# Shop Built Radius Cutter



## dnalot (Apr 16, 2013)

This is my version of a turret radius cutter. It is made to fit a Grizzly 12 X 36 lathe. It cuts to a max diameter of 1.375" and can cut an inside arc to the same radius. The cutting tool is a 3/16" round and I call it the "Weasel" because it will pop up and out of its hole if you loosen the setscrew. I used the spring from a ballpoint pen under the bit to make it easier to adjust the height. A clevis pin cut to length serves as a tool for adjusting tool height.  The pin is also used to plug the hole in the top of the turret. That hole is for access to the set screws that secure the tool post to the compound and as a point to oil the mating surfaces of the turret.  The turret is made from cast iron and the arm is drill rod "W1" with the tool post and handle made from mild steel. The tool post was silver soldered to the rod.  10-24 set screws were used throughout so only one tool is needed.  The turrets pivot is a 5/16" shoulder bolt with a stack of 6 bearing springs to take up any slack and to give some feel to the movement "firm but smooth". I know the handle looks a bit out of scale but I wanted something that fit well into my hand. 
     My first cut was steel and I laid into it hard (.05) to see if the solder would hold. It did and the tool cut surprisingly well. The bit got pushed down a little so to correct that I ground the flat side a little deeper at the bottom end to make the bit wedge shaped. The set screw now will hold good without being overly tight. The final light & slow cut produced a very good finish and only a quick pass with fine emery was needed to make it ready to polish. 
 Disassembled the tool will fit into a small shallow toolbox drawer. Or you can use it as a paper weight on your desk. I love this tool; it's easy to set up and is fun to use. 
Note: the Shoulder bolt needs to have its head cut down a little and a few threads cut off. The spring washers "for ball bearings" came from McMaster Carr. I gave my handle a tulip shape end. 
This is another skill building exercise to build confidence in my ability to complete the next step in my grand "First Engine" project.  It also fills my need to complete something. Seeing this thing completed has given me a much needed second wind for the bigger project. 

Mark T


----------



## hobby (Apr 16, 2013)

Now that is a nice design,
and with the machining you accomplished, I can tell your not a novice to machining parts, so when you take on your first engine project, you will do real well, with the skills you have already demonstrated.


----------



## Huntinguy (Apr 16, 2013)

That is a clever idea and very well executed.


----------



## AussieJimG (Apr 16, 2013)

Well designed, well made and beautifully presented. I particularly like the combination of photos assembled and disassembled and the included drawing. Congratulations.

Jim


----------



## tarawa (Apr 16, 2013)

Very nice. Thanks for sharing.


----------



## Rivergypsy (Apr 17, 2013)

Very nice indeed - thats just jumped to the top of the project list, many thanks!


----------



## Davo J (Apr 17, 2013)

Very nice, and nice design.

Dave


----------



## J. Tranter (Apr 17, 2013)

What is the finish on it and how did you do it?
Great work by the way...


----------



## dnalot (Apr 18, 2013)

The finish was "Kleenbore Black Magic" A cold gun finish. It actually looks much better than the photos. The steel parts after five treatments with a light steel wool between treatments and a light buff after turned a nice blue black. The cast iron parts turned a grey black. Cast iron will take the treatment better if it is glass blasted first, you will get a very dark black finish if you do that. Note that the Kleenbore comes in a tall skinny bottle that is easy to tip over. Save yourself some grief and secure it. 

I want to thank you guys for your comments and support for this post. 

Mark T


----------



## kquiggle (Apr 18, 2013)

That is a really nice design - simple (in the good sense) and effective. I'm definitely going to add that to my "collection:"

https://sites.google.com/site/lagadoacademy/useful-links#lathetools


----------



## stew (Apr 27, 2013)

HI,
Very Nice Work Thm:. Thank You for sharing the Pictures and the Plans.


----------

