02GF74
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 posted on 3/9/06 at 07:30 PM |
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today's homework - template to mame a cone
it's been yonks since I did TD and I am sure I knew how to do it but my brain ain't what it useda be.
I need to make a truncated cone, 48 mm dia at top and 124 mm dia at base; angle of side is 45 degree - what is the shape I need to cut?
would be most grateful is someone could either post the shape or explain how to derive the template (I know it needs to be curved).
Ta.
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JoelP
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| posted on 3/9/06 at 07:46 PM |
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you need to draw a circle with a radius of 87.7mms. Draw a smaller one inside this with a radius of 34mms. You then need to take a segment of this
(70.7% (1/root2)?) i think and turn it into a cone.
edit to confirm, its 70.7% you need, or 254.5 degrees.
[Edited on 3/9/06 by JoelP]
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907
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| posted on 3/9/06 at 08:10 PM |
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quote:
Originally posted by JoelP
you need to draw a circle with a radius of 87.7mms. Draw a smaller one inside this with a radius of 34mms. You then need to take a segment of this
(70.7% (1/root2)?) i think and turn it into a cone.
edit to confirm, its 70.7% you need, or 254.5 degrees.
[Edited on 3/9/06 by JoelP]
I've been making cones for years and I couldn't follow that Joel.  
Paul G
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02GF74
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| posted on 3/9/06 at 09:01 PM |
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thanks - just did that on paper and looks pretty good - it is to fit in the front/back of the exhaust can to get round the sharp edge problem.
now what if the cone had base angle of 60 degrees? (like previous one but would be taller)
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02GF74
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| posted on 3/9/06 at 09:26 PM |
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how embarrassing - school boy maths 
it is explained in here:
http://jwilson.coe.uga.edu/EMT725/CarlCone/Solution.html
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MikeRJ
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| posted on 4/9/06 at 06:05 PM |
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quote:
Originally posted by 907
I've been making cones for years and I couldn't follow that Joel.
Paul G
Do you stick a flake in the top of yours though ?
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JoelP
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| posted on 4/9/06 at 06:46 PM |
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60 degrees should equate to 50% of the circle, buit obviously different sizes. That link seems to make it sound a lot harder than it is!
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907
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| posted on 4/9/06 at 08:42 PM |
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I would work out the circumference of the finished cone using pi
124 X 3.142 = 389.6
and measure this round the edge of the disc I'd cut out.
Paul G
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02GF74
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| posted on 5/9/06 at 08:30 PM |
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quote:
Originally posted by JoelP
60 degrees should equate to 50% of the circle, buit obviously different sizes. That link seems to make it sound a lot harder than it is!
yep - that is what I used in the end; kept the match simpler for working out the angle; 180 degreess of 1/2 the circle.
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40inches
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| posted on 8/9/06 at 08:19 AM |
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You can get a trial version of a cone layout software here http://www.pulserate.com/ Havn,t used it yet, you have to buy it to use it after 16 days
(I think)
[Edited on 8-9-06 by 40inches]
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