Raduis Cutter
Radius Cutter
One of my very first projects was to design and make a tool / attachment for cutting a radius. I looked at various designs on the web and took some ideas from various designs and made my version.
I still need to make some modifications...or perhaps version II...but overall I'm pleased with the outcome.
As you can see...the cutter attaches to the cross-slide using the same bolt holes as the factory compound.
The parts
As you can see....It's a really simple design with few parts. The ring on the left functions as a stationary hold-down device and houses the two metric hex head cap screws that attach to the factory holes in the cross-slide. This ring was turned from a 1" peice of 6061 aluminum plate. You can see the lip that holds the center portion (right hand side of picture)
The center tool holder is also turned from 6061 aluminum plate and was designed fit rather snugly. Just enough clearance to allow for lubrication. (viper lube works great and makes for a nice smooth motion) The tool holder has a stainless pin in the center that rests in the factory hole that is used by the compound. This pin is held in place by the "L" shaped carbide holder and keeps the bottom from rubbing on the face of the cross-slide. (totally necessary....??? probably not....but hey.....It's extra stability and it keeps the center tool holder from putting much force on the sides of the hold-down ring.
The steel bar and brass knob attach to the center tool holder for obvious reasons. Oh yeah....the brass knob attached to that bar was my first project with the radius cutter.
I'll talk about the carbide holder parts in the next picture.
The carbide holder
I chose to use 1/2" square cold rolled steel stock for the carbide tool holder. My first design was to use a single peice of steel cut into an "L" shape and milled to fit. (well...long story short. at that time...my milling skills were near nill and I didn't have a saw capable of cutting 1/2" plate steel.)
I decided to use a two peice design. The left most peice is the bottom portion (horizontal) of the carbide holder and fits into the 1/2 milled slot on the center tool holder. (shown above) It was drilled on the top to accept the verticle portion of the carbide holder and drilled/tapped from the end in order to hold the verticle segment in place. This is held in place in the aluminum tool holder by two set screws that have been drilled, recessed and tapped on one side of the holder. (milling a small channel on the horizontal carbide holder in line with the set screws is needed. This will prevent deformation of the horizontal bar making it hard to slide or remove.
The verticle portion was turned to round to fit the horizontal segment and flattened in two places 180 degrees apart to allow the set screw to hold firmly withou maring the surface and making the part hard to remove or turn. 1/2 of the top of the verticle segment was milled down to accept a TNMC type triangular carbide. Drilled and tapped to accomodate a screw to hold the carbide in place.
In my mind...this combination would allow for easy transition between concave and convex cuts. It would also allow me to play with different cutters by just making new verticles.
Carbide
Just a shot of the top of the carbide holder
Another shot of the radius cutter attached to the cross-slide.
One lesson learned. In this configuration....the cross slide has to be moved WAY back to the rear in order to align the workpeice for cutting. This exposes the leadscrew to chips.
Solutions:??
1. Drill new holes in the cross slide and move it back towards the center
2. Redesign the hold-down plate to accomplish the same as above.
3. Live with it...and just cover up the cross slide leadscrew...(none of you would do this would you?)
4. Solicit comments from visitors of this site and make a decision later.
5. Design another radius cutter that connects to the QCTP....hmmmm
Drawings?
Comming soon.