Lathe stands or benches ?

I have acquired an Atlas 12" 3900 series and will need to fabricate a stand for it, which will have an under mounted variable speed motor, what makes a good base for a lathe?

My first idea is a piece of railway track i have, plasma cut into a T section beam which could be skimmed on a mill both ends where the feet are bolted?

I reckon this would be a rigid basis for the machine and cost me zero.

Railway track? That might be overkill but if it's what you have and you have the time and machinery to do it, it certainly will make a solid bench!

Mine is made from 1-1/2" steel "angle iron" legs and frame with ladder-style cross members on the top where the lathe feet bolt down, topped with a sheet of 1/4" steel plate all stitch welded together and bolted to the concrete floor. It's plenty solid enough.

I would go for a bench rather than a stand. If well constructed and the lathe is bolted to the frame itself it's plenty rigid. The added storage is a big bonus. I also put the bench on castors and added levelling pads so if I need to move the lathe it's super easy.

I used 50mm square section steel tube to make a stand for my 290 lathe. A friend with welding equipment welded the pieces together. I made it so the lathe could be adjusted to turn parallel, it has worked well for a decade.

Thor

Bench, to me, means a very much fixed location. Whereas a stand can usually be moved, if required. Entirely your choice, really. Nothing much wrong with either as long as whatever you decide on is (more than) adequate for the job.

The Atlas having a V/box type bed gives you more options in design compared to a gap bed lathe such as a Myford which is far more easily set out of true on a poor stand - however a 12" swing lathe is a quite a big beast and needs to be securely supported.

As you have decided on an underdrive I suggest that a stand would be easier to fit this to compared to a cabinet - but the drive will only take up one end so there is no reason why a custom built support could not be open like a stand at the motor end and have storage under the tailstock. Rail sounds like a bit of overkill to me, but if it is there why not.

The eseential thing about the supportr for the lathe is that it is rigid and does not flex.

Once the lathe is on a rigid base, the mounting feet can be adjusted / shimmed to remove any twist from the bed, in the interests of turning parallel..

The extra storage space underneath is very useful, keeps accessories wheer they can easily be accessed and looks neat.l

I am wary of mounting benches on castors, since what has the lathe without twist in one place may not do so in another, if the bench is not sufficiently rigid.

Howard

Castors will solve the fixed location issue, and levelling jack feet will give you the required rigidity and ability to level the bench, it is possible to have both. The added benefit of a bench/cabinet, is storage gained for all the lathe tooling.

I often warn newcomers to avoid scrap metal because of the risk it won't machine well. Railway line is a case in point! The alloy, a Manganese Steel, is formulated and processed to be tough and hard-wearing to high-standards. It's designed to take a few of decades of heavy rail traffic before it has to be replaced. In hobby circles old railway line is often used to make small anvils because it can take a beating! Although I'm sure railway line can be machined, it's going to fight back, likely more trouble than it's worth! The alloy needs flame cutting and grinding, not milling or turning.

From a lathe stand design perspective, railway line provides a girder that's massively too strong and heavy for the job in hand. OK if it's free, but it doesn't mean the rest of the stand can be skimped.

The ideal lathe stand is rigid throughout, which is usually achieved with a box structure in cast-iron or steel, built economically. No girders or other wasted materials! Steel cabinets are usual these days because they're cheaper and stronger than cast-iron and the inside can be used for storage. Small lathes can be supported on suitably braced wooden benches or even kitchen units: the main thing is the structure takes weight straight down to ground, keeps the feet on the same plane, and doesn't move when the lathe is turning.

If I were building a lathe stand from scratch, I'd go for two columns made of flat bottomed steel boxes reinforced at the weight bearing corners. Rigidity improved by binding the columns with sheet metal top and back, to stop movement rather than adding strength. No need for a strong span between columns because the lathe bed does that.

Tempting to provide a heavy flat top to ensure the lathe feet are all at the same level, to take up spring in the columns, and to help soak up vibration. Perhaps a slab of granite kitchen worktop, or a recycled headstone. (Plenty of them lying about!) Not worth the extra trouble here because I run a hobby lathe for ordinary workshop purposes; even with the best stand in the world, my machine can't provide tool-room accuracy unless I do a lot of work to improve it from end-to-end. As I don't need more accuracy, it's not going to happen!

As always what's done in workshops is often compromise rather than perfection. Many members put their machines on castors, which are bad for rigidity, even if jack feet are provided as well. But castors provide mobility, which is often very important. And if a lathe mounted on castors cuts 'well enough', and owners rarely complain, then there's no point in pursuing a theoretically better stand.

Dave