segments in the circle's circumference

[Anonymous]

hello all

new user try to smooth circumference of some circles. i want to place some screw holes on a bolt circle within a couple of thousands. when i zoom in on the circle i find that the segments of the circle where i want to place the centers of the holes are not the same as the representation of the circle.

i don't see any place that shows the zoom level or percentage

is there a way to dimension the center point of a circle?

can we specifiy the number of segments in a circle?

the only post that talked circle segments was in 2004 and the discussion appeared to use command line, ie AecFacetDev ADT object and ObjRelUpdate.

thanks all

[TrippyLighting]

It would be great if you can post a screenshot or screencast that shows the problem. I have no problem creating bolt cirles to any precision and don't see segments.

This could be related to a graphics card or driver issue.

[TheCADWhisperer · Accepted solution]

I would place one sketch point on the circle and dimension.  (withing a couple thousands??? you can dimension location out far more precise than eyeball location)

Create the hole.

Pattern the hole.

Alternatively you could pattern the sketch point.

In Fusion - the dimensions DRIVE the design.  For example - if you dimension your circle 100mm IT IS 100.0000000 mm.  If you decide you really want it to be 105mm simply double click on the dimension and change to 105mm.  Fusion will "drive" the geometry to 105mm.

Precise location of your hole center point can be ensured with a Horizontal or Vertical (as appropriate) geometry constraint (or dimension if at angle).

Use construction lines when needed.

[Anonymous]

hi trippy

i tried sending this reply via the email that showed up. wrong choice. so here is the screenshot.

this is a .045" hole centered on a 1.865" bc. 

i think i am at max zoom here. don't know where to look to see zoom level.

f360 seems to show a true circle with a segmented circle overlay. it is especially noticeable in this shot on the .045" circle. 

when i place the circle (or cylinder) center, not sure if it is snapping to some point on a segment or on the true, theroretical diameter.  at this zoom level is probably irrelavent.

will my output be segments or true circles? i am still playing with new software to see if the post processor generates the g-codes i am familiar with for arcs.

i am coming from years in 2d. the software for my plasma cutter did a super job of generating almost perfect circles and radii. 

i am entering the 3d world with a 3d printer and am seeing with our first few designs with segmented circles. but i noticed that sketchup allows increasing numbers of segments to smooth the circles.

the screen shot is the result of trying to figure out how to locate the holes on the desired bolt circle.

but i noticed while looking for something else that under sketch was a circular pattern tool. if holes can be generated from that tool, that might be my easy answer.

my biggest frustrations so far:

- being able to modify a first attempt at something, like just moving a circle or cylinder or changing the size. 

- numerically placing an object. circle or rectangle, etc.

glad you guys are out there to help a novice.

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last night i jumped into the tutorials on youtube. watched the ones on sketching. i think if i had started with sketch rather than create many of my questions would have been answered. when i installed f360 the sample tutorials started with the create functions.

thanks for you reply.

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[Anonymous]

thanks cadw
i think for the novice number driven is not all that clear in the beginning, at least using the create functions.

after watching the sketch tutorials last night i am beginning to understand how fusion works to change or modify.

i will try to implement all your suggestions. thanks for the help.

****

[TheCADWhisperer]

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@Anonymous wrote:

1. will my output be segments or true circles?

2. i am entering the 3d world with a 3d printer and am seeing with our first few designs with segmented circles. but i noticed that sketchup allows increasing numbers of segments to smooth the circles.

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You have at least 2, maybe 3 different issues going on here.

1. In the database and with certain outputs your circles will be true circles.  This is a graphics issue where circles are approximated as segmented polygons for fast view regeneration on zooming in, but they are still true circles in the code.

2. stl is faceted planar surfaces - no true curves at all. None!  So 3D printers, always segment.  But you can change the size of the segments to make them very small.  At some size there is no point in refining them further - as your printer itself has a limited resolution.  (higher resolution printer = more money)

3. I always start geometry as dimensioned 2D sketches - just like on the drawing board in the last century.  And use construction lines when appropriate.