Perhaps. Some sort binder as found in enamel paints might work as well. The drum is quite low density, and does not have air bearing heads. The head heights are actually adjustable with a bunch of set screws. The heads themselves are also pretty big. This is a late 1950s drum, not a 1970s era hard disk - there is a world of difference. I would bet the heads ride a few thousands above the surface. The whole assembly is in a very rigid cast chassis, driven by a relatively low-frills AC motor, apparently. My thinking is that the drum could be recoated (this is assuming it is indeed shot), and using the rigid cast chassis, ground down to a smooth surface with a custom made tool. This is much like a "poor mans wheel lathe" used on railroad wheels. As long as the bearings are still pretty tight, there should be very little wobble between the drum and chassis. With each head being adjustable for height, much inaccuracy across the drum becomes fairly unimportant. Inaccuracy around the drum is more of an issue, but I suspect it will not be too bad if the correct tool material and magnetic coating is used, and the drum ground down gently. I will ask my real machinist friends about the tooling, as I doubt I (or any of us) could make it. -- Will

--- On Mon, 11/24/08, Chuck Guzis <cclist at sydex.com> wrote: Interesting. He might have to experiment w/speeds so that all the material isn't pulled to the outer edge. But regardless even if you determined the right speed, you might have a globule of the crap LOL accumulating near the perimeter.

If there is signifcant play in the bearings, you have prolems anyway, since the drum won't remain at hthe right distance form the heads. You'd need to sort that out before re-coating it. I wonder if you coud remove the heads and mount something in place of each one temproraily holding a cutting or grinding tool. Then slowly feed it in with the drum spinng. It shouldn't matter if all trackes aren't exactlyy the same height, that's what the head adjustments are for :-). Afterwards, replace the heads and adjust. -tony

Jules Richardson wrote: Weren't drums and early disks done with nickel or some-such plating, rather than binder & oxide? Of course, getting a uniform thickness of plating requires careful attention as well (spoken having had bitter experience with such).

Eric Smith wrote: (Yes, I missed including the word 'alloy' in there.)

if this was the case, the surfaces just needed to be plated, you can produce a uniform thickness by polishing. Some sort of contraption (a lathe?) would be necessary, but it's not rocket science I don't think. I was between jobs a number of years ago and applied at this place in Long Island that makes some sort of microchips. The silicon wafers needed to be made *uniform*, and they used some sort of polishing operation. I asked what was the tolerance, and the guy said .0001". I figured to myself he probably didn't really know what he was talking about and the tolerance was much tighter. Cast iron surface plates can be made uniform to .000025" (that's right, 25 millionths of an inch), but that's an entirely different operation, and in fact is done - by hand - w/a glorified chisel. Carry on lads. I'm interested in learning more about this meself. --- On Sun, 11/23/08, Brent Hilpert <hilpert at cs.ubc.ca> wrote:

lost my copy of "the Metal Lathe" ~10 years ago. The best way to learn about machinery is learn how to build one! No, I haven't undertaken such a project, but know enough to modify existing designs at least. You just need to hunt and peck to find the right *tricks* to do what you want to do though. Especially w/this stuff. --- On Wed, 12/3/08, bfranchuk at jetnet.ab.ca <bfranchuk at jetnet.ab.ca> wrote:

Dave McGuire wrote: I'll see if I can unearth some dates/names. I seem to remember a couple of working projects based around non-flying heads and mounting of commercial magtape onto a cylinder for the storage medium. Longevity is obviously questionable, and rotation speed would be rather limited! Will's project is very much in a different league, obviously - hence my interest in how he gets on. To my knowledge, re-coating a non-contact drum running at 'commercial' speeds (what, typically in the 1500-400rpm range?) would be something of a first. Oh, I once read a book describing a homebrew drum in it - I think it was based around using a tin can for the drum, and the capacity was in the tens of bits. (My brain wants to say it was "how to build a working digital computer", but I could be wrong there). I wonder if anyone ever actually built one that worked? :-) cheers Jules