I am trying to cut a 30 in long leg that would taper from 2 in at the top to 1 inch at the bottom.
I am starting with a 2.5 square blank.
My issue is drawing my cross-section for the 2-rail sweep. I manage to get a tapered leg, but it is not 2 in at the top and 1 in at the bottom.
How do I calculate the height of my cross-section? Do I have to divide my variables by Pi?
If I were working on a flat surface, I would have 1 leg measuring 1in for the top and the other 0.5 at the bottom, correct?
Draw cross-section for tapered leg
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Re: Draw cross-section for tapered leg
If you start with a 2.5 square block, then round it to a 2.5 cylinder, you need to tell the toolpath that you want the start depth to be .25" to end up with a 2" top diameter. I prefer to use the moulding toolpath to make tapered legs. Much simpler than dealing with model creation and 3D cuts.
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Re: Draw cross-section for tapered leg
Littlebranch: Do note that your material might be 2.5 inches but your settings tell the program that it is only 2 inches in diameter. If you try to cut the material down by 1/4" (which will get doubled---one for each "side") to get the 2.5 down to 2 inches you're going to end up with something that tapers from 1.5" diameter to perhaps 1/2" diameter as far as the program is concerned.
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Re: Draw cross-section for tapered leg
Adze is absolutely correct. In order to get a taper from 2.5" to 1" over a distance of 30 inches your profile line needs to have a slope or angle of approximately 1.43 degrees.
Steve
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Re: Draw cross-section for tapered leg
I dont know if this will help but I started making a few tapers for walking sticks and used a flat rectangle from clipart greater than my design area, clipped the model to the design area which takes away the rounded edges. Then I used the fade function of the model which will fade up to 100% of Model thickness. I used the model because it allowed me to add some clipart to the taper stick whereas the moulding toolpath does not.
Dave
The image shown is unwrapped.Dave
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Re: Draw cross-section for tapered leg
To be exact, the actual formula for calculating the angle of the profile or slope is:
The run = 30"
so the inverse tangent of .01666 = .9548
Calculated for a 30" length by 2" to 1" diameter taper
4dthinker's vector view is probably easier to understand.
The rise = .5"The run = 30"
so the inverse tangent of .01666 = .9548
Calculated for a 30" length by 2" to 1" diameter taper
4dthinker's vector view is probably easier to understand.
Steve
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Re: Draw cross-section for tapered leg
Nice to see some math here Steve.
I learned drafting while in high school, and have used that since then to solve challenges like this. A previous department head was sure I was using calculous to create the complex joinery challenges my furniture design students presented. I didn't have the heart to tell her that all I used was drafting techniques I learned in high school.
4D
I learned drafting while in high school, and have used that since then to solve challenges like this. A previous department head was sure I was using calculous to create the complex joinery challenges my furniture design students presented. I didn't have the heart to tell her that all I used was drafting techniques I learned in high school.
4D
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Re: Draw cross-section for tapered leg
It really wasn't all that difficult. After calculating the slope by dividing the rise by the distance I just used the windows calculator in scientific mode to calculate the inverse tangent.
Steve
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Re: Draw cross-section for tapered leg
Start with Z0 at the centre of rotation, and X0Y0 at the one end of blank (spindle set up above X0Y0). Turn spindle on, set feedrates, etc. Use a 1/2" ballnose.
G1 Z1
G1 Y30 Z0.5 A172800
This will give one continuous spiral down your blank, cutting 0.0625" per pass, from a 2" diameter down to a 1" diameter at the end of your 30".
G1 Z1
G1 Y30 Z0.5 A172800
This will give one continuous spiral down your blank, cutting 0.0625" per pass, from a 2" diameter down to a 1" diameter at the end of your 30".
Russell Crawford
http://www.cherryleaf-rustle.com
http://www.cherryleaf-rustle.com