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IndustryArena Forum > Tools / Tooling Technology > Metal Working Tooling > Best way to waste a section of an end mill?
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  1. #1
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    Best way to waste a section of an end mill?

    Chinese 3 Flute endmill 100mm 40mm doc. Carbide. Really nice. I use them new for finishing and when new they shave alloy hairs into the air leaving a finish that makes a DIY proud.

    Limited to DOC of 40mm or in the case of the smaller end mills I would like to waste a small section to avoid rubbing above the flutes.

    How much? 0.5mm off the diameter for 15mm or so. I've thought about putting a grinder in the vice on my lathe to do it? But is there a proper or better way?

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  2. #2
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    Re: Best way to waste a section of an end mill?

    Quote Originally Posted by boydage View Post
    Chinese 3 Flute endmill 100mm 40mm doc. Carbide. Really nice. I use them new for finishing and when new they shave alloy hairs into the air leaving a finish that makes a DIY proud.

    Limited to DOC of 40mm or in the case of the smaller end mills I would like to waste a small section to avoid rubbing above the flutes.

    How much? 0.5mm off the diameter for 15mm or so. I've thought about putting a grinder in the vice on my lathe to do it? But is there a proper or better way?

    Sent from my SM-N970F using Tapatalk
    If you only have the lathe then that's what you would have to use, normally it is done on a tool and cutter grinder, which is very simple and quick to do, there are many types of grinding machines that could be used also, you want to use a diamond wheel to grind the relief of the end mill

    How much relief, will depend on the depth of cut you are using, so only grind enough to clear the depth of cut.

    Cover the bed and slide ways, of the lathe when grinding.

    These snips are just 2 machines that can grind anything you want on a cutter.
    Mactec54

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    Re: Best way to waste a section of an end mill?

    Thanks for that. Such a good endmill for $30. Doc is max 60mm the mill is good for 40mm. Interesting I've told the supplier if they put this grind into their endmills they will sell heaps but no interest.

    I will start with my grinder in my lathe with a diamond wheel I will source..... Just bought a horizontal bandsaw due to arrive in the next few weeks. We need to space out our purchases to keep peace. ha

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  4. #4

    Re: Best way to waste a section of an end mill?

    a bench grinder and a silicon carbide wheel is all you need to grind some relief

  5. #5
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    Re: Best way to waste a section of an end mill?

    Quote Originally Posted by metalmayhem View Post
    a bench grinder and a silicon carbide wheel is all you need to grind some relief
    Yes, that is how a hack would do it.
    Mactec54

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    Re: Best way to waste a section of an end mill?

    What if I mount the bench grinder on the saddle of my lathe? Now we talking.

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  7. #7

    Re: Best way to waste a section of an end mill?

    Quote Originally Posted by mactec54 View Post
    Yes, that is how a hack would do it.
    thats the way a machinist does it . It works fine for aerospace but sorry I forgot how much more advanced the hobby world is

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    Re: Best way to waste a section of an end mill?

    Quote Originally Posted by metalmayhem View Post
    thats the way a machinist does it . It works fine for aerospace but sorry I forgot how much more advanced the hobby world is
    No that's the way a hack would do it, doing it like this in any setting, can damage a high-speed spindle, as there is no way you can grind a relief round and true to the shank and cutter, by hand on a bench grinder
    Mactec54

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    Re: Best way to waste a section of an end mill?

    Quote Originally Posted by boydage View Post
    What if I mount the bench grinder on the saddle of my lathe? Now we talking.

    Sent from my SM-N970F using Tapatalk
    Yes, some do it like that, but you need the grinding wheel to be on center.
    Mactec54

  10. #10

    Re: Best way to waste a section of an end mill?

    Quote Originally Posted by mactec54 View Post
    No that's the way a hack would do it, doing it like this in any setting, can damage a high-speed spindle, as there is no way you can grind a relief round and true to the shank and cutter, by hand on a bench grinder
    That would be to say that a weldon which is far more ground on one side would absolutely destroy a spindle . Never seen it , nor have I seen a hand ground relief destroy a spindle . I've worked in numerous shops and only one had an end mill grinder which never got used , every other one had pedestal grinders with silicone carbide wheels

    We are talking about a disposable chinese end mill and I'm sure the mill it's going on will handle it

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    Re: Best way to waste a section of an end mill?

    With this mind. Only grinding DOC required and maybe 1mm or so. How much would I take off the diameter? 0.5mm? I am machining 6061. I was also wondering if I should go the other way and remove the top few mm off the flutes or stop exactly where they end. Thoughts?

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  12. #12

    Re: Best way to waste a section of an end mill?

    minimal needs to come off the diameter , it's only clearance . You'll want to take a bit off the flute and you'll want to back taper the top of the flute as well , otherwise your grind may cause lines whether you grind by hand or machine

  13. #13
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    Re: Best way to waste a section of an end mill?

    Quote Originally Posted by metalmayhem View Post
    That would be to say that a weldon which is far more ground on one side would absolutely destroy a spindle . Never seen it , nor have I seen a hand ground relief destroy a spindle . I've worked in numerous shops and only one had an end mill grinder which never got used , every other one had pedestal grinders with silicone carbide wheels

    We are talking about a disposable chinese end mill and I'm sure the mill it's going on will handle it
    Using a Weldon type shank tool is in balance, unless you have changed the clamping screw in the tool holder it came with. in the good shops all the tools are loaded balanced and stored in a tool crib, the machinist is not allowed to alter the tool in any way. that is why the use shrink fit tool holders and compression tool holders, to keep balancing to a minimum.

    If you choose the quality Chinese end mills / cutter. they are just as good if not better than some of the brand name cutters you pay 3 times the price for.

    I have never worked in a shop that did not have a precision Grinder of some sort. even some hobby shops have a surface grinder, or a single lip cutter grinder.
    Mactec54

  14. #14

    Re: Best way to waste a section of an end mill?

    Quote Originally Posted by mactec54 View Post
    in the good shops all the tools are loaded balanced and stored in a tool crib, the machinist is not allowed to alter the tool in any way.
    .
    Honestly that would be what I'd consider a hack shack . When a guy is making $100k+ parts the last thing he needs is someone else's error ruining a job because he didn't set the tool properly . Chinese tools can be ok but no where near better than the quality brands . Your not going to find many big shop throwing chinese tools into their machines

    Steel and tungsten carbide have a large difference in weight . The weight of the set screw vs the weight of carbide that is removed from a weldon isn't going to balance out 100% , even on a so called balance side lock . So , if that is acceptable then grinding a few though off an end mill with a pedestal grinder should not destroy a spindle

  15. #15
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    Re: Best way to waste a section of an end mill?

    You only need to take a very small amount off the diameter. The shank just needs to not rub.

    Not DOC off the diameter.

    I have always wondered why relieved shanks are not standard for all end mills, or at least long end mills
    7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)

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    Re: Best way to waste a section of an end mill?

    Cool thanks. Meaning DOC I was only going to go length down the endmill, as much as DOC I need to machine. Interesting I tried it out with an angle grinder installed on my lathe on a roughing bit that I did the same job too by hand on a linisher.

    What it proved is no matter how careful you are you just can't get it right by hand. The endmill rotating making chirp chirp chirp sounds as I ground it round again if you know what I mean.

    But with a cutting disc I got a great result.

    Hey so interested why to cover my lathe when grinding? I did btw. Sparks go rusty and burn into the lathe bed?

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  17. #17

    Re: Best way to waste a section of an end mill?

    Quote Originally Posted by boydage View Post
    Cool
    Hey so interested why to cover my lathe when grinding? I did btw. Sparks go rusty and burn into the lathe bed?
    carbide dust and the dust from grinding wheels are very abrasive which isn't good for your slides or any moving parts

  18. #18

    Re: Best way to waste a section of an end mill?

    Quote Originally Posted by pippin88 View Post

    I have always wondered why relieved shanks are not standard for all end mills, or at least long end mills
    For the most part it's about having the right length cutter for the job . To use mactech's terms , grinding a relief is a hack , but is often enough a necessary hack . Too much unnecessary stick out from the holder only increases the risk of chatter

  19. #19
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    Re: Best way to waste a section of an end mill?

    This is a good subject. Because often I manufacture parts with a height of 50 - 60mm. My home built machine, well, I haven't used an endmill larger than 14mm 2 flute except for my facing bit. It's not rigid enough for anything larger.

    So I either flip the part, not ideal it's an ok machine but not perfect. I would get a very small lip in the middle. Only a thou of an inch but still there.

    My question then is, say 55mm DOC to finish a wall, that's quite an endmill yes? What would you use?

    I actually wonder if I would get away with something like an 18mm 3 flute, new, sharp, taking off 0.2mm 55mm deep in a finish run. You have made me think about this. Thanks. Further thoughts?

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  20. #20
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    Re: Best way to waste a section of an end mill?

    Quote Originally Posted by metalmayhem View Post
    Honestly that would be what I'd consider a hack shack . When a guy is making $100k+ parts the last thing he needs is someone else's error ruining a job because he didn't set the tool properly . Chinese tools can be ok but no where near better than the quality brands . Your not going to find many big shop throwing chinese tools into their machines
    Honestly, I thought you were smarter than this, the tool from the crib is not set in any way, how could it be, the only thing with the tool being selected, it is balanced and ready to be put in any machine, whoever is setting up the machine is responsible for the tool offsets and tool pocket did you do a time served apprenticeship, or self-taught. (wedge)

    Quote Originally Posted by metalmayhem View Post
    Steel and tungsten carbide have a large difference in weight . The weight of the set screw vs the weight of carbide that is removed from a weldon isn't going to balance out 100% , even on a so called balance side lock . So , if that is acceptable then grinding a few though off an end mill with a pedestal grinder should not destroy a spindle

    When have you ever seen a Weldon type holder used on a 20,000 plus RPM spindle 6,000 to 10,000 spindles is about the limit for someone to use an unbalanced side lock tool holder, if you have ever used a balanced tool, you would know right away at the difference it makes to the finished parts.

    If you look at the likes of Datron they balance the cutter itself, you will find that any quality Weldon cutters are also in balance, by design. the ground flat on the shank does not put the cutter out of balance, the only part that will be out of balance is some of the cheap side lock tool holders.
    Mactec54

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