As dumb as this sounds, I always struggle putting casing around a door frame. I can get perfect 45 miters, that's not the problem. But getting the verticals to line up correctly with the top horizontal piece seems to mystify me. Maybe it's a matter of me not knowing where do you start. Do you put the horizontal piece on first? In the past I've mostly just started on one side, then the top, then the other side. So how do the pros do it? I've got 2 doors to trim out in the shop and though I'd take some time to learn the proper way....even though I'm not worried about how it looks.

Thanks for the topic Fred.  I have three windows to put new trim on.  It will be good to see how the pros do it.  In the past I have done the sides first and then cut the top to fit.

Edited June 10, 20206 yr by Cal

At the risk of saying what you already know, here's how the old timers taught me...

 

Mark a 1/4" reveal in several spots with a combination square.  I usually start on the left side and work my way around.  Sometimes I make the miter cut a bit long and trim the square end as needed to make it work.  On a concrete floor, you might want to leave a gap so the wood doesn't touch.  A spot of yellow glue at the miter, and also nail through the edge at the miter.  4 penny nails into the jamb and 6 or 8 into the jacks and header.

 

Of course, if the jambs aren't square there will be gaps.

 

With windows, mark the length of the sill by setting a scrap piece of trim in place and rolling it 90⁰  at each side.  Or just picture frame it.

Hope there's something here you can use.

Jim

 

 

The last door that I hung had its own casing.  So, it was ensuring that the opening at the top and bottom were the same distance apart, that it was actually vertical, off the floor sufficiently to open and close with only the sweep touching.  I had done a bedroom door that was horrible to fit.  The casing was fine, I thought.  I checked the used door and perfectly square, but it would not fit the opening.  Measured.  Unbelievable.  The middle of the door was the narrow point.  The hinge side was straight, but the latch side was concave just above the latch.  So, I put the door on the hinges, pulled it to the frame with the knob cut out, used a pencil to trace the casing onto the door.  I then used a router to make the door fit.  Of course, since it was the latch side, that side had to be angled so it would clear the casing.  It has worked perfectly for the past 16 years and no one would ever believe all the patching and adjusting to make it fit.  It looks normal, but I can point out all the flaws.  Thankfully, no one else sees all the deviations from a straight and plumb door.  

 

Yes, I would do the hinge side first, ensuring that it is plumb, install the latch side and get it as plumb as possible, then insert the top.  I think you can do this if you just do the steps.  

I never cared for the 45° corners.  I prefer this look and find it easier to do.

 

One more option.

John

1 hour ago, HARO50 said:

One more option.

John

I have used this method in my kitchen

I agree with the 90 degree joint.  I have seen 45 degree mitres and they often don't look good.  I have also seen it done on exterior parts of the windows and doors allowing rain water access to the stiles.  

10 hours ago, Gunny said:

I have used this method in my kitchen

Every interior door in our house was done that way. 

10 hours ago, Gunny said:

I have used this method in my kitchen

I have been commissioned to recreate some of those corners on the lathe over the years.  Somehow they go missing.

Here's a tutorial.  Brief overview: top first.  Don't measure, mark.

 

https://www.familyhandyman.com/article/how-to-trim-a-door/

2 hours ago, kmealy said:

Here's a tutorial.  Brief overview: top first.  Don't measure, mark.

 

https://www.familyhandyman.com/article/how-to-trim-a-door/

Don't measure? Heresy, I say! 

51 minutes ago, Gene Howe said:

Don't measure? Heresy, I say! 

Well, you don't say, "This piece needs to be 40 13/16" a little light," you say, "Here's the mark to cut to."

Chris Schwartz is quoted as saying "measuring is the enemy of accuracy".

Another take on the non-miter craftsman look...

 

And yet another variation on the craftsman theme.