You need to think about what you intend to make on that mill. At the risk of stirring up a hornets nest there are vast differences between mills that go under the generic name of mini mill or generic 'X2' as there are a number of factories currently turning out these machines. You will find a few of them on this web site Mini Mill Versions
But the list is not complete. For example the RedBull machines are missing from the list but are still available here in the UK from several suppliers under slightly different badging and I believe they are available in the USA.
I have a RedBull machine and the gears are not noisy and the mill works well as supplied. When LOL time permits it is to be converted to CNC but my aim is not to modify any of the critical castings.
Suggest you start by thinking about what you want to machine - steel or aluminium - budget. As a rough guide the cost of the machine is about 50% of the all up cost by the time you have got the necessary tools to do useful work. As a rough guide the weight of the machine is a crude indicator on which to identify the weaker models of 'X2'. Heavier approximates to more rigidity. Unfortunately the cost increases from the basic to the better quality.
The weak points in the generic 'X2' design are:-
1. The joint between the base and the vertical column a tilting head design is better but again costs more as does a knee mill. There are new versions of the X2 and X3 which avoid this tilting column and even one that is a knee mill with a rising table but at a price.
2. The gib adjustment and / or design is an issue on some models but there are fixes. The above link is worth exploring if you have not already done so as it covers most of these points if or when you need to improve the machine. The mini lathe (C3) and the mini mill X2 share a common design some where deep in the USSR and have evolved in the Far East into the machines now on offer. Each manufacturer has made variations on the design over the years - some improvements as well as others for cost reasons.
3. General lack of metal bracing in the base casting - some of the new ones look even weaker. IMHO look for mounting lugs that are formed by a single projection that runs the full length of each side of the base as the weaker ones have two separate lugs on each side.
4. Some of the 'X2' have tapper roller bearings and these tend to be more rigid if pushed hard which the rest of the machine is not strong enough to warrant IMHO . On thinking about this over supper I can't think of one but there are well documented ways to DIY the change which some people have found causes problems and others do as a pre buy extra on purchase of a machine particularly the mini lathe.
5. Two versions of spindle mount are available and each has their own following. A 'clarkson' milling collet chuck is available in either so the choice is not a deal breaker IMO.
6. There are reports of motor problems but this should not be a problem if you don't do long runs of heavy cutting. The same remarks apply to the two gear machines where there are problems experienced by some.
7. The machining envelope differs between the various version in terms of table length and traverse of all three axis.
Sorry but you pays your money and learn to machine with in the capabilities of your purchase. These machines are capable of some good work and some versions are supplied ready to go out of the box others will require a lot of cleaning and setting up prior to making anything useful.
Good luck and enjoy. Regards - Pat
Last edited by wildwestpat; 03-05-2012 at 03:34 PM. Reason: Taper roller comment under 4. added to
2. light weight
3. many have gone before you/lots of info
1. envelope, particularly the short Y axis
2. plastic gears
3. poor machining of the ways (many scrape, or hone them)
4. flex of the column
4. two part head which allows for miss-assembly when you tear it down to replace the broken gears. Ask one of the guys with tramming problems.
5. motor circuit board.
I like my X2s due to the weight and my weight restriction. If you're willing to putz with it, have access to scrap metal for a column brace, and find cheap motor circuit boards, an X2 is just fine. There are aspects of it though that take a bit of knowledge to get right. Things like indicating the spindle to the spindle column mount during assembly will let you tram it in without headaches. Not many newbees know this and run into problems.