Cribbage Holes and Tapered ballnose bits

Good evening all. Like many on the forum, I am making a cribbage board with standard 1/8" holes. Read all the helpful posts on why an 1/8" mill won’t make 1/8" holes. I have been pondering the use of tapered ballnose bits to make the holes, considering the pegs are also tapered. I have never really worked with tapered ballnose bits before. I have some but wondering - is there a tutorial somewhere on using ballnose bits, especially for drilling holes, and has anyone made a cribbage board with such holes?

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A 1/8" end mill will make a 1/8" hole using the Convert Circles to Drill Holes App.
I have not made a cribbage board using a Tapered Ball Nose bit but don’t see why it wouldn’t work with the Circle to Drill Hole App.and it will convert them to drill.
Select all the holes you want go drill then go to the App.
Russell

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I second this. Just made a cribbage board last week with the “convert circles to drill holes” app and a 1/8" end mill. Worked great. I set my hole depth to 3/8". No issues. They peg great. I purchased the fancy metal pegs you can find on Amazon.

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Thank you Russell. If the bit is defined in Easel, does Easel then calculate what depth you must plunge to in order to get the right 1/8" hole at the surface?

Thank you Theodore.

Like for a V Bit? If using a Pocket cut type and that pocket is a 1/8" circle, then Yes. . . However using the method that Russel discussed of changing to “drill holes” this performs a straight plunge move using whatever bit you’ve put in the cnc and go to whatever depth you’ve set the cut to. Using the Plunge Drill function is the way most people are making Crib boards in easel. It’s either that or using a smaller endmill (like a 2mm diameter endmill) and using 1/8" diameter circles

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So, if I used the straight plunge and drill holes, I would have to know what depth for that taper ballnose bit would result in a surface diameter of 1/8". Then plunge to that depth for each hole. Correct?

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Precisely. You’d also want to surface the board on the cnc because any variance in the top surface of the board will effect the size of the holes and they would vary across the game board.

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Easel doesn’t define Tapered Ball Nose bits, I measured a 1/16" TBN bit and at .4" its 1/8" so you would have to go .4" deep to get the hole opening 1/8".
But like Seth mentioned if your board is not perfectly flat and parallel to your gantry using the TBN bit will make the holes different sizes.
Holes on one side will measure .125" and a few inches over the holes may be .155"
I think the best thing to use is a 1/8" end-mill so if your board isn’t perfect your holes will still be perfect.
I drew some circles .125" - .155" which is only a .03" difference and you can notice the different size holes. If the board has more of a warp then the holes would look worse.
Russell


Holes all at .125"

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I might be wrong but I think TBN bits come in various angles. So I suggest checking your own bit before assuming all 1/16 TBN s are 1/8 at .4 deep.
I also think that you may over-heat a TBN if it is any smaller than 1/16 tip when drilling with it.
I use one of these and would never consider drilling with it. I only use it for 3d carving with only 8-10% stepover.

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Thank you all for your excellent advice. I will stick with the 1/8" end mill, but may experiment a little with the TBN bits on some scrap.

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I have been building cribbage boards for years now with the cnc and have been using the 3.25mm end mill to do the plunges. It cuts ever so slightly larger than the 1/8" drill or bit so the pins fit great.
You may want to try them.

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Thank you Rick. How do you have that bit defined in the Toolbox?

Douglas,
You simply use the drill selector from the left side in Easel then select for a bit a .125 bit. If you set the depth per pass to .125" and have a total depth of .5" then your bit will clear itself as it moves along.
Hopefully this helps.