This, or something adjacent, might be the post you seek Neil:

super 7 headstock bearings

https://www.model-engineer.co.uk/forums/topic/super-7-headstock-bearings-2/#post-394892

MichaelG.

Hello Neil,

Dealing first with the question of taper thrust bearings. Ken Wilson published a three page article in MEW 175 dated April 2011 which fully described the modification in detail and the rework that needs to be done on the screwed rings that hold the bearing stack in place. Having made the modification myself to taper bearings in place of the angular contact bearings I fully endorse the change and have not had to make any further adjustments to spindle clearance since that time. If you can’t track down the article I have a copy which I can email you, PM me if I can help in this way.

Now air bearings. I am no expert on the subject but I believe things like dental drills use them extensively to achieve the very high speeds, upwards of 50k rpm, that they run on. Rolls-Royce Aero in the 1960s were experimenting with multi positional air bearing measurement of components in the one fixture with no contact other than air.

I don’t think the technology is appropriate for machine tools with variable loadings from cuttings forces, and at the much lower shaft speeds they work at.

Regards   Brian

I hope this isn’t too far off-topic

Having seen the references to Dan Gelbert … I happened across ‘Cyclo’

https://youtu.be/kezh294OO-w?feature=shared

… slow paced, but very informative

MichaelG.

.

On 21 July 2024 at 11:38 Tony Pratt 1 Said:

On 21 July 2024 at 01:49 Kiwi Bloke Said:

Dan Gelbart made an air-bearing lathe, capable, apparently, of micron accuracy. Most impressive. Video in usual place…

I don’t know much about air bearings, and was surprised to discover that they can be sufficiently stiff for a lathe spindle bearing. My intuition suggests that a tapered bearing (if this is what you’re hinting at) may be a challenge, because the leakage path’s cross-sectional area will increase from one end to the other. Wouldn’t this lead to the bearing ‘air cushion’ collapsing? Sounds interesting, if a technical challenge…

I’m with Kiwi Bloke in thinking that an air bearing isn’t suitable for a lathe being used for heavy/light cuts, drilling, parting off, high/low speeds etc. but I’m open to persuasion.

Tony

He says toward the start of the video, when showing those pins in the chuck, that the machine is only for light duty work. So I would guess it is basically a cylindrical grinder with a bit of light turning capacity. A specialised finishing machine. Roughing out, (to the nearest 10 microns!) would be done on a regular lathe and then transferred to this one for final turning and finish grinding perhaps?

Certainly impressive demonstration at the beginning with his plug in a hole that will spin freely but let no air out of the captured space. I wish I could get the power cylinder and piston on my current Stirling engine project so nice!

Hello Neil,

Did you get the Ken Wilson article I sent to you by email, using the address you gave in your PM reply? I have since had a rather abrupt note from Morton’s webmaster informing me that it would not be delivered and should be sent via the Forum.

I thought that action was rather high handed and intrusive and it certainly adds to the task of sending an article copy from a simple one to learning how to do that as a Forum input.

Regards   Brian

Hello again Neil,

Second attempt send to your alternative address; it would be helpful to know if this one gets through to you.

Failing that I suggest we communicate directly by email. Mine is as follows;    wood_y(at)btinternet(dot)com   There is an underscore between the d and y, address all in lower case with no spaces

Best wishes   Brian

Air bearings suit grinders better than lathes where the forces are less. Particularly small diameter internal grinding.