In the CNC industry, Dogbones Fillets are a great way to allow vertical plates to be inserted into horizontal plates without out having to worry about the radius left from the cutter.
Depending on the thickness and size of the part will affect the size of the dogbones needed. When possible, its best to use a 0.8mm radius as this will help keep the machine time down. A small cutter such as a 0.5mm radius can be used but it will take more passes and a slower cut rate, which will increase the cost of the parts.
If you wish to not use dogbones when making slots for a vertical plate, you can also ensure that you get a better fit by making the slot longer then needed to allow for the radius of the inside corners. Although, this may make the part a bit more loose in the slot.
Types of Dogbones
This is the most common dogbone used. It’s great as it gets the radius of the cutter outside of the slot to allow a good fitment of the parts. The only issue is if the slot is close to an outside edge or another hole, it can get a bit too close as it requires a bit more room.
Here are a couple great alternatives to the above dogbone. They works well when there is less room but they have one downside. On narrow slots, the material remaining at the ends of the slot are very small and may not hold properly. This is more suited for wider slots where more material can be left behind to hold the part.
Horizontal Plate Dogbones
This is the standard slot cut into a base plate for vertical plates for such things as a camera plate or antenna holder.
This shows the results of cutting a slot with no dogbones. The red shows the area that would not be cut out from the part. This is the radius left from the cutter in each corner.
When two parts are put together when no dogbones are used, you can see that the square edge of the vertical plate would not be able to be inserted into the the slot as the radius left behind will interfere with the fitment.
With dogbones on both the vertical and the horizontal plates, you can see that the radius left from the cutter are outside of the area needed for the parts to fit properly.
Vertical Plate Dogbones
This is the standard slot cut into a base plate for vertical plates for such things as a camera plate or antenna holder.
This shows the results of cutting a slot with no dogbones. The red shows the area that would be cut out from the part. Note the radius left from the cutter in each corner.
This shows what it would look like when the two parts are put together when no dogbones are used on the parts. Note the radius left from the cutter prevents the part from fitting all the way down to make a clean contact with the horizontal plate.
This shows the result of using dogbones. You can see the radius left from the cutter is moved further up into the corners so that it doesn’t affect the fitment of the parts. There is clear contact without having to file the corners after the parts are cut.
Example
This is an example of a full frame setup that shows the base plate, top plate and camera plates all with dogbones. With a setup like this, there should be little to no filing of the parts to get them to fit together.