The multi-versatile keyhole bit

I really like the idea of the sliding perpetual calendars ever since I came across one on GrabCad.
I remodeled this one to make it a little more of my own and made one.

While I still liked the main idea of the calendar, I didn’t like the way the sliding parts worked. Especially having to put some sort of washer and screw on the back to hold it all together. I wanted to be able to mount these flush like a regular wall calendar.
So I started brainstorming and had the idea of using a keyhole bit to cut the channel for the slides. So with a little bit of experimenting, I found that keyhole bits are very versatile.
I found the best way to make these cuts is to clear with a 1/4(0.25)" endmill first, down to the bottom of your keyhole, then come back with the keyhole bit (I’m using a 3/8(0.375)"). For my calendars, I’m using a single pass at 5/16(0.3125)" deep. I’m using 3/8(0.375)“LG 10/24 panhead machine screws that I tap into the back of the calendar windows. The maze you see in this picture…I made two passes, one at 1/2(0.5)” and one at 5/16(0.3125)" deep. The keyhole section of my 3/8(0.375)" bit is 3/16(0.1875)" thick. This made a 3/8(0.375)" “hidden” pocket. I dropped a 5/16(0.3125)" ball bearing in and voila, a ball maze.
So with this little bit of information, I’m sure you guys can come up with some amazing, pun intended, projects for your keyhole bits.
As for the calendars, with a little more testing with fonts and toolpaths I feel pretty good about them. I actually have my first order of six I’m working on now.
Make sure you edit your G-code to retreat the keyhole bit slowly.

I changed the font for the months and double dates after I made these two.
They are much better now.


That is really cool - I like it!


Thanks for sharing, James!


James that is a great looking set up for a callander Did you get it from Grab CAD
And what is grab cad.
Thanks Jeff Peters

Grabcad is a site which stores various CAD designs:

mostly in commercial/proprietary formats.

Can that callender file be downloaded from a format that can be used
CC pro

It was linked in the first post above:


I got the idea from the grabcad model. The model is linked in the first post.
I just wanted to make it more my own and realized the keyhole bit could be used for the window slides.


Are you a Clemson fan?

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Yessir! Orange has been my color since birth. :smile:
I was 9yo when we won our first championship under Danny Ford.


Hi Guys coming from The UK … What is a Clemson Fan??

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Ha, I had to Google that too :slight_smile:
The paw logo gave it away


You know that unidentifiable stuff you get on the bottom of your shoe and you can’t decide if you should use a stick or just toss the shoes? It’s that.
Go Bucks!

@themillertree I respect everything else about you.


Ahhhhh a football team… Thanks Julien… The image looks great… Hope your well Julien

Neil let me just Google The Bucks now

Come on, that’s not football.
THIS, is football :rofl:

and now I heading out before I get a beating :rofl:


now your talking…Zidane and Carlos… I was nearly that good fifty years ago… finished playing 1 year ago at 65yrs young


As long as you spell it with a “soccer” :rofl:

nah, that’s just the fact that you’ve never beat us that is stuck to your shoe. :stuck_out_tongue_winking_eye:

all respect to both of you

I wanna throw in a little “Go Dawgs!” here.