Coffered ceilings

[Rmarsh]

For accuracy and good fitting crown moulding joints, I make a block of wood that represents the wall and ceiling coverage...then mark the wall, ceiling and miter saw so that the moulding is cut and then nailed at the same angle. Without these marks you are just guessing. In this case I'm installing crown moulding on a fireplace mantle that I am building.

[nightfighter]

Great illustration of how to make repetitive cuts of the correct spring angle. Many DIYers assume the spring angle is 45 degrees. It is not, normally.
I also make idiot blocks of miter cuts and mark them for left inside, right inside, left outside and right outside. This helps me avoid errors in setting up the saw and cutting the wrong end of the stock, which can be costly. Also helps avoiding cutting upside down.

It is worth noting that I back cut the inside joints whenever possible.

[Rmarsh]

Originally Posted by nightfighter

Great illustration of how to make repetitive cuts of the correct spring angle. Many DIYers assume the spring angle is 45 degrees. It is not, normally.
I also make idiot blocks of miter cuts and mark them for left inside, right inside, left outside and right outside. This helps me avoid errors in setting up the saw and cutting the wrong end of the stock, which can be costly. Also helps avoiding cutting upside down.

It is worth noting that I back cut the inside joints whenever possible.

That's right Ross very rare for spring angle to be 45. I am fluent with Autocad and at the millwork shop I worked for I drew custom moulding profiles. Once the drawing was perfect it was downloaded to a cnc machine to cut a pattern, from there the hardboard template was used to cut the profile on the steel knives used in the moulding cutter head.
We could...in an eight hour shift go from drawing board to producing hundreds of feet of custom crown moulding in any wood species required.
The moulding cutter head has three steel knives, after grinding the knives to the correct profile with a special machine using the template...they must be weighed on a digital scale, and tweaked until they all weigh exactly the same, before being installed into the cutterhead.