I “test fitted” the sensor circuits to the gantry tonight and I’m pleased to say that they work with a surprising degree of accuracy.

The sensors are wired to input pins 11 (X), 12 (Y) and 15 (Z). I used the Mach 3 “auto set” feature to configure the pins as home for M1, M2 and M3.

A neat feature of the homing functions (Ref) in Mach 3 is that it homes past the switch limit, then backs up to the on position, so the home is always referenced from the same position.

UPDATE : After giving this some thought it occurred to me that the home position doesn’t really have to be at the origin at all. It just needs to be a fixed reference point, so that the machine can “pick up where it left off” from a known location. Changing the tool on the router will typically nudge the motors and cause the software to get out of sync with current position.

I believe it is possible to script Mach3 to move to a fixed offset away from the “home” position, and use this to set the start point for the cut.

I’ll have to put together a movie that shows how Mach3 is configured too.

I finally managed to cut some material on the CNC router this weekend. (Although I needed to take a 4 day weekend to do it).

The material was MDF, which is nasty nasty stuff, hence the “Dust Control Bubble” ™.

I can cut at 100 inches per minute with a 0.1 step down on the router. Not too shabby.

Tomb of the Cybermen anyone?

A while ago I made a posting about my “Box of Mystery” and asked if anyone could guess what it was for. I got some interesting responses, but none of them correct. I’ve made some significant progress since, and so I thought I’d post a video…

I’ve just been doing some work on my box of mystery. It’s a PC in the middle but surrounded by 3 mystery components – would anyone like to have a guess what the extra bits do…?

It’s taken most of the weekend, but I finally got the clock up on the wall. The more observant reader will spot that the driver weight is missing – so it’s not ticking yet. Also despite my best efforts with a custom jig, the pendulum balance is a little bit off – so that will probably have to be re-done.

The CNC mill is cutting a little “long” in the X axis, so I think a spot of recalibration is in order.

I’m struggling to find things to weight the pendulum with. Weight discs from a lifting kit are too heavy, and fishing weights are too light. At the moment there’s no real weight to the pendulum so it wouldn’t tick for very long.

I predict about 3-4 weeks of further tweaking and balancing to get it to keep accurate time.

The plans came from Brian Law’s Clock site – this is Clock #1 – I used some telescoping brass tube from the model shop for all the spindles – it works remarkable well…

Not too bad for the first go...

I was inspired by the recent documentary on Kit Williams to look into wooden clock making. Also, I thought it would be an excellent test of the CNC router I built over Christmas.

So after a week of learning about ramping, lead in and out, cutting paths and other engineering type stuff I finally got all the parts together to start assembling my clock.

(The basement is currently swamped with sawdust, and failed gears…)

There are lots of plans for clocks out there, but in the end I went with one of the Brian Law designs.

At the moment the post holes I cut do not line up with the gears, so I need to rework them….

My first cog!

I finally got some good carbide end mill bits for my gantry router – seriously don’t wast your time with the Dremel cutting bits, they just heat up and burn the material you are cutting. I bought some 1/8″ 2 flute spiral end mills. The cutting is really clean now – and no scorching.

This is a 60 tooth gear for the clock I’m building. I always told myself that the first thing I would build if I got a CNC router would be a clock….

I down, about 20 to go…

CNC Router

I just assembled my Christmas present – a CNC Gantry Router kit I ordered from Bluumax. The kit arrived in two boxes – I needed to cut some MDF as a base and table first (this was not supplied).

It took a while to put it all together, as the instructions are provided on the Bluumax site in a picture form – sometimes you can get lost following along. Although once you get the basic idea it’s goes together without too much trouble. The parts are aluminum and acrylic, and the machined fit is very good.

The kit comes with a stepper controller board, but I opted to upgrade this with a parallel port breakout / bipolar controller board from www.easy-cnc.com.

Once it was all hooked up I spent some time trying to decipher the Mach3 software recommended by Shawn on Bluumax. It’s a bit daunting to begin with, but after a while you get used to it – along with LazyCam I was able import a design and produce enough GCode to trace out the pattern on paper with a pen attached to the tool holder.

It was also a chance to use the old laptop I’ve had on the shelf for about 5 years – it actually has a parallel port built in. (and something called a “floppy disk drive”).

Etch-a-Sketch anyone?

Who remembers Etch-a-Sketch...?