Creating tube miter correctly

[jamami]

I have been struggling with this issue for weeks using Acad2012, Win 7.

 

To draw the cope end I subtract one tube from the other, this creates a taper from wall thickness t at the intersection of the inner tube face to zero at the intersection of the outer wall face. This loss of wall thickness is not ideal. To get rid of this less than full thickness material I create a slicing plane through intersection of non-cut tube 1 and the inner wall of the tube to be cut, I establish this point by drawing a 2D cross section.

 

I realise this a bit of a hack and it never works out spot on as the slicing plan never seems to match exactly the intersection point of the 3D tube inner wall.

 

I have tried to get a work around. ie:

 

- drawing a tube inner radius only subtracting from that then shelling-this only re creates the taper.

 

-offsetting the intersection edge of the inner wall and trying to project onto outer at 90deg-this does not offset correctly due to the complex geometry.

 

 

 

I was hoping the COPE file from SEANT post in the Customisation forum may answer my problems but I cannot get to work and would like to find out if this can be acheived using in built functions or methods?

 

If anyone can provide me some help with the following I would be really grateful:

 

 

 

1. How to create a mitre maintaining full wall thickness. 90 degree intersections.

 

2. How to create a mitre maintaining full wall thickness. Non 90 degree intersections.

 

3. How to create a mitre maintaining full wall thickness. Tubes angled in 2 planes ie: for triangular space truss.

 

4. How to create a mitre maintaining full wall thickness. Tubes angled in 2 planes centres lines not coincident ie internal members offset to enable 2/3 to meet at same node.

5. How to deal with the above when using non round tubes.

[ReMark]

I can appreciate your attention to detail but I have to ask why is this really necessary? Who is going to see this level of detail when the drawing is printed? Don't you have to trust the people who are doing the fabrication to know what they are doing when coping a tube shape?

[jamami]

I need to get manufacturing drawings produced to issue to suppliers. Im trying to achieve single stage manufacture process ie laser cut. Trust would be good but unfortunately when dealing with some overseas suppliers I have found that things need to be buttoned up tight.

[ReMark]

I think this would be better handled by Inventor or another piece of software (tube design?) given the level of precision you are looking to achieve.

 

Just out of curiosity, what are you constructing?

[SEANT]

 

. . . .

I was hoping the COPE file from SEANT post in the Customisation forum may answer my problems . . . .

 

That “Cope” routine is to develop a template allowing the cope to be cut by hand (i.e., jigsaw or band saw). Probably not what you intend to do.

 

Laser cutting removes the need for a template, but still presents its own set of problems. If we just consider a perpendicular layout, would the attached describe what you need as an end result?

Cope.dwg

[nestly]

For mitered joints you'd have to thicken the inside surface toward the outside, as described above by SEANT, but then also thicken the outside surface inward. The "interference" would be the end product.

[SEANT]

For mitered joints you'd have to thicken the inside surface toward the outside, as described above by SEANT, but then also thicken the outside surface inward. The "interference" would be the end product.

 

 

Well stated.

 

 

 

The basic square butted layout in my example is probably the only orientation that does not specifically require the secondary intersect operation.

[jamami]

In this case space frame trusses. Aluminium 6082T6, modular lengths from 2m to 8m.

[jamami]

I think this would be better handled by Inventor or another piece of software (tube design?) given the level of precision you are looking to achieve.

 

Just out of curiosity, what are you constructing?

 

 

ReMark

I think you are right, I have seen exactly what I am trying to achieve produced on Inventor. Problem is I do not own Inventor or know how to use it.

[jamami]

SEANT many thanks for this example, this looks spot on for 90 deg mitre. Please excuse my lack of experience with surfaces, I have always used solids. In my mind surfaces were only needed for terrain modelling or highly complex irregular forms, or just to visualise things. Now I am enlightended.

I have tried to create a 60 deg mitre along these lines, see attached. The leading(obtuse) edge appears OK but the trailing(acute) end does not appear correct. Is this because I have only thickened in one direction?

 

Cope_60.dwg

[jamami]

For mitered joints you'd have to thicken the inside surface toward the outside, as described above by SEANT, but then also thicken the outside surface inward. The "interference" would be the end product.

 

nestly, thanks for this help. I have tried above but got some weird results, small 'blips' left over following deletion of the interference solid - any ideas?

 

Cope_60_inandout.dwg

[nestly]

The "interference" is the part you want to keep. Make sure you uncheck the box that says "Delete interference objects...." before you close the Interfere dialog box.

 

Here's a video of the process I used.

[jamami]

nestly

thats really useful, many thanks.

I have visited the laser cutting company I will be using. Their machine has a vertical laser and the tube is fed in at horizontally at 90 degrees symmetrically about its centre line. The mitre shapes are then made (very quickly) by rotating the tube and moving it backward and forwards while it rotates. It is all vey impressive, but I realise that the cuts will always be at 90deg to the material surface. Will the interference method kindly provided above be acheivable using this laser technology? ie does the interference create a non 90deg edge?

[nestly]

Yes, using the thicken method, the cuts are perpendicular to the bore, including the "interference"

 

[jamami]

Yes, using the thicken method, the cuts are perpendicular to the bore, including the "interference"

 

 

Many thanks for all your help with this. I need to change a whole bunch of drawings now that have been prepared 'the old way'. I also need to work out how best to dimension these sub assemblies so that they can be fabricated correctly.

[nestly]

Just a note... although the video shows copying the part, exploding then thickening the surfaces separately, that's really an unnecessary step, you can do them in-place.

 

With regards to dimensioning, I still find it more efficient to create 2D views of the 3D parts, and dimension those. and my personal preference is still FLATSHOT.

Here is a good tutorial that covers all the methods for making the 2D views. If you don't already have an account at Autodesk University, just sign up... its free.

 

Producing 2D documentation from 3D models in AutoCAD

[jamami]

I have always used solview/draw etc to create a 2d view to annotate. These drawings go into the ManufactureDrawings folder, while the 3d models sit elsewhere. This has always bugged me (and has caused a few issues)as changes to either drawing are not reflected in each other.

For this reason i have been investigating dimensioning in 3D. I also want to undertand more about how to tolerance objects correctly for manufacture, maybe the AU will be good for this? I do not have an account at present.

[Dadgad]

my personal preference is still FLATSHOT.

 

I've seen some pretty unacceptable images generated by both the flatten and the flatshot commands, complex 3D curves are less than reliable.

I suspect that anyone doing 2D drawings of 3D Models who is using Autocad 2012 will QUICKLY come to appreciate the VIEWBASE functionality. Just remember that when sharing with an earlier version of Autocad, DWG True View 2012 (free download from Autodesk) will be required to read the drawings. The time you save will be your own.

[Dadgad]

I have always used solview/draw etc to create a 2d view to annotate. These drawings go into the ManufactureDrawings folder, while the 3d models sit elsewhere. This has always bugged me (and has caused a few issues)as changes to either drawing are not reflected in each other.

For this reason i have been investigating dimensioning in 3D. I also want to undertand more about how to tolerance objects correctly for manufacture, maybe the AU will be good for this? I do not have an account at present.

 

VIEWBASE drawings are associative and thus clearly indicate when there is a dissimilarity between the 3D Model in modelspace and the drawings in paperspace, and can be updated with a single command. It is way better than the SOLDRAW & SOLVIEW commands, and much quicker.

[kencaz]

I have always used solview/draw etc to create a 2d view to annotate. These drawings go into the ManufactureDrawings folder, while the 3d models sit elsewhere. This has always bugged me (and has caused a few issues)as changes to either drawing are not reflected in each other.

For this reason i have been investigating dimensioning in 3D. I also want to undertand more about how to tolerance objects correctly for manufacture, maybe the AU will be good for this? I do not have an account at present.

 

If your already on AutoCad 2012 why aren't you taking advantage of the New Drawing Views... This has been in Inventor for many years and finally ported to AutoCAD. It really makes it simple to dimension your 3D objects and creates the views and viewports for you. These are also Dynamic and update as your model changes. I will be on AutoCAD 2012 soon and have been waiting for this change for a long time...

 

KC