Door Trim BEST Miter Techniques?

tyler durden

I am just wandering what is the best method for 45deg mitrer cuts on primed mdf trim like around doors and windows.

Do you caulk, glue joint.

I have seen some that are seamless and that is the level I would like to be at.

I understand a good blade and saw are the most important.

Also what about nail holes? I hate filling them and would like a one coat no shrink or sand down method.

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neolitic

Glue.
Minwax putty.

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Chris G

Pray for flat plumb walls, with jambs that are flush with the surface. Other than that, a good nailer and a pocket full of shims can help

tyler durden

I guess I mean the 90deg trim corners the actual corner.

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Chris G

I understand that. But the work of the person previous to you, (framer, drywaller) has a huge effect on you joints. If you really want tight joints, use a biscuit joiner. Ryobi makes one that uses small biscuits. All the other joiners use biscuits that may be too big for thin mdf.

toolwiz93

As you stated a good blade is key. I would use a very fine blade but not a thin kerf. From there a lot depends on the trim size, if at all possible use a biscuit. Once you have the set-up figured out, it takes very little time to cut the biscuit slots. I like to start with the head piece, cut it and nail it into place. Now that your headpiece is done you only have to fit one angle at a time for the side pieces. Start the side pieces a little long if you prefer and trim until perfect. For the glue at the miter you can use a liberal amount of regular wood glue or titebond's moulding and trim glue. It is thicker but it will act as a filler if the joint isn't perfect. If you do use this glue, don't be alarmed when you come back to a piece you put up an hour ago and see what looks like a gap in the joint, the glue dries clear. I only nail the side pieces to the jamb or frame until the glue dries. This prevents the miter from opening up when it is nailed tight. I like to stay away from the mitered corner about 10-12 inches on the sides. The miter is glued and the headpiece is nailed tight it cannot go anywhere. Be careful if you try and pin the corners, mdf likes to split. If you have large enough moulding use a screw from the top down. Make sure it is a pan head and not a flat head. As for filling the nails holes, use the "pink stuff". It is a sandable filler for DAP, goes on pink, when it is dry it turns white. MDF takes some getting use to, but it is straight and uniform which is the first key to good miters. GOOD LUCK

tyler durden

Yea I have used the pink stuff before
but it does shrink and needs 2 coats and sanding. I wish it dried pink so I could see where to sand.

I agree with what you say, I like perfection without too much wasted time. The biscuit may be a bit much for average homes. But I think itis a good idea. I have a large dewalt unit though

Does anyone use a jig or template for 22.5deg bullnose base corners?
I don't use the round trim corners. They are to sloppy looking.

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trav007

Try this....when you cut your 45's bevel the saw blade about 1 - 2 degrees in order to take off more material in the back side of your joint. ( or just back bevel it with a block plane ) Use trim glue, lock nail, fill, caulk, paint.....done, beautiful, easy.

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ELM

How do you mean "lock nail" exactly?

trav007

I mean put a brad or nail through the side and top of the mitre joint and into the opposing piece of trim; it will help hold the joint together by opposing the tension caused in both directions by the shrinkage factor.

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Stickman

Trav 007, Do you use a pin nailer to do your lock nailing?

vanderpooch

Tyler,

If you want perfect miters without a lot of fussing, you need to be pre-assembling, especially with mdf. If the casing is not too large, I like to glue it with 2P-10 adhesive. If you don't know about this stuff, you need to.

- Kit

415moto

Glue the joint.
Other than that, its just skill and experience.

Caulk doesnt hide bad craftsmanship.

Corners arent always 45s, walls arent always plumb, neither are windows.

Use a quick setting glue/adhesive or wood glue and miter clamps. Good work takes time.

trav007

18g brads. 1 1/2 to 2"

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neolitic

To lock nail MDF??

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TimelessQuality

That also works if you just take 3-4 degrees back cut off of one half of the miter. I used to do this with my old makita cms that would only bevel one direction. It all depends on the situation.

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Stickman

Like I said in other post I am still new to this and learning but I would thing using 18g brads. 1 1/2 to 2" would be risky? As far as the length goes, you don't worry about them twisting out on you? I will have to to give this a try next time. Thanks.

chris klee

i measure and cut all 3 pieces at the same time (or 4 for a picture frame window).
then i tack one side on on the door frame side with my 18ga gun with 1-1/4" nails. line up the top miters, lock nail it. line up the other corner and side piece, lock nail it, nail it to the door jamb. go back with the 16 ga finish gun to nail to the wall.

works very well for me 99% of the time.

oh yeah, slight back bevel, and glue miters are a must

Millwork

First thing I would do is stay away from MDF in any moulding or trimwork.

MALCO.New.York

Amen!

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