MadModder

The Shop => Tools => Topic started by: kvom on December 21, 2009, 09:19:59 PM

Title: Homebrew boring bar holder
Post by: kvom on December 21, 2009, 09:19:59 PM

Until today I didn't have a good way to bore on my lathe.  I previously made an aluminum holder to use with a broken endmill, but that didn't ever work very well, and the endmill is 1/2" diameter which elminated small holes.  So I tended to rely on reaming to get a precise hole.

A while back I purchased a couple of "micro" carbide boring bars from a seller on PM, but they had lain unused for lack of a holder.  Today I decided to make one.  Here's the larger bar.  The shank is 5/16" diameter and about 1.5" long:

(http://www.pbase.com/kvom/image/120480262/medium.jpg)

I started with a 3" piece of 1" diameter 12L14 steel that I faced and drilled/reamed on the lathe.  Then I chucked it in the milling vise and milled a 1/4" flat on the top.  Following this I center drilled and drilled 7 holes on the flat for set screws.  The next step was to clamp the bar with the flat against the fixed jaw and mill the relief cuts.  They are ~3/8 wide and test fit on the AXA tool holder.  Finally I tapped the holes for 5-40 set screws.  Here's the assemblage:

(http://www.pbase.com/kvom/image/120480261/medium.jpg)

Note that the boring bar has a flat on the top, so that the set screws assure a horizontal alignment of the cutting surface.  I also cut both the side reliefs at the same time so that the holder will mount squarely on the AXA holder.

Mounted on the QCTP:

(http://www.pbase.com/kvom/image/120480260/medium.jpg)

I use the quill of the tailstock to align the holder, and thus the boring bar, with the ways.  After adjusting for height, a first practice cut produced an excellent result.  I'm  pretty happy with 90 minutes or so of shop work to make this.  The other boring bar is a lot smaller, so I think I can make a bushing that will allow me to use it in the same holder.

(http://www.pbase.com/kvom/image/120480259/medium.jpg)

Title: Re: Homebrew boring bar holder
Post by: websterz on December 21, 2009, 11:17:52 PM

Nicely done! Making your own tooling is so much more satisfying than just buying it.  :dremel:

Title: Re: Homebrew boring bar holder
Post by: Gerhard Olivier on December 22, 2009, 04:37:29 AM

Nice holder and very nicely made.  Good work.

Gerhard

Title: Re: Homebrew boring bar holder
Post by: Bernd on December 22, 2009, 10:43:41 AM

Nice bit of tooling Kirk. Very easy to make. I've made a few, but not as fancy looking.

Bernd