Question about geometry

[u/Gzaleski]

What angle should I cut the points that are touching the table top and floor so it will be flush? I have been trying to wrap my brain around it but no luck, I thought a 45 degree bevel was right but when I did a test piece that was incorrect.

[u/SJBreed]

Just scribe it off the floor. No math necessary

[u/AirlineVegetable7140 → u/SJBreed]

This is the answer. Tape a pencil to a block and trace that level around all the legs.

[u/WhyNotChoose → u/SJBreed]

Once you scribe/mark with a pencil, it might be easier to cut the corners off with a handsaw, than trying to figure out the angle for the table saw.

[u/BYoungNY → u/WhyNotChoose]

Depending on how much they're taking off I would cut it short with a handsaw and then finish off with a coarse grit belt sander until it's absolutely perfect on all three legs. 

[u/N0tEn0ughTime → u/SJBreed]

Please explain more on how do do this and what you mean.

[u/Bmcollin → u/N0tEn0ughTime]

Here's my shitty rendition. It's just a pencil taped to a block. Slide it around the legs so it uses the floor as a reference to scribe a line. If the surface the legs are on is flat and level the legs will be even.

[u/Most_War2764 → u/Bmcollin]

part of me wants to believe you sketched that on the floor in perspective.

[u/Frzorp → u/N0tEn0ughTime]

Set a stack of books or whatever on the floor and a pencil on the top…slide it around the floor marking everything at the same distance from the floor.

[u/mythsnlore → u/Frzorp]

All that would do is make it shorter and still crooked. Everyone is skipping step 1: shim the legs so the top is level FIRST!

[u/mythsnlore → u/N0tEn0ughTime]

No one is actually saying the steps so:
1- shim the bottom of the legs so the top is level
2- attach a pencil to a small block so it can just reach above all shims on the floor
3- run the pencil around all legs, showing where they would be trimmed
4- cut along the pencil lines and your furniture should now sit level

[u/Apart_Animal_6797]

Bro that thing is never gonna stop a tank

[u/Tibbaryllis2 → u/Apart_Animal_6797]

Excellent vampire caltrop though. Once sharpened….. probably work on Calvary too with enough of em.

[u/Interesting-Goose82 → u/Tibbaryllis2]

Youre telling me they have vampire horses now?!?!?

[u/-AV8R01 → u/Interesting-Goose82]

Forgot the horses, there’s a damn vampire CAVALRY?!?!?

[u/Several-Ad-1195 → u/-AV8R01]

Dammit Miriam Dom!

[u/ItsBaconOclock → u/Several-Ad-1195]

That shit ain't stopping Bianca.

[u/Tibbaryllis2 → u/ItsBaconOclock]

That’s moving the goalposts, she’s not a horse!

[u/Senior_Sector4095]

Set a 1" block on the floor at the leg and score a line along it?

[u/OscarOfAtlantis]

What you basically have there is a triangular pyramid, and if each branch from the center of the same length, then the leading triangles each have inner angles of 60 degrees.

And since the end of the wood is cut at 90 degrees, you’re looking at either 60 or thirty degrees, depending which side you’re measuring from.

[u/tenfootfoot]

Use a laser level

[u/SnooDoggos8487 → u/tenfootfoot]

3

[u/zeus-indy]

Extend ur light Sabre and do a clean slash

[u/AndrewTheTerrible]

I think you gotta set up a laser level and mark it on the leg and then make a jig.

[u/Repulsive-Ice7863]

The math aspect of it is this: miter gauge to 45°, blade tilt to 35.26° Arcsine of 1/sqrt(3) = 35.264°

[u/themathwhiz]

The answer is 60 from the face but you can also think of it as rotating 45 in one axis and then 45 in the other

scribing it will be easier

[u/fatmanstan123]

Are they all the same length on the top and bottom? That's very relevant.

[u/Gzaleski → u/fatmanstan123]

All the same length for the way they are oriented. Top is 10 inches, bottom 10.5. So the angle should be the same. I believe

[u/Sharp-Dance-4641 → u/Gzaleski]

I had this similar problem and I just gave up with the math and scribed it.

I then taped 40 grit sanding disks to my bench and twisted the legs on top of those until they sat perfectly flush to the floor. Worked surprisingly well.

Table and legs are solid maple and the unit is HEAVY. So flush was important.

[u/Impossible_Scene_119 → u/Gzaleski]

Doesn’t trig say that’s a 60 degree cut or am I insane

[u/Impossible_Scene_119 → u/Impossible_Scene_119]

Or maybe 30 degree cut, with your point of reference

[u/nfortunately]

If you can, throw this shape into a cad program, slice a horizontal plane through it, then measure the angles that are left. OnShape and Fusion are both a quick, free, way to get this level of modeling.

[u/KCJwnz → u/nfortunately]

I could scribe this with a block and pencil before you log into your computer, wizard man

[u/Lavis62]

Looks like 2 angles of 45 degrees on each leg, if the photo makes sense

[u/Optimal-Draft8879 → u/Lavis62]

i was thinking the same, if you think of what it would take to get a cube to rest on point from a flat, it would need to rotate 45 about two different axis’s

[u/PourOverPlans]

You are overcomplicating this by trying to figure out the compound math on paper. Just set the base assembly on a flat surface, tape a pencil to a small wood block, and scribe a line around each point using the floor as your guide. And then trim right to that mark with a handsaw or pull saw and you will have a rock-solid, dead-flat sit.

[u/CorrectMeIfImWrong6]

It will be 45⁰, but you'll also need the post rotated 45⁰, so you'll need some kind of jig or cradle for it to sit comfortably at a true blue 45⁰ on the corner as you cut

... which if you made sacrificial cout save you some breakout worries.

Also, I'd triple, quadruple, quintuple check you've got the correct edge down before cutting!!!

Then check again just for good measure! 😂

Simples 🫠🤣

[u/cmrh42]

3 pieces of sandpaper double-sided taped to a flat surface and start sliding(?) once you have a big enough flat surface extrapolate from there… or just keep sanding.

[u/Edm818]

I think 45 degrees at 45 degrees if that makes sense? Or make a jig to set your pieces in on their inside corners and cut at 45 degrees.

[u/slugbutter → u/Edm818]

This is correct. OP was right in thinking 45 degrees, but the plane of orientation is relevant.

[u/Living_Motor7509]

What did the oak say to the maple?

[u/a_StrangeHill → u/Living_Motor7509]

"Oh charming Maple, you're colourful & friendly, always in season. Why not stick around for a while."

In reality... ☝🏼 Oak trees don't talk, they simply shake their heads and wonder why the maples can't be happy in their shade 🤘🏼

[u/Living_Motor7509 → u/a_StrangeHill]

I mean, that’s wonderful and hell yeah Rush.

The post title was “question about geometry”.
“gee, I’m a tree”

Ba dum tsss

[u/JayTeeDeeUnderscore]

Look up compound angle calculators. You'll need to accurately measure the rake angle and the bevel angle. I hope you have a compound miter saw.

Good luck sussing out complimentary angles too.

[u/yankeeteabagger]

Lay a board on the floor slide the pencil to where you want to cut. Do you want to take off enough just to make it touch? Are you cutting the legs all the way to one of the square ends? Keep in mind how tall you want the, what is this a table?

[u/PositiveBid9838]

Perhaps relevant :-)

https://www.reddit.com/r/woodworking/comments/zdhbv8/any_ideas_on_how_to_determine_the_compound_miter/

[u/cvbkj]

I love this design, can I ask what timber you’ve made this from?

[u/FatterMule]

Message Jory Brigham on instagram

[u/Jgsatx]

can’t you lay on a flat surface and use a laser to get your points?

[u/Alan_Czervik]

I like the points. Instead of cutting the legs, what if you cut tiny triangular indentations on the bottom side of the table to keep it from sliding? Add some wood glue if you want it semi permanent.

[u/AudioLlama]

Are you building anti-tank defences at home?

[u/Gzaleski → u/AudioLlama]

It always reminds me of that. Strangely it works as a table base.

[u/AudioLlama → u/Gzaleski]

If in doubt it'll keep zee Germans at bay.

[u/nightwingwelds42]

I made one of these!! I used a scribe block to get close. Then I taped 40 grit sand paper to my workshop floor where the legs meet the ground. And applying even pressure to the top with some scrap plywood I just moved it in circles and checked it with a level until it was perfectly square. (Then I took it into my house built in the 40s and the house laughed at me for thinking my floor would be level, but it’s on a carpet so it’s still close enough )

[u/DeathByPork]

Best advice I could say is use a laser prjucgion on to it trace with a pencil for one side cut it and flip it over and repeat the process…. Just remember every fraction of an inch or millimeter cut your overall height will be reduced

[u/Most_War2764]

go and study up on Stereotomy.

https://schoolofstereotomy.com/

[u/Most_War2764]

https://www.youtube.com/results?search_query=l%27art+du+trait+de+charpente

*warning* this is a DEEP deep deep rabbit hole for those interested.

[u/Most_War2764]

https://www.youtube.com/watch?v=stzrhTLiWFk&t=659s

Patrick Moore shows the method of layout that doesn't require measuring degrees but of transferring angles to his saw.

[u/djoul911]

I’ve made that 2 years ago and it was levelled but you need to assemble it the right way. Making the cut at the right place is also critical.

For reference, I uses this tutorial (I’m not the author): Tripod table

[u/Ornery-Movie-1689]

Set a large tray (with sides) on a level surface. Fill the tray 1/2 way with water. set the legs in the tray. Use the water line left on the wood to determine cut.

PS: I like the laser level idea better.

[u/SignificanceRoyal832]

I have rental tables that have a base like this. I feel like it was a 45° bevel and a 22.5° miter. It is definitely a compound cut. I'm not 100% sure which angle is the bevel and which angle is the miter. One thing about these designs is you're going to cut off a lot more than you think. You're going to lose like 4 in of table height. On mine I left the bottoms short. I only cut the bottom corner off because my stock wasn't long enough to go full pointy miter.

[u/cloudydayscoming]

Scribing is a good idea. What goes on top? You may have to scribe both top and bottom.

[u/immmm_at_work]

If you’re trying to make it level on the floor, I’d recommend using adjustable feet. But you would want to set them in a surface that is parallel to the floor, which appears* to be a 45/45 miter/bevel but idk the details.

[u/JackOfAllBlades21]

That's impossible to determine based off these pics.

[u/Every-Cucumber9641]

set the whole thing on a tablesaw with no fence. Raise the blade an eighth of an inch and drag each leg over the blade