How to set up the line boring tool

I had an email enquiring how the line boring tool would be set-up for use, specifically how it would be centred on the job.

I hope the following makes it clear.

Step 1

Two centring cones are aligned with the job and the boring bar run through them.







Grub screws (with brass tips) are nipped onto the boring bar.  This will keep the whole assembly in place, the cones ensuring the bar in on-centre.  This will be accurate enough for most purposes.





Step 2

A bearing plate is fitted to one end of the boring bar.

Pieces of flat bar (shown grey) are tack-welded between the job and the bearing to secure the bearing concentric to the bush to be bored.




Step 3

The other bearing plate is now welded into position as before.  This plate is extended to form a base for the magnetic drill to fasten to.  The fact that the UCF204 bearings are self-aligning, will help to iron-out any slight movement or irregularity which might occur during the fitting process.  However, provided care is taken, this shouldn’t be a problem anyway.

At this point the grub screws on the centring cones can be removed and the bar slid-out to release them.  At this point their job is done.



Step 4

With the centring cones removed, the boring bar can be replaced.  Note, I’ve incorporated the ‘weldon’ shank to which the quill of the drill will attach.

A cutter can be fitted into any of the tool holes along the bar.  Using this arrangement, both bushes in this example can be bored precisely to a finished diameter, and importantly, concentric to each other.

Another boring plate could be installed between the two bushes in this example to reduce the tendency for the boring bar to flex in use.


The diameter of the bore would be monitored in use, and the cutter advanced accordingly until the final diameter is reached.

Once the job is complete, the tack-welds can be ground away to remove the rig from the job.


I hope that satisfies, what was a very good question.

Leave a Reply

Your email address will not be published.