DIY CNC XYZ Table

Posted by Prof. Boris van Galvin on 7 August 2009 | 4 Comments

Tags: CNC, Electronics, Stepper Controller

I have always wanted a CNC milling machine and have decided to create my own with of course the assistance of the internet. My intention is to fist create a prototype unit that is somewhat simple in design and will allow me to use it to build a more complex unit or essentially grow bigger and better versions of itself.

I started by creating a simple stepper motor driver that connected to the parallel port and would allow me to use some freeware CNC software to send commands to the motor however after a while I began to realize there were some restrictions with this design as each motor required a minimum of 4 control lines. So searching on the web i located a project that was based on a PIC micro controller and allowed the motor to be controlled by two lines. one being the step and the other being the direction. This project is called Linistep and also has several modes that can be used to drive the stepper.

Here is a photo of the two circuits I put together, these were etched using a toner transfer method and one was etched in Cupric Acid and the other in "Servisol" Amoniumpersophate (or something like that) I tested both chemicals to see what gave me the better result and to be honest I am still a fan of the Cupric Acid.

 

 

The table is being contracted from 25mm MDF and the rails are high grade aluminum angle 25X25X6. This is probably over kill but the price difference between this and the lower grade was minimal. The bearings are roller skate bearings. these apparently were/are quite high quality however I also have a set of SKF bearings that I will be comparing to see what handles the abuse better.

 

 

 

 

 

After a day in the workshop working out how to build the guide for the router. the first attempts was not great as I lost almost 200mm of sideways travel but with a quick redesign things were back on track and I assembled the table. All axis move quite easily and there is very little slop. At the head it seems that the maximum amount of slop under pressure s around 1mm and required quite a bit of pressure to flex it that much.

 

 

 

 

18th August 2009, I finally got the table to a point where i could test all 3 axis and run a rest route with the router. I have not yet built a speed controller for the router or a box for evryting. The speed controller os less important and will be a later addition however the box will be one of the first projects created with the router (i hope) All going well i intend tyo put a peice of MDF or Ply on the table and upload the NC file then just cut all the shapes required for the case.

Ugly cabling, Notice the yeppow cables used doe the motors. I wanted somethign that was going to loose as little current as possible and as extension cords are really cheap as well as being rated for 240V 10A found this to be a freat solution for many little projects.

Cabling to the controllers was a little messy but once the case is built i expect to be able to clean up. Probibly the only thihng i really dont like is the connectors for the boards. they are not the best and have a tendencey to wiggle out and dissconnect themselves. Bending the pins of the connector a little reduces this problem however will look at an alternative connector.

The Heatsinks used were P4 or AMD headsinks, as these are only about $12.00 with the fan and provide ample cooling. The whole system runds cold to the touch with the fans running.

Curretnly i am using my laptop to tun MACH3 CNC Software, Once i am hapy with the way things are running my intention is to create a MiniITX system with an LCD Screen. However my Toughbook as a touch screen and this is really cool when controlling the system. A touchscreen would make for a nice jog controller.

 

The start of a test. This is a 40mm Dia circle using a standard router bit. The router will spiral down using the speed of the bit to dit rather than the force of the steppers to push the bit thru the MDF.

The finished item, its 10mm deep.