Radial air bearing construction.

[Lo-Fi]

Hi folks

I'm undertaking a tool grinder build. I've followed up several excellent suggestions for previous projects and plans, and come to the conclusion an air bearing for the work holder would be nice. More detail on why in my build thread when I update it shortly. I've got a precision ground shank for the work head, so I'm now looking at how to make the bearing pads. The most successful designs seem to use graphite, which is cheap and works extremely well, but I'm having some trouble tracking down graphite blocks (that don't come on the slow boat from China) to work with, so wondering if anyone has experience with constructing air bearings in general; particularly using other materials.

Its a bit of a case if "because I can and its interesting". I'm sure oilite or cast iron bushings on the shaft would work fine, but I've done that hundreds of times. The air bearings are particularly attractive because the air keeps grinding dust away from a critical area and you get super low friction and great precision. Just to be clear, we're talking about forcing air through a porous material bearing against a precision ground shaft.

I'm going for a ball bearing main spindle to begin with, but if the work head is a success I'll look at setting that up on air bearings too.

 

[tazzat]

Amazon?

 

[Lo-Fi]

I was watching that video last night

Not here in the UK, sadly. They seem to have axed everything apart from "essentials" and swathes of stuff is "unavailable". Or from the same Chinese eBay sellers... I have a lead on one UK supplier, but it's a non Web shop type of affair, and from experience those kind of places aren't interested in a hobbyist wanting a small chunk. I'll find out next week on that one!

 

[benmychree]

One thing that I do know about air bearing spindles for tool grinding purposes is that they use ground and lapped hardened steel components; owning one of the Weldon non air bearing units, I experimented with drilling through the sleeve with a carbide drill and connecting compressed air to it; it did not work at all, later I went to my old employment venue, who had one with air bearing, and we took out the spindle and measured the bore and found it to be slightly tapered, smaller at each end of the bore with a recess in the center, I recall it was in the order of .0005". I did not attempt any further modification and gave up the idea and went on to purchase another brand with air bearing on E Bay. The one that I ended up with was made by Harig.