Nomenclature

[Sideways]

Bob, despite the time that it would take, I'd take your best router out of the table, do the job and put it back
A round nose bit in a router will cut these dimples very cleanly. Better than anything I could do on my cheap drill.
You can measure the offset and clamp a straight edge to help position each row of dimples precisely. Clamp a couple of additional battons as stop blocks if you want to lock the router firmly in place for each plunge. Depth stop to control the cut. The end result should be beautifully crisp.

 

[sunnybob]

The holes are already there, but 12 mm, and they are too small. The only marbles I have been able to get are the white glass which are 16 mm. The marble should a third in the hole so that they can be easily grasped, any more than 5 mm deep and you wont be able to lift the marble.
A 15 mm ball burr will allow me to sit a third of the marble in the hole.
No way am I removing that router from the table, its hard wired in through an NVR switch, the handles are removed and its fixed to a lift.

I have smaller routers , but they arent plunge. The one plunge router I have is very sloppy and not up to this task.

 

[sunnybob]

I've ordered the rotary burr. Just got wait for the next visitors in a couple weeks time to deliver it to me.
Ta all.

 

[Phil Pascoe]

Buy ball bearings to fit the existing holes?

 

[gregmcateer]

'ere ya go, Bob - Save you hours of fun and effort;

https://www.amazon.co.uk/Bigjigs-Toys-C ... game&psc=1

 

[sunnybob]

This is the silliness of the modern world.
My home made one will top out at about three times that cost, but at least my grandchildren can say "my grandad made that".

I learnt how to do this puzzle when I was quite young, and actually won money once at a fete because the guy who had it said it couldnt be done. Me being too young and stupid for my own good immediately said "oh, I can do that". he did not beilieve me untill I won the money. Then I wanted another go and he refused. If I had not boasted and pretended it was a fluke, I might have doubled my money