Vince,
   grind some clearence on the shank behind the threads, but first run the tap as far as it will go, then grind and go easy.
I've done this a few times.

ED

I am just getting over the worst cold of my life.  I have only had about 5 colds in my life so I feel real sorry for those who get them.  On Friday I actually had water squirt out of my right eye far enough to hit the inside of my glasses.  Of course I finally got some work on Thursday and Friday, where I spent the time in jail (I was working on an electrical project in the jail facility).  I managed to suffer through it, but spent the rest of the time in bed sleeping. 

Today I got a chance to counter bore the balance disk.  I went down .25".  It looks good.  The tap came through the hole to the center.  At no point did I feel like the tap was going to break.  A 6-32 tap feels a lot worse.  I took it slow and only rotated 90 degrees before backing up 180 degrees.  On to the next part.

Vince

I spent 3 hours making another part.  If I had an automatic tool changer and I knew what I was doing, it would have taken 10 minutes.  This part is called a crank arm.  The part was pretty simple to program and make, but my trouble was parting the piece off the bar stock.  The first one I destroyed in my lathe with improperly adjusted parting tool.  The second one I crushed in my mill trying to mill off the back of the part.  I finally found a .020" slitting saw that I was able to use the cut the part off.  The part is made from 1/2" steel drill rod.

The larger hole was reamed to 5/32".  The smaller hole is drilled and tapped 0-80.  I was not able to get a pilot hole for the .046" drill ( it was too close to the boss) so I just took it easy and peck drilled it .020" at a time.  I tapped it by hand,  I was only comfortable turning the tap 45 degrees before backing it off and clearing the chip.  I did not break a tap though.

I am not a machinist by trade and these little projects are teaching me a lot.  I'm sure by the time I die I will know about 25% of what I need to.

Vince

Vince,

 Looks like your doing a good job . Myself , I'd rather work on big stuff.
Yesterday had to make repair parts for a Manitowoc Crane.

Ed

I know what you mean, I like working on the big stuff at work, when someone else is paying for the material.  I started on machining when I purchased a watch lathe to fix pocket watches.  I have gone full circle.  I went to a Bridgeport to a 4,500 pound Yamazen knee mill, to a 5,000 pound CHNC, down to a taig lathe, and now I am getting the parts together to convert my watch lathe to CNC.

Vince

I have not finished any more parts as I have been trying to fix an out of true chuck.  I was finally successful.  Now maybe I can move ahead.

http://www.practicalmachinist.com/vb/showthread.php?t=175951

Vince

I finished the top and bottom displacer plates.  What a pain.  I still have not figure out a good way to hold a piece of sheet metal (the plates are only 1/8" thick) while trying to machine out a circle.  I clamped a piece of wood to the top of my vice and used sheet metal screws to hold down the sheet metal.  Even so, it moved one time and I had to set it all up again.  The bottom plate does not have any holes in it large enough to screw it to the wood.  There are twenty four 0-80 screws that hold the top and bottom plate to the Delrin columns. 

Vince

Vince,

 Very nice job your doing.
Sometimes  , I  mill around half way , and clamp where you just machined , and move clamps till your done. I just use feed hold, and move clamps. CAREFULLY.

Ed

Vince,
To hold a piece of thin metal there are a few tricks that you can do.
Double backed carpet tape will hold it to a flat piece of wood or sacrificial plate. Another way is expoy
glue it to the plate ( Dabs and use a little heat to soften up the epxoy). Just need to be carefull
when removing  the thin plate from the other. Very light cuts also.
Works for me,
RICH
 

BTW, If your so inclinded, there are postings which analyze the thermodynamics of the miser.
The analyzation was at a rather high level if memory serves me. Some college posted it.
Just adds another dimension to a project.
RICH