How can i create a keyhole?

[tyger_purr]

How can I create a keyhole slot?
I have vcarve desktop, so no gadget.

Any other solution?

[Mobius]

I assume you are trying to do so with a keyhole bit?

I just wrote a quick Gcode file myself, since the movements are very simple. It takes like 5 lines of code to make the keyhole at ZERO, and maybe 8 lines of code to do two holes spaced at whatever distance apart.

Or (and I'm planning to do this for an upcoming project but I haven't tested it yet) you could try the following:

Set up your keyhole bit as being an endmill. I will use 1/4" for this example.

Create a rectangle with the long dimension being the length you want to cut the keyhole, and the short dimension being slightly larger than the bit (ie. 0.255).

Node edit the rectangle to make sure that the vector start point is at the bottom (where you want the hole to be).

Now, create an inside profile toolpath, set your depth, select the "use vector start point" button and cut away.

You can preview (slow the speed down) to make sure the bit raises and lowers in the correct spot.

[FixitMike]

To create a keyhole:
Draw a line starting where you want the tool to plunge and ending at the end of the keyhole.
Offset the line a small amount, say .005.
Zoom in, and draw a line across the the end where you want the tool to stop cutting, Trim the lines to each other with the scissors, with the "Rejoin trimmed trimmed sections automatically....." box checked.
Double check with the node tool that that you have a single vector.
Use the Profile On toolpath to cut. Select an end mill of the same diameter as the shank of the keyhole tool you plan to use. You can't put a keyhole tool in the tool list because the program will not accept a tool that undercuts.
Last, double check the tool path by doing a Preview at slow speed with the tool animated to be sure it does what you intended.

Note that using this method, you can cut curved keyholes.

[TReischl]

All you need to do is create a slender U shape (the long legs only about .002 apart. Use Profile cut set to "on" .

Of course you will not be able to see the actual cut because a keyhole bit cannot be defined.

Like a lot of woodworkers I have found keyhole bits last a lot longer if a slot is routed out first.

I see Mike posted about the same time I did.

[4DThinker]

You don't even need a U shape or slightly offset segments. Draw a line from start to end, then continue with another vector back next to where you started. Don't end where you started. Now turn on (N)ode mode, select the last endpoint and drag/drop it on top of the beginning point. Turn (N)ode mode off. Now you have two joined line segments that begins and ends on the same point.

[Xxray]

Probably alot easier and quicker to create them using either a router table, or freehand using a plunge router.

[TReischl]

Probably alot easier and quicker to create them using either a router table, or freehand using a plunge router.

Definitely not.

Centering them up on a router table is a pain. It is a blind operation.

Trying to do them "freehand" works with a template, but not totally freehand. Find template, put in rub collar, locate template on piece, etc.

[Mike-S]

Agree.
I have a canned file to make keyhole slots with origin at the middle so I can precisely place the slot. It's just a skinny V shape.
I run it twice. First time with an end mill the same size as the shaft of the keyhole bit so the slot gets hogged out prior to running the keyhole.
Entry and exit are on the left in the pic.

[Xxray]

Probably alot easier and quicker to create them using either a router table, or freehand using a plunge router.

Definitely not.

Centering them up on a router table is a pain. It is a blind operation.

Trying to do them "freehand" works with a template, but not totally freehand. Find template, put in rub collar, locate template on piece, etc.

Maybe "not" for you, works fine for me.
I have made dozens if not 100's of keyhole slots freehand and on a table. So long as you have the fence set to center the material when it contacts the bit, its not like the utmost precision is called for, easy enough to guesstimate where to start and stop. With a plunge router, a child could be taught to make perfect slots in 5 minutes ... But go ahead and CNC them if you must.

[Mike-S]

But go ahead and CNC them if you must.

It's WAY cooler to use the CNC.

[TReischl]

Definitely not for me, XX.

I have a keyhole program that I keep on the control. That program has zero set to the center of the slot.

Typically I use a vise to clamp up the piece that needs keyholing, so that is very quick.

Make mark on center of board, point laser at it, hit button to set x,y zero at that point.

Touch off tool with electronic zero plate.

Press start button. Done.

AND, they come out perfect every time.

Here is the vise:

Wanna race?

[Xxray]

Wanna race?

You can't be serious.
I'd have a dozen racked off while you are clamping up your 2nd one.
You have a nice setup and I respect your workmanship, but you are not going to out produce a guy pro-efficient in freehanding. Mine come out perfect every time too, if you can follow a straight line then so could anyone else.

[tyger_purr]

Thank you everyone for your replies.

I had tried something similar to what has been suggested but the simulation didn't look like it was working right. The tool went down the path then disappeared. Perhaps I was on the right track. Unfortunately my machine is down for repairs and I was not able to plug it in for a dry run.

[tyger_purr]

Wanna race?

You can't be serious.
I'd have a dozen racked off while you are clamping up your 2nd one.
You have a nice setup and I respect your workmanship, but you are not going to out produce a guy pro-efficient in freehanding. Mine come out perfect every time too, if you can follow a straight line then so could anyone else.

I think if you began with nothing setup and you wanted to create one keyslot it would be faster on the CNC but if you were producing multiple parts you could crank them out faster by hand.

[TReischl]

It sort of depends on how one is "doing them by hand".

If you are using a router table and cutting them in one pass with a keyhole bit it can be very fast, until the keyhole bit snaps off.

Most people I know do a plunge cut with straight bit to clear things out, then set up the keyhole bit to finish up.

One of my products has two parts with ten inch long tslots for hex head bolts. Pretty much the same thing as cutting a keyhole just a lot longer.

I learned long ago that feedrates can be quite a bit faster on a cnc machine than "hand routing" on a table.

When I first started making the product I wanted to route those t slots on the router table while the cnc was doing more complicated work. That did not work out the way I thought it would.

Using a vise with an end stop is very quick, about the same time as to pick up piece and drop it onto the rotating bit in a router table. But then the cnc cuts at a much higher feedrate than is possible by hand.

What I also learned is that routing a lot of tslots (keyholes) with that small shank having to take a full cut results in broken cutters.

I am all for using other shop machines when possible. It is rare when I profile a part to separate it from the stock. I cut to finished width and length and surface to thickness before going to the cnc. For instance, if I were making kitchen cabinet sides I would cut them out on the table saw. WAYYYYY faster than watching a router bit slowly eat its way through 3/4 ply (except for big honking commercial machines). I would use the cnc to cut the required lower corner notch since that is a PITA on a table saw.