Just to understand correctly, you've got 2 pieces of board which currectly have 90 degree angles on the edges. You want to know what angle to cut on the edges to join them if they are leaning inward (toward each other) 16 degrees from standing straight in the air, is that correct? If so, the fact that they lean in 16 degrees won't effect the angle that joins them, which in order to create a total 90 degree angle is 45 degrees. Please help me understand if this wasn't your question.
m0tion said:
Yes that makes sense. Cheers Motion.
Its the other angle I'm confused about - the cut angle rather than the 45 degree bevel.
Any idea's?
I have a gut feeling it will be around 20 but I don't have the luxury of guessing because I've only got one shot at this. 🙁
Read my post. I don't know if I've got the calculation right, but one thing I can assure you is that the bevel is not 45degrees. Look at the angle going from 16 degrees to 90 and see what happens to the bevel.
Sheldon
Sheldon
AHH, ok, i see now, to be clear we are discussing the angle shown below in red correct? I believe the answer to be 45 * sin(16 degrees), I think. So, about 12.5 degrees... Hope this is helpful. I arrived at that answer was by visualizing two pieces of wood meeting at a 90 degree angle, then rotating them to lean inward until they touched the ground, then went right through the ground and came up on the other side, and finally went back to the original position... I then noticed that the angle to cut would go back and forth between 45 and -45, and so it'd pretty much have to be a sine wave. Then I just imagined rotations of 0, 90, 180, and 270 degrees to arrive at "f(0 deg) = 0 deg; f(90 deg) = 45 deg, f(180 deg) = 0 deg, f(270 deg) = -45 deg.". Through Wikipedia, I found the "f(x) = 45 degrees * sin (something*x)", then I found that the "something" was 1 by experimentation, then I just needed to convert from degrees to radians to get the result.
I'd really appreciate someone checking my logic and calculations on this because apparently it's a one shot deal.
An externally hosted image should be here but it was not working when we last tested it.
I'd really appreciate someone checking my logic and calculations on this because apparently it's a one shot deal.
OK, I probably goofed...
I think something that will continue to confound those who cut compound miters for the first time is the material must be against a fence or on the table when cut. It is very hard to grasp the geometry when the cut is made in an arrangement that differs from the final assembly.
Also, think "upside down and backwards". This is a helpful phrase I remind myself of when cutting crown molding.
Consider what happens to the angles as the "slope", which is 16 degrees in Shin's case, progresses within the range of it's limits. If the slope is 0, the crosscut is 90 degrees. If the slope is 90 degrees, the crosscut is 45 degrees. So the limits of the crosscut are 90 to 45 degrees....but the gauge on a miter saw doesn't go to 90.....Now I know I goofed...
Try this: Crosscut = 56.1- 45 degrees= 11.1 degrees ON YOUR SAW GAUGE.
Let me try to figure out the bevel angle...
I think something that will continue to confound those who cut compound miters for the first time is the material must be against a fence or on the table when cut. It is very hard to grasp the geometry when the cut is made in an arrangement that differs from the final assembly.
Also, think "upside down and backwards". This is a helpful phrase I remind myself of when cutting crown molding.
Consider what happens to the angles as the "slope", which is 16 degrees in Shin's case, progresses within the range of it's limits. If the slope is 0, the crosscut is 90 degrees. If the slope is 90 degrees, the crosscut is 45 degrees. So the limits of the crosscut are 90 to 45 degrees....but the gauge on a miter saw doesn't go to 90.....Now I know I goofed...
Try this: Crosscut = 56.1- 45 degrees= 11.1 degrees ON YOUR SAW GAUGE.
Let me try to figure out the bevel angle...
m0tion said:
Excellent work Motion, thanks for that.
I can visualise what your saying and it makes sense to me.
Here we go:
An externally hosted image should be here but it was not working when we last tested it.
Solid black line indicate two pieces of wood joined on a 90 degree angle with the piece of wood on the left being angled inward at 16 degrees causing the other to point down 16 degrees. The red lines indicate the cut for each which shifts the piece that's pointing 16 degree downwards up to 0 degree's on the y axis and also rotates it on the x axis 16 degrees.
Does that make sense?
Yes, it makes sense to ME. I feel confident from your response that I conveyed to you what my solution was. I BELIEVE this to be correct and if it makes sense to you give it a shot, but if anyone could chime in with a third agreement that would give me more confidence. BTW, you have mad skills with drawing things.
m0tion said:
I think your 1st angle is correct (12.4degrees) but the second seems wrong. I am pretty sure it's 45*cos(16degrees)=43.25degrees. Damn, can't be sure tho.
As the slope varies from 0 to 90 degrees, the bevel varies from 45 to 90 degrees. This is relative to the adjacent face, which is the hang-up with miter saw gauges. They typically go from 0 to 45 degrees, maybe a little more.
Try this for the bevel angle: 90 - 46.7 = 43.3 degrees. See if these work with the stock flat on the table of your saw.
Try it on scrap first!
Try this for the bevel angle: 90 - 46.7 = 43.3 degrees. See if these work with the stock flat on the table of your saw.
Try it on scrap first!
There is a SECOND angle being discussed? Man, this is more confusing than I thought. I don't really understand what you mean, did I give an answer for a second angle?
Thanks, Ed, Sheldon, Alex and Motion. Really appreciate the input, I've didn't have a clue before I posted this question but feel confident that its close.
So the bevel is 12.5 degrees. And the cut angle is either 45 or 43.3. I'm cr@p at visualising things in 3dimensions so the 45 degree thing that works in 2dimension I'm inclined to believe but I don't feel confident.
It seems like a simple question on face value but this always gets me, like I said before, last time I gave in trying to work it out and just did trail and error. If I can get something that works everytime it will make my life so much easier for future stuff.
So the bevel is 12.5 degrees. And the cut angle is either 45 or 43.3. I'm cr@p at visualising things in 3dimensions so the 45 degree thing that works in 2dimension I'm inclined to believe but I don't feel confident.
It seems like a simple question on face value but this always gets me, like I said before, last time I gave in trying to work it out and just did trail and error. If I can get something that works everytime it will make my life so much easier for future stuff.
m0tion said:
I know how you feel motion.
There's only 1 angle per-se and that's 16 degrees the two pieces of wood form a 90 degree angle when joined and looking from above ie. 4 pieces joined makes a rectangle/square. The only thing I'm concerned with is the bit we've been discussing already.
EDIT: The second angle is the 45 degree (or is it 45 degrees?) one that forms the 90 degree right angle when the two pieces with the 45 degree bevel are joined.
visualise
Along the way, take 2 pieces of stock and place them in about the 16 degree orientation. Mark them to signify the DIRECTION of the miter before you go to the saw. This will help you maintain a reference for cutting them properly.
Each side of the cut will require a unique set-up. Mark the gauge in order to make the fine adjustments necessary and for repetition.
Along the way, take 2 pieces of stock and place them in about the 16 degree orientation. Mark them to signify the DIRECTION of the miter before you go to the saw. This will help you maintain a reference for cutting them properly.
Each side of the cut will require a unique set-up. Mark the gauge in order to make the fine adjustments necessary and for repetition.
Re: visualise
Sorry for being a bit thick but could you explain what you mean?
Thanks.
Ed Lafontaine said:
Sorry for being a bit thick but could you explain what you mean?
Thanks.
Sorry I dont have the drawing tool that you do but here's what I got...
You take your rectangular piece of wood, draw the 12.4* line. Set the saw to cut at 43.3* (or as close as you can get it obviously) along this line.
You take your rectangular piece of wood, draw the 12.4* line. Set the saw to cut at 43.3* (or as close as you can get it obviously) along this line.
m0tion said:
I'm quoting myself here, I know, but how in the world would this angle be 43.3*?
45*cos(16degrees)=43.25degrees
I don't understand what this formula has to do with that angle...
I feel pretty confident 12.5* and 45* will do it...
alexcd said:
That drawing gives me knightmares, brings back memories from the Perceives.
All this thinking has turned my brain to mush, well that and the fact its nearly 3.00am here in the UK.
Gonna sign off now and get some sleep ready for a full day working on these again tommorow, hopefully a definite and firm answer to this will magically appear by the time I log in again so I can be 100% sure.
BTW thanks again to those that have helped out.
Reminds me of thick as a brick,
and I rather like that album, though I don't think of you as thick at all...I would rather lapse into admiration, but more to the point...
Before you cut the wood, take the 2 pieces which will join at the miter. Set them together on a flat surface in aproximately the orientation you want to achieve. Angle them in to aproximate the 16 degree slope.
The wood you will remove by cutting is that which is touching...and a little further out...so make a pencil mark across the edges and faces of the wood to represent where the saw has to enter. These marks have been helpful to me many times with saw set-up.
Signing off as well, my bet is on 43.3 and 11.1
and I rather like that album, though I don't think of you as thick at all...I would rather lapse into admiration, but more to the point...
Before you cut the wood, take the 2 pieces which will join at the miter. Set them together on a flat surface in aproximately the orientation you want to achieve. Angle them in to aproximate the 16 degree slope.
The wood you will remove by cutting is that which is touching...and a little further out...so make a pencil mark across the edges and faces of the wood to represent where the saw has to enter. These marks have been helpful to me many times with saw set-up.
Signing off as well, my bet is on 43.3 and 11.1
m0tion said:
Because as you tilt the two sides (16*) then the angle between the pieces is no longer 45* even. I may be wrong but I'm somewhat confident that it's a 1.75* difference.
If straight down on a saw is 90*, then you want to set the blade to 46.75*. It's not a big deal but you would end up with a gap otherwise.
Ant, I dont blame you for signing off. My head hurts too.
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