A simple and inexpensive stereo cutter YOU can build!

[grooveguy]

Hi, xave,

I looked back through my purchase history but couldn't find reference to the ones I bought. Here's a link to some that come directly from China that look to be the same thing:

https://www.ebay.com/itm/Small-Perfume-Mini-Funnel-Liquid-Oil-Transfer-Bottles-Container-Funnel-3PCS-Hot/263852620678?hash=item3d6ed77b86:m:m7Dwt88CO-q2YHaCK8J4Lpg

And these appear to be identical, except the price is higher because they are in stock in the US:

https://www.ebay.com/itm/Metal-Mini-Funnel-For-Perfume-transfer-Diffusers-Bottles-Mini-Liquid-Oil-fill-JH/113425125427?hash=item1a68aa1033:m:mWgh-KMc84-BdUVvDZVNlLQ

Note that the tops of the funnels have that wide lip that is not flared. I cut that off with scissors and then ground the top edge on sandpaper so it was even. Also the small neck of the funnel is too long and very thin. I drilled in from the small end with a 1/8" drill bit so that the hole had parallel sides, and then pressed-in a piece of 1/8" aluminum rod until it just came through into the flared part of the funnel. I also used cyanoacrylate (super-glue) adhesive so that the rod became part of the funnel neck. Next I drilled a 1/16" through-hole down the center of the neck for the pushrod, and finally cut the neck of the funnel off so it was just long enough to drill in from the side for a 2-56 setscrew. I think you can see all this in the pictures.

The mouth of the funnel can be super-glued to the transducer voicecoil bobbin-end, but be sure to clean-off the sticky stuff that comes on the transducers. If you are able, two 1-80 setscrews about 45-degrees apart would grab the little pushrods better, but make sure you glue that funnel so the setscrew(s) are accessible from the front of the head. It would be a real bummer not to be able to reach them with a hex driver.

The cyanoacrylate holds really well, as I found out. At one point I dropped a piece of pushrod down the funnel neck into the voicecoil. That meant taking the funnel off. I soaked the glue joint in acetone for about an hour and was able to separate the pieces, but wasted a lot of time doing that. Be careful.

[xave2000]

I'm sorry I thought this project was yours.I found exciters on express share and I thought the project in photo belonged to you that's why I asked you the link for the funnel.
i'm looking for this funnel

[grooveguy]

Hi, xave,

Yes, the funnels in my project, and in your picture, are the same ones in the eBay link. It's just that you have to modify them somewhat.

Snap9.jpg

Snap10.jpg

Both the top and the bottom of the eBay funnels need to be cut-down, not only to reduce the mass but to fit in the confines of the cutterhead. In the upper photo here from the eBay link I've indicated with the red arrows where I cut the funnels. In the closeup of the cut-down funnel, you can see the 'plug' in the neck and how it was drilled for the stylus pushrod.

These funnels are so incredibly cheap that I recommend getting a few lots-of-three so you can experiment. I ruined about four before I developed the knack of whittling them down.

[xave2000]

hi,
the work is so well done that I thought you bought them to measure! bravo what a beautiful job.
I left the same exciter and cone you on a project that I will soon put on the forum only with a 3d printer and the bottom in sheet as you for the heating part of the stylus and suction fixation.

Your project and the knop too will make mine.

ps: sorry for my bad language but i'm french.

[grooveguy]

Beautiful work, xave; I can't wait to see it all come together! And your English is just fine. Please keep us updated on your progress; you might want to start your own thread so it will be easier to follow the project.

[TonyD]

What exciters are everyone using? This looks amazing well done

[grooveguy]

Hi, Tony, thanks for joining the discussion; I'm delighted to see that others are interested and are improving on this project. xave looks to have done a superb job of a 3D-printed housing; maybe he'll share.

As for transducers, Version 1 of the head used these exciters from adafruit.com:

Adafruit.jpg

They are well-built, compact and look as if they could dissipate substantial heat, although that was never an issue in my tests. They were a bit stiff, however, so Version 2 used these:

Tectonic.jpg

These are from partsexpress.com, although Amazon also carries them (at more than twice the price!). Parts Express also carries what looks to be the same thing from Dayton Audio, although I'm not sure about the dimensions being identical:

dayton.jpg

Compared to other designs you see on the group, these all look to be pretty small for the job. But instead of anchoring the stylus holder or 'torque tube' to the backplate, I floated it in rubber, which makes the head much easier to drive. The main argument for stiffness is to keep the resonant frequency high for extended top-end response. I simply used bodacious amounts of equalization to achieve frequency flatness, and find that just a few watts will fully modulate a microgroove recording.

[TonyD]

Now when you say you floated the stylus holder in rubber what do you mean? Sorry I'm just having trouble really grasping what to do. I really.would.love to give this a shot. I have some 8ohm 3 watt Dayton audio exciters. You think they would work?

[grooveguy]

Hey, Tony, I'm working on a sketch that may make the whole thing more understandable. Time is at a premium, but give me a day or two more.

[soeffingodly]

grooveguy - fantastic article! Well explained. Fantastic documentation.

Would you happen to have a copy of the .pub file by any chance?

Warmest Regards.

-S

[grooveguy]

Hi, S; you bet, I will PM you.

[grooveguy]

At TonyD's request, here's a second sketch of the second cutterhead, which better shows how the stylus is suspended in a rubber damper. Note that the damper-holder is now screwed to the backplate, a more solid coupling than the setscrew shown in the photos.

Cutterhead 2B.pdf

[TonyD]

Thank you so much that is a whole lot easier to understand!

[dx7tnt]

This is a brilliant build, thank you so much for such detailed instructions in your engineering notes. I'm putting together a simple lathe for fun and have tons of questions that I'll try and work out before spamming them on the thread, but one simple one was how do you cut the holes in the phenolic resin like that? I'm trying to work out how I'd do it with a drill press and a circle cutter, but I don't know how I'd undercut the second circle without using a Dremel or something. (My knowledge of machining is patchy compared to my understanding of audio.)

Thanks again!

[grooveguy]

Hi, dx, and thanks for the props. I used Forstner bits:

forstner-bit.jpg

...to create the stepped hole, got this set off Amazon:

ForstnerSet.jpg

[Estrada]

Hi this, this is a really fantastic. I'm still very much a newbie and in fact am still getting my first lathe with mono head working. My goal is to work my way up to a stereo cutter and this could be a great option, thought the DSP side of things is beyond my current knowledge. Perhaps one day I will attempt to make this, with that in mind I am wondering where I could purchase a pair of the audio exciters used on the second head, this seems key to it being successful. Is there any chance you could provide a link? many thanks

[grooveguy]

Hi, Estrada. Thanks for the comments and, yes, it's a quite easy head to build. The DSP business should not be a worry, as the ready-made boards are available from a number of sources, and I'm happy to provide the DSP project files that proved successful for me. You'll find that, once you get your feet wet with DSP, it's a shoo-in using the Analog Devices utilities and you'll find many uses beyond the project here.

I had shown the exciter sources back on March 23 (scroll up), but checked just now and found these links to be good:
https://www.amazon.com/Tectonic-TEAX19C01-8-19mm-Metal-Exciter/dp/B0066AYMTS (very pricey!)
https://www.parts-express.com/tectonic-teax19c01-8-19mm-metal-cup-exciter-8-ohm--297-208 (very reasonable)
...as well as what looks like a drop-in alternate:
https://www.parts-express.com/dayton-audio-daex19ct-4-coin-type-19mm-vented-exciter-5w-4-ohm--295-218

Best of luck with your lathe-building endeavors, and be sure to keep the group posted on not only your successes but lessons-learned too!

[Estrada]

Hi, thanks so much for this. My sincere apologies, I thought I'd seen those links but couldn't find them when I was re-reading the thread, I think I was only looking at page 1 of 2 of comments - it must have been getting late! Thanks for your patience. Also thought I'd mention that your drawings look great despite not being drawing in CAD.

I've put up a post on my lathe here. https://www.lathetrolls.com/viewtopic.php?f=22&t=8287&p=53048&hilit=horseshoe#p53048 I've got a way to go yet before I'm ready to make a stereo cutter head but it's nice to know it's in the realms of possibility.

Thanks again for sharing this so openly, and thanks for the positive and encouraging tone of your posts.

[Mrgordyp]

Hi, Estrada. Thanks for the comments and, yes, it's a quite easy head to build. The DSP business should not be a worry, as the ready-made boards are available from a number of sources, and I'm happy to provide the DSP project files that proved successful for me. You'll find that, once you get your feet wet with DSP, it's a shoo-in using the Analog Devices utilities and you'll find many uses beyond the project here.

I had shown the exciter sources back on March 23 (scroll up), but checked just now and found these links to be good:
https://www.amazon.com/Tectonic-TEAX19C01-8-19mm-Metal-Exciter/dp/B0066AYMTS (very pricey!)
https://www.parts-express.com/tectonic-teax19c01-8-19mm-metal-cup-exciter-8-ohm--297-208 (very reasonable)
...as well as what looks like a drop-in alternate:
https://www.parts-express.com/dayton-audio-daex19ct-4-coin-type-19mm-vented-exciter-5w-4-ohm--295-218

Best of luck with your lathe-building endeavors, and be sure to keep the group posted on not only your successes but lessons-learned too!

Newb here, so thanks for taking the time to answer a simple question... but what are you using to power the transducers.? I also see the wattage is low pretty low compared to what I’ve seen people suggesting for regular speakers to drive the needle ..? Please help

[symatic]

Not long ago I read the biography of Cecil Watts, the Brit who was deep into developing recording lathes and lacquer blanks between the wars. An entertaining read that, to me, somewhat demystified the making of a lacquer blank, although wide-groove 78s were more forgiving of imperfections than microgroove recordings. Cecil used a commonly-available lacquer (paint, I guess) and added some ingredients of his own. Every now and then, in the course of doing chores around the house, I come across paints and varnishes that suggest themselves to our line of work. My only warning to someone experimenting in this area is to remember how volatile most of these things are, and from vapor-high/health and explosion/fire standpoints, one would want to be very careful.

have you got a link for the biography you read? with the transco thing people may need to get inventive.... any hot tips on what paints to be looking at?

amazing project by the way! real gem of a thread here