# Half Ball Cup Formation Method?



## Mr.Shing-A-Ling (Nov 21, 2019)

Newbie here. 

I have a project where I want to form a half ball rounded hole in a 60 x 60 mm piece of wood. 

This will hold a 40mm diameter ball half way within the wood and half protruding. 

I want the ball to fit snugly within so that it cannot move. 

I cannot seem to find a drill or router bit for this task. 

Is there an easy way to form this hole?

Thanks in advance.

MSAL


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## Stick486 (Jan 4, 2013)

https://www.freudtools.com/search?h=1


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## Mr.Shing-A-Ling (Nov 21, 2019)

Stick486

Thanks for the reply, but your link just goes to a blank page, no product?


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## OutoftheWoodwork (Oct 4, 2012)

Hey Newbie:

Would love to know who I'm talking to; can you change the N/A for your name? As for creating your crater, I would be one to trace the ball, and using a round nose bit, slowly work at it. But I'm a improviser, like some of the others on here.


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## Mr.Shing-A-Ling (Nov 21, 2019)

OutoftheWoodwork said:


> Hey Newbie:
> 
> Would love to know who I'm talking to; can you change the N/A for your name? As for creating your crater, I would be one to trace the ball, and using a round nose bit, slowly work at it. But I'm a improviser, like some of the others on here.


Thanks Barb

I can see that a Round Nose Cove router bit would do the job, but I'm struggling to find a bit 40mm in diameter? I've looked on-line generally and on ebay. I thought this would have been easy!


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## Stick486 (Jan 4, 2013)

Mr.Shing-A-Ling said:


> Stick486
> 
> Thanks for the reply, but your link just goes to a blank page, no product?


https://www.freudtools.com/products/18-138


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## Cherryville Chuck (Sep 28, 2010)

He's looking for an exact fit Stick and I'm with him, I know of no manufacturer making a 40mm round nose bit. In Imperial it would be a little more than 1 17/32".

MSAL you can get Whiteside Manufacturing to make you one but it would be pretty pricey or maybe if you can find one that's 3/4" radius it might be close enough. The ball would sit a little higher than halfway but not much.


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## Stick486 (Jan 4, 2013)

Get close...
Sand to fit...


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## sreilly (May 22, 2018)

Stick486 said:


> Get close...
> Sand to fit...


That was my thought. I mean usually it takes a bit more that just a single pass to get the perfect fit on most anything unless you plan on using the bit sizes you have and work from there. Sand paper is perfect for those small adjustments.


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## Mr.Shing-A-Ling (Nov 21, 2019)

Thank you for the replies and information. 

Since a 40mm radial bit will be bespoke and costly, I'm now thinking of forming the hole with a 40mm Hinge Hole Boring Cutter Wood Drill Bit Flat which are readily available. It won't be conical round, but should do what I want it to do.

Thanks all.

MSAL


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## roxanne562001 (Feb 5, 2012)

Welcome to the forum. If you drill the hole with an adjustable circle cutter aka fly cutter in a drill press then use a round over bit with a pilot bearing to form the rounded edge. Then sand to get the exact fit you want.


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## Biagio (Mar 2, 2013)

Lee Valley has a pneumatic ball nose sanding drum, which looks almost purpose-designed for the sanding part of this job.


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## Stick486 (Jan 4, 2013)

Two mating flats made w/ a fostner bit...
as soon as the rim of the bit touches the ball stop drilling...


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## Biagio (Mar 2, 2013)

MSAL,
I think you are on the right track. 40mm Forstner bits are fairly common. A cylindrical 40mm flat-bottomed hole, 20mm deep, will hold your ball exactly as you want it, with no complicated sanding, etc. The fact that it is not a half-round cup hole, will not be visible. If you want the ball to rotate in the hole, so much the better - only one friction point at the bottom of the hole. If you do not want it to rotate, one dab of hot-melt glue at the same location.
Interesting how one gets to overthink situations.


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## Stick486 (Jan 4, 2013)

Biagio said:


> MSAL,
> I think you are on the right track. 40mm Forstner bits are fairly common. A cylindrical 40mm flat-bottomed hole, 20mm deep, will hold your ball exactly as you want it, with no complicated sanding, etc. The fact that it is not a half-round cup hole, will not be visible. If you want the ball to rotate in the hole, so much the better - only one friction point at the bottom of the hole. If you do not want it to rotate, one dab of hot-melt glue at the same location.
> Interesting how one gets to overthink situations.


you could use the point from the fostner bit to accurately install a dowel, dowel screws or a blind nail...










.


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