40mm ball end drill bit

3762 Views 24 Replies 12 Participants Last post by Tomchimera, Jul 15, 2021

Tomchimera

Discussion Starter · Jul 11, 2021 (Edited)

Hello everyone, I'm new here

Can you help me find a 40mm diameter drill bit, that have a round end.
I need to make bowl shape cut so that 39mm ball can sit inside, having half of the ball exposed like in the picture, but from wood of course.

I saw this A which said 40mm in the title but then bellow it had different numbers.

It assume what I need can be either:
1. Ball bit
2. round top routing bit (like in the picture)
3. regular drill bit but with a round end

Thank you very much for any advice!

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1 - 20 of 25 Posts

BigCountry79

· #2 · Jul 11, 2021 (Edited)

Edited to use the right name

They make some for routers called core box bits. I think a plunge router would work great for this.

That burr ended drill bit will likely not cut the divot quickly. I suspect you will spend a lot of time clearing the waste from the area. I've never used one.

John Smith_inFL

· #3 · Jul 11, 2021

Tom - welcome to the forum.
perhaps if you describe your project to us, we could understand the tools that you need.
how many do you have to make ?? what is the ball made of and what does it do ?
what kind of wood are you using ?
understanding your project, there may be other options available.

Bob Bengal

· #4 · Jul 11, 2021

Welcome to the forum.

Cove bits typically have a bearing at the end, they cut a 1/4 circle out of a corner etc.

MLCS Core Box and Round Nose router bits

MLCS Woodworking Core Box and Round Nose router bits cut a round bottom groove

www.mlcswoodworking.com

A "core box" or "round nose" bit can work, if you can find one the right size, most are smaller than you want. In that link there is a 1 5/8" bit = 41.28mm.

John Smith_inFL

· #5 · Jul 11, 2021

I am seeing a two step process: a Forstner bit to make the hole, then another bit of some kind to make the round bottom.
depending on the project and how many to make would be a determining factor in the selection of tools.
also - what tools the O/P has access to and his skill level.

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woodnthings

· #6 · Jul 11, 2021 (Edited)

Reason you can't find a round end drill, is because that type is NOT a "drill"! A drill will not drill if it has a ball end. What you want is a core box router bit:

www.amazon.com

Amazon.com: Rannb Core Box Router Bit 1 1/2" Cutting Dia 1/2" Shank Round Nose Router Bit : Everything Else

Amazon.com: Rannb Core Box Router Bit 1 1/2" Cutting Dia 1/2" Shank Round Nose Router Bit : Everything Else

www.amazon.com

Dimension
Standard 1/2" x 1 1/2"
Radius : 19mm / 3/4"
Total Length : 57mm / 2.24"
Shank Diameter : 12.5mm / 1/2"
Cutting Diameter(Approx) : 38mm / 1 1/2"

You don't need a plunge router, a drill press will work.

Reactions: 1

ajdragon

· #7 · Jul 11, 2021 (Edited)

Hi

Is this what your looking for, it is 2mm bigger then what you are looking for. As for that ad, the numbers are for the tread size to determine what angle grinder they can be attached too.
2" core box router bit

m.n.j.chell

· #8 · Jul 11, 2021

Welcome to the site. Perhaps the better question is ... Are you only wanting this done once? If you're thinking of doing such work more than once, then it might be time to look into getting a lathe.

Tomchimera

Discussion Starter · #9 · Jul 11, 2021 (Edited)

Hi all, thanks so much for the answers!
I learned a lot of things.
So I understand what i'm looking for is not a drill , or a burr drill but a core box router bit / cove bit without a bearing.

I have pretty good hobby workshop, but my friends have big furniture carpentry/small factory, so I can work there anytime.

I'm planning to make about 50-100 at the moment, but wanting to be able to produce more in the future.

This project is for resonance dampening

I wanted to have my PC, few sets of speakers and other equipment have less resonance, both for the sound and the safety of the devices, I'll be making a lot also for my musician friends with music studio.
After some research I found out that among the endless inventions that can costs thousands of dollars, many people use Squash Ball for dampening.
Specifically people say "Tecnifibre Double Yellow Squash Ball" have the best dampening qualities.
Many people in the 3d printing community also making mountings for these, that you can see here:

Search Thingiverse - Thingiverse

Download files and build them with your 3D printer, laser cutter, or CNC. Thingiverse is a universe of things.

www.thingiverse.com

The ball is made of mostly rubber, and the wood I'll be working with will be oak, but if it will be too hard perhaps pine or birch plywood.

A device can sit on 4 balls or 8 or even 12 or more.. hence the large amount.

The Ball diameter is 39mm so I thought to get a bit that 39-42 mm as I'll be filling glue anyway between the ball and the bowl.

I see that the 1 1/2" core box router bit is 38mm! almost

I guess I better search for 1-5/8" or if I can't find it 1-3/4".

I also found this but your options are much cheaper, also, the reviews are not good..

www.amazon.com

OrbiCut 40 Low Speed Cutting Tool by Plano - - Amazon.com

OrbiCut 40 Low Speed Cutting Tool by Plano - - Amazon.com

www.amazon.com

Thanks!

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epicfail48

· #10 · Jul 11, 2021

Look for a ball-nose end mill

Bob Bengal

· #11 · Jul 11, 2021 (Edited)

I'm confused, a few minutes ago @Tomchimera had a post here that better explained his needs etc, I guess moderators removed it for a terms of use violation?
Edit: Now his post is back. Some kind of weirdness.

He said he needs to fit a 29mm squash ball to make vibration isolators etc for equipment. A 1 1/4" core box bit is 2.75mm larger. Or you can use a 1 1/8" bit and with a template for your router to enlarge the hole.

The examples linked to seemed to fit the ball, not have a large glue filled gap? There only needs to be enough glue to hold the ball in?

HoytC

· #12 · Jul 11, 2021

Spherical burrs and box core bits can be difficult to plunge and control. I would avoid that by using a 40 mm Forstner bit first. Then 3D print an insert that provides the inside hemisphere, gluing it in at the same time as the ball.
Of course you need a 3D printer

Tomchimera

Discussion Starter · #13 · Jul 11, 2021

Hi @Bob Bengal, I edited my post because I mistakenly wrote 29 instead of 39mm, so probably it needed to be reapproved by moderators.

As for the glue, I'm not an engineer, but in my little understanding, with subwoofers for example, if there is a small gap between the mounting and the rubber ball or they are not connected, due to vibration the speaker box can jump against the rubber like a spring (in microns), whereas if the speaker is connected/glued to the mounting and this is glued to the ball - the vibration can travel to the rubber ball which than act with it's modulus of resilience and convert the vibration into heat.

I think in those 3d printed, some are gluing it but not all..
My backup plan is to just drill a 40mm diameter hole, in the depth for half the ball and fill it with glue..

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John Smith_inFL

· #14 · Jul 11, 2021

Tomchimera said:
Hi @Bob Bengal, I edited my post because I mistakenly wrote 29 instead of 39mm, so probably it needed to be reapproved by moderators.
My backup plan is to just drill a 40mm diameter hole, in the depth for half the ball and fill it with glue..

yes - the edited post had to be approved by a mod (it just tripped the sensor, and was approved).
if you drill just a flat bottom hole with a forstner bit, then put in some epoxy and put in a round object the size of the rubber ball and let the epoxy set, then removed the mold, would that work ? then you would have and exact fit between the bottom and the ball. (just thinking out loud here).

Bob Bengal

· #15 · Jul 11, 2021

Tomchimera said:
As for the glue, I'm not an engineer, but in my little understanding, with subwoofers for example, if there is a small gap between the mounting and the rubber ball or they are not connected, due to vibration the speaker box can jump against the rubber like a spring (in microns), whereas if the speaker is connected/glued to the mounting and this is glued to the ball - the vibration can travel to the rubber ball which than act with it's modulus of resilience and convert the vibration into heat.

Ok, a 1 5/8" core box bit = 41.28mm, or a little over one mm gap all the way around to be filled by glue. With a 40mm Forstner hole I wonder if the characteristics of the glue or epoxy would be an issue, I don't know.

HoytC said:
Spherical burrs and box core bits can be difficult to plunge and control.

I haven't done this before. The way I'd try it:
The work piece is a wood cube, with a drill press drill a 1/2" hole to almost the depth of the finished hole, to make it easier for the core box bit.
Put the cube in jig that holds both it and the base of a plunge router steady, so you don't have control issues.
Plunge a 1 5/8" core box bit, but probably not all the way with one stroke, raise the bit out to allow the heat and chips to get out, maybe have an air hose handy to blow out the chips.

kwoodhands

· #16 · Jul 11, 2021

Tomchimera said:
Hello everyone, I'm new here

Can you help me find a 30mm/40mm diameter drill bit, that have a round end.
I need to make bowl shape cut so that 49mm ball can sit inside, having half of the ball exposed like in the picture, but from wood of course.
View attachment 429098

I saw this A which said 40mm in the title but then bellow it had different numbers.

It assume what I need can be either:
1. Ball bit
2. round top routing bit (like in the picture)
3. regular drill bit but with a round end

Thank you very much for any advice!

View attachment 429099

Your hole will be quite large, 40 mm is about 1-9/16" or so.

Tomchimera said:
Hello everyone, I'm new here

Can you help me find a 30mm/40mm diameter drill bit, that have a round end.
I need to make bowl shape cut so that 49mm ball can sit inside, having half of the ball exposed like in the picture, but from wood of course.
View attachment 429098

I saw this A which said 40mm in the title but then bellow it had different numbers.

It assume what I need can be either:
1. Ball bit
2. round top routing bit (like in the picture)
3. regular drill bit but with a round end

Thank you very much for any advice!

View attachment 429099

Diablo 1-1/2" round nose bit
DR18134 Home depot sells these at about $46.00
I bought one and have used it for about 15+ hours total. Still sharp .
mike

epicfail48

· #17 · Jul 11, 2021

Wait, i missed the size. Yeah, dont bother trying to drill a spherical hole that size unless you need to. Go with your backup plan of just potting the ball in glue, way simpler and itll do the job just as well

John Smith_inFL

· #18 · Jul 11, 2021

the outside diameter of a ping pong ball is 40mm - - - - if that could become an option to cut it in half then epoxy that into the bottom of a flat bottom hole that a forstner bit would leave.

Reactions: 1

Tomchimera

Discussion Starter · #19 · Jul 12, 2021

I just realized, like @epicfail48 said, that my backup plan was the simplest solution, to just drill a 40mm diameter regular hole and fill it with glue with the ball. I guess in the back of my mind it seemed crude and cheating.

Luckily I have a lot of Hybrifix super 7 from another project.

I'll upload pictures of the project.
Thanks again for all the good information!

Reactions: 2

epicfail48

· #20 · Jul 12, 2021

Tomchimera said:
it seemed crude and cheating.

If it gets the job done it gets the job done, any other descriptors dont matter. Simple is better in the end

Reactions: 1

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