Nomenclature

[sunnybob]

Posh word for "I dont know what I need"

i'm making a wooden marble solitaire board out of teak. I want to cut indents for the marbles to sit in. The marbles are 15 mm diameter. I need the holes to be around 5 mm deep
I've searched ball rasp, ball burr, circular bit, and got nowhere.
help for the dunce please?
Oh, i'll be using a pillar drill, not a router, and the max speed is 2500 rpm.

 

[Woody2Shoes]

https://www.axminster.co.uk/axcaliber-b ... ter-666043

(don't see why not in a drill press)


or

https://www.axminster.co.uk/kirschen-sh ... eep-600033

?

 

[custard]

I'd use a jigged router with a Core Box bit,

https://www.wealdentool.com/acatalog/On ... x_202.html

 

[loftyhermes]

Ball end drill bit/end mill. https://www.rdgtools.co.uk/acatalog/Ball_Endmills.html

 

[sunnybob]

I will be using a pillar drill, NOT a router because my best router is in a table and i wont be able to see the holes if the wood is upside down.
Not sure how I would cut 33 circular holes 15 mm x 5 mm with a scoop.

dont really want to spend 20 plus quid on a special bit a and make a one off jig either.
I tried a double blade round bit in the drill, even at 2500 rpm it was a disaster, chattered and shook itself all over the place.
I was hoping for a cheap ball rasp for this one off use for under a tenner.
remember I'm at the cheapest end of the woodworking spectrum
That RDG link didnt work.

 

[loftyhermes]

Sorry the link didn't work for you, just google ball end drill bits I'm sure something will come up.

 

[Argus]

Bob,
Not certain what constitutes ‘expensive’ but presented with that problem, I would use a chair-maker’s spoon-bit in a hand brace. With a bit of practice, it will cut a round-bottomed hole of any depth.... without any noise or dust.
As you probably don’t have one, I’ll lend you mine if you promise to send it back….

 

[galleywood]

If you have a large enough drill bit you could drill 'dimples' - stopping before you start cutting on the diameter.

 

[Duncan A]

Bob
Try searching for ball rotary burr:
https://www.mytoolshed.co.uk/dormer-bal ... -16mm.html

https://www.zoro.co.uk/shop/cutting-too ... pe-/f/3378

Or just drill the start of a hole with a metal-working drill - the marbles will sit in the hole quite securely, even though it may not look quite as good.
Duncan

 

[novocaine]

got a bench grinder bob?
if so, cut down a 12mm jobbers bit so the flutes are about 20mm from the end of the shank with an angle grinder then use the bench grinder to create a round profile on the nose then add in back relief on the cutter face like you would a normal drill then sharpen with a handstone to get the shape and cutting edge right. you only need to grind to shape in 1 plane (across the cutting edges) and you might need to thin the web out a bit so you get a complete cutting profile across the tip.

then it's down to feeds and speeds, I'd run it slow at first to see how it does (slowest the machine will go which I think will be around 50rpm) with a gentle feed pressure, let the cutters do the work like a chisel would (which is how sharp you want the edge to be, hence stone it instead of relying on a grinder). you haven't got the rigidity to do this really so nice an slow so you can see what's happening.

and why cut the drill down to so short? stops it flapping all over the place.

if I'm allowed in the workshop tonight with my bench cleared (got a mud kitchen on it at the moment, little lads birthday next week, but it should be going next door for storage tonight hopefully) I'll have a play and send you the piccies of what you are trying to achieve.

 

[novocaine]

also, who the **** is Norman?

 

[sunnybob]

Again, thanks all for suggestions, but... i dont have a spoon bit, or a jobbers bit (huh?). In my normal state of complete ignorance i was thinking of something very simple and very cheap because i have no plans to ever make another marble solitaire.

offering to lend me the tool is really nice, but the shipping and return will kill the deal, even if the 3 weeks each way mail run wouldnt.
I dont want to waste the teak, its a big piece, so that ball rotary burr looks my cheapest option. There is a shop in nicosia that sells that kind of stuff. I dont have any problem doing a day trip up there, its only a mile past IKEA.

novocaine, do not disturb a womans cookery. That should have been rule 1 in your wedding handbook. I'll get by, Norman will help me, wont you Norman?

 

[Woody2Shoes]

I tried a double blade round bit in the drill, even at 2500 rpm it was a disaster, chattered and shook itself all over the place.

The way to avoid this - with any rotating cutter-type tool - is to only have one side of the cutter cutting at any point in time i.e. you move the cutter in a small circle around the edge of the hole - exactly the same logic as conventional vs. climb cutting with a router http://www.leevalley.com/us/shopping/Te ... px?p=56809 . By not doing this, your cutter is simultaneously trying to cut uphill and downhill, on opposite sides of the cutter, creating dangerous instability.

There's a video somewhere out on the web showing someone doing exactly this very successfully (cutting round-bottomed holes in hardwood for a gameboard - just like you want to do - using a jig and core box router bit in a drill press) but I can't for the life of me remember where!

 

[novocaine]

Bob.
Jobbers bit also know as a common all garden drill bit. You must have a couple of them floating about?

I had a 12.5 ground flat as a 2 flute cutter so i modded it to test.

Here you go, like this. Total cost. Free.
Sorry about the links. Cant poat images from phone apparently.
https://flic.kr/p/MxHjDd

https://flic.kr/p/MxHjxw

 

[novocaine]

And now i have a cutter can you guess what i want to make? Damn you Bob. Lol

 

[sunnybob]

imitation is the sincerest form of flattery....
ta very much. 8)

cant be bothered with that though, I'm getting lazier with each passing year. :roll:

 

[novocaine]

You're right. You are

 

[MARK.B.]

Just a thought but could you use a countersink bit,i have one that leaves a great finish which i think would easily hold a marble.

 

[sunnybob]

Unfortunately the countersink is too deep. by the time the holw is the right size it would be through the piece of wood. And no, I'm not going to grind the end off a perfectly good countersink :shock: =D>
Novocaine, no i'm... uhhh.... whatever.

 

[Lons]

Tha holes don't need to be 15mm dia although you might still want them to be and in fact if only 5mm deep surely 15mm will be a little oversize for the marble?

I made one for my kids well over 30 years ago and still being used by my 5 year old granddaughter so can't take a pic.
they are standard glass marbles, whatever size they are, and all I did was use a 12mm bit followed by a ball shaped grinding stone "thingy". Just used an electric drill as no pillar drill at the time.

You would struggle to use a rotary ball without a starter hole as it will move all over the place.

EDIT:
This is the type I mean Bob https://www.ebay.co.uk/p/Toolzone-5pc-1 ... 1097468947 You have to drill the hole first as the stones will just burn, no problem for me as Istained the holes dark anyway.