How to rReduce the taper size on a MT drill
Close
Login to Your Account
Results 1 to 14 of 14
  1. #1
    Join Date
    Sep 2004
    Country
    UNITED STATES
    State/Province
    Alabama
    Posts
    566
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    92

    Default How to rReduce the taper size on a MT drill

    I have lathes and drill press that have #3MT sockets, but some of the drills I want to use are #4MT. I have an adapter that will let me use them, but the adapter makes everything too long.

    If I had collets that would go up to 1-1/4" then I would put the bits in a collet and turn the #4MT down to a #3MT. However, all I have are 3 and 4 jawed chucks.

    Any proven techniques for turning these #4MT drills down to #3MT?

  2. #2
    Join Date
    Jul 2004
    Location
    Houston, TX USA
    Posts
    29,638
    Post Thanks / Like

    Default

    Worked for me in making them straight shank - would seem to work as good making taper smaller

    Assumes center in tanged end in good shape

    Put suitable stock in chuck

    Bore 1/8 to .200 deep same size as drill point

    Then bore under size about 1/2 deep

    Put drill point in bore

    Put center in tang

    Do what is wanted to taper

    Drill is driven by shoulder in bore - assuming one is not hogging away on taper

    And to respond to Gordon - not a hard one in the several I did this to - maybe I was lucky

  3. #3
    Join Date
    May 2010
    Country
    DENMARK
    Posts
    3,248
    Post Thanks / Like
    Likes (Given)
    4016
    Likes (Received)
    12701

    Default

    The tapers are different plus almost certainly hardened so I'm interested in hearing any advice you may get.

    Morse Taper (MT) Dimensions Chart | AutoDrill

  4. #4
    Join Date
    Aug 2009
    Country
    AUSTRALIA
    Posts
    522
    Post Thanks / Like
    Likes (Given)
    108
    Likes (Received)
    72

    Default

    All the drill shanks I have used were soft. Even some drill sleeves are soft. I think if you using a sleeve on a live center it should be hard for precision locating, but for drills soft so there’s some deformation to get a good grip.

    Someone told me they were friction welded together the main body and the shank. Even small twist drills can have soft shanks. It would depend on manufacturer.

  5. #5
    Join Date
    Dec 2014
    Country
    UNITED STATES
    State/Province
    Washington
    Posts
    201
    Post Thanks / Like
    Likes (Given)
    334
    Likes (Received)
    84

    Default

    we turn a lot of drill shanks here. some come in soft as a millennials hands some are harder than a goats head. for the hard we use cbn for the soft regular carbide.

  6. #6
    Join Date
    Sep 2004
    Country
    UNITED STATES
    State/Province
    Alabama
    Posts
    566
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    92

    Default

    I agree with BSCustoms, but the question is how do you hold the drill using only a 3 or 4 jaw chuck so that you can turn it?

    I believe John's method will work, but is there another way?

  7. #7
    Join Date
    Mar 2005
    Location
    Kansas
    Posts
    7,429
    Post Thanks / Like
    Likes (Given)
    426
    Likes (Received)
    3405

    Default

    I have several drills where a previous owner turned about 1" of the end straight so it could be held in a chuck. It can still be held with the taper.

  8. #8
    Join Date
    Jul 2011
    Location
    Brusly, LA
    Posts
    726
    Post Thanks / Like
    Likes (Given)
    20
    Likes (Received)
    291

    Default

    simply trade them to me for 3mt drills!!! PM sent

  9. Likes Rudd, jims liked this post
  10. #9
    Join Date
    Aug 2009
    Country
    AUSTRALIA
    Posts
    522
    Post Thanks / Like
    Likes (Given)
    108
    Likes (Received)
    72

    Default

    Quote Originally Posted by nt1953 View Post
    I agree with BSCustoms, but the question is how do you hold the drill using only a 3 or 4 jaw chuck so that you can turn it?

    I believe John's method will work, but is there another way?
    If your jaws are long enough they should bridge the flutes and grip the lands. With some packing and not over tight should be ok. Or use the tail stock and use packing on the jaws and grip the neck? Of the drill between the taper and the flutes where it’s parallel.

  11. #10
    Join Date
    Jul 2006
    Country
    UNITED STATES
    State/Province
    Arizona
    Posts
    4,587
    Post Thanks / Like
    Likes (Given)
    18413
    Likes (Received)
    4305

    Default

    Quote Originally Posted by nt1953 View Post
    Any proven techniques for turning these #4MT drills down to #3MT?
    Just buy the MT3 drills you need on ebay. TONS of them on there for cheap.

    You need a 1-1/4" drill bit? Here you go (not mine just found on a search):
    NEW HSS 1-1/4'' #3 Morse Taper Shank Drill Bit, 13'' OAL x 3/4'' Shank | eBay

  12. #11
    Join Date
    Dec 2014
    Country
    UNITED STATES
    State/Province
    Washington
    Posts
    201
    Post Thanks / Like
    Likes (Given)
    334
    Likes (Received)
    84

    Default

    We make a split bushing of aluminum to grab on the lands of the drill.

  13. #12
    Join Date
    Sep 2011
    Location
    Langley, B.C.
    Posts
    1,661
    Post Thanks / Like
    Likes (Given)
    335
    Likes (Received)
    970

    Default

    Quote Originally Posted by Philabuster View Post
    ...Just buy the MT3 drills you need on ebay. TONS of them on there for cheap...
    My thoughts exactly. I can't imagine wasting time turning down the shanks of a bunch of drills. You can
    go to all that trouble and if you don't get them damn near perfect they won't hold worth a damn anyway...

  14. #13
    Join Date
    Sep 2004
    Country
    UNITED STATES
    State/Province
    Alabama
    Posts
    566
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    92

    Default

    I am trying John's method and so far it appears to be working OK. I will post more when I have made the tangs on the ends of the drills and can try them out.

    I have looked for MT3 drills over 1-1/4" on eBay and while there are a few, there are not many, and those that I have found are priced too high for me.

  15. #14
    Join Date
    Aug 2006
    Location
    N.W. Ark.
    Posts
    403
    Post Thanks / Like
    Likes (Given)
    238
    Likes (Received)
    68

    Default

    Quote Originally Posted by nt1953 View Post
    I am trying John's method and so far it appears to be working OK. I will post more when I have made the tangs on the ends of the drills and can try them out.

    I have looked for MT3 drills over 1-1/4" on eBay and while there are a few, there are not many, and those that I have found are priced too high for me.
    Just got off e bay looking for motorized work head and everything is priced TOO high...

    many moons ago i made a live center with a female 60* center. what i used to do was put center in head stock, put drilling end in tail stock with modified live center and if you want to make 3 MT get indicator to read 0 length of taper then take drill you want to convert install in lathe and cut away til you get the size you want..


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •