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Thread: Carbide reamers..........

  1. #16
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    Quote Originally Posted by Butch Lambert View Post
    My only carbide reamer experience was one that I borrowed from a high production barrel chambering shop. They only use CNC. I wasn't even aware that it was a carbide reamer until I mentioned to my friend that it cut a beautiful chamber. He said it was a carbide reamer. I usually chamber at around 350rpm. I do drill and taper bore before chambering. Throat and leade looked great and had very fluff.
    "very fluff"?

    GsT

  2. #17
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    Quote Originally Posted by GeneT View Post
    "very fluff"?

    GsT


    "very little"

  3. #18
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    For all practical purposes we can ignore the finish on the body, shoulder, neck and freebore. They are background noise in this discussion. Having used carbide reamers for 5 years now I can tell you for certain the leade angle cut with carbide is noticeably smoother. Even as they dull they cut a pretty good finish. The throat is one thing I pay very careful attention to. In my chambering routine I inspect every reamer as it's used. With experience you will see the leading edge of the neck and shoulder start to break down. Scalloping on the face of the flute means the edge has also broken down. The same thing is happening to the most important surface on the reamer. The leade. You can cut a lot of chambers with a compromised reamer but you can't cut good chambers/throats. As far as sharpening them. I have had mixed results. I should be able to get detailed pics of cutting edges on new HSS and carbide. If I can I'll post them.

  4. #19
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    Quote Originally Posted by Dave Tooley View Post
    For all practical purposes we can ignore the finish on the body, shoulder, neck and freebore. They are background noise in this discussion. Having used carbide reamers for 5 years now I can tell you for certain the leade angle cut with carbide is noticeably smoother. Even as they dull they cut a pretty good finish. The throat is one thing I pay very careful attention to. In my chambering routine I inspect every reamer as it's used. With experience you will see the leading edge of the neck and shoulder start to break down. Scalloping on the face of the flute means the edge has also broken down. The same thing is happening to the most important surface on the reamer. The leade. You can cut a lot of chambers with a compromised reamer but you can't cut good chambers/throats. As far as sharpening them. I have had mixed results. I should be able to get detailed pics of cutting edges on new HSS and carbide. If I can I'll post them.
    Dave, I have used Marcus at http://mcctooling.com/contact.html to make and or sharpen tools of all kind for about 35 years. He has some really nice CNC grinders as well as the manual tool and cutter grinders. I also use him for wire EDM work.. I will take a reamer for him to look at next week.

  5. #20
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    Mar 2012
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    With insert tooling, carbide usually has a duller edge prep for durability. But with uncoated tooling like a chamber reamer the edge prep is very sharp, like hss. Theres no doubt it leaves a better finish in a chamber, but I do still prefer hss reamers. Handled correctly they last a long time and produce a finish very close to carbide. I do not like coolant for reamers, I think cutting oil will help your tool life. I also chamber about 300 rpm hss or carbide.

  6. #21
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    Remember, "carbide"is a powdered metallurgy. Titaniumcarbide, talladium carbide, etc. compound.

    The most common grade is C5 (VC5,VC!25, etc).



    .

  7. #22
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    HSS reamer. Note the ridges on the top line. They are an indicator of the height variation of the cutting edge.Click image for larger version. 

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  8. #23
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    Carbide reamer You decide which one will cut the smoothest chamber. I'll post another pic of a 308 carbide reamer that has done over 300 chambers.
    Click image for larger version. 

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  9. #24
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    Well done Dave

    Also of note IMO is that, to those who are good enough to stone their reamers to remove the striations and clean the edge, one can equally effectively stone a carbide reamer to an even higher gloss. I routinely renew edges on carbide tooling by hand. Once I experienced truly sharp carbide, carbide which cuts exactly like HSS I've never looked back. I "sharpen" it just as effectively as HSS and it does everything HSS does, better.

    I don't know "what" this modern "carbide tooling" is ..... I'm imagining it as a product of sintering technology..... but whatever it is, it's come of age!

    YMMV

  10. #25
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    Here's a pic of a 308 carbide reamer that has done over 300 chambers. All the edges are breaking down. You can see the end of the neck and then the leade. I've been keeping an eye on the finish of the leade for a while now. It is cutting like some new HSS reamers I've had. I'll retire it after the next contract is completed. I have had some HSS reamers look like this after 15 chambers. I use oil and run most at 300 RPM's. Some large calibers I run at 250 RPM's
    Click image for larger version. 

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  11. #26
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    Another aside with carbide..... I spent this afternoon threading a half dozen barrels for suppression (well, disassembling/jigging and fiddle-farting around cuz I hadda' do two between centers etc...... SUPPRESSED stuff, not nice long fatty barrels) and was reminded of another thing.

    Threading.


    I don't use a flowing lube/coolant system.....


    Useta'could I'd get the shiniest threads with HSS... TOOK all friggin' day to not burn the end off but man, sliced the steel off like cheese. Then the liddle triangular standups came out, the ones with all flats so scrubbing them on a diamond stone is easy, and MAN!!! Friggin' ROCKIN'!!!! Laydowns, multi's etc all cut real good then get dull. And so do the standups. But when the edge rolls off a standup it's dead easy to flatscrub it back in a pinch... most times I DON'T, but I have a dozen times or more in the past .... I've got a whole drawer full for when I'm broke I can resharpen em right now I spin 'em thrice and grab another but I CAN re-sharp them.

  12. #27
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    Feb 2003
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    Kev! I haven’t seen you in a while. I hope all is well.

    Keep in mind that carbide needs high speeds and feeds. Even with the sharp edge that’s typically ground on the chambering reamers commonly available (unlike a carbide porting tool used in industrial production), you’ll still have to feed it at a higher rate and keep your surface speed high. If you dwell too long with carbide, you can work-harden the surface in the barrel which can contribute to premature wear. If your using a rimfire reamer, using the higher surface speed shouldn’t be a problem unlike with the compromised speeds you’d have to use with a bottle neck cartridge, where the optimum surface speed on the body would only be half of what it should be at the throat and neck diameter. If you ran the optimum surface speed for the throat on the bottle neck cartridge, you’ll potentially be too high on the larger diameter and would have complications (breaking down the edges on the body and chatter) without a really good rigid setup.

    You also need to truly flood cool the reamer…in that pumping coolant down the barrel at a reasonable pressure and volume from the muzzle to the breech, so there’s no intermittent cooling on the edges. Insufficient coolant flow will create uneven heat zones at the microscopic level and break down the sharp edge quickly. With carbide (except certain coated grades), you should either have high flood coolant flow, or nothing at all. Furthermore, water-soluble coolant with a high mineral oil content would be better than cutting oil because it will dissipate the heat more efficiently, although that might not be practical with your manual lathe.

    Greg Walley
    Abraxas LLC

  13. #28
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    Hi Greg.... Abraxas??

  14. #29
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    Quote Originally Posted by alinwa View Post
    Well done Dave

    Also of note IMO is that, to those who are good enough to stone their reamers to remove the striations and clean the edge, one can equally effectively stone a carbide reamer to an even higher gloss. I routinely renew edges on carbide tooling by hand. Once I experienced truly sharp carbide, carbide which cuts exactly like HSS I've never looked back. I "sharpen" it just as effectively as HSS and it does everything HSS does, better.

    I don't know "what" this modern "carbide tooling" is ..... I'm imagining it as a product of sintering technology..... but whatever it is, it's come of age!

    YMMV
    The 'grain ' structure in carbide is many times larger than the grain in HSS.

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