Molding on the CNC

[jteneyck]

Ever wanted to make a special piece of molding?  Maybe the gooseneck molding for a grandfather clock, or a molded oval mirror frame, or a few pieces of crown molding for a cabinet?  It can all be done by hand, of course, but none are quick or easy to make.  With a CNC, however, it's readily doable.  The design phase is incredibly easy in VCarve Pro.  You just create the outside shape you want and "join" the cross-sectional view of the profile you want to it.  To try it, I drew this simple curve and picked one of the stock molding profiles.  



After you run the toolpaths this is what the simulator shows it will look like.



There are two toolpaths that need to be run to turn a piece of wood into the molding.  A clearing cut and a finishing cut.  They are shown at the lower right in the photo above.  

The clearing cut was done with a 1/4" end mill (spiral upcut router bit).  It looked like this after it was done.



What it's doing is cutting retangular recesses to get rid of the bulk of the material.  When that's complete, you change bits, to a 1/4" ball nose endmill in this case, and run the finishing cut.  When it was done, it looked like this. 



You could cut the outer dimensions out of the board with another toolpath, but I did it by hand, imagine that, on the bandsaw and then sanded the edges smooth.  And here is the final piece of molding.





Those surfaces are straight from the CNC with no sanding.  If you look closely, you can see some striations on the curved section, but they should be easy to remove with light sanding.  

This piece took about 30 minutes to machine, so you wouldn't want to try to make a lot of linear feet this way, but for small quantities it's probably the cheapest way to go about it because you don't need to buy tooling.  Stock router bits used for typical CNC work are all that's needed.  

If you need moldings for a special project and are having a hard time sourcing it, or don't want to make it yourself, I might be able to help you out.  Happy to help if I can.  

John

[barryvabeach]

John, thanks looks very good.  I would have guessed that it would have taken much longer and a lot more passes to get something looking that good and avoid a lot of tearout.

[jteneyck]

John, thanks looks very good.  I would have guessed that it would have taken much longer and a lot more passes to get something looking that good and avoid a lot of tearout.

I was as surprised as you Barry.  But I'm learning that the machine is capable of amazing precision and smooth cuts if I follow the preselected tooling parameters.  Whoever developed the programming at Vectric knew what they were doing.  

John