Rounding square door trim

HouseRemodJune 19, 2014

I'm trimming some interior doors. For esthetics, I'm going to be doing a square type trim. By that I mean, I'm not going to be doing 45 degree angles and putting them together but rather doing something like this

I'm going to use MDF trip pieces from a box store for this. Does anyone have any idea of how I round the cuts that I make. They typically have some saws at those stores, but I don't think they'll properly round off the edges that you cut.

Anyone have any ideas on how I get this done?

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I don't understand what you mean by 'rounding the cuts'.

That type of trim is usually done by simply cutting to length and installing.

If you mean easing the edges---taking the sharp edges off the material, there are a couple of ways. A trim(or even regular sized) router with a roundover bit, simply sanding the edge with a sander, or a hand tool designed for that purpose.

MDF is acceptable for several uses as trim, doorways are not the best place. The MDF will dent/chip/delaminate if hit.

    Bookmark   June 19, 2014 at 12:19PM
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Same advice here. I'd probably go with poplar as it works and paints well. MDF is also prone to damage if wet.

Hereis a tutorial on round-over bits and techniques. I would definitely recommend a ball bearing bit and not just a bushing.

You might be able to rent a router at a big box or rental store, or for a one-time use, just go to Harbor Freight.

    Bookmark   June 19, 2014 at 2:35PM
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If you are butting the trims to each other (as opposed to mitering/picture-framing) remember not to round over the head casing, as you will not get a nice joint as the rounded-over edge meets the square butt end of the vertical member. A lot of people prefer to treat the head as an architrave and trim ot out accordingly, with a half-round bead added across the bottom and a crown-molding -like cap. Like:


    Bookmark   June 19, 2014 at 4:36PM
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Casey,that is a humdinger of a doorway. Is the whole place done in that? Quarter sawn white oak????

    Bookmark   June 19, 2014 at 11:22PM
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Thanks for the compliment! I fooled you; that;'s grain painting from my artistic youth. I had a fair faux quartersawn, and got the "golden oak" color pretty close, didn't I?
It's a hollow-core door, and new pine trim. Well, new in 1987.

    Bookmark   June 20, 2014 at 7:41AM
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Casey, you are too much!

    Bookmark   June 21, 2014 at 1:08PM
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Thanks for the information.

For the MDF, all but one door will be interior, so I don't think water will be an issue. The exterior one is completely covered in a foyer outside. I'm having a hard enough time finding MDF I like and I think rounding raw pieces of wood might be tough.

In terms of the tutorial, what I'm not getting is how exactly you use a hand tool and make the pattern precise and straight. I would think you need some sort of table device for that.

Is there likely a shop that can cut this and route it for me. i'm sure Lowe's or wherever can cut it but I don't see them edging the wood.

    Bookmark   June 21, 2014 at 11:10PM
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You need a router and a roundover bit of your preference (between 1/4"R an 1/2"R). Time to gear up. Unless you have a nearby relative or pal who's into woodworking.

    Bookmark   June 22, 2014 at 9:29AM
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The moisture we are speaking about is more humidity than actual water(rain/etc.) MDF is simply paper glued and formed in a huge press into 4' by 8' sheets(unless a speiall press is used for different sizes/etc.). That means it is especially susceptible to moisture damage from simple humidity.

And the fact door trim is constantly being hit/rub into. MDF is simply not, by far, the better material for the application. MDF molding is used for crown molding(out of harms way). MDF is difficult to handle when produced in sizes like that for door molding---a piece 3" wide, 1/2" to 3/4" thick, and 7 feet long can break easily is mishandled.

Go to a real lumber yard and you should be able to buy poplar or pine boards in the size you need. A full service yard might even have the roputer facilities to do the rounding over.

Other wise, a hand router---a small detail model and the roundover bit Casey recommended---is the only inexpensive tool.

    Bookmark   June 22, 2014 at 10:21AM
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Thanks. I'll hunt for a local wood shop and use your advice there. I'll sound less clueless now for sure.

    Bookmark   June 22, 2014 at 3:58PM
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Definitely go with the poplar, Baird Brothers sells this round over modern trim.

Here is a link that might be useful: moulding

    Bookmark   June 22, 2014 at 8:53PM
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"â¦(MDF)susceptible to moisture damage from simple humidity."


Can you substantiate this please?

    Bookmark   June 29, 2014 at 9:14AM
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Humidity begets condensation.

MDF stands up to moisture about as well as graham crackers. A few water drops will raise small bumps on the surface. A long soaking will make it swell to twice its original thickness. So MDF is a risky choice for baseboards in entryways and trim near tubs or sinks. My all-time greatest MDF mistake was using it for windowsills in my own home. Condensation from the windows made them swell just like the baseboard shown here. If you use MDF as baseboard, be sure to paint the lower edge before installation. That will provide short-term protection against occasional spills. Also install the baseboard about 1/4 in. above the floor and then cover the gap with wood base shoe molding. There are moisture-resistant versions of MDF, but theyâÂÂre hard to find. To find manufacturers and dealers, search online for âÂÂmoisture resistant MDF.âÂÂ

Read more:

Here is a link that might be useful: Web site

    Bookmark   June 29, 2014 at 11:19AM
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