[thelostelite]

Hi guys, I'm a mechanical design engineer, me and my colleagues will be working on a precision lathe which has a spindle runout of 0.0001", and has a swing distance of 6", it's a small lathe that can be mounted on your desk but can turn various materials from cupper and aluminum to titanium... so considering the precision aspect of the lathe, what should we take into consideration while designing that, specially it's our first time to design lathes? what are your opinions so we don't make costly mistakes?

[hfjbuis]

If you need this kind of precision (0.0001") than you also need a constant room temperature, a solid table (not a desktop), guides without play, special lubrication, special tool holders, special chuck/collet, an educated measurement technician and a lot of high precision measurements tools that are periodically calibrated!

Are you sure you really need this?

[thelostelite]

If you need this kind of precision (0.0001") than you also need a constant room temperature, a solid table (not a desktop), guides without play, special lubrication, special tool holders, special chuck/collet, an educated measurement technician and a lot of high precision measurements tools that are periodically calibrated!

Are you sure you really need this?

Yes, I need that ! What do you think about the spindle?, what should be the main things that I should consider?.

And yes you're right about the foundation of the machine to be as rigid as possible, I said that just for you to imagine it.

[footpetaljones]

The spindle is one thing I would not try to DIY with the accuracy you want. You can certainly get a shaft to the right dimensions without much equipment, but do you have any way to grind a tube, flip it 180, and grind the backside concentric to the front?

For the amount of work involved, I would save my pennies and buy a spindle from Dunham that is garunteed to have 50 millionths runout. Their 2 bearing 5c model would be under $3k.

A cartridge spindle also makes other aspects of construction easier. The headstock doesn't need tolerances as tight, and vertical alignment can be done with shims. Horizontal alignment can be done with the usual push pull bolts.

[awerby]

If you could live with .0002" runout (or maybe better) you might try the 5c headstock that Taig makes for its lathes. It's turned on its own bearings for concentricity. See Taig Tools - Desktop Milling Machines and Lathes. If you're just looking for a headstock, it would cost a lot less than $3k. We sell these parts at a discount, if you're interested.