23 Replies Latest reply on Oct 1, 2009 3:56 PM by Anna Wood

    Saving a region of a drawing (clipping)

    aaron hoover

      Is it possible to save just a small region of a drawing as a dxf file? I have a machine tool with limited cutting field, so I'd like to break a large file up into smaller dxf "tiles." For example, the CAD software ABViewer has something called a clip rectangle that allows you to select a portion of a drawing and then save just that region. I know Solidworks can do tiled printing, but I really need individual dxf files.

       

      If this is possible, what's the best way to do it?

       

      Thanks,

      Aaron

        • Re: Saving a region of a drawing (clipping)
          Mark Kaiser

          Never heard of it inside of SW.

           

          You might try making a master dxf file, opening this in SW, then trimming away to get your individual dxf's.  Doesn't sound like much fun, though, neither does splicing them back together?

            • Re: Saving a region of a drawing (clipping)
              aaron hoover

              Actually, the reassembling isn't an issue - the machine tool software can handle that pretty easily. The master drawing would still be in a slddrw file, I'd only export to dxf for the machine tool. It's the process of getting the original drawing into those individual dxf tile files that I'm having so much trouble with.

                • Re: Saving a region of a drawing (clipping)
                  Mark Kaiser

                  I really don't think there's an automatic way to do this, unless someone familar with API can write a program for it.

                   

                  Here would be the individual manual steps:

                  1. Save your slddrw as a dxf (the entire file).
                  2. Open the resulting 'master' dxf into a SW drawing file.
                  3. Draw a rectangle around the first quadrant/corner of the dxf file you need.
                  4. Trim away the lines outside of the rectangle.
                  5. Save as dxf.
                  6. Re-open master file and do a different quadrant/corner.
              • Re: Saving a region of a drawing (clipping)
                Kelvin Lamport

                Have you tried using the Crop View tool with views on separate sheets?

                  • Re: Saving a region of a drawing (clipping)
                    aaron hoover
                    Our drawings are not generated from 3D parts - they're just sketched by hand (they're flat parts that are cut out on a laser). And, it's my impression that the "Crop View" tool only works on generated views - is that correct? At least I've tried to use it on sketches, but since the sketch doesn't belong to any view it doesn't seem to work at all.
                      • Re: Saving a region of a drawing (clipping)
                        Anna Wood

                        Why are your flats sketched by hand in the slddrw?   Why would you not want to create sldprt files?

                         

                        Cheers,

                         

                        Anna

                          • Re: Saving a region of a drawing (clipping)
                            aaron hoover

                            This is probably more detail than is necessary, but here goes anyway. We have a pretty unique process in our lab whereby we laser machine composite laminates, lay them up with a polymer film layer sandwiched in the middle, and then fold up the resulting articulated flat sheets into

                            flexure-based mechanisms like fourbar, fivebar, and Sarrus linkages. Because the laminates are so thin (~100um), the resulting structures are also very thin. But, even if we did make solid models of the flat parts (still useless because functionality of the end product depends on how it's folded), the lines in the generated drawings wouldn't really map well to cutting operations because of order-of-operations constraints embedded in the fabrication process itself.

                             

                            Beyond that, I don't really know what to tell you (if you're curious about the process, an analogous process for prototyping is described in this paper). However, it doesn't really change the nature of the problem.

                              • Re: Saving a region of a drawing (clipping)
                                Anna Wood

                                Interesting.....

                                 

                                We design automation, custom stamping tooling and also contract manufacture products for the medical diagnostic strip industry.  We regularly work with the thickness of materials you talk about.  We have been doing this type of work in thin films for the last 10-15 years or so.

                                 

                                We also do laser prototyping of the laminate structures for our customers.  We model everything in SolidWorks as parts.

                                 

                                I do not see why your parts can't be model as SW parts.  It would be interesting to see your process more in depth.

                                 

                                Cheers,

                                 

                                Anna

                                  • Re: Saving a region of a drawing (clipping)
                                    aaron hoover

                                    So, basically, the process works like this:

                                     

                                    1) Laser machine flexure gaps from two laminates (cuts are mirrored) - I usually store just these cuts in one layer of the drawing

                                    2) Laser machine the polymer that will form the flexure layer  - These cuts are stored in as many layers as I'll have thicknesses of polymer film in a single part

                                    3) Align the two laminates from step 1 with the polymer(s) from step 2 sandwiched between

                                    4) Cure or laminate the stack

                                    5) Laser machine the outlines of the parts

                                     

                                    What comes out is a flat sheet with flexure hinges where the gaps were machined in step 1.Then we fold that up to make linkages and mechanisms.

                                     

                                    If you're interested, you can check out the attached file. I'll warn you though, since we're a research lab and I'm the only one using my drawings, I don't follow an conventions that'd normally be used in industry (GD&T, title blocks, rev. #'s, etc.). Also, since our laser cuts directly from the Solidworks drawing, I either have to hide all or just not use any annotations.

                                      • Re: Saving a region of a drawing (clipping)
                                        Anna Wood

                                        Aaron,

                                         

                                        Thanks for the example file and pdf.

                                         

                                        Looks like I have a project for the coming weekend.  These can definately be modeled in SolidWorks using sheetmetal features.

                                         

                                        Thanks for sharing your research work.  Very elegant process you have developed.  Simple but very effective for building your structures.

                                         

                                        Cheers,

                                         

                                        Anna

                                          • Re: Saving a region of a drawing (clipping)
                                            Anna Wood

                                            Aaron,

                                             

                                            What is the cutting envelope of your machine?  Also what is the typical size of one of your structures you are trying to cut on the machine?  LxWxH after it is all formed up.

                                             

                                            What is the brand name and model number of your laser?  What software are you using to run the laser?

                                             

                                            Do you color code the lines for different types of cuts on the laser?  i.e., Thru cuts as opposed to kiss cuts.

                                             

                                            Cheers,

                                             

                                            Anna

                                              • Re: Saving a region of a drawing (clipping)
                                                aaron hoover

                                                The laser of interest for these files that need to be tiled is a custom system from a company in NH called Photomachining. It's a 2W Coherent Matrix DPSS laser with a Scanlab (I believe - we just got the system so I'm totally up to speed yet) galvanometer and f-theta lense that has a working field of approximately 69mm square. Since we sometimes cut uncured prepreg composites, we prefer to use the galvo for all of the cutting to minimize the size of the heat affected zone in the matrix. Galvo control is handled through WinLase Pro. But, we've also got an XY stage that enables macro movements (10" x 14") at much slower speeds (max 9mm/s).

                                                 

                                                Structures we build in the lab can range from sizes on the order of 10mm (http://robotics.eecs.berkeley.edu/~ronf/MFI/Figs08/steltz-mfi07_1.jpg) to sizes on the order of 10-15cm (http://robotics.eecs.berkeley.edu/~ahoover/ForSam/DSC_0075_1.JPG).

                                                 

                                                In the drawing I posted, yes the color coding actually corresponds to power settings (on a different laser than the one I described above - a more typical C02 laser). For example, the black outline cuts have to go through two layers of laminate and the polymer whereas the blue and red lines are only going through a single sheet. Basically, we try and get the cleanest cuts by dialing back the power (and adjusting the PPI and speed of the laser) so that the laser barely cuts through for a given thickness.

                                                 

                                                Aaron

                                                  • Re: Saving a region of a drawing (clipping)
                                                    Anna Wood

                                                    Aaron,

                                                     

                                                    Thanks for the info.  That is all very interesting.  Besides our big Mitsubishi production laser we also have a smaller CO2 laser from Universal Laser Systems.  The laser set-up you describe sounds very neat and geared for the type of very small scale structures you create.

                                                     

                                                    I would think you would want to use the smaller laser for your smaller structures.  The bigger structures on the CO2 laser.

                                                     

                                                    I have some ideas on how you could set-up your layouts, but I need to wait for the weekend to do some modeling.  Been very busy at work the past few days.  No time at all to even check on the forums during the day today.

                                                     

                                                    If you wanted to take the time you could model your structures in SolidWorks and do some digital prototyping.  Although working with the real physical models looks like more fun.

                                                     

                                                    I am pretty confident that modeling the structures would make the drawing creation easier after you some different structures modeled that you could copy and clone.  A big advantage is being able to scale the drawing views of the model to create the different scales of structures.  Model it 1:1, then easily create a 2X or 10X scale version by scaling drawing views of the model.

                                                     

                                                    One area I am really curious about is what the motors and actuators for your structures look like and how they work.  Could you indulge my curiosity and post some pictures of those details.

                                                     

                                                    These look like some very fun things to play with and build.  I can see some projects for our CO2 laser at work and for our cnc router at home with a bigger structure.

                                                     

                                                    Thanks for taking the time to answer my questions.

                                                     

                                                    Cheers,

                                                     

                                                    Anna

                                                    • Re: Saving a region of a drawing (clipping)
                                                      Anna Wood

                                                      Aaron,

                                                       

                                                      I have been thinking about your dilemma.  I have a possible solution using your current process of doing 2D sketching in a slddrw file.  It is not automatic, but may get you where you need to be so you can automate through some API programming saving out your dxf's.  Doing this with sketch geometry in the slddrw could be a bit tedious in some instances.

                                                       

                                                      On your drawing sheet lay out a grid pattern on a grid layer.

                                                       

                                                      Set up a layer structure in your drawing that corresponds to the grid pattern.  Each cell in your grid has a layer associated with it, plus the grid pattern layer..

                                                       

                                                      When you are drawing your structure, be sure that you are placing your line work unto the correct layer corresponding to the grid cell you are working in.

                                                       

                                                      As a line crosses the grid pattern your will need to break it into multiple entities so each portion of the line is placed on the appropiate layer for the grid cell it is located in.

                                                       

                                                      When you go to save out your dxf, you would turn off the layers you did not want to save out.  I am pretty sure this task could be automated with a macro to cycle through all the layers and saving off into separate dxf files.

                                                       

                                                      I would label the layers the same way Windows Excel indentifies each cell in a spreadsheet.

                                                       

                                                      You could create drawing templates with this structure pre-configured for the different size laser work envelopes you have.

                                                       

                                                      Cheers,

                                                       

                                                      Anna

                                                        • Re: Saving a region of a drawing (clipping)
                                                          aaron hoover

                                                          Thanks for the suggestion. I've also come up with a number of manual approaches that would work, but I'm still holding out hope for an automated, post-processing step that could handle either a Solidworks drawing or a DXF. I've sort of conceptualized it as a custom printer driver that would just output the tile files directly without me having to worry about changing our drawing process.

                                                           

                                                          As for the structures we make, it's not strictly size that determines which laser we use. Obviously the DPSS laser is a lot more precise than the CO2 laser from ULS, so it's better for smaller structures. But, since it's also more of ablation (as opposed to thermal, like the C02 laser) we use it to cut heat sensitive materials like prepreg composites and metals that simply won't cut under the 20W VersaLaser.

                                                           

                                                          Also, the actuators we use depend on size scale. At the 10gm range, a single 6mm DC motor is an okay choice. Getting down to the 1gm and under range, we've used piezoelectric bending elements and shape memory alloy wires integrated into the structure. This legged robot: http://robotics.eecs.berkeley.edu/~ronf/Ambulation/Roach.html uses SMA, while these flapping wing structures: http://robotics.eecs.berkeley.edu/~ronf/MFI/index.html were designed to use piezos.

                                                            • Re: Saving a region of a drawing (clipping)
                                                              Anna Wood

                                                              Aaron,

                                                               

                                                              Thanks for the info on the actuators.

                                                               

                                                              For your issue with saving out your dxf's that is going to be a tough nut to crack.  I suspect with some custom programming by a very good and imaginative SolidWorks API expert it could be done.

                                                               

                                                              You may want to explore having the other software package you talked in your first post do the job for you.  That may be more cost effective then having some custom programming done.  Doesn't matter what the tool is if it can get the job done.

                                                               

                                                              Cheers,

                                                               

                                                              Anna

                                                          • Re: Saving a region of a drawing (clipping)
                                                            Jerry Steiger

                                                            Aaron,

                                                             

                                                            Did Anna ever show you how SolidWorks could handle your parts as solids? It seems to me it would be a natural fit. You could use the split part function in SolidWorks to break your parts up into the smaller sizes that your cutter needs, then generate drawings for each one. You could assemble your various layers and use the Sheet Metal functions for the inner flexible layer to fold the assemblies.

                                                             

                                                            If you don't want to do that, it seems a shame to waste your time with SolidWorks. It seems you would be better off using AutoCAD LT or some other 2D drafting tool. SolidWorks is not a very good 2D tool.

                                                             

                                                            Jerry Steiger

                                                              • Re: Saving a region of a drawing (clipping)
                                                                aaron hoover

                                                                I agree that Solidworks is not a very good 2D tool. We are simply using it because it's been grandfathered in a result of the work we do in my lab with solid freeform manufacturing, designing 3D molds for fabrication on a ThermoJet wax printer.

                                                                 

                                                                I should mention that I managed to solve this tiling problem with software other than Solidworks or AutoCAD. I discovered that the laser driver software we are using has a COM interface with a function that is capable of tiling a DXF file and saving the results as objects in its own file format. True, this approach doesn't generalize, but it gets the job we need to do done.

                                                                 

                                                                I never heard back from Anna on approaches to modeling our mechanisms as solids. I'm definitely still interested in ways we can use Solidworks to model and simulate our mechanisms. One thing that's been very difficult is solving redundant kinematic constraints. That is, some of our mechanisms are sort of massively parallel in the sense that we may have six parallel fourbar linkages connecting two parts. That's an overconstrained system that works perfectly fine in practice, but is somewhat difficult to simulate in an assembly. I'd love to see a mockup of a compliant linkage that uses the sheet metal tool too, though.

                                                                 

                                                                Cheers,

                                                                Aaron

                                                                  • Re: Saving a region of a drawing (clipping)
                                                                    Jerry Steiger

                                                                    Aaron,

                                                                     

                                                                    Unfortunately, SW doesn't handle overconstrained systems very well. Sometimes it is able to cope with them (when you use 3 coincident planes to mate parts for example), but you never can tell when it will suddenly decide that it can't handle them.

                                                                     

                                                                    Sheet metal doesn't work for truly flexible parts. You can define multiple configurations of your part with bends at various angles, but you can't move smoothly between them.

                                                                     

                                                                    Jerry Steiger

                                                                    • Re: Saving a region of a drawing (clipping)
                                                                      Anna Wood

                                                                      Aaron,

                                                                       

                                                                      I am not entirely sure that solids will be faster for your needs.  Not initially anyway, maybe after you get a library of assembly models for the different types of mechanisms you create.  Sometimes the simpler methods, including cut and paste from paper work just as well for concepting the types of mechanisms you are creating.

                                                                       

                                                                      You can definately model you mechanisms in solids.  There are a few example your group as already done that I can see from the material that is already posted by your research group on the internet.  Having the models act like you want with the kinematics is another matter entirely.

                                                                       

                                                                      You can model your part with sheet metal tools also.  You need to model the middle compliant layer and then add the structure layers after the fact.  I would model the middle layer complete, then turn that into a sheet metal part at the end.  It would not be compliant however.

                                                                       

                                                                      To have compliance you will need to model the structure as an assembly with hinges at each joint.  These can be simple hinges, but can take a bit of time to assemble initially.

                                                                       

                                                                      One thing is for sure if you stay the 2D route is that SolidWorks is not the tool to use.

                                                                       

                                                                      Do you have DwgEditor on your computers?  This is a 2D clone of AutoCAD and will be much better then trying to sketch 2D in SolidWorks.

                                                                       

                                                                      Neat project....  It is a matter of how much time you want to devote to learning how to model in SolidWorks.  You already have the 2D process down pat.  Your initial foray into SolidWorks will take some time to gain the same level of efficiency as you are learning to use the tool.  How much time are you willing to spend?

                                                                       

                                                                      Cheers,

                                                                       

                                                                      Anna

                                                • Re: Saving a region of a drawing (clipping)
                                                  Feroz Mahomed

                                                  Aaron,

                                                   

                                                  You could save parts of the drawing as blocks. Then, you can open a new drawing sheet and insert the block you require and save as dxf.

                                                   

                                                   

                                                  Feroz

                                                  • Re: Saving a region of a drawing (clipping)
                                                    Tony Cantrell
                                                    You can put each region or detail on a seperate sheet and then save as dwg/dxf all sheets.