Head groove-o-mania

[Makymak]

i never tried any other methods than the lapping film one

Vince, I know that lapping film IS the way to go, that's why I don't suggest my way to anybody.

But I like improvising. And since my way works for me, I'm ok!

By the way, the majority of the heads at manufacturing are lapped on a similar way. They give the final contour with special sanding and then they polish the contact area with centrifugal brushes and some special "soap". My father worked on a factory and their machinery shop has used this method to manufacture a lot of products.

 

[vince666]

Vince, I know that lapping film IS the way to go, that's why I don't suggest my way to anybody.

But I like improvising. And since my way works for me, I'm ok!

By the way, the majority of the heads at manufacturing are lapped on a similar way. They give the final contour with special sanding and then they polish the contact area with centrifugal brushes and some special "soap". My father worked on a factory and their machinery shop has used this method to manufacture a lot of products.

Sure!
On factory they would use different methods.
And, of course, there are more viable methods for doing it at home.

The lapping film method is the one I've learnt from Alex and which I've used myself, just that.

Also, about lapping film, there are (at least) two kinds of it, based on different abrasives.
There is the Aluminium Oxide one which is preferable (at least on metal alloys) because it's gentler and it removes the metal more slowly and without that the abrasive changes the rate it removes material while it's clogging.
And there is the diamond one which is more aggressive and it removes the metal a lot faster at first and, while clogging, it removes it lesser and lesser and which isn't the best choice for lapping metal alloy heads.

So, what I use here is the 3M Aluminium Oxide lapping film with self adhesive (PSA) on the back, and I use it dry.

But, anyway, there would surely be other viable ways to do the work.

 

[e30m3mon]

Interesting thread, guys. I've never tried lapping a head - assumed it would require some precise milling kind of equipment, but this sounds like a kind of DIY project. I usually look at YT vids for "entertainment value" but is there a particular poster that does this process correctly?

 

[vince666]

Interesting thread, guys. I've never tried lapping a head - assumed it would require some precise milling kind of equipment, but this sounds like a kind of DIY project. I usually look at YT vids for "entertainment value" but is there a particular poster that does this process correctly?

I fear at YT there isn't anybody doing it the right way, even if i didn't check them all.
for sure, there is a guy who makes it in a way that, after "lapping", the head is good to be trashed!

I use to avoid spreading such stuff on public just to NOT encourage people to DIY... it needs a small mistake to ruin an otherwise salvageable head.

for example, this is a video where the guy shows how NOT to lap a head!
he uses diamond lapping film but, most of all, he bends the guides (!!!) and, since he bent the guides, then he scrubs the head flat over a large area at the center of the lapping film sheet (do notice the very long grey traces on his lapping film) so that he makes the gaps area totally flat (!!!)...
this way, he removed a lot of metal just from where you should try to remove the least or none at all (from the gaps!).
Also, he didn't try to keep the original contour shape of the heads.
But, for sure, lapping like he does is a lot faster work... but the head is totally gone.
(the latest comments there in the video are of mine )

 

[J!m]

I would not fear the "lapping"* of a head at all; however, getting it reinstalled correctly is more daunting without all the right equipment to ensure it's in correctly. And I'm not making that investment.

So, I could collect some heads and re-lap them myself but then have someone with the right equipment and experience install them for me.

*Lapping generally implies a compound, which is basically abrasive in grease. I assume the "soap" mentioned above is this...

 

[Makymak]

I assume the "soap" mentioned above is this...

Exactly! It's a microcrystal substance (like a polishing paste) in a hard form so it is easy to stay on the highly rotating brush. There are different types of soap (measured in grades, if I remember correctly - my dad retired 17 years ago), according to the machine and the metal to be polished. It's purely an industrial matter, but I guess there are equivalent for indoors use. "Soap" is the slang word used at the factory (but I have heard it from other machinists, too, in my country).

 

[J!m]

Sounds a lot like the hard bars of compound I used to load the polishing wheel for guitar finishes. Different colors for each grade.

 

[vince666]

I would not fear the "lapping"* of a head at all; however, getting it reinstalled correctly is more daunting without all the right equipment to ensure it's in correctly. And I'm not making that investment.

absolutely, so.
in most situations, to properly reinstall the head you need some kind of alignment gauge.

 

[J!m]

As a bare minimum.

 

[vince666]

As a bare minimum.

for example, i am reinstalling those Technics AX heads i've put the guides on the opposite side as they originally were, to install it on a AIWA.
( I mean the heads mentioned and shown here: https://forums.phxaudiotape.com/threads/what-cassette-deck.9921/page-5#post-328342 )

Checking with a gauge is of critical importance in such situation, since this mech doesn't have tuning screws ( it has only 2 screws on head ) and the head isn't its own original one.
So, this AIWA is a PITA to align in this situation just because it has not tuning screws for height or tilt, only for azimuth... then I must add some DIY shims of the needed thickness (i've used a few layers of copper adhesive tape) behind fixed screw to adjust both tilt and height, obviously checked with a gauge... then it's a matter of making a few trial and error tries until it's OK.

Finally, tilt and height seem just OK then the shim is OK.... Now, I need to remove the head again to solder the wires on it, which i hadn't made before! LOL

tilt check



guide/height check



EDIT: soldered

 

[vince666]

good that i've made a close-up pic of the soldered joints.
at first sight everything looked ok... now, looking at it again, there might be an unwanted bridge between two soldered joints.
Tomorrow, will need to check it better.

LOL...

 

[J!m]

The Sony D5 used shims. I have a couple spares from the three used to make the one I have.

 

[WOPL Sniffer]

The Sony D5 used shims. I have a couple spares from the three used to make the one I have.

I have a bin of Sony reel to reel head spacers if you want them (and some new Walkman parts). I found them in the old guys parts hoard.

 

[J!m]

I'd be interested if the box isn't too huge... Let me know what you need to cover shipping and aggravation and I'll square up with 'ya.

 

[WOPL Sniffer]

I'd be interested if the box isn't too huge... Let me know what you need to cover shipping and aggravation and I'll square up with 'ya.

Jim, the parts are so small that they would fit in a ciggy pack. You can have the stuff. PM me your address and I'll send it to you in a small USPS box.

 

[WOPL Sniffer]

I'd be interested if the box isn't too huge... Let me know what you need to cover shipping and aggravation and I'll square up with 'ya.

Maybe I'll even throw in a 2 Meg fuse

 

[J!m]

Ooooh! A fuse too?

PM to you inbound shortly...

 

[vince666]

The Sony D5 used shims. I have a couple spares from the three used to make the one I have.

The AIWA AD-F880 just has a couple shims installed and they would be enough with the original head, while with this other head I had to add some more thickness to reach the right head height... and I also had to also tweak tilt angle a small bit, which is easy to do by adding a half shim only above or below the fixed screw.

In theory, all those decks where the head has only two screws (one spring loaded for azimuth and the other one is fixed) might need shims, just because you have no other way to tweak the head height and the tilt angle.
I feel very comfortable in making shims with the copper adhesive tape because its thickness is around 0.05 mm then I can add/stick more layers in small increments until I am OK.
Also, I happen to make such shims in a sort of C shape, so that I can insert them by unscrewing the fixed screw by just a small bit and slip the shim behind the "wing" of the head's plate, without totally removing the head from it's place.

While the heads with at least 3 screws, which usually are all spring loaded, no shims are needed because everything is directly tuneable and, IMO, it needs a lot less time and effort to get it right.

In any of the above situations, some kind of M300 alignment gauge is absolutely needed.

 

[J!m]

The Sony ones are brass and C shaped as well. Non adhesive.

 

[vince666]

The Sony ones are brass and C shaped as well. Non adhesive.

actually, the point I use adhesive copper tape isn't because i need them being sticky.
but when I must make a shim of a thickness which needs more layers of such copper tape, i stick the layers against each other and the final result is a non sticky shim.