Some really naive dragknife questions

[Burkhardt]

I would like to try cutting some design in thin vinyl and I do not have a proper drag knife.

As an experiment I whacked off an X-acto swiveling knife (http://www.amazon.com/Elmers-X-Acto-Craft-Swivel-Knife/dp/B003W0SKQ6/ref=sr_1_1?ie=UTF8&qid=1409200419&sr=8-1&keywords=x-acto+swivel) and clamped into the spindle collet.

It seems to work but getting the vinyl flat and the knife exactly to proper height (within 2 or 3/1000") is not really trivial. Are there some tricks I can read up?

Thanks,

GB

https://lh3.googleusercontent.com/-ewkXYDvLNBk/U_6y8-7vF0I/AAAAAAAAFJI/A4vBKFzBGaU/w1431-h853-no/DSC02649.JPG

[Burkhardt]

That is how it looks like on my machine. I still have to figure out the slow motion sections. It may have to do with the settings of my controller.

https://www.dropbox.com/s/b1r8c2hwr0pdsk8/X-Acto_Dragger.avi?dl=0

[Burkhardt]

Found the slow motion problem... when doing the same vectors with a simple milling tool path for my project it comes out at 185 kB of g-code. Doing the same vectors with the Vectric dragknife gadget I end up with 2.6 Mbyte. Some sections of the tool path are broken down in very tiny pieces which slows the whole thing down. Can that be avoided?

[tlempicke]

Sign cutters are so incredibly cheap that you can't spend a whole lot of time and effort on sign vinyl. See how your corners are tearing out when the knife changes direction? Dedicated software will have a fancy little dance incorporated into it that eliminates that problem.

US Cutter has been pretty good to deal with. You can see them at

http://www.uscutter.com/?gclid=Cj0KEQjwpvufBRCwzp_zyqfkhrcBEiQA8b-SHMyaAaMHE4hAS8ipiCYeOAo8ZHJxQxzMnX1W797qrQIaAkFF8 P8HAQ

[gene]

look on e bay for a vinyl plotter cutter VERY inexpensive

[adrianm]

VCarve and Aspire have a fillet option to add the loops on corners to eliminate tearout.

[Burkhardt]

It is just for a single job and I was curious if I could do that with simple means. It is actually no big deal I it turns out it does not work. But I always like a challenge.

I did use the new dragknife gadget within Vcarve to create the tool path and it calculated the loops for corners correctly. Maybe the enormous number of path points is because I used a very detailed vectorized image for the test. But since the film and the backing are both only 5/1000" thick, the z-zero position of the knife, the cut depth and the flatness of the spoilboard are extremely critical.

Maybe it is just not a good idea.

[adrianm]

Proper drag knife tools are spring loaded so the flatness isn't so critical.