Author Topic: Help with a DXF oddity please !  (Read 406 times)

Offline awemawson

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Help with a DXF oddity please !
« on: December 01, 2018, 06:37:21 AM »
Today using Autocad I added an opening on the end of the previous spanner that I had cut for the Baruffaldi powered tooling to hold the flat on the 90 degree unit.

All looks exactly as I want in Autocad, as a .DWG. I then save it as a .DXF and within Autocad it still looks fine. If I then import the .DXF into SheetCAM in preparation for cutting on the plasma table, a mysterious circle appears between the jaws of the original spanner.

If I go back into Autocad there is no sign of this circle. Only one layer is in use, and if I do a 'LIST' selection of where the circle is, there is no circle listed  :bang:

Now I'm sure that if I went back to the original drawing and started over, this strange artefact in all probability would not be there, as if I load the .DXF of the spanner that I originally cut, the circle isn't there. But that's not good enough - a chap needs to know WHY? and HOW? so come on chaps save my sanity, where is this circle in the .DXF that doesn't show in Autocad and yet does in Sheetcam.

NB the file "ER32-Spanner-Mk2-dxf-as-txt.txt" as it's name implies is ACTUALLY the DXF renamed so that it will upload to the forum.
Andrew Mawson
East Sussex

Offline David Jupp

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Re: Help with a DXF oddity please !
« Reply #1 on: December 01, 2018, 06:59:39 AM »
Andrew,  If I open it in Alibre Design the circle is there.
In eDrawings the circle isn't there.
In EasyCAD the circle isn't there.

In eDrawings and EasyCAD there is a tiny dot which looks as though it coincides with a point on circle diameter in the V of the jaws.

Not sure what that tells us....   your image from ACAD also has the dot when zoomed right in.   

Offline awemawson

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Re: Help with a DXF oddity please !
« Reply #2 on: December 01, 2018, 07:20:08 AM »
Thanks for looking David. In any of those programs can you examine the properties of the entity?

Is it deletable in Alibre ?

I had assumed that it must have been on a 'turned off' layer or maybe the line properties were odd, but there is no turned off layer nor entity to examine  :bang:
Andrew Mawson
East Sussex

Offline David Jupp

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Re: Help with a DXF oddity please !
« Reply #3 on: December 01, 2018, 07:51:44 AM »
When trying to delete the circle, I found there are 2 copies of it.  They will delete.

I can't find any properties beyond 'circular arc'.


Offline awemawson

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Re: Help with a DXF oddity please !
« Reply #4 on: December 01, 2018, 08:21:46 AM »
By zooming in on that point you spotted (well done eagle eyes!) I found the two circles and could delete them and now all is well in Sheetcam - very odd though that they don't display in AutoCAD

Spanner now made  :thumbup:

Here are the properties in AutoCAD :
Andrew Mawson
East Sussex

Offline Spurry

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Re: Help with a DXF oddity please !
« Reply #5 on: December 01, 2018, 08:47:13 AM »
Andrew
Could the stray circle be related to the origin of your drawing? If I open the drawing in Turbocad, the DXF displays without any problem, with and without the grid.
Pete

Offline awemawson

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Re: Help with a DXF oddity please !
« Reply #6 on: December 01, 2018, 09:26:27 AM »
Origin of the drawing is 0,0
Andrew Mawson
East Sussex

Offline David Jupp

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Re: Help with a DXF oddity please !
« Reply #7 on: December 02, 2018, 07:15:05 AM »
Yep radius of the circles is 20mm.

My guess is that AutoCAD and other software treat start/end angle differently.


Both being zero probably gets interpreted as 'don't draw any of the arc' by AutoCAD, but as 'draw full circle' by others (on grounds that 0 = 360 ).   The centre of the circles is at 0,0.

Offline Chuck in E. TN

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Re: Help with a DXF oddity please !
« Reply #8 on: December 02, 2018, 07:23:40 AM »
The .dxf imported into Fusion 360 with no extra circles. The first time I imported it I had the dimension units set to imperial and the spanner was huge in length, but thin as paper. Changed units to mm and all's well.
Chuck in E. TN
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Offline needleworks

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Re: Help with a DXF oddity please !
« Reply #9 on: December 07, 2018, 10:00:26 AM »
I just opened the .dxf in Cambam > No circle.

I then tried Solidworks > The circle is there.

Offline ddmckee54

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Re: Help with a DXF oddity please !
« Reply #10 on: December 07, 2018, 11:00:10 AM »
Not ALL DXF files are created equally.  I have had software packages that react differently to different versions of the DXF file.  Are you using the same version of Autocad that you used for the previous spanner?

Autodesk loves to change things, they might have changed something in the format of the header for the DXF and Sheetcam thinks they are telling it to draw a circle?

Don
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Offline awemawson

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Re: Help with a DXF oddity please !
« Reply #11 on: December 07, 2018, 11:42:39 AM »
Yes Don, but if you look 'up thread' you'll see that the issue is solved  :thumbup:
Andrew Mawson
East Sussex