Author Topic: Flatbed Cutter - Tangential, Oscillating Knife, Creasing  (Read 1893 times)

0 Members and 1 Guest are viewing this topic.

Offline xxtoni

  • Active Member
  • Posts: 26
    • View Profile
Flatbed Cutter - Tangential, Oscillating Knife, Creasing
« on: August 20, 2016, 02:35:11 PM »
Hello,

I've been a lurker for a while now and I have finally decided to make myself a CNC flatbed cutter.

First a little intro.

I own a signage company and we already have a pretty decent CNC router that we have bought from a local manufacturer and we are pretty happy with it.

Now however we want to build ourselves a CNC flatbed cutter.

In case some of you (probably most) don't know what a flatbed cutter is...it's basically a CNC gantry router that instead of having a spindle has various cutting heads, usually knives, that cut light materials like PVC foam board, lexan, vinyl, paper, rubber and so on. We actually consider/ed making these heads ourselves but it's a bit beyond us at this time so we've decided that for the time being we will buy them from
https://www.damencnc.com/en/tools/tangential-knife---accessories/tangential-knife/1583

We are looking for a travel speed of some 30m/min. I'm actually not sure if the oscillating knife will be able to keep up with it in thicker materials but as said, we will try to develop these tools in the future so we want the machine to be able to travel these speeds.

One advantage of a flatbed cutter is that there aren't as many resistance forces at work here as in a traditional CNC router as for say wood because most of the materials are very light so the cutter doesn't have to be as rigid as it would be if it needed to cut these heavier materials.

There are some things I've decided and the rest I don't really know a lot about and am still researching and hoping for advice here as well.



Size: 300x200cm

This is the standard size of most materials in our industry, I don't see why the size should be a problem in a CNC like this (because it doesn't have to be extremely rigid) but if it is I guess we could cut it down some if it's absolutely necessary.

Speed - Around 30m/min


Those are really our only requirements. The gantry needs to carry the 3 tools, they around 2.5kg a piece so a total of some 7,5kg which I think isn't that heavy.

The rest I am pretty clueless about to be honest.

For the bed we are going to be using a special vacuum foam for holding down stuff, I was planning on using side channel blowers to power the vacuum table but I am not sure what kind of table design to use for the mat, the seller of the mat told me to use a vacuum table with 5mm blind holes that let the vacuum through a 0,6mm opening in, according to him we would get the effective vacuum of a 5mm hole but only a loss of a 0,6mm hole once a cut in the material is made. Ideas ?


Regarding the rest, I honestly don't really know what to do.

I am currently looking at:

- Motors. Stepers vs servos ? Suggestions ?
- Rails - No clue in this regard
- Construction - What design and what material.  I have a team of pretty skilled welders so welding a sturdy construction together is no issue. My current CNC router is made mostly out of steel (the base anyway but a whole lot of steel on the gantry as well)
- Software - I was planning on using Mach3 because of it's wide support as well as having native tangential cutting support.


- Everything else [/B

This is the part that concerns me the most at this point to be honest. I am currently researching but it's a bit overwhelming right now, I do know a fair bit about CNC routers and have been doing research for years but now that it's coming all together it is a bit too much at once.

I would appreciate any advice you can give me, not just answers to these questions but these are some that come to mind right now:

- Belt vs  ball screw

I read somewhere and while doing research on the most prominent flatbed cutters like Zund and Konsberg found that most of the flatbed cutters use belt drives instead of ball screw drives. Any suggestions here ?

Stepper vs Servo

I know that steppers are cheaper and easier to setup because of the lack of encoders but I also know that servos are much better for high speeds so any suggestions here would be much appreciated.


The rest of the parts...

I am a bit clueless here in my mind the major things here are:

- Motors
- Drivers
- Cutting heads
- Construction
- Control Board


What about the rest though, the linear rails, the carriages, nuts, bolts and so on ?


For the end a flatbed cutter that seems to work quite well and seems DIY, I could show you a $200k Zund flatbed cutter but that would be unrealistic so here is a pretty good looking DIY one:

https://www.youtube.com/watch?v=H7s24MxNbDo

https://www.youtube.com/watch?v=a3hVeC1Ub1Y


I really hope that some of you guys can help me out with this.


Thanks in advance!