Bosch GKF 550 Circle Cutting Jig

A circle cutting jig to cut circles from 80 mm diameter to 300mm diameter (minus half the radius of the cutting tool). 

It has a adjustment slider to set the radius, and a split adjustment to allow for you to set the radius and move into the work rather than plunging down into the work (think of it as a stop). 
 

Print Instructions to minimise overhangs

• Print the adjustment sliders (both connected and split) as is
• Flip the Main Body such that the T-track is facing upwards (flip upside down)
• Flip the adjustment knob upside down, such that smaller radius is facing upwards. There is a overhang with bolt hole, I found this to not need supports and just squish the bolt over the top of any sagging

Assembly Instructions 

• Print all components, ensure the main body is placed with writing up 
• Press an M5 bolt or screw (designed for a countersunk machine screw) into the hole near the triangle on the adjuster. 
• Press an M3 nut into the adjuster 
• Press the M3 bolt or screw (designed for a countersunk machine screw)  into the printed knob, I had to use superglue to keep it fixed
• Place the adjuster underneath the slot of the main body, and fix with the knob. Use this to position the M5 screw to set radius and attach the Bosch GKF550 router with the 4 set screws to the provided base. 
• Optionally cut a tape measure between the 40mm and 150mm marks and super glue to the recess underneath the jig for easier indication of radius size. Note I didn't have the correct tape measure so thats why mines from 104-115cm. 

To set the distance remember to offset for the radius of the cutting tool and the pin, i.e if I require a 100mm diameter circle and have a 22mm bit. The jig must be set to 50 - 11 - 2.5 = 41 on the underside scale. 

I've attached the onshape CAD for any remixing - just fork the design and go for it! Ideas for enhancements 

1. Add mounting patterns for other routers
2. Increase (or decrease) size
3. Add a supporting handle on the opposite side to the router 
4. Generally fix issues in the design 
   1. Using an M5 threaded screw as the pivot may not be ideal
   2. The adjustment slider has a suboptimal print layout and has a very thin section
   3. The knob should use a bolt would avoid any slippage from the round screw head

Onshape Link: https://shorturl.at/puwVY