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Thread: Need mini boring bar recommendations

  1. #1
    Join Date
    Jun 2018
    Posts
    2

    Default Need mini boring bar recommendations

    Hello,
    I am trying to find a reasonably priced boring bar for use on a Chinese mini lathe. I need something that can fit in a <0.25" hole and go about 3/4" deep. This isn't something I'll use much so looking for middle of the road quality. In other words, maybe something like Shars quality and price?
    Thanks, Scot

  2. #2
    Join Date
    Dec 2015
    Location
    Chilliwack, BC, Canada
    Posts
    4,066

    Default

    Make up a holder for a two flute 1/4" end mill. They actually do quite well for home shop boring use. You can't load them up like a solid bar because of the reduced strength due to the flutes. But we're not in that much of a rush.... usually

    If you get the usual Weldon shank style with the 3/8 body the 1/4" cutter might or might not get you a full 3/4" into the bore. But if you can find a double ended 1/4" end mill that has 1/4" shank in the middle (pretty typical for double ended cutters) you can reach in further and do so more cleanly.

    Now the trick is that you will need to cock the end mill SLIGHTLY tip to you so the side flutes don't rub. But it only takes a hair of an angle to do that. And if you're working to a blind ended hole you may also want to grind away the opposite tooth that will try to dig in when it reaches the bottom of the hole.

    I've used a couple of small size old end mills in this manner for something like a dozen or more jobs over the last 6 years and I still have both of them intact. One is 1/4" and the other is 3/16. I limit the 3/16" to something like a .007 to .01 cut and feed slowly to where it just makes clean chips instead of dust. But it's handling that like a champ. The 1/4" cutter has no issue at all with up around a .015 to .02 cut in steel using hand feeding to get the same sort of light chips being formed. And they are cheap and easily replaced.

  3. #3
    Join Date
    Jul 2005
    Location
    Chester, NH
    Posts
    5,395

    Default

    What do you want to do with it? Could you use a reamer instead?

    Solid carbide boring bars in that size range are the bees-knees, IMO. They are much more rigid than steel bars but they are also pricier. If they are out of the budget, I'd just get some blank HSS and grind your own. It wouldn't take that long at a bench grinder to make one up.

    Example solid carbide boring bar: https://www.mcmaster.com/3301a44

  4. #4
    Join Date
    Dec 2008
    Location
    Kendal, On
    Posts
    1,204

    Default

    I've got a couple homemade solid carbide (and HSS) bars for boring under 0.25".

    Nothing cheaper than taking a broken or dull EM or reamer shank and making a boring bar from it.

  5. #5
    Join Date
    May 2015
    Location
    Somerset UK
    Posts
    1,619

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    Single Iscar and Sandvik mini carbide bars come up on ebay for about 15 each in the UK, I was lucky a couple of years ago, when I picked up 10 Iscar Picco's and the holder for about 30.

  6. #6
    Join Date
    Jan 2017
    Posts
    100

    Default

    Quote Originally Posted by Dan Dubeau View Post
    Nothing cheaper than taking a broken or dull EM or reamer shank and making a boring bar from it.
    +1. I've got an insert set that goes pretty small, but not that small. I'd grab a broke solid carbide endmill (or new for about $10) and go to work. If you are set on a boring bar proper, maritool as a solid carbide 0.200" min bore, up to 1.3" depth for $24.

  7. #7
    Join Date
    Jul 2007
    Location
    Earlville PA
    Posts
    305

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    Micro 100/s are nice.

    http://www.micro100.com/

    Stu

  8. #8
    Join Date
    Jan 2003
    Location
    Deep in the Heart of Texas!
    Posts
    7,511

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    Shars quality and price? Go with McMaster-Carr. They're 1/6 the price and solid carbide. Plus, you'll get it in 1-3 days. The choice is a no-brainer.

  9. #9
    Join Date
    Jun 2018
    Posts
    2

    Default

    Thanks for all the replies! That one from McMaster is perfect...priced right for my budget and should work great. The DIY route is good, but I’m always short on free time so ready made is easier for me. Good ideas for when I can’t wait and need it now though.

  10. #10
    Join Date
    Dec 2016
    Location
    Helsinki, Finland, Europe
    Posts
    2,352

    Default

    Add Horn solid carbide boring bars to list. Made holder for them and love those.

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