Across the pond

The problem with building things in the UK is that all the interesting surplus equipment seems to be in the US. Because the axes are heavy they were expensive to ship. The shipping and duty cost me about as much as the items themselves. Worse than that the XY table took about three weeks via USPS when it was supposed to be 3 to 5 days.

23-01-2007 18:48     HOUSTON TX                     Enroute
24-01-2007 22:37     CAPE ISC CHICAGO IL (USPS)     Left origin country
04-02-2007 16:50     International Hub              Arrived in destination country
04-02-2007 17:23     International Hub              AWAITING CUSTOMS CHARGES
04-02-2007 17:23     International Hub              AWAITING CUSTOMS CHARGING
05-02-2007 21:57     International Hub              RELEASED WITH CHARGES
05-02-2007 23:33     International Hub              En route to delivery depot
06-02-2007 02:31     National Hub                   Sorted in hub
06-02-2007 14:42     Manchester Piccadilly Depot    Awaiting payment of charges
07-02-2007 07:33     Manchester Piccadilly Depot    Delivery rescheduled
08-02-2007 18:23     Manchester Piccadilly Depot    Delivery rescheduled
12-02-2007 16:09     Manchester Piccadilly Depot    Delivery rescheduled
13-02-2007 01:25     Manchester Piccadilly Depot    Out for delivery
13-02-2007 09:40     Manchester Piccadilly Depot    Parcel delivered

Mysteriously it spent 10 days in no man's land between the two countries. I didn't know planes could fly that slowly! To add insult to injury the UK Parcel Force failed to deliver it three times because "it was on the wrong shelf". In contrast the Z axis only took 6 days and although I ordered it much later they arrived together.

Chicken and Egg

The problem with making machines that make themselves is how to make the first one! A bootstrap machine has to be made by hand first. This has come to be known as a RepStrap machine in the RepRap community. Lots of people are trying different approaches using whatever materials are easy to come by locally. Wood, Lego, Meccano, copper pipe and drawer slides have all been used by different RepStrappers. The machine needs three axes of motion and an extruder head to extrude molten plastic filament. Most RepStrap machines use threaded rod as a means of creating accurate linear motion from a stepper motor for the axes.

This was the approach I was planning to take when I started looking at this in mid January. I had a look at how professional CNC machines are put together and saw that the prices are a lot more than I wanted to pay but the accuracy and speed was a lot better than I could hope to achieve with drawer slides, etc. I had a quick look around to see if I could get anything second hand or from the surplus market. To my surprise I found an XY table on ebay for $400 which has a super small step size of 6 um but is able to move quickly and has very high stiffness.



This gave me the idea that I could make a very accurate machine that is also stiff enough to do milling. I found a Z axis on CNCzone for $150 and the project was born.

Hello

My friend Wes pointed me to www.reprap.org and I immediately decided it was what I going to do with part two of my life. I have been collecting motors and other "useful" junk for years and have at last found something interesting to do with them. My hobby, starting as a child, used to be electronics but it is increasingly hard to find something to make that you can't buy cheaper and better. Consequently I haven't built anything at home recently. My skills lie in electronics and software and I can get by in woodwork and metalwork which I learnt from my father who was a patternmaker by trade. This project involves all these disciplines plus material science and chemistry which I know virtually nothing about but am interested to learn more.

In short, making machines that make other machines is the perfect hobby for me. Hopefully my experiences along the way may be interesting to others so I decided to start this blog.