Converting DWG files to DXF files for CNC machines.

I am not sure if this is the right place to put this, so if the admin or moderators need to move it, that is fine.

Here is the question I have: I have to sometimes make files for a router table, water jets, and plasma cutters. Some of the shapes are created from splines and or polylines. Our router program and some of the programs that our vendors use (waterjet and plasma cutter) programs that have major trouble with the amount of control points (nodes) that are required to hold that shape as it should be. When I try to remove the nodes in autocad the shape changes.

One of the methods I have to use is to import the DXF file into Corel Draw X3 and remove all the extra nodes that the program will allow me to delete without changing the shape of the item. This works sometimes depending on the program that the vendor is using. I have to do different things for different vendors, and as I said this only works 50 percent of the time, and I will not know if it worked or not, until the vendor starts complaining about open files or not. On one occasion the final product came in from the vendor, and it was a mess, inside corners were blown out in large circles, and outside corners were rounded off into large circles.

I was wondering if any of you had the same problem and have come up with a solution that could remedy this issue.

The powers that be at my company are getting frustrated, and seem to think after all this time, this issue should be overcome by now.

The inhouse router table issue has been overcome, it is the water jet vendors and plasma cutter vendors that we are still having issues with.

Thanks for any and all information.

Different machines will use different programs. Newer equipment, usually, should accept R12 DXF with closed geometry and layers applied. Most older/cheaper equipment will require post-processing the DXF.

This is not a CAD issue, but a CNC software issue. Any vendor should accept a R12 DXF and have in house method to send to the equipment. If not find out what they need.

This issue has been overcome for many years now.

Find out what equipment the vendor is using and contact the manufacturer to determine method to use convert DXF or what file type is needed. Plenty of software you can obtain (some FREE) to convert DXF to G-Code or whatever the machine requires.

I used to set up drawings for an in house 3 axis Mill and plasma and a vendor that did laser and metal forming never had a problem, you just need to know the equipment and software and input required. The in house equipment came with the conversion software over 20 years ago.

I really can't recall the program(s) used, the plasma and laser had a nesting program as well, seemed to be one program. The shop supervisor usually sent the info to the in house equipment, only problems I know he had was some of the other engineers had gaps and stacked lines etc. in their line work so he had me go through and eliminate all gaps and overlaps, Usually MPEDIT and OVERKILL cleaned everything.

I am trying to get them to switch our plasma here to CNC, maybe I will stick with plotting burn templates.

Try CNCZone for more.

I understand that it is a CNC issue. Usually the shapes are closed geometry. As I have stated, the issue has been solved on the in house router table.

Most of our water jet vendors, are expecting plug and play files. They state that they will charge for any "clean-up" they have to do. Of course when they say that "management and sales" think that there has to be an easy button, and that we are obivously not doing our jobs to make it plug and play. One of the common things that say, " but it is cad, what do you mean it can't do that"

Usually when we are creating our files, we have no idea whether or not they will be used in house or out of house. We usually find out after the screaming and flailing starts. In one case I did contact the manufacturer of the Program used to run the vendor's waterjet, he was dumbfounded. On this particular item, the artwork was first created in Adobe Illustrator, then exported out of AI to a Dwg file, used in the drawing creation itself, then the artwork was converted to DXF. Then I imported into Corel Draw, remove any nodes that I can, close nodes that need close, then export it to a DXF file again, and then sent to production. Production decided that this particualr item needed to be cut out of house, this was followed by 2 weeks of trial and error.

I have had issues where polylines and splines have changed shape by saving them to a Version 12 DXF. Sometimes dramatically. Usually I do not like to go much past a 2000 DXF.

I have attached a PDF of what the Vendor Printed out from his program, and a screenshot from my computer screen.

Palm Print from Waterjet Program.pdf

Actually AutoCAD may be contributing to the problem - it is not just a CNC related issue. You might try searching for some lisp files that "weed" the polyline or the spline. Basically they work by establishing a toleranced corridor that the modified spline/PLine are allowed to conform to. Then as it parse the nodes it will create a new (or modified) spline/polyline with fewer nodes.

I've done this in my own programming and I've been able to knock 360 nodes down to 10-12 nodes.

By the way - that is a really difficult font to be reading.

Actually AutoCAD may be contributing to the problem - it is not just a CNC related issue. You might try searching for some lisp files that "weed" the polyline or the spline. Basically they work by establishing a toleranced corridor that the modified spline/PLine are allowed to conform to. Then as it parse the nodes it will create a new (or modified) spline/polyline with fewer nodes.

 

I've done this in my own programming and I've been able to knock 360 nodes down to 10-12 nodes.

Right you are, I forgot I used to also run WEED.LSP as well. I still have a copy, though haven't used it lately on newer version of AutoCAD. Hopefully it will work for you.

Weed.lsp

Sorry About the font. I will try this weed.lsp, and see if it works for me.

Thanks Guys.

Sorry About the font. I will try this weed.lsp, and see if it works for me.

 

Thanks Guys.

Apology accepted (just kidding - it wasn't needed)

Let us know how it works out.