Any geometry geniuses here?

[LuckyCharms]

I'm going to post a picture from Reddit, as well as a link to the thread.

The title of the thread is 'How to trim around this corner"?

I have a similar situation in which I need to form an outside corner joint where a level plane meets a sloped plane with a profiled baseboard.

In my case, it's where my dining room floor slopes down slightly to my kitchen floor. I did a quick solution years ago, but it doesn't look good. I stare at the thing every day, and I can't figure out the miter cuts.

Based on the comments in the thread, it seems like other people have this problem too. I don't really see an understandable solution in the comments, but some of them are hilarious....like "just caulk it".

I can *almost* visualize the cuts if the trim was flat with no profile, but it becomes tricky on profiled miters.

This post is kind of like a hail Mary pass for me, because all of the good old-time carpenters that I used to know have passed on, so I can't ask them. And the problem is...this is one of those things where it is very difficult to find a video or diagram that someone like me can understand.

Picture, followed by link so you can see the comments. The question is...how do you join those two pieces of trim at the corner?



https://old.reddit.com/r/Carpentry/comments/1sxj8it/how_to_trim_around_this_corner/

[multigraincracker]

1. No idea, but I'm great at cutting corners.

[LuckyCharms]

3. Haha! Me too!

I was going to put an outside corner block, and then just run each piece into the block with one angle cut on each piece. But, there has to be a way to cut both a miter and a bevel on each piece that enables the pieces to meet.

I just can't visualize it.

[pfitz59]

2. DY failure

Measure all the legs. Copy to a piece of cardboard. Cut the cardboard. Check to make sure it fits. Use the cardboard cutout as a stencil for the filler piece. Use a jig saw and cut the filler piece. Use a router to cut a 45 degree angle on the inside of the right leg to make it fit flush. Glue into place.

[LuckyCharms]

4. So you are saying to add a third piece at the corner?

[Harker]

5. I've become a square, Lucky.

And I'm fine with it.

Slap a little putty on it.

[LuckyCharms]

6. I think I'm just going to...

put a piece of duct tape over the gap.

One of the comments says...just pee on it.

[Harker]

7. That's brilliant!

Was the poster a beagle?

[LuckyCharms]

8. Chihuahua

[Harker]

9. I nearly blew a mouthful of twenty year old pu'er out through my nose.

[LuckyCharms]

10. .

[Kali]

11. Say the corner isnt there.

How would you fit that angle to a horizontal normally? I have to break things down to smaller problems. To me it doesn't seem like it works at anything other than a 90 degree angle but I watched one of your videos of a window job that was amazing.

[LuckyCharms]

13. If both pieces were on the same plane...

meaning...if it was something close to a 90 degree corner, you would just cut a 45 degree bevel on each piece, and join them together.

Or, if the angle was not exactly 90 degrees, you would measure the angle, divide it by 2, and cut the bevel to something different than 45 degrees.

ie: you might cut each bevel at 44.5 degrees.

My problem here is that the solution can be explained to me as in a comment above, but I need a clear picture or drawing that shows it to me before I can understand it.

[Kali]

12. If I had to do it I would slap decorative stone at base and run to that

[LuckyCharms]

14. You can put a corner block that wraps around each side of the corner...

Then, the piece on the right would just be a 90 degree cut butted into the corner block.

The sloped piece on the left would butt into the corner block by cutting a simple angle on the left piece.

But that looks real busy to me, and I don't like the look.

[Ptah]

15. This might be exactly what you should do:

[LuckyCharms]

16. But...

The only tool I own is a screwdriver!

[Harker]

17. I've seen you own quite a few tools here.

[LuckyCharms]

19. Well, a lot of people call me a tool.

It's a compliment.

I think.

[Harker]

20. I know I like to be useful.

[sorcrow]

18. A screwdriver?

Light on the orange juice, I suppose.

Regards,
Sorghum Crow

[Whip-poor-will]

21. Compound miter

45 degree face cut 42 degrees stair rake angle.

At this piont three coats of bondo with the last coat fiinishing off with a light sanding. PRIME FIRST before a final coat

Use a 4/6" putty knife to flow the profiles together.

[LuckyCharms]

22. This sounds like something I can look at, but...

I've got factory pre-finished oak that I'm working with.

Can't use caulk or Bondo. Can't sand to flow the profiles together.

[Whip-poor-will]

23. If you have replacement

Ask around for someone with a compound miter set blade at 45 Degrees angle should be 42 degrees. These saws are common among woodworkers or trimmers.

I always start with a scrap wood to guess an angle 1X3 or 1X4 pine just to check look.

[applegrove]

24. I was great at geometry but have since forgotten

all the proofs.

[Alpeduez21]

25. Not a genius of any type

Except in the sense that Wile E Coyote was a super genius.

I would first line the stair board up with vertical corner line. Cut straight down (across) the stair side trim board so that board now has an acute angle at the bottom of the stair and the vertical corner. Mate that with the horizontal trim. Probably use a coping saw for the cut. The stair side trim board will need a portion of the bottom angle cut flush to the flat section. I would concentrate on the stair side before the horizontal trim piece. Horizontal just seems easier to match up. The acute angle can be measured using on of those angle things that lock into place. Draw a line on the stair trim and cut it with a 45 degree bevel. (Edit) make the bevel if you are not using a coping saw That’s what I would do

[Niagara]

26. Measure twice, cut once

[LuckyCharms]

32. No. No. it goes like this...

Measure twice, cut once, and if you cut it too short, cut it again, and keep cutting until it is long enough.

If it is still too short, pee on it.

While praying.

[FullySupportDems]

27. I think you're looking for a wood worker more than a geometric whiz

But I'd be pretty dangerous with Patch & Level. I hate cutting molding, and that looks tricky.

White duct tape, definitely.

And BEAGLES! And Chihuahuas!

[Brother Buzz]

28. Can you use a ticking stick and an old school coping saw?

I learned Japanese geometry from a Zen Buddhist cabinet maker, but my proofs mostly work on transferring pyramid angles to a table saw.

[Maninacan]

29. A Post

I would put a square post in the corner.

[Pobeka]

30. It is impossible to make that a perfect join

Because the piece coming down the stair has a longer "intersection" across its face. So no matter how you do it, the stair side moulding will not match the horizontal piece.

You could do it if the moulding cross section was a perfect rectangle...

[LuckyCharms]

34. You're right. Please see post #33.

[Pobeka]

35. Two years of calculus and 31 years of a math intensive career.

Lots and lots of sines, cosines and integrals, and drawing pictures.

Glad to help you figure it out.

[LuckyCharms]

36. I was just talking to a college kid...

asking about his upcoming finals.

He's doing really well with grades, but he is worried about his upcoming Calc II exam.

The only calculus course I ever took was Business Calc at university.

I loved that course, and aced it. Teacher was a grad student from France who drank wine out of a bota bag while we took our exams. One of the best instructors I've ever had.

The hardest math related course for me was statistics. Before that course, I never realized how difficult that stuff can be to conceptualize.

[Niagara]

31. Cut three times, measure once

[LuckyCharms]

33. OH THIS VIDEO CLEARS IT UP ALRIGHT.

Last edited Thu Apr 30, 2026, 12:23 PM - Edit history (1)

JFC!!!

Post number 30 is correct, and that is the entire problem.

To get it to fit correctly, you would have to rip down the raked (slanted) piece on the left to reduce its width. But if you did that on a profiled piece of molding, it would not look right.

So you would need to add a triangular piece to make the corner transition.

I can sort of understand in theory how the triangular piece would be cut, but actually doing it as a practical matter on the saw...that's where I'm struggling.

This video just made me drool in stupidity. I don't really understand it, because I'm no rocket surgeon. Well, I understand the first part, but when he starts drawing the profile lines...holy shit...

Have a look if you want to challenge your brain...

[Harker]

37. Ow. My brain hurts...

and I got a rare (for me) B in high school geometry.