CNC Routing From PDF
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Definition of a tap file, and whether or not PDFs provide precision. August 17, 2004
Question
A local sign shop has a CNC machine that works off of tap drawing files. I'd like to hire him to make patterns for stair parts based on my dwg CAD files. I've not been able to find any reference to a file converter to tap. I've found nothing on this tap thing at all.
His machine will, however, work with a PDF file. I'm skeptical that this will be accurate. The printing of CAD drawings I've converted to PDFs has not scaled accurately at all. I'm using Paperport to do the pdf'ing
Anyone know anything about this?
Forum Responses
(CNC Forum)
From contributor R:
So this shop has a CNC machine, and it won't convert .dwg or .dxf files? That's just wacky. These two formats are the most prevalent formats used in the CAD world. If this guy can't work with them, I suggest you find a new CNC facility. Using PDF files will never yield satisfactory results - not precise enough.
I did a search for the file type ".tap" and all I could find was some references to an embroidery program.
The most common usage for a .tap file that I've seen is the g-code file. A number of CAM programs will output the tool path for the CNC router in what will look like a simple text file, but using the .tap file extension.
*.tap is the file extension that was previously used to refer to NC Tape Code files.
*.tap is just some kind of ASCII G-Code variant.
A CAM program is necessary to generate toolpaths from a CAD drawing.
PDF files are not vector drawings and generating NC code from them in a CAM system is a foolish idea and a worthless feature because it can only work for the most basic of drawings.
Tell your vendor to get a CAM system and do it the right way.
He might be referring to Adobe illustrator files, not Acrobat. Mastercam can bring in Adobe illustrator files and generate g-code from them.
You can open a PDF file in Illustrator and extract the vectors for use in generating toolpaths, but only if it was vector art before pdf'ing, and it's not very precise...
Sometimes I really feel stuck in the past. I read these threads a couple of times a day and find many people doing amazing things with their software. My hat is off to them.
Unfortunately, many of these people are taught to run this software proficiently but have ignored what the software is doing. It’s simply creating g-Code. Making straight line and arcs. That’s it. Maybe plotting points and drawing arcs on a sheet of paper and then writing your own g-code (as an exercise) would give enough insight to enough people that it would solve 70% of the “programming problems” discussed in this forum. TAP is simply short for Tape. A tape was the paper or card with thousands of little holes in it used to transfer data to your CNC machine from your computer. Today’s TAP extension is a carryover from that. These files can be simply written and edited in a word processor.
I can imagine how the “new school” software could perform with a little “old school” prerequisite. Relying on the software’s ability seems to be a common thread discussed here. Remember that the “A” in both CAD and CAM stand for “aided”. It’s there to help you, not to do your work for you.
I think it’s scary to find out that someone would want to produce stair parts from a PDF. A sign shop is probably not the best place to produce architectural products.
I echo the above assessment. It's nice to know there are still dinosaurs like me out there that have actually output code to tape. It may have been slower and prone to typos, but I recall having more fun back then. Hmm...
From the original questioner:
Silly me. Found a shop with a Busselato just down the road. I'm heading over there tomorrow to do a sample run. Thanks for the responses, and yeah, I found the PDF thing pretty scary, too.
The .tap extension is definitely the file ext. for the coded program. It is just like a txt file. Microsoft Word reads it in just the same way. The txt file extension can be changed to .tap when saved for his machine. Relating to AutoCad… He is not talking about a drawing format. If he has a means of posting and generating the NC/Tap/TXT or whatever file, he should be able to work from an IGES drawing file. Usually converts very well from A-Cad. That is, of course, if he is using something other than Corell Draw or other simple program which is sometimes used for sign-making. Complex 3D is not for PDF files.
A quick check and found that ShopSaber is using software called WinCNC which saves files with a *.tap extension.
Even still... If this guy were running a shopsabre, and he was using winCNC, he should be able to use dxf files, the most prevalent CAD format out there.
If shopsabre provides software that doesn't read or convert standard dxf or dwg files, I sure am glad I went with shopbot. The software provided with my Bot reads in dxf, dwg, ai, eps, and a few others that I can't think of.
Files with a .tap extension are used by the WinCNC controller but have been output by another software program as toolpaths. I use Enroute 3plus for that purpose. The tap files are text files with the lines of G Code that drives the router. I don't think the WinCNC controller opens anything but tap files that have been output via the driver loaded in Enroute. Enroute can of course handle dxf, dwg and other vector files. If one wanted to use a PDF file in Enroute, it would first have to be traced and converted to a vector file and imported or it could be converted to a bmp file by other software and imported and vectorized in Enroute. Results, of course, would not be guaranteed. However, never say never.
My ShopSabre came with RAMS 3D CAM software which will allow me to open .dxf, .ai, .EPS, .cnc, .plt,.igs, .vda, .3dm, .stl and .sla file extensions and generate toolpaths from them that are then saved as .tap files. The WinCNC controller software that came with the machine will open .tap, .nc. and .h (whatever that is...) file extensions. I use CorelDraw exclusively for creating drawings that I save in .dxf, .ai, or .eps formats. I have been able to open .pdf files in Corel and extract vector graphics from them, so it can be done. I only do that as a last resort, though, if I can't find the graphic I'm looking for from other sources, but can find it in a .pdf file. The ShopSabre, coupled with RAMS, WinCNC, and CorelDraw is an excellent combination for me.
WinCNC will import dxf and hpgl files for a g-code conversion. However, the preferred method for the CNC professional is to use a CAM package for smart toolpathing. This is what a CAM package is for. WinCNC is a motion control package.
As for the .tap extension, this is just a txt based g-code file output by a cam package. The .tap extension is the default for WinCNC, but your extensions can be .nc or anything with g-code text.
