On Sat, 01 Dec 2018 19:56:13 -0700, Bob La Londe wrote:
On 11/29/2018 2:18 PM, Bob La Londe wrote:
On 11/29/2018 1:24 PM, Bob La Londe wrote: I bought a commercial
tension compression tapper for use on my
non-C-axis CNC mills.Â* [...] lately I've found myself
tapping three different sizes commonly.Â*[...]
My solution.Â* Make a couple more TC tappers.Â* The first two blanks I
destroyed on the lathe by trying to shade tree it.Â*Â* Nothing is
really critical except that the bore for the tap holding collet
chuck and the shaft of the TC tapper are concentric.Â* Well on the
third one I had some success, but I failed to get the proper
alignment turning concentric. [...]
Mine is in front:
http://bbs.homeshopmachinist.net/attachment.php?
attachmentid=4017&d=1543523014

Anyway, I thought about my steps and processes and I know how to
make the next one better.Â* Now I am thinking about materials.Â* The
first ones were all made out of 304 stainless except the straight
shank collet chuck which [...]

I was busy cutting molds and inserts all day today for customers, so I
didn't have time to make another TC tapper. I did modify the first one I
finished. All I did was bore out the nose and let the collet chuck slop
around a little more. CNC tapped 20 holes to 10-32 holes with it.
Looked a little sloppy, but as soon as it entered the hole it was nice
and straight. The threads look good, and it didn't waller them out any.
Maybe next week I'll have time to make a couple more. I bought some
1144, but that stainless one looks so pretty I'm tempted to make more of
them out of stainless even though it is a little touchy to work with.
Just changed one of my processes and order them a little better.

I hope you can post some more pictures, eg of the TC tapper parts before
you assemble the others. My impression (or possibly misunderstanding) is
that having a spring with the right spring constant is important to how
well a TC tapper works -- how did you pick out what spring to use?

--
jiw