Project "Groove Scribe"- A DYI stereo 45/45 head.

[Bahndahn]

Pole-facing-pole magnet & steel sandwich also looks good!

PoleToPole.png

[EpicenterBryan]

Pole-facing-pole magnet & steel sandwich also looks good!

Try swapping polarity on both those magnets. As it is now, see the coupling in the center to the driver section?

Bryan

[Bahndahn]

Pole-facing-pole magnet & steel sandwich also looks good!

Try swapping polarity on both those magnets. As it is now, see the coupling in the center to the driver section?

Bryan

I eventually figured that out

[opcode66]

Let me ask. Does a stereo cutterhead have one channel? One set of drive magnetics? One setnof feedback magnetics? Nope.

Why are you all only simulating one set of magnetics? Seems to me that at the very least, due to the relatively short distance between the feedback magnetics in nearly every design, one should account for those influences from the other feedback magnets in these simulation. That is only, I suppose, if you want to actually model reality, instead of dealing in completely hypothetical scenarios. My 2 pennies.

[Bahndahn]

Let me ask. Does a stereo cutterhead have one channel? One set of drive magnetics? One setnof feedback magnetics? Nope.

Why are you all only simulating one set of magnetics? Seems to me that at the very least, due to the relatively short distance between the feedback magnetics in nearly every design, one should account for those influences from the other feedback magnets in these simulation. That is only, I suppose, if you want to actually model reality, instead of dealing in completely hypothetical scenarios. My 2 pennies.

Easily done, and not necessary. Particularly in the sandwich case, the nestling of the coil inside the inner diameter of the magnet is plenty of 'shielding'. Regardless, the fields are fixed! It's not like the nearby system is a drive system where fluctuations may affect the measurement.. Relative measurements will not be affected.

[opcode66]

Another large permanent magnet at a 90 drgree angle that close to your other magnets has an effect. I am strictly talking about the two permanent magnets for feedback in each channel. The other magnet skews these pretty little pictures you are making. It does. Ask the software.

[Bahndahn]

Another large permanent magnet at a 90 drgree angle that close to your other magnets has an effect.

Certainly, an interaction/influence is present; this influence is static therefore the coils of the feedback will not be unpredictably inflicted– this is if that flux was actually effecting the coil location: inside the inner diameter of the magnet, which it is not in this current design proposition.

The other magnet skews these pretty little pictures you are making.

There is no apparent skew in the center of the magnet, however on the outer flux paths [ones of no interest to us, for this proposed design] no harm is done.

Ask the software.

Here is what the software responds, annotated with a pretty little legend!

Dual Transducer Emulation.png

In this rendering, we are seeing a cross-section of the radius of each transducer. Note the location of the coil via the legend and observe the nestled safety of the unaffected flux. If I were a coil, thats where I'd hide from angry flux monsters who are out to get me!

[Bahndahn]

Oops one polarity arrow is incorrect on the drive left drive transducer.

[opcode66]

Your magnets must be spaced 2 to 3 times further than mine.

[Snug Music]

Hi there...

We wish all Lathe-Trolls ( specialy: flo, opcode todd, epic bryan, ciuens, fela borbone, bandam ect. )
a very, very best christmas time with your family and a best happy new year 2016.

Best wishes to all trolls...stay tuned.
Snug Music
(Scotty)

[Bahndahn]

<3

[EpicenterBryan]

My last big family event for this winter is Sunday, so I hope to dive back into this project next week. I'll do an update on a new material I'm using for the diaphragms (springs) and some other changes for the next Groove Scribe version.

One of the changes is that I will be using either magnesium or aluminum for sections of the push rod - at least up to where the feedback coils are wound. Then they will be drilled to accept the final more flexible segments that will connect to the torque tube.

Without having a lathe, I came up with a rather simple scheme to drill a 1mm hole in the center of a 3mm rod using my mill (as a glorified drill press). The length of the rod is still to be determined, but I wanted to come up with the method first. The final hole size of 1mm is not cast in stone. I have several options that I'm thinking about.

IMG_4115[1].JPG

What I did was to first take a piece of about 1/8" aluminum and put it in the vice. Then drill and tap a 5mm hole. Then I cut the head off a 5mm cap screw so there was a non threaded section that extended to the upside of the block, and put a 5mm nylock on the bottom to keep the non threaded section from moving. I borrowed the 5mm to mini chuck adapter and key chuck from my wire wrapping machine (shown on the bottom).

Then I chucked the rod into the mill chuck on one end, and the mini chuck suspended on the bottom and lowered the mill chuck until the aluminum block was inside the vise, and adjusted Y on the mill until the block just touched the vise and closed the vise. Then I opened the upper check and retracted the Z stage and installed the drill bit and drilled the hole.

The result? I got a nicely centered and straight hole the full depth of the drill bit!

IMG_4117[1].JPG

Some time ago I showed a coil winder I put together. Now that I plan to wind the coil directly to a section of the push rod, I'm interested in ways to do that which are stable without bobbin ends.
There is an interesting video here on YouTube:

But I wonder if it may be as simple as telling my coil software that the coil wire width is 1.25 times as wide as it actually is, and adjusting the Gcode at each end by 0.25 x the diameter of the wire so the next layer lines up in the center of the previous coil winds like in the shot below:

20_wijdeven_spoelen_07.jpg

Damn, that's a nicely packed coil. And a honeycomb like structure like this must be more stable than what I have tried before and shouldn't need bobbin ends.

Comments?

Bryan

[juba bc]

maybe if you can machine a stand with the exact measurements , I think it would be easier

[EpicenterBryan]

maybe if you can machine a stand with the exact measurements...

That's a good idea. I guess I could always use removable bobbin ends like I have been doing but put some release agent on them and apply more glue as I wind the coils and let it all set up and harden before I remove the bobbin ends. One issue I have run into is having the ends of the coils stick to the bobbin spacers and peel off some coils when trying to take it off the machine. Either it does that, or if the glue hasn't hardened enough, the coils want to fall off the wind on their own.

I would like to get my head around that video though. Why do the coils stay in place when there are no bobbin supports on the ends? How many coil winding would really be needed to use that scheme? As you see in the video though, there are several bumps that develop over that distance that make it necessary to also change the distance from the source wire to the wind coil. It looks goofy, but it's dense.

Hummmmm let me think about this.

Anyone else have inputs?

Bryan

[opcode66]

If you study the coils in an RCA head you will get insight on how to roll a coil on a bobbin with removable sides. The trick is to use thread to suture the coil after rolling/gluing. Then the sides can be removed and the coil can be baked. That's how a lot of old coils were made. There is a guy on ebay that sells a bunch of cd's on transformers and coil winding. All the answers are in there.... All you have to do is a little research and pay $19.95 Cheers!

Here is an original RCA coil epoxied to a mounting board.

0411-30.jpg

This is one of my early clones. My final ones are better looking.

IMG_4783.JPG

[Bahndahn]

Hey!

I think the winding machine 1.25 overlap gcode method sounds great!

Maybe you could get some PVA filament, wind the coil, dissolve the bobbin in water!!!

[Mulchefye]

wow u live in Montreal? im like 45 minutes away from you! i have 2 Mongomery Ward airline lathes with burnt heads, been looking for someone who knows about coil winding, which u clearly do...is it possible we could hook up at some point and i could show you the heads, see if u can help me get them up and running? my alternative is to send them to Westrex but thats a last resort.

[Bahndahn]

wow u live in Montreal? im like 45 minutes away from you! i have 2 Mongomery Ward airline lathes with burnt heads, been looking for someone who knows about coil winding, which u clearly do...is it possible we could hook up at some point and i could show you the heads, see if u can help me get them up and running? my alternative is to send them to Westrex but thats a last resort.

Hey Mulchefye, I do live in Montreal, and I'd be happy to help you with your cutterheads. I will send you a PM with my info regarding how to get in touch with me, we can go from there.

Looking forward to helping!

[EpicenterBryan]

Hey guys,
Like usual everyone has had great inputs on the whole coil winding issue among other topics! I'll run with some of those ideas this week as I start to pull the final version together.

As I get going on the project again I've decided to "backfill" some info.
The first topic is one I know some people are curious about and I've already shared this with our energetic Canadian Brother some time ago. But for the rest of the people - here goes:

The question came up about how I cut the carbon fiber discs. It's simpler than you think.
What I did was take a standard hole saw kit and removed the center drill bit. I found some aluminum rod that was the same diameter so I could still chuck the hole saw into my mill (big drill press). First, I took the raw 1mm thick sheet of carbon fiber and taped it down to a piece of wood that was held in the vice. Then I used a 3mm drill to make a hole. Then I removed the drill and inserted the hole saw and cut the final circle.

IMG_4012.JPG

The result is a bit rough but can be cleaned up rather easily with a little hand sanding like this:

IMG_4114.JPG

I used the same hole saw idea to make the "Ciuens copper shields" for the drivers. I'm not really sure if these are needed but were easy to make. More on that later...

IMG_4276.JPG

As you know, I've been messing with the Taulman Nylon Bridge material for some time for the diaphragm replacements on these drivers. What you don't know is that I have probably spent 2 months trying everything in the book to get this stuff to print correctly and consistently. Everything from different nozzle sizes, extrude temperatures, print speeds, you name it. Oh yes, I also set up a custom dryer to bake the stuff for several days ahead of time and stored it in a special moisture absorbing container between prints.

The stuff spits steam randomly which then creates a void in the melt chamber of your print head and can't extrude until it fills back up. The result is random voids in your prints.

I also tried every infill method including: Line , Rectilinear, Concentric, Honeycomb, Hilbert Curve, Archimedean Chords and Octagram Spiral. In various infill percentages. Like this chart:

infills.png

CONTINUED ON NEXT POST

[EpicenterBryan]

Most of the tests were tossed.
But the "honeycomb" infills were the most interesting so I actually saved samples. Once I decided to eliminate top and bottom 100% infill and dove into specifics on what seamed to be working the best, I tried several infill percentages as well. Again, I had to make several of each to get two that were the same.

IMG_4277.JPG

Here is a shot at how random the print results were for ONE infill setting:
So which two prints using the same material, and the exact same print file is actually correct?

IMG_4278.JPG

I hate this material. It is not repeatable. I sure hope no on ever buys this crap....

So I started the quest to find a totally different material that is flexible but eliminates some of the crap this Nylon Bridge material exhibits like spitting steam and causing voids in a print.
For the solution, you will need to check back for the next update. Don't you just Hate cliff hangers?

Bryan