Re: Commodore 1520 supplies + programs

From: MikeS <>
Date: Wed, 25 Jun 2014 12:56:39 -0400
Message-ID: <7555DBB8EF434DDD99129AB3DEBB74AE@310e2>
> we know - not only the directly adjacent gear can be affected.

Oh? How could a badly made gear affect anything other than the gear with 
which it mates (assuming they can even rotate in the first place)?

As I said, instead of speculating on the various reasons why it can't be 
done, why not just mail Gene a pair of split gears from one of your several 
units that all have this problem and see what he can do?

Re the pens:

As you probably know, the Alps mechanism used in the 1520 was also used in 
various other printers, eg. Tandy CGP-115 and the PC-2 printer, Atari 1020, 
several Sharp models etc.

But they were apparently also used in some medical equipment and several years ago a German company made replacement pens; it might be worth while to follow up and see if by chance they are still available:

"The pens correspond actually accurately to the defaults of the models 
EA850C and EA850B including the crucial ball point. We worked at the project 
nearly 1 year; and first we experimented with a fiber tip, but this wasn't 
acceptable by the technical examination of international medical technology 
manufacturers. We now sell the current version to Scandinavia and into the 
USA with no objection. Our actual emphasis lies in the medical technology 
but the pens are also useable for computer plotters.

The company sells the pen sets internationally and has 2,000 sets at its 
stock. Contact Christane Lass by email: if you 
want to get more info or if you want to order the set(s)."


Paper should not be a problem, although a single roll at a reasonable price might be hard to find; it's just an ordinary calculator/cash register roll, 4 1/2" x 2 1/2" diameter.


----- Original Message ----- 
From: <>
To: <>
Sent: Wednesday, June 25, 2014 5:37 AM
Subject: Re: Commodore 1520 supplies + programs

On 2014-06-25 at 00:53:26, geneb ( wrote:

> Send me an STL file of the gear and I'll give it a shot.

Somebody would have to make one first. I didn't do it yet.

> Worst case, it doesn't work.

No. Worst case is that the rest of the mechanism degrades quickly.

Please don't get me wrong. I am sure you or Shapeways can print something 
that will somehow fit and turn and maybe even drive the other gears ;-) What 
I wouldn't like to risk is having it somehow work for some time, only to 
discover that more damage has been done to other parts due to inaccuracies 
(centering, teeth shapes, tooth walls smoothness, etc). And as we know - not 
only the directly adjacent gear can be affected.

Having said that - I am still very curious what would be the output. It is 
so small that maybe you can try just a quick shot of a generic gear that has 
the (I don't know the English terms for the gear parameters) outer diameter 
of 3.7mm and 1.5xx (don't remember exactly - maybe somebody can check it 
directly with his device) inner hole. There should be some generic designs 
with appropriate number of teeth that one could resize. Not to work with 
this one later but just to have a kind of POC if spending time on exact 
reversing the actual gear makes sense as of now.


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ea850c_equivalent2.jpg ea850c_equivalent2.jpg
Received on 2014-06-25 18:00:03

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