newb question regarding joining primitives

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newb question regarding joining primitives // Work in Progress

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Post by jcleland // Jan 28, 2009, 5:53am

jcleland
Total Posts: 11
I've been watching tutorials for the past couple of days (thanks for the pointers!), but I still haven't been able to figure out how to clean up the junction between objects when I want to preserve their exact size and produce a clean joint. Here's an example:

http://www.jamescleland.com/images/hosted/truespace/fillet.png

These three junctions occur at odd angles. The joint (to be) on the left is overlapping with one object rotated 0,0,0, the other 25,0,0. I could always drag vertices, but this would be inaccurate and change the size of the square tube. What I need is a miter of 12.5deg on either object and a clean junction. How?


The second joint is more complicated as the junction will not be contained within the face due to the angle of the junction. This angle is not obvious in the first image, here's another perspective

http://www.jamescleland.com/images/hosted/truespace/fillet2.png


Preserving the size of my objects is important, otherwise a mm here and there would not bother me. Thanks for your advice!


James

Post by TomG // Jan 28, 2009, 6:05am

TomG
Total Posts: 3397
Lots of options here.


Sweep - Don't make these separately and try to join them. Just take one tube and sweep the face out to make the next tube. This avoids the complications of other solutions. You could use a drill object to cut the tube with a new face at the correct angle, then just sweep it out.



Point Edit - you can do it so you are just moving along one axis (use the axis locks for this, the X,Y,Z buttons, to turn off movement in unwanted directions). You can use the Object mode to move relative to the object you are editing rather than relative to the world. This preserves the width of the tube.


Will be easy to slide one edge in this way back inside the tube it connects to. Not so easy to line up both tubes though as you'll need to accurately place both sticking out edges at the correct place, could be hard.



Boolean Add - Fuse the tubes together and tidy up with Point Editing afterward. Easy for this to be hard though, lots of editing to do to tidy it up.


Boolean Subtracts - clone the tubes so you have multiple copies. By subtracting A from B, then B from A, you'll remove the bits that stick out (may need to delete any extra bits that "hang over" beyond the intersection using Point Edit, or another boolean). You could then either use Boolean Intersection for the part where they meet, or you could join the two faces together with the Bridge tool if you Boolean Add the resulting tubes.



Mostly though its easiest not to try and stick them together later, but instead sweep out the face and make them as one initially.


HTH!

Tom

Post by TomG // Jan 28, 2009, 6:12am

TomG
Total Posts: 3397
More I think about it, maybe I'd just use Point Edit to move the faces pretty close but not touching or overlapping, boolean add them together, then use Polygonal Bridge to fill in the gap.


HTH!

Tom

Post by Nez // Jan 28, 2009, 6:40am

Nez
Total Posts: 1102
pic
For the first joint, I would normally just boolean subtract a cube object from each component to form a true mitre type arrangement - i.e. the angle of the cutting cube has to be such that the faces to be joined are the same size and angle (so you need to know the angle between the parts). Obviously this may not be too straightforward for more complex joints, and everyone complains about booleans around here....


mind you, I also use the model-side exclusively, where this sort of thing is usually pretty straightforward....

Post by marcel // Jan 28, 2009, 6:53am

marcel
Total Posts: 569
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Put the axe at the corner of the objet - rotate - objet union

Post by Nez // Jan 28, 2009, 7:00am

Nez
Total Posts: 1102
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That's a really neat and tidy solution Marcel, thanks...

Post by jamesmc // Jan 28, 2009, 7:00am

jamesmc
Total Posts: 2566
Elegant solution Marcel. :)

Post by jcleland // Jan 28, 2009, 7:06am

jcleland
Total Posts: 11
Hi Tom,


Thanks for the reply! I thought about sweeping the face of one tube, but the problem I had was that I first needed to rotate the face to 25deg which deformed the square tube to start with. I'm going to try using a drill with a specific rotation to miter both pieces and magnet them together.


J

Post by TomG // Jan 28, 2009, 7:27am

TomG
Total Posts: 3397
Yes trying to sweep and bend would be hard - best to slice then sweep if you wanted to that, using a drill to leave the cut face at the right angle (I guess not too different from actually cutting a tube in real life).


I like the move the axes then rotate version too, that one is very neat! So many ways to solve a particular problem, and usually always some new ones too!


Thanks!

Tom

Post by RAYMAN // Jan 28, 2009, 9:35am

RAYMAN
Total Posts: 1496
pic
I come from the nurbs front and we do cutting all the time

see the nurbs thread in the roundtable section.

I see no problem in drawing the bend with the poly draw tool

and cutting inside block out with boolean subtraction.

I write here for the people from Caligari including Thomas that we

need more exact ways of drawing 2d.

My favorite nurbs modeler does someting like trimming 2d curves and I show you how it works here.Its 100 % more exact then eyeballing it in....;)

Peter

Post by jcleland // Jan 28, 2009, 1:46pm

jcleland
Total Posts: 11
Wow, lots of cool ideas. Thanks guys, I'll start playing around. I should probably familiarize myself with various solutions.


J

Post by jcleland // Jan 28, 2009, 6:08pm

jcleland
Total Posts: 11
I'm having trouble figuring out how to move the object axes to the edge or vertex at the end of the object. I can move it in X/Y by locking movement to these axes (Can't get Z to work though). Is there a way to snap the axes to the edge?

Post by fahembree // Jan 28, 2009, 6:22pm

fahembree
Total Posts: 123
pic
I think the only way to make them match up is to rotate one end 25 deg as you considered and then sweep out the face. Tnen use 4 views to adjust the edges to be as close as possible. In really the tube do not intersect at a miter joint, its physcially does not not happen.


See attached image for adjusting in 4 views. If you look close you can see that one tube ends up wider then the other one to make a miter joint

Post by TomG // Jan 29, 2009, 4:31am

TomG
Total Posts: 3397
You might want to move the axis by typing in the value for its location - get the location of the edge to rotate around (ie its x,y,z in the information dialog) and then copy those values into the axis x,y,z to accurately place the axis exactly at that edge.


I don't think you can snap the axis there visually.


HTH!

Tom

Post by jcleland // Jan 29, 2009, 5:26am

jcleland
Total Posts: 11
This sounds like what I need, but I'm confused as to how to locate the axes. It doesn't appear to be an object that I can set coordinates for in workspace or model (model is just three lines and X,Y,Z letters). I can't select it, for instance. In workspace, I can highlight a vertex, edge, etc and get the coordinates from the dialog. The dialog doesn't seem to update in model view when I pick vertices or edges. I hit the manual, but I don't see anywhere in 4.9.10 that describes locating the axes precisely.

Post by TomG // Jan 29, 2009, 5:55am

TomG
Total Posts: 3397
Is possible on the Model side - swap there, use Axes, open object info dialog (right click on the Object Select arrow), then type in the location of your axes.


This won't affect rotation on workspace side, so you may need to do that Model side too. Alternatively, you can use the axes movement widget on the workspace side, and just use the dialog box to position it by eye, checking your co-ords in there, could be fiddly getting the last 100th of a degree of precision etc though.


Unsure if you can adjust the axes info directly in the LE or not, that might be another workspace possibility. Or folks may have some other ideas too :)


HTH!

Tom

Post by marcel // Jan 29, 2009, 6:12am

marcel
Total Posts: 569
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Fahembree : "I think the only way to make them match up is to rotate one end 25 deg as you considered and then sweep out the face"


1 - The intersection between both objets must 12.5 degrees, not 25 and the sweep should not be perpendicular (90+12.5). Otherwise sections will not be the same.

2 - Rotate the end of the objet is not a good solution because the others faces of the objet are no longer parallel. You can create a cube, rotate 12.5, and cut the first objet with a booleen operation.

(but the simplest is to merge the objets as I explained before. If you have problem with axes, try on the model size and select his icon to move the axe at the corner).

Why complicate what is simple? :rolleyes:

Post by marcel // Jan 29, 2009, 6:27am

marcel
Total Posts: 569
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"try on the model size"

sorry, it was "model side"

Post by jcleland // Jan 29, 2009, 10:38am

jcleland
Total Posts: 11
Moving on :) Thanks for the suggestions! My next problem will most likely involve a bicycle wheel, but I'll revisit lathe and sweeps before I start asking ?'s.

http://www.jamescleland.com/images/hosted/truespace/union.png

Post by fahembree // Jan 29, 2009, 5:40pm

fahembree
Total Posts: 123
pic
Fahembree : "I think the only way to make them match up is to rotate one end 25 deg as you considered and then sweep out the face"


1 - The intersection between both objets must 12.5 degrees, not 25 and the sweep should not be perpendicular (90+12.5). Otherwise sections will not be the same.

2 - Rotate the end of the objet is not a good solution because the others faces of the objet are no longer parallel. You can create a cube, rotate 12.5, and cut the first objet with a booleen operation.

(but the simplest is to merge the objets as I explained before. If you have problem with axes, try on the model size and select his icon to move the axe at the corner).

Why complicate what is simple? :rolleyes:


You are right, I meant 12.5 degrees, I didn't read the post as close as I should have, as I thought that there was was rotation around the z axis also making it more complex. I do have a another question thought. Why does the boolean operation need to be done on the model side. I thought workspace was supposed to have improved boolean operations. I can only get the results you show to work on the model side.

Post by marcel // Jan 29, 2009, 11:08pm

marcel
Total Posts: 569
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You can do boolean operation on the workspace. I say "use the model side" only to move the axe of the objet because i don't know how to move the axe on the workspace. somebody knows if this is possible?

Post by TomG // Jan 30, 2009, 3:20am

TomG
Total Posts: 3397
You can move the axes in the workspace side, the tool is in the fly out under the object selection arrow (Axis Tool). You can't though type in a value for the axis location - if you type in a value to the info box, it moves the object. You have to use the widget to move the axes around, though you can see the resulting values in the info box.


So for exact placement, you may be best using the Model side still. For placing by eyeball, the axes tool on workspace is fine.


HTH!

Tom

Post by trueBlue // Jan 30, 2009, 5:50am

trueBlue
Total Posts: 1761
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It is possible to move the axis in Workspace by way of the Info panel.
With your object selected, select the Axis tool. This will install a Pivot node inside your object and you can use the Axis's Widget to move it but as Tom says you can not use the values in the Info panel to move it. Select the Axis tool again or the Object tool and the Axis's Widget will hide. Now with your selected object select the Down arrow key until you see the Pivot selected in the Info panel. With the Object's Pivot selected you can use the Object Widget or the Info panel to move the Axis.

Post by marcel // Jan 30, 2009, 8:12am

marcel
Total Posts: 569
pic
Thank Tom and Trueblue ! A good info

Hope i can remember this:

select Axis tool - select objet tool - select the Down arrow key - use info panel

Now it's as easy as the model side.

This function might be easier but it work. :)

Helping people, you learn as much.

(I learn English with this forum, it is my school but I still have much to do.)
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