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  1. #11
    Quote Originally Posted by Robin Hewitt View Post
    The thread cutters look so flimsy I would be wary of practicing with an expensive one unless I had a lot of iron and huge floods of coolant to back it up
    Robin,
    It's not in the least bit scary, I've never broken a cutter and I've cut internal threads down to M3.
    Provided you run at the recommended rpm you are fine, air + mist lube is sufficient to clear chips and lube the tool and the lovely part is that if you need to or if you are prototyping you can take multiple passes until you get where you need to be ;-)
    Regards,
    Nick
    You think that's too expensive? You're not a Model Engineer are you? :D

  2. #12
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 7 Hours Ago Has been a member for 4-5 years. Has a total post count of 964. Received thanks 162 times, giving thanks to others 5 times.
    When I first saw this thread, I wasn't sure whether it was referring to tools for screwcutting (in effect, using the CNC mill as a kind of vertical axis screwcutting lathe) which would need a spindle encoder to synchronise the spindle rotation with XYZ movement but would be appropriate for a single-point tool, or for thread milling where the cutter revolves at higher speed and only needs XYZ synchronisation, which should be achievable on any reasonable CNC mill. In the course of doing a little bit of research to try to understand the differences myself I stumbled across this, which is a very nicely written document from Sandvik that talks about these different operations and has a lot of useful information (well, if you start out ignorant, anyway...).

    Still not sure whether a single-point tool could be used for thread milling (although I don't see why not) even if it wouldn't have the "full hole-depth thread in one rotation" capability of the "proper" cutters as used for production.

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  4. #13
    Hi Neale, plenty of vids online about using single point tools for thread milling but I'm also learning. I'm trying to explore cost effective tooling for it for my hobby use and also get my head around how many tools you would need and what the limitations are. I've been surprised at the pricing of them given they are nothing more complex than any other indexable cutter but I guess there are a lot less sold.

    I've cut threads on my old manual lathe but its a slow process and if I can switch to a CnC mill then so much the better. Got to be one or the other with 75mm diameter threads, I'm not buying a tap that big!
    Last edited by Lloyd Barnes; 20-03-2017 at 06:16 PM.

  5. #14
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 4 Hours Ago Has been a member for 9-10 years. Has a total post count of 1,792. Received thanks 189 times, giving thanks to others 5 times.
    Quote Originally Posted by Neale View Post
    Still not sure whether a single-point tool could be used for thread milling (although I don't see why not) even if it wouldn't have the "full hole-depth thread in one rotation" capability of the "proper" cutters as used for production.
    They're used all the time. No different from any other milling cutter, as it's rare more than one cutting edge is in contact anyway. The main drawback (or could be classed as advantage depending on how you want to look at it), is a lower feed rate as you only have one tooth doing the work. If you have the horsepower available along with the rigidity to handle it, a multi-thread/tooth thread mill is far quicker, as you can do the whole thread height in a single circular pass.
    Off course, tapping is usually quickest, but then you're into needing enough torque to handle the tap, having the capability to handle the required synchronisation, and a tap being available in the correct size.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  6. #15
    Quote Originally Posted by m_c View Post
    If you have the horsepower available along with the rigidity to handle it, a multi-thread/tooth thread mill is far quicker,
    That way you will also need the budget to buy a cutter for each pitch you wish to cut.
    I have cutters capable of full thread depth in a single pass for frequent jobs but a single point cutter can give you a lot of flexibility for one-off jobs and you don't end up with a drawer full of "once-used" threadmills.
    You think that's too expensive? You're not a Model Engineer are you? :D

  7. #16
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 7 Hours Ago Has been a member for 4-5 years. Has a total post count of 964. Received thanks 162 times, giving thanks to others 5 times.
    Something to put on the shopping list - slightly further down than the CNC vertical mill conversion...

  8. #17
    The reasoning is I have 4 nuts to make. 75mm diameter thread, can you imagine the cost of a 75mm diameter tap!! I would use it twice and in fact need 2 (2 nuts LH thread, 2 RH).

    Single point threading seems a very sensible option as I'll be able to use it again for other large but different threads. I'd only need to buy a LH and a RH insert. That's assumes I can find one of course!
    Last edited by Lloyd Barnes; 23-03-2017 at 07:00 PM.

  9. #18
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 7 Hours Ago Has been a member for 4-5 years. Has a total post count of 964. Received thanks 162 times, giving thanks to others 5 times.
    Do you need two different inserts? Surely the only difference between cutting LH and RH threads is the movement in the Z axis?

  10. #19
    Quote Originally Posted by Neale View Post
    Do you need two different inserts? Surely the only difference between cutting LH and RH threads is the movement in the Z axis?
    That's correct, thread milling tools cut left or right handed threads.
    You think that's too expensive? You're not a Model Engineer are you? :D

  11. #20
    That was my logic too but the inserts still seem to be available in left or right handed versions which makes no sense to me.

    I need to spend some time browsing the links provided earlier in this thread at the weekend.

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