How to make new multi-track tape heads?

[cjs]

Over in this post NF6X came up with a really interesting idea, that I think is worth its own thread. (I, at least, am fascinated by this idea.)

If I could get my hands on even a good DECtape drive head, I think I could make at least a read-only imager. The electronics would be in my area of skill, the mechanical portion of the transport would be more of a challenge for me but still achievable, but the head itself feels inaccessible to me.

On that topic, I would really like to learn how to design multi-track tape heads with geometries suitable for at least DECtape, if not 1/2” 9-track tape. Also how to fabricate prototypes, and how they would typically be mass-produced. How were they made with 1960s technology, and how might we make them with readily accessible technology in 2024?

Do any of y’all have tribal knowledge and/or references to information about practical multi-track tape head design and fabrication? I’ve only ever seen cartoonish sketches of how a tape head works, but never detailed drawings or photographs. Short of sectioning vintage tape heads with sandpaper, I don’t know how I could learn how they’re made.

I currently work at a small defense contractor, and we have a big machine shop with CNC milling machines and lathes, surface grinders, wire EDM, welding, and injection molding. I don’t think I could use any of that equipment off-hours for personal projects, but just for the sake of discussion let’s pretend that we have access to all of those kinds of equipment. My last job was at a company doing veterinary RFID microchips and readers, so let’s also pretend that we have access to coil winders and/or we know how to make them. Feel free to fork this discussion to another topic if desired.

 

[Al Kossow]

JRF Magnetic Sciences: Tape Heads-An Introduction

NOS 1/2" 9-track tape heads are still available. I've bought many, many, many of them.
7-track has been out of production for 50 years and are very difficult to find
combo 7/9 track heads are even less common

 

[Chuck(G)]

...or, if you're just interested in reading tapes, take a look at, say, the IBM 3480/3490 tape heads.

 

[NF6X]

I’m interested in making unobtanium read/write heads for DECtape/LINCtape, as well as other silliness.

 

[NF6X]

What I’m really interested in is having DECtape/LINCtape drives and experiencing them fully. I have the impression that there are approximately zero of them available at most moments, and that when they do appear they’ll sell for about as much money as a used car. So I have to wonder whether it might be less expensive to make one than to buy one. On a scale of “it’s the sort of project Ben Krasnow or that Breaking Taps guy might take on” to “forget it; win the lottery first”, I wonder where making DECtape-compatible read/write heads in one’s garage might lie.

I speculate that there may be a few other nutcases like me with similar dreams.

 

[NF6X]

Aha! Page 84 of this document describes LINCtape head geometry and wiring:

http://www.bitsavers.org/pdf/dec/linc8/F-L87_LINC-8MaintVol2_Nov67.pdf

I found it through this page which includes photos of a LINCtape drive head:

LINC tape drive

If I understand what I am looking at, I think the ten shorter rectangles are the ends of the pole pieces, each with a 0.0005” gap through the middle, perpendicular to tape travel. I think the eleven longer rectangles are probably magnetic shields between the tracks. Are my assumptions correct?

I still hope to find details of the internal construction, materials, and manufacturing processes used in tape heads of the DECtape/LINCtape era. The gap width and skew tolerances are pretty tight.