Recommendation on accurately cutting molding

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Forum topic by Zod posted 12-14-2017 08:24 PM 659 views 1 time favorited 4 replies Add to Favorites Watch
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24 posts in 1471 days

12-14-2017 08:24 PM

Topic tags/keywords: molding trim question advice

I have got some very valuable information on this forum and wanted to see if I can get some advice on cutting molding. For a Christmas present, I am making my wife a nightstand tray that will sit on top of her nightstand. It will also have a stand for her cell phone to charge on it (I am also thinking about making it a lamp with the trendy industrial pipe style she likes). I was thinking that some molding around it would be a nice touch but I have never measured it out or cut it before. I have seen people add molding to the bottom jewelry boxes and that would probably best describe what I am trying to do. I was wondering if anybody had some advice on how to accurately cut the molding. I imagine myself building the sides of the tray and then cutting the molding, only to find out that I cut it too short, or can’t properly adjust it down. I was planning to make the cuts with my miter saw because I haven’t had the time to unbox and setup my table saw (that will be a long process from what I’m seeing online, needing a day) and Christmas will be here soon.

As I complete smaller projects, I always try to add some detail that will help me moving forward. If I can learn to cut the molding correctly, I will be better prepared to add that onto the bookshelf that is on my list of projects. Thanks in advance for any advice.

4 replies so far

View JBrow's profile


1368 posts in 2212 days

#1 posted 12-18-2017 03:24 PM


A 45 degree drafting triangle or perhaps even a speed square could be used to set the mitre saw to 45 degrees. However, I prefer a jig that cuts complementary angles since the jig allows for cuts with minimal set-up time.

Trimming a box with moulding requires mitered angles that when added together equal 90 degrees and each length must be a perfect length and moulding that is of equal thickness. My method for achieving these results is to use a jig at the radial arm saw where the blade remains unadjusted and perpendicular to the fence. This approach could also be used at the mitre saw. It requires moulding that has a portion of the profile that will register flat against the edge of the jig.

The jig is a right triangle where one angle is a true 90 degrees and the other two angles are 45 degrees. It can be made from plywood or MDF screwed together until its thickness is at least 1-1/2” to 2”. One corner must be 90 degrees. A 45 degree diagonal is then cut into the jig (as close to 45 degrees as possible).

The jig is held firmly against the saw’s fence on the left side of the blade. The work piece is held firmly against the jig and the angle is cut on the left side of the blade. While the jig remains flat on the table, it is rotated and positioned to the right side of the blade to cut the opposite end of the moulding. That is the same face of the jig is up whether positioned on the left or right side of the blade. Thus the 45 degree angle of the jig that was away from the fence when on the left side of the blade is now at the fence on the right side of the blade. The second cut is made on the right side of the blade.

If the 45 degree cut of the jig is not a true 45 degree angle, these two angles will produce mitre cuts in the two mating work pieces that add to 90 degrees resulting in a tight fitting mitred joint.

I use short set-up pieces cut from the same moulding stock as that is used on the project. Each set-up piece is cut to a 45 degree mitre using the jig, one cut on the right side of the blade and the other on the left side of the blade. Each set-up piece should be shorter than the smallest dimension of the box.

The first work piece cut is a mitre on one end of the front piece of moulding, leaving the moulding extra-long. The work piece is held on the front of the project and the complementary set-up piece is held on the side of the project and is used to close the mitre joint with the front piece of moulding. The set-up piece on the side of the project is clamped (spring clamp or masking tape) to the project. The front piece of moulding is clamped in place and the opposite end is marked using the second set-up piece. A mitre is cut at the opposite end of the front piece of moulding, but the moulding is cut long. Then it is a matter of positioning the front moulding against the set-up piece clamp on the side of the project and re-cutting the opposite mitre until a tight joint is achieved using the second set-up piece.

Once the front moulding is cut to proper length, it is clamped in place and a similar process is used to cut the remaining pieces of moulding. I prefer to affix the moulding to project at the one time; rather than as I complete the cuts on each piece. This makes it easier to fine tune any pieces that are not quite right.

Milling some extra moulding is my standard practice. I always manage to measure wrong or cut a mitre in the wrong direction no matter how careful I try to be.

View waho6o9's profile


9110 posts in 3868 days

#2 posted 12-18-2017 03:29 PM

Practice on scrap

View Zod's profile


24 posts in 1471 days

#3 posted 12-18-2017 03:32 PM

Thank you for such a detailed response! There is A LOT more involved to successfully doing this than I could have imagined. I try to learn something new with each project and an going to try to work more with molding. I had no system in place and couldn’t get accurate lengths. But following a process has got to be a big help. Thanks!

View Robert's profile


4799 posts in 2772 days

#4 posted 12-18-2017 08:20 PM

On small mouldings like this I prefer to cut the miters with a hand saw and miter box.

Cut them a bit long and sneak up on the perfect fit using a hand plane and shooting board.

Use scrap test pieces to fit each corner so you know what to do.

-- Everything is a prototype thats why its one of a kind!!

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