Marble board game

[uglystick]

Say I have 1" diameter marbles for a game board. I want to cut recesses to hold the marbles on the board (think chinese checkers). Do I use a bit of the same diameter (1") or one that is slightly smaller than the marble, maybe 3/4" ?
I'm thinking slightly smaller is the way to go so, since I don't want the marbles to wiggle and size could vary slightly.

[LCHIEN]

generally i would think that you would want holes about 1/2 the diameter of the marble. Too large a hole and you risk the marble setting in so deep it'l be hard to pluck out.
Also your depth is key. It has to be deep enough (and you'll have a cylindrical hole) so the marble is supported on the edge so it doesn't sit on the hole bottom and roll around in the hole.
The easiset thing to do is to take a scrap board and try different sizes and depths until you find one that works well for you.

But the real deal for marble games would be to get a core box or round nose router bit and use a plunge router to make a round bottom dimple that cups the marble. You'd want a bit dia just a little less than the marbles diameter so it would still sit on the edges of the round depression. The plunge depth should be very small, I would guess no more than 1/8-1/4" maximum - you don't want the marble buried.

http://www.mlcswoodworking.com/shops...s/bt_core.html

[cabinetman]

An alternative to a core box would be to use a straight faced mortising bit, maybe 3/8" in diameter and plunge a hole for the marble to seat. The marble would be captive on the edges of the hole. Would be tougher to clean the bottoms of the holes than a core box.

.

[LarryG]

Do I use a bit of the same diameter (1") or one that is slightly smaller than the marble, maybe 3/4" ? I'm thinking slightly smaller is the way to go so, since I don't want the marbles to wiggle and size could vary slightly.

You're thinking correctly. Assuming the marbles are a true 1" in diameter, a 3/4" diameter hole that is 3/16" deep will allow the marble to sit on the holes edges and not bottom out. Since a 3/4" hole is 75% of the marble's diameter, it shouldn't easily roll out of the hole accidentally. Only about 20% of the marble will extend down into the hole, leaving 80% to grab onto.

You wouldn't want to go much bigger than 3/4", but you wouldn't want to go much -- if any -- smaller, either. For example a 3/8" hole only 3/64" deep is enough to keep the marble from bottoming out. The slightest accidental jarring of the board would send marbles flying everywhere. A 1/2" hole is better, but not much. Your 3/4" choice looks optimal to me.

[uglystick]

But the real deal for marble games would be to get a core box or round nose router bit and use a plunge router to make a round bottom dimple that cups the marble. You'd want a bit dia just a little less than the marbles diameter so it would still sit on the edges of the round depression. The plunge depth should be very small, I would guess no more than 1/8-1/4" maximum - you don't want the marble buried.

http://www.mlcswoodworking.com/shops...s/bt_core.html

I'm considering purchasing a core box or roundnose router bit.
At the MLCS link, the 3/4" core box bit is $15 vs. 3/4" roundnose for $17. The roundnose has twice the carbide depth at 1 1/4". Is there any disadvantage or will it do everything the core box will do & more? I will be using it to plunge the dimples and groove a track around the edge of the circular board.

[LCHIEN]

I'm considering purchasing a core box or roundnose router bit.
At the MLCS link, the 3/4" core box bit is $15 vs. 3/4" roundnose for $17. The roundnose has twice the carbide depth at 1 1/4". Is there any disadvantage or will it do everything the core box will do & more? I will be using it to plunge the dimples and groove a track around the edge of the circular board.

the core box should do everything you need. Its a half round plus a straight side of about 1/4" long (since the carbide length is 5/8", or 1/4" over the radius of 3/8"). If you are cutting a deep groove with straight sides then this will do it if you go in less than 1/4" depth increments per pass.

The round nose will also cut a deep groove, of up to 1.25" but you can't cut it all in one pass unless you are cleaning out a dadoed groove perhaps. It doesn't say you can plunge the round nose... that may make a difference.

I'd get the core box. or maybe ask advice of MLCS - they're very good and knowledgable about router bits.

[LCHIEN]

Porter cable 3/4" core box bit $9.49 but its 1/4" shank...

http://www.rockler.com/product.cfm?p...campaign=V1934


It's $15 at MLCS for 1/2" shank, and they have free shipping... probably still your better buy.