Extended Tool Post

I needed to do a job that required a small face grooving tool with a very long reach due to the size and shape of the part, a housing. The housing to be re-grooved was within 1/8” of contacting the bed ways on my 14” swing lathe and the carriage contacted the end of housing way before I could reach it with a tool. Turning the compound parallel with the z axis and using it’s full travel still left the tool well short of the groove, so……I decided to make an extended Tool Holder to use in place of my Tool Post.
I grabbed a 6” long piece of 2.5” square 1018 steel bar and squared it up in the mill using a 3” face mill and skimmed .005” off of the sides.

Probably not the correct way, but the ends were then skimmed using an angle plate and a machinist’s square for setup.

Next, I drilled it to accept the 5/8” mounting stud on the compound slide that normally holds the QCTP in place.

Then chamferred it.

Since the QCTP is taller, I needed to make a spacer to go on the stud so I didn’t run out of thread for the nut that will hold it in place. 2 1/4" steel round bar was used.

I cut a little relief on the underside of the spacer so it would distribute the load a little nicer when the nut was tightened.

Next, I attached it to the Compound and indicated it parallel to the Z travel so it would be easy to setup in the future.

I then located the edge with an edge finder, moved in .400” and drilled a 15/32” hole to accept the required grooving tool.

Then the bore was finished using a .500” Jig Reamer which leaves a very accurate nearly mirror finish bore.

Next it’s back to the mill for drilling and taping for set screws to lock the tool in place.

I then ground up a face grooving tool from an old boring bar and assembled the whole deal. The bore size is perfect as when you push the tool in the air pressure behind it pops it back out and when you get it to stay in, the suction draws it back in when you try to pull it out!

The housing is in the chuck and indicated in and we’re ready to groove! (Actually enlarge an existing groove) You can see how the new tool holder just reaches around the housing and places the grooving tool right where it needs to be with PLENTY of rigidity. I originally thought about tapering the new tool holder and rounding the edges so it didn’t look like a block of steel, but the way it is, if I cross drill the hole for the mounting stud I can rotate it and have four more surfaces to attach various cutters to it if needed in the future.

You can see above, by looking in the right lower corner of the image, just how close the carriage is to the housing even when using the extension.

Thanks for looking!!

Glenn