Hi,

I am new to DIY CNC insofar as I haven't built one yet. I have been hanging around the edges of these forums getting an education and feel that it's time to get doing.
I have been basing my build ideas off the Solsylva belt drive table plans but also trawling through everything from Mechmate and Lumenlabs.

Everything I find assumes the use of rotary tools or laser/plasma. If blades are mentioned at all it's for vinyl with swivel mount blades. I would basically like to build a flatbed tangential knife cutter for use on cardboard and architectural chipboard. This is a cardboard material like gameboard backing which is used for modelling. I have seen it referred to as "beaver puke" if that helps
The main use of this machine would be for architectural modelling although I would also like the option of putting a router on it. If the knife carrier were a dual mount with pen-plotter that wouldn't hurt either.

So lets say a standard 3 axis router build with an option to mount a tangential cutter assembly. And let us assume about a 30" x 40" cutting surface.

At this point, I know nothing. That being said, let the laundry list of my questions begin.

Would the force involved in dragging a knife through 3 ply (~ 3/16" ) or thicker chipboard require a stronger machine than one would need for a router ? (I have no idea at all what the forces involved are. All I know is that my fingers hurt like hell after a day with the Exacto knife).
Would a belt drive do it or would there be excessive backlash ?
Ditto gas pipe rails. Do I need more rigidity than the Solsylva machine ?
Motors... 425 Oz / in ? I've seen anything between 250 to 600+. What would the benefit be ? Would progressive dulling of the blade cause the machine to chatter if the motors are underpowered ?

My previous architecture school had a Zund 1200 in the shop which was mainly used for stepped terrain models. This was in Switzerland, i.e lots and lots of curvy contour lines in cardboard.
Having seen that thing go, my expectations are now entirely unrealistic. I have to remind myself that gas pipe and skate bearings are not going to get me 600 ipm. But in the interest of argument I would be more than interested in what your impressions would be.

These are the kind of knives I'm talking about.

http://www.smp-sign-systems.com/prod..._Messer_e.html

The main reason why I would like to have a router on this thing as well is because, once it's built, it's first job is probably going to be making it's own vacuum clamp bed to hold the cardboard down.


Thank you all for any and all assistance with this project. I hope that this will evolve into a build thread before long.

jfmonod