Radius turner from boring bar

[Tio Loco]

I'd been wanting to do this for a while, finally got a



(sorry, a little quarantine humor)

Pretty much copied the design in this video by Ade Swash:

Parts almost complete, waiting on the M2.5x.45 insert screws (finally found them at Shars).



Is it incestuous to use a new tool to make the last part for the tool?



All done.



See her chooch...

 

[WesPete66]

Wow, loving it! I snagged a boring bar out of the scrap bin at work a while back, and have been trying to find a use for it on my lathe. I think I just found it. Thanks!
What is the tool/insert that you are using?

 

[benmychree]

A good holder for that style of ball turner is the Aloris boring bar holder with the hole through it, the hole is quite accurate and provides a good bearing surface for the rotating shaft.

 

[Tio Loco]

@WesPete66 The cutter is RCMT-0602 https://www.ebay.com/itm/RCMT-0602-C-6-TiN-COATED-CARBIDE-INSERT-6034-3062/232563558261

Screws: https://www.shars.com/mts-255-m2-5-x-45-insert-screw They take a T7 driver if memory serves.

@benmychree The problem, at least with my PM1022, and I suspect all small lathes is that the Aloris (and the like) tool holder pushes the boring head too close to the centerline of the lathe, even withe the cross slide full retracted, leaving zero clearance between the boring head and the work. That's the reason for the offset rectangular mount for the body of this design.

Also, notice the cutter holder in first picture of the assembly, compared to the last photos. I had to neck it down to prevent it from rubbing the 1" brass. It's a downside of the small cutter...

 

[aliva]

The price on Ebay is pretty reasonable, but the shipping is ridiculous. That's why they can sell the insert so cheap.
It wouldn't cost 21$ ship an envelope

 

[Tio Loco]

It's a Canada thing... US shipping is $8.90...

 

[ttabbal]

The price on Ebay is pretty reasonable, but the shipping is ridiculous. That's why they can sell the insert so cheap.
It wouldn't cost 21$ ship an envelope

It's $8.90 here to the US. Still overpriced, but not quite so much. Those round inserts are available all over the place though. I'm sure you can find some that are more reasonable on shipping.

 

[benmychree]

@WesPete66 The cutter is RCMT-0602 https://www.ebay.com/itm/RCMT-0602-C-6-TiN-COATED-CARBIDE-INSERT-6034-3062/232563558261

Screws: https://www.shars.com/mts-255-m2-5-x-45-insert-screw They take a T7 driver if memory serves.

@benmychree The problem, at least with my PM1022, and I suspect all small lathes is that the Aloris (and the like) tool holder pushes the boring head too close to the centerline of the lathe, even withe the cross slide full retracted, leaving zero clearance between the boring head and the work. That's the reason for the offset rectangular mount for the body of this design.

Also, notice the cutter holder in first picture of the assembly, compared to the last photos. I had to neck it down to prevent it from rubbing the 1" brass. It's a downside of the small cutter...

The boring bar holder that I have been using has about the same offset as the one that you made; the one that I and a friend made uses a purpose built adjustable head to hold the cutting tool, also made special out of HSS.

 

[brino]

@Tio Loco ,

I have been wanting to build one like this for years.......but I cannot find any of those round tuit's.
Someone must be hoarding them all!

Anyway, yours is a great execution!
Thanks for showing it.

-brino

 

[mattthemuppet2]

very neat, way fancier than mine, though the principle is the same. Means I can use the boring head in the mill too.

If you need to get into a corner, a CCGT/DCGT insert face mounted like your round insert works well.