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Drag Knife Software

Posted: Sat May 21, 2016 4:40 am
by gav wa
Hey there guys, just starting to try some drag knife work and I'm wondering what software you guys are using for making your programs?
Are you just manually modifying your programs so you end one cut and start the next in the same direction or pause the program every change of cut?
I looked at a couple of options like Vetric but it's a bit pricey for me at the moment.
Interested to see what you guys are using.

Posted: Sat May 21, 2016 11:25 pm
by falls
http://donektools.com/free-cnc-router-software/links-2/
I don't have a drag knife but I remember watching a video about the donek drag knife and at corners it makes special g code to create square corners by sending the knife in a curve defined by the offset of the cutting point. I'm sure the video explains it better than that

Posted: Tue May 24, 2016 5:44 pm
by amidnightproject
I struggled with this battle for a while. There's no free method and rightfully so I decided. You can use a few cheaper tool pathing software methods, or simply cut things that don't have sharp edges, however in the end I ended up going with the latest software from Aspire/Vectrics.

Pricey? absolutely. Is it easy to use? Damn right.

There are a few mentioned options if you dig around here. I think you'll find in the end your going to have to spend some money. How much you spend depends on what you want to get out of the software. Good Luck!

Posted: Wed May 25, 2016 3:51 pm
by MontuckyMadman
Cheapest option is to go with what donek sugests the british software will do ur edges 200bucks as straightlines and then run it through his free macro.

Posted: Thu May 26, 2016 6:06 pm
by gav wa
Thanks for the replies guys.
Looks like I'll have to check out the Donek site. Considering what we use it for most of the software options are way over the top.
That Donek option sounds more like my price range :D

Posted: Thu May 26, 2016 8:12 pm
by twizzstyle
I have a vinyl plotter, and I've often wondered if I could figure out a way to export usable gcode from it that I could use on my CNC router. I've never really looked into it though. I just don't do sharp corners.

Posted: Fri May 27, 2016 11:12 pm
by falls
I think my vinyl cutter uses HPGL which I think is different to gcode.

Posted: Sat May 28, 2016 5:28 pm
by gav wa
Yeah Twizz I'm staying away from sharp corners too. I'm more interested in the way the software always aligns the knife for the start of the cut.

Posted: Sun May 29, 2016 7:51 am
by twizzstyle
Gotcha. Does any drag knife software do that? Every drag knife I've seen is just passive.

When I cut bases, it's only a couple of cuts so I just reach under the router and spin it roughly in the directly the cut will be. If it's 90 deg off, it will correct itself no problem (I use homemade drag knife blades made from 1/8" carbide drill blanks). I just have to be careful that it's not 180 deg off cause it will actually track that way for a while, and spin around and leave a big gouge.

The one time I did a complicated base with lots of cutouts and different colors, I actually spent the time with the tool paths to make sure after each cut, the start of the next cut was roughly in the same direction so the blade was already close. Pain in the butt to do that manually.

Posted: Sun May 29, 2016 7:52 am
by twizzstyle
Also, if you have this ability in your CAM software, doing some kind of ramping lead-in will help, versus dropping straight down and running. That way you are slowly engaging the tip of the blade which helps it align itself, with minimal damage to your material.

Posted: Sun May 29, 2016 7:25 pm
by MontuckyMadman
The donek software macro after an export of lines will do all that and offset for the blade behind center and plot pickups for the thickness of the material all based on the angle of the curve you set. Its pretty sweet.

Posted: Sun May 29, 2016 8:52 pm
by gav wa
I've been running a couple of tests already by just pushing the tool to depth as it travels along it's first move and then repeating that line at the end. Lines up the cutter sweet, I'll look out for any that will put the tool at about 180' though Twizz, thanks for the heads up.
The tests look OK so far.
Image

I'm just using home made blades similar to what Twizz and others have done. I had some little 1/8" carbide mills handy so they were easy to modify, they are cheap as dirt too.
[/img]Image

Just grind the drag knife edge on them as sorted. Just need a finer wheel on the bench grinder now so it's easier to get a nice finish on the tool.