DXF problem

TIG

the dxf files were creted in another cad program vectric aspire and autocad
they have slots in them that are 1/4 inch wide .25
they import as inch into sketchup and show .25 fine after import
if i do nothing to them at all and then export them back to the external cad program they now show 0.2889 on the slot width
so i tried creating a similar file using native sketchup tools and i get the same issue if i create a 1/4 inch slot and export the DXF i get the same or simliar result
where/how would i upload a file for you to check this yourself ?
regards
Paul

Make a zip file.
Start to type a reply, like you just did.
Below the typing-pane there's a tab titled 'Upload Attachment'.
Click on it and pick the 'Browse...' button.
Navigate in the resultant file-browser to your zip file and then select it + Open [I know you are not 'opening' it but a standard file-browser says that, even if you are just 'selecting' it for later use!].
It's added to the Filename field.
Now pick the 'Add the File' button to add the file to your message.
Finish your message and Submit it...
There are file-size limits but a <4Mb shouldn't hurt !

TIG

I have just tried to repeat what you reported.
At first I thought it might be due to the number of dps 0.0000 set in Model Info > Units, but it's not.
It exported , imported a series of circles as 3D DXFs without any affect on the circles' sizes or accuracy, BUT exporting it as a 2D DXF it does mess up the radii.
The exported/imported 2D circle is not a circle but a series of segments - however, it should still have its vertices on the circumference BUT they are not - even the segments mid-points are not - there appears to be 'no rhyme nor reason'!
Typically a 1" radius ends up exporting in 2D as 1.158239" an error of ~16% which is, as you say, pretty useless !

Solution export as 3D DXF to give perfect Circles and Arcs.
Avoid 2D DXF like the plague...
When you import these from a CAD program they should come in as good Circles/Arcs - you can change their segmentation from the fixed 24 to much more in Entity Info if required...

Anssi

Did you have Camera set to Parallel Projection?

Did you try DWG instead?

Anssi

outland86

Hi DWG is not useable for the CNC tool path software only DXF
i do not want to create another step for the end user where they have to do yet another conversion with outside software

not to sure why changing the camera that views the polylines should effect the actual drawings export dimensions
can you tell me why this may have an effect ?

thomthom

@outland86 said:

not to sure why changing the camera that views the polylines should effect the actual drawings export dimensions
can you tell me why this may have an effect ?

Because when viewing in perspective things gets distorted.
When you export to 2d you are exporting what you see.

To export exactly what's there, export in 3D - as the content exported is then 1:1 and not bound to the viewpoint.

honoluludesktop

outland86, The fellows here who are trying to help you are probably too nice to complain about your attitude:

"i cant believe that people could deal with these problems and still find this a useful program "

"does google know that this is a problem?"

Just because SU doesn't work the way you "think it should" doesn't justify your attitude. Floating point calculations is not exact, only precise. I don't know of a computer system that can does integer math. If it did, you would complain about speed!-{

TIG

@thomthom said:

@outland86 said:

not to sure why changing the camera that views the polylines should effect the actual drawings export dimensions
can you tell me why this may have an effect ?

Because when viewing in perspective things gets distorted.
When you export to 2d you are exporting what you see.

To export exactly what's there, export in 3D - as the content exported is then 1:1 and not bound to the viewpoint.

I've made tests and even with a pure plan view the dxf circle is NOT the right radius.
With plan view and parallel projection a 1" circle 2d DXFs as 1.000014" [pretty good] BUT in pure plan view but with perspective 'on' - with the circle at z=0 it's ~16% out !

Motto = always do a 3D DXF... that way a 1" circle is DXFed as a 1" circle always...

outland86

@honoluludesktop said:

outland86, The fellows here who are trying to help you are probably too nice to complain about your attitude:

"i cant believe that people could deal with these problems and still find this a useful program "

"does google know that this is a problem?"

Just because SU doesn't work the way you "think it should" doesn't justify your attitude. Floating point calculations is not exact, only precise. I don't know of a computer system that can does integer math. If it did, you would complain about speed!-{

i did not know attitude even came into this equation
but i am sorry if you were offended by anythiung i have said
i appreciate all and everyones help more than you could know
but did that justify your own ending remark
pot calling kettle black me thinks

Gaieus

Offences aside...

@outland86 said:

pot calling kettle black

Thanks for this proverb or saying or expression... - I am not a native speaker so when I realise there is something I exactly understand and we have one with the exact same meaning but totally different expression, I am always glad!

TIG

@gaieus said:

Offences aside...

@outland86 said:

pot calling kettle black

Thanks for this proverb or saying or expression... - I am not a native speaker so when I realise there is something I exactly understand and we have one with the exact same meaning but totally different expression, I am always glad!

In England there's my favorite -"it's six of one and a half a dozen of the other..."- used when there's no real or meaningful choice in something - in the North it's simplified to -"it's six and two threes..."-
I'm sure most cultures have something similar...

outland86

ah ok i see

its just that the CAD software i am used to working with adds dimensioned constraints to the 2d polylines in a given drawing and no matter how they are viewed they are always exported with those contraints in place
but i see now that this software does not function that way. no problem though its just a matter of knowing this information. and finding the workflow solution to achieve the same end result

thank you much for your input and work on this Tig and others and i am sorryif something i said pissed anyone off

regards

Paul

Gaieus

@outland86 said:

i am sorry if something i said pissed anyone off

I don't think you'd pissed anyone off - in fact, although I am a bit ashamed to push your topic a bit "off..." (so I am sorry for that), I am enjoying it, especially that you seem to be closer to a satisfying solution to your problem

TIG:
"pot calling kettle black" = "owl calling sparrow big headed" (here big headed meant literally)
"it's six of one and a half a dozen of the other..." = "it's nineteen of one and twenty but one the other..."

outland86

thank you

pot calling kettle black = pot is black from fire burning just like kettle so why is pot calling kettle black when he is also black

not too sure where it came from but is somthing i grew up with in New Zealand and have bought too the USA i guess lol
perhaps in 50 years it will be part of the language here

us kiwis have many of these little jibes and colloquialisms in our street speak my MInnesotan wife is forvewr looking at me sideways when i talk not knowing if i just insulted her of paid her a compliment usually its a compliment

fair sucka the sav aye mate = please give me a fair share of the credit from this deal or idea we are talking about

Gaieus

@outland86 said:

pot calling kettle black = pot is black from fire burning just like kettle so why is pot calling kettle black when he is also black

Yeah, I understood that (although never heard before). We have that sparrow one for the same meaning here.

outland86

here is what the wiki says about it

The phrase "The pot calling the kettle black" is an idiom used to accuse a person or thing of being marked with or guilty of the very thing they are pointing out

Gaieus

Yes, exactly. Now if you think about it, if an owl (which is a bird with big head) says to the sparrow that it has a big head, it means the same (just of course, in Hungarian).

outland86

here is a common one

Bob's your Uncle: roughly translates to 'there ya go - that's all there is to it!' Just press this big red button that says 'Launch Missile', and "Bob's your uncle".

i better go to bed before i make an even bigger dork of myself lol

thanks again for all your help

TIG

We drift off topic into the sunset.........