3D import Issue- STL and IGES files enlarged?

[Finchasers]

Hello All,

I have been playing with my new machine for the past few months as I build large prototype parts for motorhomes in Australia. The files from the designers are from SolidWorks and AutoCad Inventor and they come into ASPIRE just a bit bigger -around 1mm larger per 180mm. I had them increase the file size before they sent it to me and things did get better (appr. 1mm increase per 300mm)

This ends up being a big deal when all nine spliced parts are put together to make an 8 ft piece of custom molded plastic. It ends up being about 30-50mm too large.

Has anyone else experienced this?

Cheers,
Eliot
Melbourne, Australia

[gravirozo]

hi eliot

i made you a sample to explaining a possible situation...
long time before brian explained, when we import a triangulated file aspire put on some"" extra pixels""
it is actually dont change the model geometry... however it looks like larger, i mean aspire measure it larger...

i attached a 3ds file, 96 sample...
(need to rename to 96sample.3ds from 96sample.txt , forum dont let post 3ds file)

i imported in aspire...

you can see aspire shows, as it would be 96.16, and across 5.16
the extra measurement is the added pixels..

after this i simply exported out this model and the exported stl shows again rigth size...

so, if you derivate contur for milling clicking on the bird icon, youll get larger contur than need
if you made in a cadprogram the original models, then the simplest would be generate a contur in the original cad program and using for cut out vector...

so summarized these, original is a 96 inch long model,
the 3d toolpathing also will result a 96 long model.

but if you create a contur of the grey bitmap, in 2d window, then that conturline will be larger...

viktor

the 96sample.txt need to rename to 96sample.3ds

the 96sample zip is an stl file, exported from aspire

[Finchasers]

That is exactly what I assumed to be happening.

I will look into the solidworks and AutoDesk side of things to export for the contour beforehand.

Thank you for your input and time... I had searched the forum for the answer for the past few weeks to no avail.

Thank you again,
Eliot

[gravirozo]

eliot

actually, as i remember vertical walls gave more addition... but i dont know the exact explanation...
importing a conturline, you can center the model to the imported contur..
imagine, where the model connecting to the modeling plane, aspire makes a ""transition""
however these transition pixels are """transparents""

means they have no affect for 3d milling... but as a bitmap can contain transparent pixels, same way aspire model can contain these pixels..


viktor

hopefully someone explain it better..

[Finchasers]

Viktor,

You seemed to have gotten me down the right track even better...

However, as I try to measure in the digital image of the 2D view there are "shadows" on the edges. This makes it hard to determine where the edge actually is. And it seems that the vector bitmap does make the piece larger but then again I'm not sure where the edge is.

No matter what the real problem still persists when I try to place a 9 foot piece of foam on the top of a motorhome chassis and have it not be off by 40-50mm. Quite disheartening after a week of milling the 8 pieces of foam and building the model.

The rest of the design team is still trying to figure out how to get just a contour out of an AutoDesk program or Solidworks.

I'll keep searching the forum here for more of an answer.

Cheers,
Eliot

[gravirozo]

eliot

of autocad... if it were a solid model, the section command create a vector on a defined plan of a solid...
you can show this screenshot autocad users if you dont have autocad... they knows it.
in this example i created a block, and definiing 3 point i created a vector on an angled plane...it is angled only for the example, it can be on the bottom too, still giving a continous conturline...

another method you can use the exported stl file from aspire... open in accutrans, and ask for watertigth mesh...
aspire export stl file without backside, an open mesh... so you can get the contur this way...
checking on its size you can see what size actually your model...
also you can zoom in,, in accutrans and check on if model has hozrizontallly added extrapixels... and you can erase them..

i put your pm my email... if you dont mind, please send the iges, or stl file... i can take a look on and send you back an aspire file, what already works...

what i thinking about your present project, if it is larger, i think from the two end can be milled off the excess...

after you click on yes, at watertigth check, youll get an extra layer, with conturline...
turn off the layer, contain the model, and you can save in dxf format the contur... what you can import in aspire...

viktor

[Finchasers]

Is there a better file format than .stl that I should be trying to get the image into? One that harbors "the most, clean" information to work from?

.x, .dxf, .lwo, etc.??

I thought I could just bring a bitmap in but Aspire does not want that it seems.


And what is becoming quite bothersome is the search ability on the forum. Everything I try looking up is "just too common" of a word.

"3d file format"
"best 3d format"
"best 3d file format"
"which 3d file format should I use?"

[gravirozo]

eliot

file formats despite their names are different, they are basically same... all of them triangulated, or some of them has quads... but as result, they all of them same...

if model not too complex, you can give a try to model directly in aspire...

for search, on the vectric site.. www vectric com
you also find a search input window... that works without """common words"""
means that wont return empty...

viktor

[Finchasers]

Thanks to you both,

The file is very complex and must mold to the rounded forms of the roof of our chassis in several odd areas so it would be too intense to bring all that info into Aspire.

I just want to deal with "pixellation noise" that occurs or gets added onto my bitmaps when I bring these files in.

I'll keep plugging away at the solution

[gravirozo]

eliot


i just wondering what result you got...

reason i asking, because already over 5000 user of vectric programs, and no one reported 2 inch error on 96 inch object...
this error so large that it can not came from known issues..
what i explained, the pixelisation error, that is a virtual error, but can be eliminated..
and it is ONE of possible reasons getting larger output.

as i mentioned the 3d dimensions are in an accepted tolerance for wood and plastic...
the output from aspire, stl output shows a 0.0001 error... your error is 0.02 what is 100x larger

in simple words, no exist cad cam can produce this error..

since it is an open forum new customers users read this post.. and they migth think these programs just cant calculate a simple toolpath...

best regard
viktor

[Finchasers]

Viktor, et al.
I have found out there are a few likely issues.

We were saving files in the other programs with minimal information. I have increased the file sizes in .stl and .iges and the variation, or tolerance has gone down but not to acceptable levels.

On Friday when I heard of the announcement of the 3.5 Update I realized I couldn't install it because we were given version 2.5 even though we bought the machine in August. I am waiting to hear back from the company we purchased from so we can resolve that issue and move forward with up to date software.

As I "measure" the objects in Aspire I am unclear regarding where the edges of my object are since they are represented with a certain "3-dimensional shadow" look. Acording to our measurements however it is still off a bit so I have yet to cut into hundreds of dollars of foam on my machine to see how it turns out.

My next step is really looking into SolidWorks forums for answers there.

Thank you for the follow-up and since this effect has happened to another company that we have sent programs over to for cutting, I am thinking the problem persists outside of Aspire, but I'd like to figure out where in case others run into it.

Eliot

[gravirozo]

eliot

here i try to give some explanation how you can solve this issue on your own, without expenses cad like solidworks or inventor..
the iges format can be imported in the free cad and exported as stl... so if you have only iges format you can convert it...
http://sourceforge.net/apps/mediawiki/f ... =Main_Page

after you have a whole model, the following pictures shows how you can get the rxact size within aspire..
this type of model as aspire use very handy to creating reliefs, shapes... modeling a flower, or orother organic objects, i think it is the simplest... for models as you need migth not, but still you can use effectively to toolpathing..

1st picture..
check on size, sure it is exact..

2 set jobsize larger , in this example 1 inch around... aspire place model on center... pixels are eqally added around, so it will be on center

3 after import since it is the lowest res the added extra pixels showing larger size.. but as earlier showed the model in 3d exact size..

4 create an exact contur for your model.. this contur can be centered like model.. and this contur can be used for the actual cutpout, not the derivated vector of the greyscale pic..

5 created a part contur, as model will be parted for 5 equal part...

6 multiplied 5 times

07 creating vector to separate 5 equal part the whole model

08 copy model in modelarea, and cut off the unnecessary part... (in version 3 of aspire and up aspire copy automatically part in modelarea, and baking create component)

09 the component (orversion3 baked part) shows larger about 0.35 ..
but this is the added horizontal pixels... they have no effect on the 3d model... however if you use the greyscale picture for cutout contur, 5 times this 0.35 will result the 2 inch extra

so summarized the best is if you have concrete vectors of model, and dont try to use the 2d greyscaled representation derivating conturs...
if anyway this is the only option, then you have to zoom very close in 2d and hollowing with cursor aroud the modeledge, you can see on the bottom displayed the z values... where is it changing from zero to other values on that point is your model exac border.. but it is very tedeious... thats why need contur on a simpler way...

hope you can get trough... i think this is what approximately happened to you.. so your cutted foam, if model was exactly imported, then they are ok... and only need to cut them around with the rigth vectors...

viktor

[gravirozo]

rest of pitures


for solidworks and other modelerprograms... all similar program can extract shells of a solid model... on shells edges also can be extracted... so both program can make simple vectors of conturs..
another way simply subtract the ready model of a larger block, and extracting this surface of the block, will result also the exact conturline...

for aspire versions... version 3.5 has great enhancement on the toolpath depth.. well this addition missing from the pocketing... also pocketing issue is not solved yet...
with reversing each second layer of toolpath, tool could stay down...
another great thing the arc in drawing tool...

this issue is not tied to version 2 or 3 it will be exist with pixelrepresentation...
so for conturing you need vector from the model directly not from the 2d greyscale pic...

and within import double check, sure the imported model correct.. aspire calculate an accurate toolpath... so if you enlarge your model, it will be larger after milling...
also make a test, drilling 4 hole on the 4 corner within your workenvelope, and a simple tapemeasure could shows how much exact, squareness and parallelity

viktor

[Finchasers]

so for conturing you need vector from the model directly not from the 2d greyscale pic...

Viktor,
Thank you for helping to clarify and find a solution. I hear that you are saying that the 2D grayscale bitmap will not work for what we are trying to accomplish.

So, How should I import the vectors directly from the model which was made in the other software? Is there a feature in Aspire that I haven't found yet? Or what do you suggest I for to get the vector direct from the model.

Making our model in Aspire is not an option for us.

[gravirozo]

eliot


i saw your post last nigth, i just was too tired for anything...

only format you can import in 3d the triangulated surfaces...
for 2d, dxf and eps working...

i really sorry your situation.. those people who draw out, or design a trailer (camper) with inventor or solidwork, they can derivate conturs for you... i cant suggest method...

both program is the top of cad... to derivating any contur of a solid model, is an elementary function...

if they dont give you, then you can try something i suggested above...
if you have only aspire, you can try to give an offset on the vectorized greyscale picture, as much as the cutted part is larger..

but all solution is on your side a subtitution compared, with original vectors...

and for the end a few question...

as you said you made of five part your project.. have you measured the first part? after it was ready ?

you cut all five part when you noticed the result is larger...

do you think seriously, a program like autodesk programs, or solidworks, you can design a space shuttle, or catia was used in the french renault, you can not get a simple contur of a model?

last question is, i tried to make some samples you, but still know nothig about you trying to make... even a screenshot could made easier to help... you only provided, your cut was larger... but it can happen even by your machine...
so if you really like more help, then please post your triangulated model, or send in mail and me, or other can help you more...

best regard
viktor