The boring bar holder is the second accessory I have made for my Cowells Lathe. Like the Rear Cutoff Toolpost I used a Sherline Toolpost. I made a similar one for my Sherline and it is easy to setup. Again the reason for using the Sherline is it readily mounts the Cowells table and I had a spare. You could certainly just make a block and mounting hardware. The holder will take .125, .1875, and .25 shank bars. This provides a large range of boring bars and/ or internal threading bar.
To start the block must be aligned to the edge of the table. Next line up the spotting drill .25 in from the edge as seen in the photo. Then just take your time drill all the way through. The last pass is with a reamer. The first hole is a .25. The second hole is a .1875 and is at a right angle to the first see pictures. In the fifth picture you can see .1875 bar in the not finished holder.
The next job is to take block and tap the boring bar locking screw holes. I used brass screws to avoid marring the boring bars. I may switch to brass tipped cap screws just so I do not need a screw driver just an Allen wrench . The tapped hole position for the .25 shaft is critical. As you can see in one of the last photos I made a collet that slides into the .25 hole. It is for the .125 bars. The collet has a slot milled so the screw can clamp directly on the .125 bar. Whatever dimension you use for the center of the slot is what is needed for the tapped hole into the .25 hole. My collet is .875 under the head and the slot is .400 under the head. My hole for the .25 boring bar is .25 x .400 from the corner of the toolpost. I milled a flat on the collet collar so it was easier to set the collet in correctly to line up with the tapped screw hole. The .1875 boring bar hole tapped hole was .25 x .620 from the corner of the toolpost.
The last three photos show the completed holder. Took me about 3 hours or so. Saves lots of setup time during projects.
This was the first cuts the Cowells took so it is now officially used and a bit dirty ie initial break in.
Next accessories are a 4 way toolpost and a groover toolpost. I have the blanks cut and am just finishing the drawings. These are being made to hold the Arthur Warner 1/4” tooling.
Bob
