Jig for Cutting Perfect Crown Molding

by darbinorvar

26K14611

Intro: Jig for Cutting Perfect Crown Molding

Cutting perfect crown molding can definitely be a little tricky, as the various angles and compound cuts can be quite confusing. I made a simple jig to make it easier and safer and in this video I'm will go over how to create your own. Also, make sure to watch the video for a better perspective on the process!

STEP 1: Angles

What's really confusing about crown molding is the fact that it sits half way between the ceiling and the wall, so in order to have it line up in the corners you need to make angled cuts. When you're working with crown molding you're primarily working with inside and outside corners.

STEP 2: Cutting the Angles

There are two main ways to cut the molding. You can either flip it around (so it's positioned opposite from the way it's supposed to go on the wall), thereby gaining support by finding the sweet spot and holding it at an angle when cutting. The one thing about this method, is that you have to think upside down. The other option is to hold it the way it actually will sit against the wall, however in that case it's a lot easier and safer if you have a jig.

STEP 3: Making the Jig

To make the jig, first position the molding as it will go on the wall, and measure how far out and how far up it will go.

STEP 4: Get Your Cutlist

These measurements will determine the interior distance of the jig which you will need the molding to be cradled within. Now you can create a cut list based on these measurements.

STEP 5: Cut & Assemble

Cut your plywood to size and assemble with glue and a pin nailer.

STEP 6: Use the Jig!

Now you can hold the molding within the jig when cutting the crown molding and it's nice and sturdy.

STEP 7: Cutting Inside and Outside Corners

When it comes to actually cutting inside and outside corners it can be a little confusing, and it's usually helpful to do some practice cuts and models. Here's a map of what cuts you need.

STEP 8: Conclusion - Watch the Video!


For a much better perspective of the process, to see the jig in use, and for more tips, make sure to watch the video!

9 Comments

curiousity shop 5 years ago

Like the idea. Might suggest making the jig a little longer and mitering the ends to give more support near the blade so there is less material hanging out in mid air. Of course it would require 2, one for inside and one for outside.

Norm1958 5 years ago

Thank you for this video, your solution to a problem is brilliant in it's simplicity.
Having renovated some old houses I can say crown molding is for covering big gaps in corners that are never square or straight or plumb. Accurate measurement is difficult.
With this simple jig you have a secure way to hold the material in a way that presents the material in the way it will be installed, so you don't have to flip the cuts over in your head which frequently leads to errors on a Saturday afternoon.
If the place is crooked, cut the bits a little long and fit them with a block plane or coping saw after this brilliantly simple jig has done the hard work safely and put you into the finishing arena.

Timbergetter 5 years ago

Hi Linn, Thank you for your excellent videos. I do enjoy your work.

I prefer to cut the moulding with the board lying flat on the saw bed and set the required angles for mitre and bevel from these formulas:

Mitre Angle = ATAN(COS(b)*TAN(a/2))
Bevel Angle = ASIN(SIN(b)*SIN(a/2))

where a = angle between walls
and b = angle of moulding incline

Key the formulas into a spread sheet and you will be set.

RobDeVoer 5 years ago

Having done my entire house with the same moldings i understand the dilemma of mixing a corner up inside your head. Messed up a few cuts for sure. I really enjoyed your honest and practical advice. Keep up that humor! You made me laugh. Very much appreciated, thanks.

charlessenf-gm 5 years ago

Thanks for sharing the idea and jig. Appreciate that, in Step 7, you showed the actual guide you made - corrections and all! Crown does get confusing. And, as it is not cheap material, cutting a 12 or 16-foot section incorrectly - well, you know.

billbillt 5 years ago

GREAT IDEA!... MY PROBLEM IS THE WALLS ARE NOT AT RIGHT ANGLES.. THAT THROWS ALL OF THIS OFF... I HAVE NEVER SEEN AN OUTSIDE CORNER THAT WAS PERFECTLY 90 DEG....

charlessenf-gm 5 years ago

Yes, so true. As well, the walls are not necessarily 'perfectly' plumb nor square to the ceiling.

As my grandpa would say " 'tis a poor workman that blames his tools."

And yet, literally millions of homes (over a hundred years or more) have had crown molding installed professionally and otherwise so it certainly is possible.

Do you know what coping is?

As well, precise measurement of the angles and transfer of said to the cutting tool helps.

I like: https://www.thisiscarpentry.com/2015/04/03/install... Katz is the man!

charlessenf-gm 5 years ago

In Step 3 "Making the Jig," you placed the molding on the Mitre saw, holding it (tenuously) such that the face that would fit flush to the wall was held flush to the back of the mitre saw to measure the depth (2) and the height (3).

Now, if you rotate the piece and position it as in "Step 2 Cutting the angles (image first)."
Would it not be easier (possibly more precise) to measure the distances required?