work for a wear surface on a file guide. What do you think Jerrod. 

 

For anyone who wants some in-depth reading on the subject of C scale on carbide hardness and selection! I found this on another machinist site! It is amazing what you can find if you understand what you are looking for!

 

These are the traditional "C" grades. 

Tungsten Carbide Grades

There is no comprehensive comparison of tungsten carbide between and among tungsten carbide suppliers. A big part of the problem is the huge number of suppliers, grades and trade names. There are at least 5,000 different grades of tungsten carbide sold under more than 1,500 different trade names by more than 1,500 different companies. 

There is no true standard. The US "C" designation, The ISO designation and other designations are not necessarily relevant. Tungsten carbide from two different manufacturers may have identical designation but vary widely in almost every imaginable way including performance. 

C grades 
The original concept was to rate tungsten carbides according to the job that they had to do. If you had a particular job you would specify a "C" grade of tungsten carbide and you could buy from anybody. This has lead to a situation where a C-7 tungsten carbide can be almost anything as long as it does C-7 style work. According to Machinery's Handbook it can range from 0 - 75% tungsten carbide, 8 to 80% titanium tungsten carbide, 0 - 10% Cobalt and 0 - 15% Nickel. The problem is that two C-7 tips from two manufacturers will almost certainly work very differently in two different applications. 

A common misconception is that there is a straight progression from C-1 to C-14 or wherever. A common view is that each higher grade has less cobalt in the binder and is therefore harder and more likely to break. Following this line of thought is belief that the higher C number is harder and better for wear resistance. This is like classifying automobiles by size from a moped to an eighteen-wheel semi. This is clear and handy but unfortunately it is not true. 

C grades classification
C-1 to C-4 are general grades for cast iron, non-ferrous and non-metallic materials
C-1 Roughing
C-2 General Purpose
C-3 Finishing
C-4 Precision
Steel and steel alloys - these grades resist pitting and deformation
C-5 Roughing
C-6 General Purpose
C-7 Finishing
C-8 Precision
Wear Surface
C-9 No shock
C-10 Light shock
C-11 Heavy shock
Impact
C-12 Light
C-13 Medium
C-14 heavy
Miscellaneous
C-15 Light cut, hot flash weld removal
C-15A Heavy cut, hot flash weld removal
C-16 Rock bits
C-17 Cold header dies
C-18 Wear at elevated temperatures and/or resistance to chemical reactions
C-19 Radioactive shielding, counter balances and kinetic applications

Every task using tungsten carbide is different. Northern sawmills know that the cutting varies with the temperature. Identical knotty pine cuts differently frozen in December than it does warm in July. Boeing machinists can often tell the difference in different lots of Aluminum that are supposedly identical. Each and every cutting job needs a different set of factors to be successful.

Edited by C Craft
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C Craft Customs ~~~ With every custom knife I build I try to accomplish three things. I want that knife to look so good you just have to pick it up, feel so good in your hand you can't wait to try it, and once you use it, you never want to put it down ! If I capture those three factors in each knife I build, I am assured the knife will become a piece that is used and treasured by its owner! ~~~ C Craft

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I don't know if you could work them into your file guide design very easily, but there are a lot of broken solid carbide drill bits in the world.  The shanks could be reused as wear surfaces. 

-Brian

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11 hours ago, C Craft said:

If I am reading this correctly, the guy says; C2 or C1 are usually the toughest and most abrasion resistant and are much harder to grind

So I would think that would work for a wear surface on a file guide. What do you think Jerrod. 

You are interpreting what he said correctly, but I am not sure what he said is true.  Pretty much by definition harder = more brittle = more wear resistant.  The foundry I work at makes high chrome white iron castings for rock crushing applications (and such).  When a part isn't going to receive heavy impact we make them harder so they don't wear out so fast.  When there is a chance for the occasional BIG rock or rebar to come through the system then we make them softer so the parts don't break/shatter.  As such, I would imagine either his C1 isn't really C1, he is just off on his test (doesn't sound like he did some rigorous scientific testing ;)), or there is something else entirely going on.  I lean towards "something else", as it is most likely a scenario laid out by the post from the second site you found.  One of the frustrating parts of older industries: standards that sounded good when they were created, but over time they change and become less clear/useful.  Almost as bad as lumber.  Why anyone would think calling a 1.5"x3.5" cross section of wood a 2x4 is any kind of acceptable is beyond me.  At least the C scale here is vague in meaning, not actually tied to a specific hardness.  

The bottom line is that the softest carbide you get is likely going to be harder and more abrasion resistant than your file, so you should be safe to use it as a file guide.  

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Thanks Jerrod! I an wanting something I can run against the 2x72 KMG clone I built and not wear! When I throw a 36 grit on the brute and let her eat I want to be able to slip right up to carbide and it not even know I was there. However I brought this subject up on another forum and someone threw this out there. 

Quote:

If you can go thicker than the 1/16 you will be much less prone to cracking. carbide can tolerate all kinds of heat but doesn't like rapid cooling...so if you are dunking your guides along with the blade when using on a belt grinder thicker is better....if you're just filing 1/16 is fine.

My file guides are made of 3/8" key stock. Harder than 3/8" square stock but not by much. I will brazing the carbide to the finished file guides! So I am planning on

1/8" THICK X 3" LENGTH X 3/8" WIDTH. So that is why I am trying to figure out which designation has the best wear surface, and can with stand a plunge in the cool bucket!! 

It seems the more I am learning the more confused I am getting!!  Image result for confused emotions 

I guess I should have been more specific with what I had in the works. 

So given the above parameters:  

1/8" THICK X 3" LENGTH X 3/8" WIDTH

 "I am trying to figure out which carbide designation has the best wear surface against a 2x72 belt grinder, and then can withstand, from heat to a plunge in the cool bucket"!! 

What would you recommend as for carbide strips???????  Image result for what are the funny face called emoji

C Craft Customs ~~~ With every custom knife I build I try to accomplish three things. I want that knife to look so good you just have to pick it up, feel so good in your hand you can't wait to try it, and once you use it, you never want to put it down ! If I capture those three factors in each knife I build, I am assured the knife will become a piece that is used and treasured by its owner! ~~~ C Craft

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They actually don't like rapid heating or cooling, so gently introduce the heat for brazing.  It is the thermal expansion and contraction that causes the cracking (like when quenching a blade).  If you get a good solid braze on a fairly beefy backing you get a couple good things going for you.  1) Thermal mass.  The braze will transfer heat from the carbide to the backing material (if there are any gaps this will reduce heat transfer) slowing the temperature build-up.  2) Even if it cracks, the brazing should hold the pieces to the backing material and the guide should still function as normal.  

Please note that I haven't actually done this, it is just the theory of what is going on.  I don't think you will be getting hot enough to be a problem anyways.  Also, if it were me, I think I would just epoxy it rather than braze, just to be on the safe side.  I'd try to use an epoxy that was good with heat transfer.  I think JB Weld claims to be good for this.  

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3 hours ago, Jerrod Miller said:

  I'd try to use an epoxy that was good with heat transfer.  I think JB Weld claims to be good for this.  

I used JBWeld to close up some pinholes in shoddy welds on the old headers on my Firebird years ago. Lasted for a number of years right at the header flange. Don't know what that tells you for this application, but it does hold up to heat well...

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Jerrod, Decker, The set (file guide) I had before this I did the JBWeld, weld.

They held up well for about 2 yrs. Till one day I am finish grinding and take them off and thoss them up on the dirty bench. I spend some time checking the freshly ground blade. Satisfied with the grind, I reached and grabbed my next blade and reached for the file guide and I suddenly realized as I am about to tighten it down one side is not lining up with the other side. Then I realize it is not that one side is not lining with the other side, one of the carbides is missing!!! Turning and looking at the other bench I see the carbide strip laying on that bench!!

Now I will say this, my JB Weld, was very thin and I think it may have been shock that caused the breakage!! I am not sure whether the shock came from the last grind to cooling or when I lightly tossed it on the other bench, or a combo of the two! I did not have pockets in the file guide itself. The reason why is IMHO without pockets in the backside of the carbide you don't have a good bond. 

It boils down to the same thing I do with my handle material. If you do not have pockets in the handle material and holes drilled thru the blade itself, you can not tie together the epoxy from the pockets in one side of the handle, thru the blade and into the other side! Like I said this my opinion, so don't throw rocks if you don't feel the same way!

Back to the subject at hand. When I said braze them to the file guide. It was not exactly what I meant!!! Sorry my fault. What I am planning on doing, is soldering them to the file guide!! I have been told that using solder will hold them as well as brazing without creating the amount of heat that is needed for brazing.

This time I put the file guide to gather and lightly ran it into the band-saw creating a line every half of inch behind where the carbide will set. Now before someone says it, I am breaking my own rule. If there was some way to pocket the backside of the carbide I would do it!! However I do think that the solder if properly done. will bite into the back of the carbide, better than the JB Weld!!

So I have decided to go with a thicker carbide to help with the heat and cooling cycle. Now I just got to figure out which carbide to use that will laugh in the face of a 36 Grit belt and say the tickles! LOL

EDIT:  I put in an email to a Carbide Processors asking for info on which carbide would be the best for what I am intending to use it for. If they do post me back I will add the info to this thread!!

Edited by C Craft

C Craft Customs ~~~ With every custom knife I build I try to accomplish three things. I want that knife to look so good you just have to pick it up, feel so good in your hand you can't wait to try it, and once you use it, you never want to put it down ! If I capture those three factors in each knife I build, I am assured the knife will become a piece that is used and treasured by its owner! ~~~ C Craft

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