mwg
Member
Registered: 19th Feb 04
Location: South Lakes
User status: Offline
|
If you have a circle of a known radius and you want to measure off at certain intervals around it, say 10m around along the line of the circle. How do you work out where those 10m points are?
I'm sure I've done this before but its Monday and my mind has gone blank 
|
Cavey
Member
Registered: 11th Nov 02
Location: Derby
User status: Offline
|
Will be every 36 degrees?
Edit to say, i don't think that's right at all... that'll just give you 10 points...
[Edited on 17-08-2009 by Cavey]
|
ed
Member
Registered: 10th Sep 03
User status: Offline
|
Do a drawing of it to work it out 
|
RichR
Premium Member
Registered: 17th Oct 01
Location: Waterhouses, Staffordshire
User status: Offline
|
or put it into Solidworks and do a circular pattern at equal intervals  No Maths involved then Solidworks FTW
|
ed
Member
Registered: 10th Sep 03
User status: Offline
|
That's what I would have done
|
mwg
Member
Registered: 19th Feb 04
Location: South Lakes
User status: Offline
|
quote:
Originally posted by Cavey
Will be every 36 degrees?
Edit to say, i don't think that's right at all... that'll just give you 10 points...
[Edited on 17-08-2009 by Cavey]
Thats not right.
Dont have solidworks. I'm sure there is a command in CAD for doing it, I've done it before FFS
|
Leighton
Member
Registered: 21st Feb 01
Location: Liverpool
User status: Offline
|
I can tell you how to do it in Microstation
|
Simon
Member
Registered: 24th Apr 03
Location: Oxfordshire
User status: Offline
|
Autocad? ARRAY command
|
Paul_J
Member
Registered: 6th Jun 02
Location: London
User status: Offline
|
don't you have to convert something to radians?
|
Paul_J
Member
Registered: 6th Jun 02
Location: London
User status: Offline
|
What about this?
2r * pi e.g. r = 10.
2*10 * pi = 62
then take 10mm off the circumfrence...
= 52.
Then 52 / 62 = 85% of the circle... so 15% of the circle = the 10mm.
Then get 15% of 360 = 54 degrees.
|
Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Offline
|
Depends very much whether you want to draw a polygon with the straight lines or take the 10 meters out of the circumference itself. The latter being somewhat more simple.
|
Daveskater
Premium Member
Registered: 29th Apr 08
Location: Oxford, UK Drives: Jap wagon
User status: Offline
|
quote:
Originally posted by Simon
Autocad? ARRAY command
+1 
Numberwang!
Originally posted by AlunJ
I like you Dave, you are a man of men
Originally Whatapp'd by Neo
Dave's maybe capable of a drive-by cuddle
Look at my pictures
|
mwg
Member
Registered: 19th Feb 04
Location: South Lakes
User status: Offline
|
10 metres around the circumference. Sod it, its someone else thats trying to do it
|
Paul_J
Member
Registered: 6th Jun 02
Location: London
User status: Offline
|
quote:
Originally posted by Matty G
10 metres around the circumference. Sod it, its someone else thats trying to do it
Would help if you told us the radius.
|
Robbo_Corsa
Member
Registered: 5th Jul 06
Location: North Lincolnshire
User status: Offline
|
I've just read all of these comments.. I do not understand a single thing!
Maths + Me = NO GO!
|
Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Offline
|
If the 10 metres follows the line of the circle and doesn't describe a polygon then just work out the circumference (6.28 x radius) and then find 10 / circumference which equates to the percentage of 360 that you need.
Similar to how Paul did it already.
|
Dom
Member
Registered: 13th Sep 03
User status: Offline
|
This should do it -
Interval * (2 x PI x r/360)
Basically, you divide the circumference by 360 which will give you how long each degree is. Then multiply that by how far you want measure around (ie: 10m).
So if the radius was 20 then -
Circumference = 2*Pi*r = 125.663706
Each degree = 125.663706 / 360 = 0.34906585
10m around would equal = 0.34906585 * 10 = 3.4906585 degrees
every 3.4906585 degrees is 10m etc
[Edited on 17-08-2009 by Dom]
|
Robbo_Corsa
Member
Registered: 5th Jul 06
Location: North Lincolnshire
User status: Offline
|
Thats what i thought..
|
mwg
Member
Registered: 19th Feb 04
Location: South Lakes
User status: Offline
|
Right asked him for one of the radius to try it out. Radius = 82.929m
6.28x82.929 = 520.79412 = circumference
520.79412/10 = 1.446650333m = 1 degree
10/1.446650333 = 6.912520442 degrees = 10m around the circumference of the circle
Drew it out to check in CAD and it came back as 10.0051m which is only 5mm out, can live with that
[Edited on 17-08-2009 by Matty G]
|
alan-g-w
Member
Registered: 9th Nov 07
Location: Glasgow
User status: Offline
|
My head just imploded from a maths overload after reading all the replies in here.
|
Corsa_Quadz
Member
Registered: 24th Feb 08
Location:
User status: Offline
|
quote:
Originally posted by Paul_J
What about this?
2r * pi e.g. r = 10.
2*10 * pi = 62
then take 10mm off the circumfrence...
= 52.
Then 52 / 62 = 85% of the circle... so 15% of the circle = the 10mm.
Then get 15% of 360 = 54 degrees.
That just made my brain implode 
|
Corsa_Quadz
Member
Registered: 24th Feb 08
Location:
User status: Offline
|
Shit repost
|
alan-g-w
Member
Registered: 9th Nov 07
Location: Glasgow
User status: Offline
|
Instant repost ftl
|
Corsa_Quadz
Member
Registered: 24th Feb 08
Location:
User status: Offline
|
|
