The MDF CNC Router

23 Mar 2007

Due to the number of requests I have received on how to build this CNC router, I have decided to put pen to paper (actually fingers to keys:-) and write an FAQ (frequently asked questions) guide on the way I went about it.

First of all, let me tell you the reasons for building this ÒmonstrosityÓ. Fun - yes really. My hobby is radio controlled model aircraft, and I kept seeing all these nice CNC-cut kits - both laser and router cut. So the quest began, how do I do this - this was 1997. As an electronics engineer, I had the necessary electronics knowledge to handle this side. I have also done a fair bit of software over the years and felt that I could handle this also. While I am not a fully trained mechanical engineer, thirty or so years of DIY, model aircraft and various other projects at work have put me in good stead for the machinery. So, how to start?

With the advent of the ÒnetÓ over the past ten years or so, information in general has become more widely available and the days of having to send regular ÒlettersÓ and the resultant delays in reply are over (thank God!). A quick keyword search and - bingo, youvÕe got your answer - if only that were the case! If you have ever tried searching the keyword ÒCNCÓ, I guarantee that you would spend days at your computer checking out all the hits that you make - how long did it take you to find this small article? However, you can invariably get a measure of information that can lead you down a specific track to your goal - and that in essence is what I did.
Practically all the information I have gleaned about this subject has been through the net in some way or other.
Please let me say from the outset - I am definitely NOT an expert on this subject - everything I know (not much really) has been found empirically.

Anyway, enough - how do I make a CNC router?

One thing, this isnÕt rocket science, anyone with a modicum of ability and determination can produce a useable machine.
I wanted to spend VERY little on this as I wasnÕt sure if it would really work. My first attempt was a couple of leadscrews made from M6 threaded rod and brass nuts coupled to two stepper motors from an old electrostatic plotter we were throwing out at work. A bit of MDF as the base board and some 10mm steel bars as  the guides using 10mm ID brass tube from the hobby shop. The stepper drivers were removed from the plotter to drive this ÒmessÓ. The next problem was software, where in hell do you get the stuff (apart from writing it yourself)? After many fruitless searches, I came across Dan MauchÕs CCNC site (http://www.seanet.com/~dmauch/) - what a find! Dan has a lot of good information at this site and also sells a lot of odds and ends to do your own thing. The main part was the software - DanCAD, DanCAM and DanPLOT (thereÕs actually a copy on my website now - have a look at http://www.sea-gull.demon.co.uk).
All this software was for the PC (unfortunately for me, as IÕm a MacIntosh person - like all intelligent engineers:-) - as it happens, I had an old 386 PC which I had built, so this was pushed into service. The Dan software is shareware.
The author of this software is a guy called Dan Hudgins. I would like to take this opportunity to give Dan Hudgins my sincere thanks for producing this software. So, with the use of DanPlot, I managed to get this array of bits to actually move. After attaching a third axis (Z) along with my old Dremel router, I could even get it to cut something discernible. The major problem was - it was slooooow! Armed with all this new data, I decided to build the machine you see on my web page.

OK, some real headings, youÕll need the following...

1)   Software

2)   Hardware

3)   A PC (286 or better with a parallel port) - a Macintosh would obviously be the best thing, but I havenÕt
     found any software to drive a system directly for it - yet :-)

4)   Stepper Controller

5)   A minimum of tools.


Tools -  I used a minimum of tools to produce my router, a bandsaw, vertical drill, electric sander, handsaw, handplane, square, ruler and elbow grease. No lathe, no mill or any other fancy tools. I didnÕt even have a router to start with, I bought the router during the build!

Software - as I mentioned - DanCAD - this is a CAD drawing package which can output 2D and 3D files to input directly to DanPlot or DanCAM. I hate to say this, but having been brought up on all the nice drawing packages on the Mac, I gave this a miss. It is very clunky and the interface is not what you might call intuitive, but, it works and will produce stuff for you - and itÕs CHEAP! If you only want 2D output, then most CAD and drawing packages on the Mac or PC will do - as long as you can get HPGL from it (I mean good old fashioned vanilla flavour HPGL - I would recommend an HP7220 driver, it will give up to an A3 size output). For the Mac, I highly recommend MiniCAD or Ashlar Drawing Board (both of which have now been ported to the PC). The old favourite - AutoCAD will also do - I hate this program as much as Microsoft (actually thatÕs a lie - not _THAT_ much :-) YouÕll need a plotter driver - like MacPlot to give you an output file. For some reason, CAD packages on the PC usually give you that option - not so on the Mac.

DanPLOT - this is the 2D driver for the system. It takes the (HPGL or DanCAD format) files and sends the step and direction signals directly to the PC parallel port. DanPLOT is amazingly configurable - far more than any of the other software applications of this type that I have seen (commercial included - by commercial I mean you have to pay serious money for it :-) Again, it has a slightly clunky interface, but again it works amazingly well. It can also be driven from a batch file.

DanCAM - as DanPlot, but it will work in 3D. The only drawaback is that it can only read DanCAD format files - so I havenÕt really played with it yet.

Hardware - I chose to make the main frame of the system fom MDF - medium density fibreboard - mainly because it was cheap, stable and you could machine it with standard tools, plus the fact that it was easily available at the local DIY store. The whole of my machine is held together using either M6 or M5 bolts - I tap directly into the MDF rather than using woodscrews which tend to split the material - it also offers the added advantage that you can easily make adjustments or take it apart again (which you will do a lot of at the trial stages :-). The other parts can be the expensive bits.

To be continued when I have time - last updated 16 Sep 98.