Arc Orientation?

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THREAD FROM ARCHIVE
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From: PeteB Date: 24 Jan 1999

I'm currently using Autocad 14 for making my DXF files and I'm having a problem with arcs. Once my design is finished I join all my lines/arcs into a polyline then explode it (This puts all my lines/arcs in order). The problem is my arcs always come out reversed, the only way I can fix it is by edit the .sbp file.
Any suggestions on how to fix this problem?

[Argyle2@concentric.net]

A trick I made up goes something like this: Draw your line design using normal cad commands. Then change to another new layer and use a different color. At this point think about the tool path you would like and start using gravity line points around the project. Save the drawing and erase the original layer leaving the new layer. Make shure your origin point is set up properly!!!
Try it and experiment with your own Cad system. It's a great way to control the exact tool path.

[timwing]

Maybe someone can help me with ellipses; I am using AutoCAD r14. What is the easiest way to create a .sbp file of an ellipse? Currently I draw the ellipse then trace with polyline then spline and erase the original ellipse. This is very time consuming and dose not provide the best results.

Any suggestions would be greatly appreciated.

Tim W.

[phil]

TO CREATE AN ELLIPSE USE THE CC FUNCTION IN SHOPBOT. CC IS CUT CIRCLE, BUT YOU CAN USE THE PROPORTION FACTORS TO EITHER STRETCH IN X OR IN Y, THUS CREATING AN OVAL (ELLIPSE)

[Ron B]

Tim,
Phil has the same answer I would have except, I would use the CP command and place a new color on the point, the center of the elipse. Then I would edit the .sbp file in a word processor with a find 'MZ, XX'. This would work on all elipses on the X-Y axis.

Ron B

[timwing]

Phil & Ron,
Thanks for the info.

What I neglected to mention is that the ellipse is 60" x 108". So what I am really trying to do is cut a portion of an ellipse. If I enter the dimensions 60" x 108" into CC, Obviously the line runs off the table. Do I have to text edit the .sbp file to cut only a section of the ellipse? UUUGGHH I am confused!!!

I am probably making a simple solution very difficult, Huh. 8>(

Tim W.

[phil]

You can draw an ellipse in Autocad or any CAD program and then save the file as a dxf file.

Position your ellipse so that the 60 x 108 portion that you want cut will fit on your material. In this way the origin or 0,0 of your drawing will be at the right spot to cut on your material.
Save your ellipse as a dxf file and use the shopbot dxf coverter to get the sbp file

There are a few more steps to do but hopefully this will get you on the right track. I'll let you discover all the steps for yourself but if you can't get it to work with this instructions, let me know.

[Ted Hall, ShopBot]

Hi Tim,

Along the general lines suggested above, you can still use CC or CP to do your elipse if you know the starting and ending angles.

If what you are creating is a symetrical arch, then the CA function might also do it for you.

CP and CA are both circle function in the new software that you can explore with the 2b8 beta download, here. There are a couple of glitches in the 'Fill-in Sheet' so you'll have to enter the parameters (we'll have that fixed shortly).

[dlaking@home.com]

I draw in Autocad, then export dxf. I then import to Mastercam. My Manual says that splines are not supported in dxf. When I import dxf with ellipses they do not show up. I have to redraw them again in Mastercam. I think the best option is to use CC and scale x & y
Dale

[GordonB@Shopbottools.com]

PeteB,

The most recent UX converter in SB2.8 will now convert polylines with arcs (A.K.A. polyarcs) without exploding them. This will keep the entities in order and the arcs in the right direction. You can also order the cut, the first entity drawn is the first cut.

As for the double lines of code from the DXF converter, I will be looking at any sample files that are sent to Ted regarding this problem.

[birdsofplay]

I use MicroStation and have had pretty good luck with DXF exports.

I have noticed, however, some faceting at times. To fix this I discovered a config file that controls the way things are converted to DXF.
BTW MicroStation can export to dwg, dxf et al.

This file contains settings like "tolerance" and
segmentation settings for curve convertions and other messy stuff like that.

I was having trouble with larger but not smaller
curves. Smaller ones being nicely smooth and large ones having a serious faceting problem.

After some experimentation I found the setting that "did the trick" .

I verified that the CAD program was actually at fault and not SB convertions by displaying the "exported" dxf file with Paint Shop Pro 5.0 from JASC (shareware available.)

This paint prog will display dxf files, so I could see the faceting ( or not ) as it came from the CAD. PSP 5.0 will NOT convert raster to vector :-(
but it does a grea job of everything else.

IF your DXF file looks OK in the paint prog THEN
it ought to be OK in SB, otherwise, contact Ted !

I use a lot of 3-point arcs to "interpret" images
since direct convertions from scans has been less
than satisfactory ( depending on your desired outcome )

These 3-point arcs are modifiable (with rubberband effect) in end point and radius so they can be used to approximate just about any curve.

I too have seen some curve reversal and have contacted Ted re this issue.

Regardless of system we ought to be able to put a line, of most any type, down in our CAD programs
and then cut it without having to revert to individual editing sesions. Now that poly lines are converted ( thanks Ted ) I can even do a pretty good b-spline style cut and ellipses too.

If you are having CAD problems call the CAD mfgr for some assistance. They probably have a quik fix

enjoy your holiday :-) Bob

[giggalo]

I have never had duplines, so I tried to make as many mistakes as I can and still cannot get turbocad to make them? I did this with turbocad, Artcam, Mastercam,Casmate pro, Coreldraw, and Autocad and still no dups.

But I did find out Coreldraw 8 will not work right if tuobocad is running on my 300mhz but will work on my 400mhz? So the problems might not be in the software or the converter but in the computer? Bill Palumbo had this problem and a few other shopbotters.

So on my spare computer all I had was win98 and 1 cad program at a time installed, everything worked fine, now with all 5 cad programs installed on the same computer only turbocad and autocad would work without any mishaps? Bob I agree with useing Paint shop pro to view the files before cutting them, I feel it has a lot to do with the programs on 1s computer that make converting diffrent.

Ron

[Rfpaul@hotmail.com]

Has anyone tried the free TurboCad v6 yet, I'm using it but can't convert text & pictures together to make a SBP file, I get a 'not enough memory' in the S/B software! I do the pictures on T/Cv6 and the text with a different computer that has T/Cv5 and it work's, weird!!!!! Rick

[timwing]

Rick,

I am relatively new at this but I have experienced the same error "not enough memory" in the past. What I found the problem to be in my case is the file name; it can not have a space or dash in it. I hope this helps.

Tim W.

[chandler@n-link.com]

I downloaded sb2b8 and when I try to convert a *.cnc file to *.sb I also get the not enough memory error. I haven't been able to get it to work at all. I tried changing the extension to Gcode, using no extension, ect and no luck. Any ideas?
thanks.

[giggalo]

With Turbocad you might have to set the explode text in the setup when you save the file as a dxf, you will see this when you cilck save as and select dxf first, then click in setup and make sure the explode text is checked.

Best way to do it is before you do text right click on the text button and choose text and check the flexable, this will make sure all your text will cut in order.

If you ever need to have cut out letters try this.
1. Type the letters you want to cut out and size them.
2. Select all and copy.
3. Open a new page and paste them and set them to 0,0 and save as a dxf , now when you cut them the insides of the letters will be all cut out first like the A B D O P Q R then it will cut the outline of them, with the copy and paste useing Turbocad it will do it all backwards so the letters will be cut in reverse order, a neat little trick.

Ron

[bruce_clark]

Don,

If you are trying to convert a CNC (like from
Bobcad or Mastercam) then you need the G-code
converter. Either email me or Ted/Gordon at
ShopBot and they will email you a copy.

Right now, you have to exit the ShopBot software
to convert a file (as far as I know). Very soon
you will be able to convert G-code files from
inside the ShopBot software (along with HPGL and
TIFF files) but all the hooks are not finished
yet.

Bruce Clark
bwclark@centuryinter.net (mailto:bwclark@centuryinter.net)

[chandler@n-link.com]

Thanks Bruce. I got the file from Shopbot today. Haven't tried it yet. I just got my unit together and haven't finished all of the odds and ends yet.
Soon I hope. Other work keeps getting in the way.
Don

[bruce_clark]

Don,

Just a note. Read the manual (at least read part
about setting up your post processor). Anyways,
the G-code converter is set to read FANUC style
G-code.

If you have any problems, let me know. I can help
out on the Bobcad end, and Dale Laking can help on
the MasterCam side.

Bruce Clark
bwclark@centuryinter.net (mailto:bwclark@centuryinter.net)

[birdsofplay]

Well THIS looks like the bestplace to put my ...
Thank YOU to ShopBot for fixing the DXF converter.

I had some issues with arcs ocassionally and then
with the new line string capability.

Ted reviewd the samples I'd sent and fixed both problems.

Get the new Sb2B10 for these fixes :-)

Way To Go, Guys ! :-)

[bruce_clark]

Just like to add that Sb2b10 now incorporates the
G-code converter! No more having to exit SB to
convert G-code files!

Another WAY TO GO! (hopefully HPGL & TIFF will
be next)

Bruce Clark
bwclark@centuryinter.net (mailto:bwclark@centuryinter.net)

[robin]

A few months ago Bob Neitzke wrote:

"I use MicroStation and have had pretty good luck with DXF exports. I have noticed, however, some faceting at times. To fix this I discovered a config file that controls the way things are converted to DXF ... This file contains settings like "tolerance" and segmentation settings for curve conversions and other messy stuff like that. "

Does anyone know if the equivalent settings exist for Turbocad?

[seaside@esva.net]

Robin,

If you right-click on a spline in TurboCAD and select "properties", then click on the "curve" tab, you can set the number of segments between the control points. There's a limit to the number of segments, though I'm not sure what it is. I have found that if you have a spline with a bunch of control points ( 50-60 ), you may be limited to 10-20 segments between nodes.

Since arcs are saved as a center, radius, start angle and end angle in TurboCad, my guess is that you would need to set the segment length in the ShopBot software. You can however split an arc into smaller arcs by right-clicking on the arc, selecting "node edit", right-clicking again, then selecting "arc divide"

Hope this help,

Bill Young
seaside@esva.net (mailto:seaside@esva.net)

[robin]

Bill,

I use bezier curves exclusively (almost) so adjusting the Shopbot arc segment length doesn't really help since beziers are converted by TurboCad into straight lines when saving as a dxf. However, the properties/curve tab does the job perfectly! I searched high and low for this feature in Turbocad without success. A million thank yous!

Robin