turning drill shanks - Page 3
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  1. #41
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    With all the money he is spending having drill shanks reduced the customer could probably afford to buy a bigger chuck.

  2. #42
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    Quote Originally Posted by Froneck View Post
    Thanks for the chart Matt Problem is I can't read it! When it come up when clicking on it the size is larger than the thumbnail but still can't quite read it, If I zoom the chart don't. Clicking on the chart in the linked page it becomes larger but still can't quite read in nor will it zoom, When I close the Forum page is so big I can't see the entire page but it's a clear as can be but I zoom back down to 90%, If I zoom down to 50% I can still read the page. I have quite a few 883 it does have good wear resistance. What I'm looking for is something as hard as 999. Maybe harder though I know it's very brittle and does not like interrupted cut.
    The difficulty I'm having with the chart is the same I have when googling the needed information the charts are not readable and when zooming get blurry. I found a few sites that have PDF format but don't list all the grades.
    I guess you got it then? Mostly I just right click & save something as YMMV a lot with browser renderings... BTW that's a pretty old listing I have others but they are harder to cross things HTML 'chit on the screen.

    Good luck,
    Matt

  3. #43
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    Quote Originally Posted by Illinoyance View Post
    With all the money he is spending having drill shanks reduced the customer could probably afford to buy a bigger chuck.
    My customer doesn't use them either, sells them to Hobbyist. I test then to assure they will drill on-size so that when someone complains when using a Chinese drill press that they cut way over size. Yes I do send him a few with uncut shanks for those that can chuck 5/8". These guys will pay the extra bucks to buy a drill made in the USA but use cheap import drill presses and I assume lathes. They are cutting acrylic plastic.

  4. #44
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    I still think a very solid set-up is/can be an aid to to turning hard to hold parts such as turning drill shanks..
    Perhaps useful might be a set of female centers for the tail. designed to entrap perhaps the last 1/16 or 1/8 of the original shank diameter, with that portion snubbed off after the diameter has been reduced..such centers would reduce chatter and deflection when turning. IMHO.

  5. #45
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    I'm not having problem with rigidity. Biggest problem is bad heat treat. I assume the shanks are induction annealed. Someone didn't do a good job! Some drills are actually harder on the very end of the shank. Then some cut with no problem at all but in this batch I had only one so far. Usually the shank don't start getting very hard until the last 1/4" of a 1-1/2" long cut. At the most the shanks extends 1-5/8" out of the chuck or slightly less. I get a situation where the center of the cut is a few thousandths smaller than either end. The problem was solved by using the hard Carboloy 999 but it's hard to find. From time to time I cut crazy things that sometimes I can't grind. The extremely hard carbide has served me well and I'd like to stock up on a few that will be available when needed. I often do work that required delivery yesterday! Having the tooling needed to get those jobs done keeps me on the need to call list of my customers.
    My main interest at this point is to get an available grade of Carbide that is equal to or harder than the Carboloy 999 and a supplier that has them. That way it does not add time for me to make them, I can order a few and let them sit waiting for the next crazy application!

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    Get ceramics or cbn for those crazy jobs.
    I have turned the flutes off from hss-co ”cobalt” taps with cnb when the only suitable looking piece of HSS at hand was large tap..

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    Speaking of those crazy jobs, here is a 6mm tungsten carbide endmill shank turned down to 5mm


    Old crapped out CBN insert sharpened on diamond wheel
    edit: and if you ever attempt at hard turning tungsten carbide take care of that fine dust. Not good for your machine or your lungs.

  8. #48
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    Very interesting accomplishment. Has my interest. What spindle speed will I need being my machines are the older but top of the line lathes made in the USA. I think the fastest speed I have is on a small Hendey 12", 1200RPM.
    what most here don't understand is this issue is probably a screw-up buy someone at the drill making company, the shanks are not properly annealed. I have cut hundreds of these drills in the past, only the last 1/4" of the 1-1/2" long reduced shank starts to become hard but nothing the general grade carbide couldn't handle. But who knows exactly what the problem is, in today's manufacturing the blank might come from China or some place similar and ground in the USA then marked Made in USA. I expect the next batch to be back to normal.
    I'm not looking to do production runs turning hard material, I don't do production! Mostly I want the hard carbide for crazy one of in house projects but from time to time find I have to cut something that is not withing in the "normal" range of machining so a hand full of very hard carbide is nice to have on hand when the situation comes up.

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    At the big shop we would specify a salt draw to the hardness we wanted in the shank.
    Likely now-a-days perhaps in china an eyeball color then set in ashes or the like is being used. So, the shank hardness is all over the map. Many small size bargain drills are hard all the way including the shank so are easy to break and hard on a drill chuck.

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    Quote Originally Posted by Froneck View Post
    Very interesting accomplishment. Has my interest. What spindle speed will I need being my machines are the older but top of the line lathes made in the USA. I think the fastest speed I have is on a small Hendey 12", 1200RPM.

    I'm not looking to do production runs turning hard material, I don't do production! Mostly I want the hard carbide for crazy one of in house projects but from time to time find I have to cut something that is not withing in the "normal" range of machining so a hand full of very hard carbide is nice to have on hand when the situation comes up.
    I used 1500 rpm and that should about right for cutting d=6mm tungsten carbide with CBN.
    For hard HSS you should use more speed if you go "by the book" (around 300-500fpm) but even considerably slower than that appears to work if you are doing only crazy one-offsies.

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    You might want to look into inserts by Sumitomo in grade AC503U. They list it specifically for hardened steel, I think HSS is actually called out in one of the marketing examples in the brochure. Available in a number of different configurations, including the ever-popular CN*G43*. I think the one you want is the one with the EGH chipbreaker geometry, which has a very slight positive rake to it. They also make a flat top version but it's only listed for dedicated finishing applications.

    Disclaimer: I haven't tried these myself, but every thing from them I have tried has done what the catalog says it will.


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