Radius & Ball Turning Attachment for Mini Lathes – Precision Concave/Convex Turning Tool HSS & Carbide (DCMT11T304) Options Fits 7x14 & 7x16 Lathes

Whomever made this piece of tooling must have skipped the bulk of their schooling. They laid out the tool in such a manner that the cutting bit does not align with the actual centre of the yoke resulting in a substantial misalignment of the cutter bit as it swings in the yoke. Completely useless since nearly 1/4” or 5mm of useful space has been lost which prevents the tool from being properly centred on the work. The work in the photos is only 23 and a bit mm in diameter. QUALITY CONTROL during manufacture and testing of these would have gone a long way since the tool would otherwise have rated 5 stars.

The replacement for the first tool (received without a cutter bit) was complete. After I insured all screws were tight, I attached it to my lathe using a quick-change tool holder. First thing I tried was to simply turn a rounded end on a piece of Delrin plastic. It took a bit to get used to the process, but I turned a very nice half round onto the end of the plastic. I then chucked up a short length of 1/2" aluminum rod. I insured the rod end was far enough out of the chuck that the tool would not impact the chuck jaws in use. I undercut a length of the shaft from about 1/2" from the end of the rod back about an inch and turned that down to roughly 1/4 diameter. Then I set the tool horizontal to the work, touched off at the dead center of the rod. I moved the cross feed out far enough that the cutter was clear of the work. I then started the lathe and moved the bit in until it made contact with the right hand end of the work. I swung the handle left and right and knocked the edges off the work. I advanced the tool and swung the handle between the center of the end of the rod and back as far as it would go - that is, until it struck the undercut section of the rod. I continued advancing a little at a time until I was cutting the entire surface of the nicely-forming ball on the end of the shaft ! Once I had tool cutting during the entirety of the swing I stopped cutting and polished the ball and shaft with 400 grit sandpaper. The result a smooth, shiny ball about 3/8" diameter. I hadn't measured anything exactly in this test, just wanted to see if it worked. IT DOES!! Feed slowly and use enough speed to prevent chatter. I think this will work for all the small projects I may want balls for. I will try drilling and tapping the next one with 1/4-20 thread so I can screw it onto a "handle" - this is still test, try, learn mode. But think it will get lots of practical use in the future.

This part is made in India and is a very sloppy fit. Chattering is a huge problem even for a small radius, you end up filing the part to to have any kind of half decent finish. Cutting tool is too long and does not allow you to cut a full radius unless you flip the cutter upside down and cut from the back side of the part. Essentially this is a poorly designed copy with bad build quality.

spindle the handle is connected to isn't keyed, so slips. Thats the negative part. Can be fixed with a bit of machining, but something the manufacturer didnt care about, so you shouldn't care about supporting the manufacturer. FYI issues: 1. limited to diameter. Something I didnt consider when purchasing. Hopefully that helps you make a decision. 2. Handle on bit doesn't clear my QTP top ,so had to rotate the handle on the bit which could interfere with other things or introduce a safety issue.

Meh... it works but not very strong.