On Mon, 4 Feb 2019 16:59:16 -0600, Terry Coombs
wrote:

* I finally figured out that the reason the drill chuck that came with
my bench top milling machine was so wobbly is the mandrel . The JT taper
is all weird , too loose in the bottom of the hole . And since I like a
challenge (sometimes) I decided to fix it . BUT FIRST before I go
screwing up a serviceable though ****ty part , I figured I needed to
make sure I can recut that taper . So out of the corner comes the home
made taper attachment - which I used exactly once before today . After
an entire afternoon of adjusting and cutting and adjusting ... I finally
got it dialed in and made a successful taper on some scrap stock . I did
try making very light cuts on the mandrel , but ran out of length before
I got it quite right . Now I have 2 ways I can go , I can build up the
taper with the TIG welder , or I can machine a bit off the bottom of the
R8 section of the mandrel to get a little more length . I'm concerned
about warpage if I weld it , but can chuck it in the 4 jaw and dial it
in to relocate the center hole in the taper if it doesn't run true . If
I machine some off , I have about a quarter inch at the bottom of the R8
taper that's cylindrical before the taper starts . I'm not sure that's
going to give me enough length to get the taper right and I'll end up
welding anyway - but without that cylindrical section to dial it in on
the lathe . Or maybe I'll just order a new one on ebay and save this one
for another project ... last time I looked I couldn't find any , this
time there are several choices .

Frankly..unless you like farting around..order a new one. Saves you
time and likely..money.

__

"Poor widdle Wudy...mentally ill, lies constantly, doesnt know who he is, or even what gender "he" is.

No more pathetic creature has ever walked the earth. But...he is locked into a mental hospital for the safety of the public.

Which is a very good thing."

Asun rauhassa, valmistaudun sotaan.


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On 2019-02-12, Gunner Asch wrote:
On Mon, 4 Feb 2019 16:59:16 -0600, Terry Coombs
wrote:

* I finally figured out that the reason the drill chuck that came with
my bench top milling machine was so wobbly is the mandrel . The JT taper
is all weird , too loose in the bottom of the hole

[ ... ]

Frankly..unless you like farting around..order a new one. Saves you
time and likely..money.

One thing to consider -- before your (now snipped) attempt to
re-turn the taper -- you should have checked what the taper *really*
was. Note that there are both the more common Jacobs tapers (JT?), and
some for German tapers (B?? series), which are not necessarily
interchangeable with Jacobs tapers. There may even be other tapers for
chucks.

Just to be sure -- get the chuck and the arbor at the same time,
so you are sure that both are Jabobs tapers.

Enjoy,
DoN.

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On 13 Feb 2019 01:05:34 GMT, "DoN. Nichols"
wrote:

On 2019-02-12, Gunner Asch wrote:
On Mon, 4 Feb 2019 16:59:16 -0600, Terry Coombs
wrote:

* I finally figured out that the reason the drill chuck that came with
my bench top milling machine was so wobbly is the mandrel . The JT taper
is all weird , too loose in the bottom of the hole

[ ... ]

Frankly..unless you like farting around..order a new one. Saves you
time and likely..money.

One thing to consider -- before your (now snipped) attempt to
re-turn the taper -- you should have checked what the taper *really*
was. Note that there are both the more common Jacobs tapers (JT?), and
some for German tapers (B?? series), which are not necessarily
interchangeable with Jacobs tapers. There may even be other tapers for
chucks.

Just to be sure -- get the chuck and the arbor at the same time,
so you are sure that both are Jabobs tapers.

Enjoy,
DoN.

Well said! Here is a decent listing of all the various common taper
systems and their measurements

https://en.wikipedia.org/wiki/Machine_taper

One can..can with some success..fill the hole with melted candle wax
and pulling/pushing it out..measure the existing hole. It wont be
perfect..but it will come close in most cases..to narrow down the
taper family and size.

https://en.wikipedia.org/wiki/Machine_taper


Gunner
__

"Poor widdle Wudy...mentally ill, lies constantly, doesnt know who he is, or even what gender "he" is.

No more pathetic creature has ever walked the earth. But...he is locked into a mental hospital for the safety of the public.

Which is a very good thing."

Asun rauhassa, valmistaudun sotaan.


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On 2/12/2019 7:05 PM, DoN. Nichols wrote:
On 2019-02-12, Gunner Asch wrote:
On Mon, 4 Feb 2019 16:59:16 -0600, Terry Coombs
wrote:

Â* I finally figured out that the reason the drill chuck that came with
my bench top milling machine was so wobbly is the mandrel . The JT taper
is all weird , too loose in the bottom of the hole
[ ... ]

Frankly..unless you like farting around..order a new one. Saves you
time and likely..money.
One thing to consider -- before your (now snipped) attempt to
re-turn the taper -- you should have checked what the taper *really*
was. Note that there are both the more common Jacobs tapers (JT?), and
some for German tapers (B?? series), which are not necessarily
interchangeable with Jacobs tapers. There may even be other tapers for
chucks.

Just to be sure -- get the chuck and the arbor at the same time,
so you are sure that both are Jabobs tapers.

Enjoy,
DoN.

The chuck/arbor in question came with my mill . And the original chuck
and the replacement - I bought 2 from Iggy some years ago - are
identical in dimensions . Both fit a known 33JT taper . The new mandrel
came a few days ago , mounted the chuck and tried it out in the mill and
it runs true to the eye . I haven't put a dial indicator on it yet , but
it sure beats what I had . The original chuck is now on my small drill
press , and it runs true too . The original mandrel is in the box for a
future project , TBD at a later date .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !