Bosch RA1150 Centering Cone

If you ever take off your sub-base you will need this to recenter everything, and its a must for centering your collars for accuracy went doing dovetails and other precision work.

Whenever I got it I took it out of the package and wondered why I had to pay 7.50 plus shipping for this little piece of steel. But it is a must for your router work and a worthwhile buy however simple and somewhat overcharged (ok I am a grump about it, its not the mild extra money its just the principle of what you give for what it is) this item is.

I am very pleased with the centering cone I recently purchased. I can be sure my router is properly aligned when mounting it in a stand.

Nice centering cone...it really...centers. Yeah
Too bad Bosch wouldn't include one with the router. Gee whiz.

My Bosch 1617EVSPK has a smooth base attached to the bottom of the router.
Bosch is very careful to center the base plate on the base (in case you say remove it to attach to a router table). Although it is easy to provide a very close center, it is not as good as the factory center.

Using this centering cone, you can easily provide an improved center for the base for better algnment. Then again, the routers shipping now include the centering cone.

This centering cone should be standard equipment with any router. It's absolutely essential for accurate template guided work. I made a lot of firewood before I realized that my baseplate and template guide were not centered on my bit. It's especially frustrating when doing inlays and your work pieces don't mate perfectly. This simple centering cone fixes all that and you don't necessarily need a Bosch router to use it.
Most higher-end routers come with baseplates that have two sets of holes to mount it to the router base. One set is fixed and is used at the factory to align the baseplate close to center. The other set is elongated and allows you to fine tune the placement of the baseplate on the base. The factory holes are close, but not perfect. If you need to do precise work like inlays, you'll want to use the second set of holes, and to use those, you NEED this centering cone.
Attach a medium-sized template guide to the baseplate, say or 3/8" or 1/2" then attach the baseplate to the router base loosely using the elongated set of screw holes. Gently push the long end of the centering cone into the router's collet and tighten the collet to the point where the cone is snug, but can be moved in and out of the collet with a little force. Now continue to push the cone into the collet until the cone comes in contact with the template guide and keep pushing until the cone can't be pushed in any more. This will pull the baseplate into exact center on the collet. Before removing the cone, gently tighten the baseplate screws without moving the baseplate. Remove the cone, chuck a bit, and you're ready to do some precision work.
Remember, all template guides are not made alike, so it' a good idea to pull out this cone and re-center whenever you change the template guide.