imrichb

I'm trying to cut a semi-circular groove along the edge of a piece, pictured in the attached. I can do this easily along a straight edge using my router table and a round nose bit. The challenge is that I'd like to do this along an edge that is curved (and to make it more challenging, a concave curve).

Any advice? I had thought maybe I could use a 3/4" ball cutter bit with a 1/2" bearing around the shank to guide it along the edge of the workpiece, but unfortunately I can only find a ball cutter bit of that size with a 1/2" shank, meaning that I can't put a bearing around it.

(In case you're curious, this is for a children's toy I am working on. The groove will essentially form a track for a marble to run down.)

Thanks in advance!

Rich

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Mike

You need to make a template from 1/4" hardboard or plastic, some people prefer using 1/2" MDF. Attach it to your wood with double sided carpet tape or build a jig with hold down clamps. A guide bushing installed in your routers base plate will follow your template and a thumbnail bit should give you the profile you want.

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Mike

kp91

Heres a couple of options

You could play with the bearing diameters to adjust your cut if desired.

http://magnate.net/index.cfm?event=s...roup&theID=114

http://magnate.net/index.cfm?event=s...roup&theID=158

I can confidently recommend the Magnate bits.

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Doug
1 John 1:9

imrichb

Perfect! That's exactly the bit that I had visualized in my mind for this, but couldn't find something like it anywhere.

Thanks for the help,

Rich

bobj3

Hi Rich

The bearing on router bits,,, it's just fence so to speak, that said, make a fence like the one below, this will work a guard and let do your concave curve pass easy and safe...just ease into the bit and once your on push your stock around the guide...the guide will act like a start pin and let you get on the bit
safe and let stay ,hardwood be best for the guide/jig but it can be plywood or MDF....

The bits below also work great for what you want to do...
Making toys

Train Track Router Bits
http://www.mlcswoodworking.com/shops...ack_bit_anchor


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Bj

imrichb

I like that solution as well!
Thanks,
Rich