18 Dec
2007
18 Dec
'07
9:25 p.m.
Thank you very kindly for the offer. I'd be glad to study whatever
materials you have, and I'd pay for the postage; if I can't use them
I would send them back. Maybe ought to wait until I get some of the
logic up and running first, though.
So far, however, I'm having zero luck finding washing machine
platters or spindles. There are a couple Data General drives on
ebay, but I sure can't afford to ship those to Australia!
What I need is something like the drive unit from a Data Disc F-
series hard drive. IIRC, they had 12" platters, which would be
perfect for my machine (plus bitsavers has got the schematics!). I
wouldn't turn down 14-inchers, mind you; the smaller size would fit
in my car easier.
Twenty-five years ago I remember being annoyed that I had to trip
over gear like that to get to the *good* stuff at United Products in
Seattle. Ah, well, I was a poor university student at the time, and
even if I had bought one and hung on to it, my wife would surely have
had me committed if I had even proposed dragging such a thing to
Australia...
-Bobby
On Fri Dec 14 2007 Chuck Guzis wrote:
...
About the only item of the correct size and tolerances that's readily
available today, it seems to me, would be the drum unit out of a
laser printer or copier. I don't know if the OPC layer could be
easily stripped off and replaced with oxide, but it might be worth a
try.
If you're really serious abou this, I'd be willing to donate a head
from a CDC 808 disk unit--4 bit parallel recording.
Cheers,
Chuck
19 Dec
19 Dec
9:16 a.m.
New subject: Washing Machine Drives [was: Homebrew Drum Computer (magnetic heads)]
Robert Nansel wrote:
So far, however, I'm having zero luck finding
washing machine platters
or spindles. There are a couple Data General drives on ebay, but I sure
can't afford to ship those to Australia!
If all of this is some proof of concept step anyway, why not use ST412 type
5.25"-form-factor drives? The platters are still large enough that you could
do something with them, surely, and they're still reasonably available.
Heck - get a multi-platter drive, rip out all but one platter, and figure out
a way of mounting all the existing heads in parallel on just the one surface
in order to simulate drum tracks. For a backyard engineering project, that
can't be any worse than screwing around with VCR heads. Keeping things clean
during assembly will be interesting, and you'd presumably need to seal
everything afterwards to keep particles out (but use plexiglass so you can see
the guts). On the plus side, you get a balanced spindle, data surface, and a
bunch of matched heads 'for free'.
%deity% knows what issues there'll be with suitable amplification / processing
of the read signal, and with writing - but that's no worse that a VCR solution
or a homebrew drum running at a few thousand RPM :-)
I'm not convinced it can be done due to the fine tolerances involved - but I'd
be really interested to see someone try! Maybe for version 0.1 just use a
single head on the surface (i.e. use the existing head arm) and figure out how
to write data and read it back again...
cheers
Jules
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