How to rReduce the taper size on a MT drill

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nt1953

Hot Rolled

Joined

Sep 4, 2004

Location

Huntsville, Alabama

• Apr 8, 2019

• #1

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?

 

johnoder

Diamond

Joined

Jul 16, 2004

Location

Houston, TX USA

• Apr 8, 2019

• #2

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

 

Gordon B. Clarke

Banned

Joined

May 29, 2010

Location

Denmark

• Apr 8, 2019

• #3

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

 

N

number 2

Hot Rolled

Joined

Aug 13, 2009

Location

Western Australia

• Apr 8, 2019

• #4

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.

 

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BSCustoms

Cast Iron

Joined

Dec 29, 2014

Location

WA

• Apr 9, 2019

• #5

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.

 

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nt1953

Hot Rolled

Joined

Sep 4, 2004

Location

Huntsville, Alabama

• Apr 9, 2019

• #6

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?

 

gbent

Diamond

Joined

Mar 14, 2005

Location

Kansas

• Apr 9, 2019

• #7

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.

 

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akajun

Stainless

Joined

Jul 1, 2011

Location

Brusly, LA

• Apr 9, 2019

• #8

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

 

N

number 2

Hot Rolled

Joined

Aug 13, 2009

Location

Western Australia

• Apr 9, 2019

• #9

nt1953 said:

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?

Click to expand...

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.

 

Philabuster

Diamond

Joined

Jul 12, 2006

Location

Tempe, AZ

• Apr 9, 2019

• #10

nt1953 said:

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

Click to expand...

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

 

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BSCustoms

Cast Iron

Joined

Dec 29, 2014

Location

WA

• Apr 10, 2019

• #11

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

 

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LKeithR

Stainless

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Sep 1, 2011

Location

Langley, B.C.

• Apr 10, 2019

• #12

Philabuster said:

...Just buy the MT3 drills you need on ebay. TONS of them on there for cheap...

Click to expand...

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...

 

N

nt1953

Hot Rolled

Joined

Sep 4, 2004

Location

Huntsville, Alabama

• Apr 14, 2019

• #13

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.

 

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batw

Cast Iron

Joined

Aug 13, 2006

Location

N.W. Ark.

• Apr 14, 2019

• #14

nt1953 said:

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.

Click to expand...

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..