[Table of Contents]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [ARSCLIST] Record Diameter (was: playback curves for some 78s)

My First post (With more than one topic)
Steven your guess is wrong Your first is not quite right either They simply used different dies at some stage most likely later after the "rush" However it is possible that they just simply ground them back to size but after a new pressing plate was made to allow for the smaller diameter disc you can tell by looking at them edge on Today since the cost of a set of dies for the 10" Vinyl (the demand not been so great) some people press them on a 12" die but cut the acetates for a 10" therefore the pressing plates for a 12" pressing but with only tracks for a 10" Once they are pressed they trim them back to the 10" size required ( about $2000 per side for a 12" die set) One can do that with the vinyl but not with the "shellac" type of record since the fillers used quite often included ground down slate as well as other items as gypsum
Since it was a stop gap measure they where rarely done by a mechanised setup it was done by the hands of an operator, therefore the variation in size as Mike pointed out
I am not so sure about the cantering issue mentioned being of different size It was normal practice to solder the centres up with a threaded spigot at the rear of the master so the plates did not get "wet" This was punched out at the cantering stage prior to forming the stampers so any size centre hole could be punched
On another point The lead in grooves where always cut after the area where the dies come together to seal when on the presses They have to take about 100 tonne of pressure Sure there are quite a few records out there that they start right at the edge But it was not, and it is not common practice as the plates are at the weakest point right at that point It is called "cut weakness" It was a troublesome problem with plates splitting right at the point where the cut was at the seal face of the dies
On another point inner and outer grooves where commonly recut on the mothers prior to a pressing plate or a stamper being produced, Ollard and Bennet in the 20's and 30's talk about it in more than one publication at the time It seems that this was done by hand, at least in Europe, Juke boxes need to be triggered to the off position at the end of play, quite a critical requirement, something that a reproducer, record player, that was attended by a person did not require one as such.
Of course that was until cutting lathes where modified to take care of the correct lock groove which required it to be right inside very close to the label The modification necessitated a cam as well as some gears to be replaced something that was not off the self since most of the lathes where inside jobs Quite often these lathes had no ability to do a lock groove The lead in groove was done by speeding up the machine, the same at the locked groove end It was a bit of hit and miss affair which can often be seen in older records Therefore recutting by hand on the mothers prior to a stampers being made It is not as hard as it sounds a little template and a scriber was all that was required It was also observed at the time that the original groove was soldered up first than recut on the mothers There is a mention where they also re-cut them on the stampers, they where made from copper backed with another copper plate which was soldered on so as to provide strength It is not such a hard task

C. Moss
----- Original Message ----- From: "Steven Smolian" <smolians@xxxxxxxxx>
To: <ARSCLIST@xxxxxxxxxxxxxxxx>
Sent: Tuesday, May 19, 2009 7:42 AM
Subject: Re: [ARSCLIST] Record Diameter (was: playback curves for some 78s)

If memory serves, the smaller 1930s diameter was required to clear the jukebox mechanisms. I've heard that Decca, gunning for the jukebox market, had made its first release in the slightly larger size and had to redo it. I don't know if they used different presses or adjusted the plate area appropriately- my guess is the latter.

Steve Smolian

----- Original Message ----- From: "Michael Biel" <mbiel@xxxxxxxxx>
To: <ARSCLIST@xxxxxxxxxxxxxxxx>
Sent: Monday, May 18, 2009 4:05 PM
Subject: [ARSCLIST] Record Diameter (was: playback curves for some 78s)

I sent this out last night under a different subject title but didn't see it get posted or even get a duplicate posting rejection, so I am trying again with some added information. Maybe my joke in last night's revision of the subject line was blocked?

From: "Steven C. Barr" <stevenc@xxxxxxxxxxxxxx>
Reissues of original Columbia or Okeh records from the 1925-3? era
are VERY commonly dubs...since the originals were 10.25" discs and
the stampers don't fit onto modern-day 10" records...! Steven C. Barr

Get out a ruler and some records, Steve. You (and most others here) are in for a big surprise. Those "oversize" Columbia pressings are the ones that are 10-inches. Most other "10-inch" records are 9 7/8-inches. Many Columbia/ARC pressings from the 30s are 9 15/16-inches, and eventually got down to 9 7/8-inches. Yes it is true that the Columbia and Columbia-OKeh pressings are larger than later records, but the are not and never have been 10.25" . And many or most of the early George Avakian produced Columbia re-issue sets were master pressings, at least the earlier copies were. New stampers were always produced from the metal positives (mothers) because the center mounting hole sizes were different in from the late 30s on, so the outer diameter of the original metal part is not of consequence. What IS of consequence, of course, is the diameter of the outermost grooving, and that is what Steve was really talking about. I think that there occasionally were problems -- even in newly recorded items that had to be issued in a dubbed fashion if the cutting engineer goofed when setting the outer cutting diameter on the lathe -- but thre was enough lead-in space on most 1920s Columbias and OKehs to allow them to be reissued on the slightly smaller pressings from the later 30s.

Also, when those in the metric world call those records 25 cm, they are
the ones who are correct.

One other point, Edison Diamond Disc diameters can vary a great deal.
I've never checked to see if the outer grooving diameter on these also
vary, but the size the discs are ground down to after "printing" can be
seemingly random.

Mike Biel mbiel@xxxxxxxxx

[Subject index] [Index for current month] [Table of Contents]