Miter Angles

[crokett™]

There's a piece of 6.5" wide trim on my stair railing that the bottom ends of the balusters are attached to.  It's about 3' long.  The upper end terminates at the edge of a vertical wall.  The lower end under the newel post is a mitered corner with the piece that is vertical and drops about 9" to the floor.   My phone measured the slope of this trim at 40 degrees.  So this means that the angle between it and the vertical is 130 degrees, correct?  90 degrees for the horizontal plus the 40 my phone measured?  When I go to cut that miter, do I use 65 as the miter angle (130/2) or do I use 20 (40/2)?    If I use 65, then I need to set the angle on the miter saw to 25 and make the 25 degree side  the off cut. 

If I can figure out the correct angles I can model and 3D print some setup blocks for this project as well as a clamping jig to ensure the correct angles during assembly.    

[museumguy]

DO it the old fashioned way, draw it on the trim.

[jteneyck]

If possible, hold a piece of scrap plywood up to it and draw the angle on it.  Cut and check the fit.  Who cares what the actual angle is.  If you can't draw it on the scrap, then cut it at the angle you calculated, check it, and adjust as needed until it fits correctly.  

Calculated angles almost never work out perfectly, even if the calculation is correct.  

John

[Stwood_]

DO it the old fashioned way, draw it on the trim.

This, as simple as it gets

[JosephP]

RE calculating angles:
Years ago I was building a bookshelf that has a solid cherry crown molding (external corners) around the top.  I tried multiple times to figure out the angles experimenting on pine to not waste 6/4 cherry.  Couldn't get the math down.  I'll call my brother...rocket scientist (literally) about 5 out of school - he should know how to figure out that math.  His reply "I tried and couldn't figure it out either...just prop it at the angle you want and cut it at 45.  Of course, now there are charts on the internets to tell you these things...Didn't have time to wait for dialup and didn't want to waste the precious metered KBs we were paying for to go looking.

Story #2:  Guy I knew was building his own timber frame house.  Building his own as in:  felling trees on his property and running them through the mill.  Going out the stream and picking up stones for the chimney (side bar - his foundation:  he was a veterinarian - told the guys at the local concrete place if they'd empty their trucks into his pre-made molds at the end of the day, he'd take care of their pets...he made 3'x3'x5' long blocks with "dimples and knobs on top/bottom" to keep things in place).  This is a 5000+ sqft house.  Anyhow, he asked a mutual friend who was a college math teacher "Hey Walt, how do I figure out the angles where the beam coming down from the ceiling hits the beams on top of the wall?"  Walt's reply:  "I don't know...find yourself an Amish guy and he'll figure it out for you."

Point being...like jteneyck said, it seems you'll be more accurate by fitting the piece than calculating.

[MstrCarpenter]

There's a piece of 6.5" wide trim on my stair railing that the bottom ends of the balusters are attached to.  It's about 3' long.  The upper end terminates at the edge of a vertical wall.  The lower end under the newel post is a mitered corner with the piece that is vertical and drops about 9" to the floor.   My phone measured the slope of this trim at 40 degrees.  So this means that the angle between it and the vertical is 130 degrees, correct?  90 degrees for the horizontal plus the 40 my phone measured?  When I go to cut that miter, do I use 65 as the miter angle (130/2) or do I use 20 (40/2)?    If I use 65, then I need to set the angle on the miter saw to 25 and make the 25 degree side  the off cut. 

If I can figure out the correct angles I can model and 3D print some setup blocks for this project as well as a clamping jig to ensure the correct angles during assembly.    

I'm assuming your using a compound mitre saw and tilting the blade because even my 15" Hitachi's can't miter 6-1/2" vertically. But yes, is if the angle indicator says 0° when the blade is vertical and actually cutting at 90° to the face and you need the angle that is 25° less than 90° you set the bevel angle to 25° on that gauge. The stairs are at a 40° angle to the floor, so 20° (40°/2) would be the angle cut for the skirt board molding to baseboard molding and sloped handrail to level.

Now let's see if we learned anything. If the angle to level is 40° (which was measured) than the angle to plumb must be 50°. Right? So why would we set the angle to 40° on our chop saw to cut the end of the rail to meet the newel?


Anyone???

[crokett™]

I'm assuming your using a compound mitre saw and tilting the blade because even my 15" Hitachi's can't miter 6-1/2" vertically. But yes, is if the angle indicator says 0° when the blade is vertical and actually cutting at 90° to the face and you need the angle that is 25° less than 90° you set the bevel angle to 25° on that gauge. The stairs are at a 40° angle to the floor, so 20° (40°/2) would be the angle cut for the skirt board molding to baseboard molding and sloped handrail to level.

Now let's see if we learned anything. If the angle to level is 40° (which was measured) than the angle to plumb must be 50°. Right? So why would we set the angle to 40° on our chop saw to cut the end of the rail to meet the newel?


Anyone???

I'm replacing the entire railing, balusters, newel post, all of it.   As to just take some pieces of wood and mock it up, I could, but  a) I want to see if my thinking is correct and b) that is much less fun than modeling a jig and printing it.   Besides which I can also use the jigs as alignment guides for assembly and glue won't stick to them. I'm printing the jig right now.  If it works I will print the other jigs I need to set the miter saw and make the cuts.    I will still use test pieces before cutting the real stuff.

[jteneyck]

I'm replacing the entire railing, balusters, newel post, all of it.   As to just take some pieces of wood and mock it up, I could, but  a) I want to see if my thinking is correct and b) that is much less fun than modeling a jig and printing it.   Besides which I can also use the jigs as alignment guides for assembly and glue won't stick to them. I'm printing the jig right now.  If it works I will print the other jigs I need to set the miter saw and make the cuts.    I will still use test pieces before cutting the real stuff.

Printing the jig?  What makes it so special that you can't make it with your miter saw.  

John

[MstrCarpenter]

Printing the jig?  What makes it so special that you can't make it with your miter saw.  

John

I like jigs. When I build a set of stairs I usually make about 3 dozen; the cutouts from the stringers. They work great to drill the baluster holes plumb on the bottom of the rail, especially when the rail is resting upside down on the stairs. Just don't forget to spin it around. (Top end of rail goes at the bottom of staircase while drilling.) Don't ask how I know!

B.T.W. No takers for the quiz question on my previous post yet.

[Bill Wilson]