Using a mini lathe. Experiences with a chester 7x12 mini-lathe and ATM amateur telescope making - small parts made on a 7x12 mini lathe
Click here for my main mini-lathe page
NEW Guide to Threading on a mini-lathe
NEW Guide to Home Anodising Aluminium
As documented elsewhere on this website I dislike having to spend money on astronomical things. Its much better to devise your own solution to a problem that it is to throw money at a problem.
As my hobby has advanced, I have wanted the capacity to manufacture more and more complicated parts. To this end I decided to invest in a smill mini lathe. Such a mini lathe is not cheap - several hundred pounds, but is an endless source of amusment. Few things relieve stress after a hard day driving a computer than hacking into a lump of metal to death on your hobby mini lathe. *grins*
This mini lathe also lets me explore amateur telescope making.. I have not got so far into ATM that I have made my own telescope, but I am working that way.
Lots of bad things are said about "chinese" mini lathes. Many of these date from a period some years ago when these devices were of a quite dreadful quality. These days things have improved. They do not match the work from a "big" lathe. But they don't match the price either. Mine has reasonably accurate ground and hardened ways, and I'm able to face a job off flat without too much trouble.
After a lot of research I eventually purchased a 7x12 Conquest Lathe from Chester uk ltd. I would stronly recommend this mini lathe to anyone after a similar machine.
Here you can see the mini lathe after a nice long period of work, covered in aluminium swarf and looking a right mess. If you want to see some nice clean pictures, go and look on the Chester UK website. My mini lathe in this picture is currently setup to do some boring on a job held off axis...something you are supposed to need a 4 jaw chuck for... but nevermind. :-)
In southampton we have many sources of raw material. I can visit the The Metal Supermarket or RS Componants for various metal stock. Mainly I have worked with aluminium, with some steel.
My stock at home is shown on the left. I have 1 inch, 2inch and 3 inch round aluminium bar, some 1/2 inch ground silver steel bar, and several other bits. THe most popular raw material for metal work is the 2inch aluminium bar.
I have spent many hours learning how to use this machine. My main sources are the internet, and various friends. Not to mention my own cunning! The best webpage I have found. I have a collection of carbide cutting tools - but I have not learnt to grind my own tools yet. I've a dead center, live center and a 13mm chuck to go in the tail stock. Owning a lathe does make you very susceptible to buying tools. I also have little resistance left to buying alumnium stock and steel stock.
The picture on the left shows a few early experiments. Main in learning how to thread on a lathe. It was around this point I learnt you need a 60 degree cutting tool to make proper threads. It also appeared from my lathe instructions that it could not cut the common 0.75mm thread. This turned out to be untrue. The mysteries of the lathe lead screw and thread dial had me very puzzled for a while, but once you work out in your head the mechanical relation ship between the lead screw, change gears and the cutting tool itself, it becomes very simple.
One of my most useful gadgets... this filter holder. IT is a homemade M42 extension ring with a slit cut in the side. This allows you to hold a colour filter between the camera and telescope and swap between filters easily. This filter holds in place with a bit of velcro. It is made from 2 inch aluminium bar. here is an RGB image I made using this device.
A small adapter I made for my friend Carsten. My first paid commission. ;-) It is made from 2 inch aluminium bar
A job currently being worked on. This will form part of my homemade DIY filter wheel. I started with some 2 inch aluminium round bar. The piece was faced off on both ends, and the sides tidied up. I think drilled a 13mm hole down the middle. The job never left the lathe during this process. I used the drill bit in the chuck in the tailstock. I am in the process of boring out the hole so it can take in internat M42 (42mm) thread.
Another shot of the same job
A beginners guide to using a mini-lathe can be found on the 7x12 mini-lathe site
My biggest project yet - the spectrograph. The matching parts that all join together with a moveable slit made from a CD ROM drive. It is made on the mini lathe with 2inch and 3 inch aluminium bar
The current project is to make a filter wheel.. this is progressing slowly... designing as I go.. but I hope to have some results soon
Tom How, Curdridge Observatory, November 2005.