I know this topic has been talked to death on this forum but I still have a couple of questions left . The first question is sort of a revisit since it was posted here before. I may have the opportunity to explore the option to manufacture new center gears. I was wondering if all DD Walkmans use the same size center gear (silly question I know). Also does anyone have any spare (broken or new) center gears that they would loan or sell them to me for this purpose? I know center gears are like gold coins and everyone wants to hold on to them but is anyone willing to sacrifice one for this purpose? Any feedback or suggestions would be appreciated from the pros and the non pros.

This is an interesting proposition.

I believe nearly all use the same gear, with the DD30's being the most recent and supposedly, reliable.

The market is sort of "there" for a remanufactured gear, especially if it has been slightly redesigned to allow for more shrinkage tolerance. Should sell well on ebay.

However, I believe that the center metal ring is actually molded inside the gear, meaning that it may be incredibly expensive to manufacture in small quantities at such high precision unless a different design for insertion of the metal ring is proposed.

Thankfully the gear is not used to drive the capstan so I believe it is ok if a slightly different design is used, as long as the precision is maintained.

I was reading a story about 3D printing a couple of weeks ago and thought about this very predicament.

Within that same article I came across this company that can print you any 3D object in various materials - nylon, stainless steel, etc... So you just need a repaired or intact centre gear to use as the original and they'll "print" you out a copy or two.

I wonder if the print resolution for the plastic is high enough for such precision, though.

*Dreams of a owning one to make spare parts/design own walkman mechanism

Looking at the repair post by member stumm7

it appears that the plastic part can be taken off of the metal ring easily but that may be because it's cracked. What if it was manufactured with the "crack" or slit so that it was easy to assemble it back on to the wheel? Here's the post I am referring to:

My WM-DD Center Wheel Repair

LINK ERROR.4#193392314111966814

My idea:

You need a gear intact.

You cut it below all around .

So that you can lift plastic-gear-ring ,away from metal disc. Now,this plastic part you need for 3D print .

The copy-part from 3D printing you can easily put on metal disc with adhesive.

Might good be.

@renzgi

Yes, I would think it is only necessary for the plastic part to be copied and replicated Once you have the data for the 3D scanned image it should be possible to produce may new gears. The website above claims to be able to produce "prints" using ABS quite accurately.

Alternatively if there is someone who knows how to use AutoCAD or 3D Max they could create a digital model of a new centre gear.

I was thinking about the 3D printing technology recently.  Just imagine, a few years from now people will be trading data files to print spare gears, knobs and battery covers from their home PCs.  One consideration is the actual material that's being "printed".  Is it a durable plastic that could hold up in a cassette mechanism?

I used to receive email from some eager people in China who would fabricate LCDs and plastic parts.  I'm sure there's someone out there who could do this if they have an original part.

There's a person on eBay who sells replica battery covers.  I wonder how he does it?

http://cgi.ebay.com/250694576196

I was thinking about taking a sample to a more traditional small scale manufacturer to where I will be traveling soon. However, this 3D printing technology is a great idea. The only question is how accurate it is in replicating small parts like this one.

I still need to find a part that I could use for this purpose. I have acquired a few DD Walkmans recently but I have never worked on one. I am not sure how hard it is to get that piece out of there.

The other question is what type of material should it be. Can it be made of metal?

From their website, this is the full list of materials you can "print" to :

1 Polyamide - A strong and flexible material with a high level of detail.
2 Alumide - A Polyamide-like material with a distinctive look.
3 Multicolor - Read more » A full color material.
4 High detail resin - Lovely fine details on this photopolymer.
5 Paintable resin - Will look beautiful painted. If it has to be flawless.
6 Transparent resin - See through.
7 ABS - A strong & tough material with the highest level of dimensional accuracy.
8 Titanium - Light and the strongest 3D printing material in the world.
9 Stainless steel - Not your grandmother’s Stainless steel.

What's the URL for this site?

sorry, it was mentioned in my post above, but I guess it needs to be in bold for others to notice the hyperlink.

http://i.materialise.com

I can't find a phone number on the site. I sent them an email asking if they would make a replica of a small electronics part. It seems like the smallest they can handle is 0.1 to 0.2 mm which I am assuming should be good enough for the DD gear. 

Found this in the terms and conditions.

Materialise NV
Technologielaan 15
3001 Leuven
Belgium
Phone: +32 16 39 66 11         
Fax: +32 16 39 66 00

Hello!

No, a metal gear is out of the questions. The difference in static and dynamic friction coefficients between a metal (aluminium or steel) and plastic mold gear would be too great causing damage the the plastic gear on the motor. We have a 3D scanner/printer in the firm but the costs are pretty high and this machine was designed for a different purpose altogether.

What we need is a plastic material with adequate elastic properties. Teflon is the material of choice in my opinion. It is extremely light, temperature induced deformation is always elastic (within specified tolerances that is) and it has one important feature. The bigger the force on the material, the friction coefficient is actually lower. Low mass means less centrifugal force and thus less axial inertial force that would counter the motor.

Teflon is elastic yes but not highly so like poly-ethylene for instance and that is why the best thing would be to have a composite material with internal PE mold and teflon coating. However, manufacturing would be demanding and I think costly so we could do with teflon only. As for CAD design, I can do it. But the dimensions would have to be precise to +/- 0.05mm tolerance I would estimate if we want the gear to last and not cause damage to other gears at the same time. The procedure by which the gear would be installed to the metal disc is another thing. I would not recommend using adhesives like Renato suggested because there's a chance tit wouldn't be applied properly and the gear could go off axis. Also, adhesive would mean introducing another material into our teflon part and adhesives rarely have dependable specifications and they change over time. So I think applying another part of teflon rim on the other side would have to be done by temperature making the entire gear around the metal disc one uniform material. It would guarantee longer service life. Just my opinion.

This sounds more complicated than I thought it would be. Tuna if you provide the design would it be easier to take the design to a manufacturer as opposed to the actual gear? Or were you just referring to the 3D printing?

Hi! Well, it would depend on the manufacturer. Some small workshops like hands-on approach and others use CAD as much as possible. What in my opinion would be the best idea is to scan a perfect example of the gear with a 3D scanner, export the file as a vector drawing (dxf or other format type) rather than a image drawing and then transfer the file to standard CAD file (dwg). Then we could find a 3D printshop that could manufacture it with our choice of material. Or we could scan it to best of our ability and do the necessary schematics in CAD and print them out for the workshop. It can all be done but the question remains who would do it and for how much.

Mold industry has advanced considerable in the last 2 decades and now they can manufacture plastic composite materials with properties to suit every field of use and environment.

If you guys get this figured out I'll need one or two of these center wheels. Or I am out there looking for spares too! You can email me ! Thanks

I took my DD apart and was able to extract the gear out. I think I might have wrecked my player in the process but I needed this part to get something started. It's a pretty amazing gear with a lot of detail. I tried to understand how other part come in contact and work with the gear. I noticed one of the smaller magnetic pieces attached on top (or bottom) of the main gear piece magnetically. That may explain why the center part of the gear is made of metal. I took a few pictures.

I found a small scale manufacturer who is willing to make these in small quantities. However, they would only make them out of steel. So my question for the pros is this:

If it matches the specs exactly would it work? Would there be any anticipated issues?

Hi Folks

Should we start a request on Facebook and see if we can get some social networking site to help us convince SONY we need these replacement parts?

Just a thought and we pay fair money for the defective part clearly but we need their engineering help here?? There are hundreds of thousands of these Walkmans that need this fix

What do you think?

JM

I think making the whole thing out of steel would work for an occasional-use machine, but would eventually take its toll on the three other gears that this large ring drives or is driven by. I wonder if copper might be better.

I have sacrificed the part from a DDII to get my D3 going again- it's a train-wreck in there but the machine works, clicking slightly but with no wow. I'd post pictures but I've nothing new to offer- cutting a tiny piece from the donor gear & gluing it into the gap.

other posters have done this, & for their pictures, many thanks.

actually, while the circuit board was still folded back in the D3, the test cassette ran out & the auto-stop kicked in. this opened up my repair, demonstrating very well that the stresses on the part are great when the cassette reaches its end. this, coupled with the shrinkage of the part, is the origin of the problem.

there may also be, as others have speculated, a weakness along the radius of the part where it's been invisibly welded shut during the assembly.

the central gear design overall is very clever; the use of a magnetic slip-clutch like this would've improved a great many high-end cassette transports. it's just a shame that the mixture of materials shortens the life of the part.

I am a broadcast engineer of some 27 years experience, much of it on sony VTRs, & I've seen this sort of problem with mixed materials before- brass, aluminium & steel used together in an assembly, that sort of thing.

anyway.... if I'd been designing this, I think I would have created a disc-gear to fit onto the steel centre from the upper (PCB) side, with enough room for the rest of the magnetic clutch to fit as normal.

the disc would have to be recessed to bring its outer (toothed) edge level with the steel inner, so that the operation of the three gears around it is correct. sort of like a soup-bowl with a hole in its centre, & teeth around the rim.

as regards the inner diameter of the part, I think the material could be slightly thicker than the original, & extend beneath the magnetic clutch, perhaps even using the small holes in the steel disc as locators for some sort of securing pegs. I'm pretty sure the magnetic clutch system is strong enough to still work with 0.5mm of plastic or copper in the way, & there's enough vertical play in the mechanism for the slight separation of the two magnetically-coupled gears to both still work.

so... I'm determined to come up with a permanent fix, based on this thinking. I've also noticed that the broken gear is the same diameter as the middle part of a regular CD, so (rather ironically) I might have a go at fabricating a part out of a CD-R before trying to get one pressed/cut in thin copper.

for now, though, I will repair my DD33 next, still using donor parts from the poor DDII.

duncan (around 40 walkmans here- sony, aiwa, panasonic, fisher, & a load of 1/4" machines- revoxes, uhers.... & a revox 710mk2 cassette deck)

Using a CD center to fabricate a part is an excellent idea. Great thinking there. My questions: Is the CD material strong enough to withstand the stress involved? How would you go about attaching it to the metal? How would you cut teeth into the CD center (after you have successfully cut out a circular disc)? I am assuming you would need few more tools than a file . Please keep us posted if you go through with this plan.

still looking into fabricating the part the hard way, i.e old-school watch/clock-making, start with a disc & cut the teeth myself.... I do a lot of work on seikos, but I've never cut a gear before.... :-)  to be honest, I think the CD-inner may be a frustrating material to work with... I have been looking instead at copper washers from plumbing suppliers...

BUT

while browsing the interweb today for candidate materials, I found these on ebay:

http://www.ebay.co.uk/itm/Stea...;hash=item20bd5478df

they're a tiny bit too small- 35mm instead of 37mm, but it might be persuaded to work. there are fewer teeth too. so I'll try this out in my donor DDII first.... :-)

it might be possible, if this is too small, to fit it with a thin tyre.... that would solve both problems at once. we will see.

I have also approached a company about manufacturing a toothed copper disc to the exact specification (37mm OD, 24mm ID, 1-2mm thick & with 120 teeth); if they're up for it, I'll order ten or so. the plan is to solder this onto the steel disc in exactly the same place as the current nylon part.

more soon.

The tire sounds like another brilliant idea. I think it would be worth trying.

Let me know how the manufacturing of the disc works out. I can give you the contact information of the company I had contacted months ago down in Florida. They were ready to make the whole gear out of steel but you are just getting a disc made. That will be a much cheaper approach. 

Waiting to hear the results.

You can fix those crack center gear with high strength epoxy, you have to crack the other side so you have two equal haft, the you have to space both crack spot equal to one teeth size and add epoxy to the spaces, then wait a day or two, and sand down the excessive, then use a file and down a groove to look like the other teeths on the gear, Sure fit and contact the other gear perfect, done this to two WM-D3 and no more clicking or wow. The trick is getting the spacing right!!

I will post a video, when I work on another WM-D3, unfortunately it not just Sony DD walkmans that have that problem, some boomboxes and JVC walkmans, are known for this problem. It cause by plastic shrinkage, due to the lubricant and temperature, so gear ends up cracking. Even one with good gear now will end up failing.   

I've found a company in the UK who have many many gears as standard on their website, so I've written to them about producing a special item in copper.

this will be rigid enough, & easy to solder to the steel disc, & won't interfere with the magnetic clutch. I hope also that it won't chew up the other plastic parts & that it will last longer than a plastic piece.

actually the gearwheel itself is (as one might expect) a standard form.

it's called M-0.3-120, which means that with a tooth size of 0.3, 120 teeth (yes, I did count them!) gives a diameter of 37mm.

a gear manufacturer would be able to build this- the UK company has them in stock, even- but the problems are the inner diameter (to work with the rest of the assembly) & the thickness.

if they can't cut a hole big enough in the middle, then the new gear would have to be fitted on the underside of the steel disc instead, & this means a lot more dissassembly of the machines. I'm trying to avoid this as the brass clip that holds the centre gear onto the arm will be damaged & compromised by being removed, & in any case the whole job will be much quicker if it can be done from the top.

anyway, I'll let you know what I hear back from them with regards cost, lead time & so forth. then, if I go ahead & it works, we have our fix. :-)

d.

the quote's in; to make exactly what I want, which is a copper gear of 1mm thickness, the right diameter, the right number of teeth & so that it will fit over the top of the steel disc from above & leave room for the magnetic clutch..... £47 ex VAT. each.

(I think that's about $85)

well. I think it's worth it, if it makes my D3, DDII & DD33 work perfectly again. I'm going to order one initially (see if it works in the DDII) & then potentially more.... once it's fitted in the DDII, I will upload a youtubeo so you can all see it & decide if you want the same fix.

I'm happy for you to deal with the company yourselves or have me do the repair for a small fee, but let's not get ahead of ourselves.

in about a month or so, we'll know if this is a goer.

d.

Hi

If its $80 its a bit steep but I am up for it. Maybe the smart thing is to find one gear wheel in good shape and get some Chinese outfit to supply us all. I am learning the Mandolin and I have been forced to use a really nasty quality tape recorder. I bought this tape records WM-D3 for the high quality tape recording yet now its a pain because I can't use it. Its a shame we can't start a Facebook page on this.. We could easily get more traction and maybe force Sony to start making high quality/high fidelity Walkmans again.

If you can get a perfect copy / reworked gear wheel i am in.. 

oh, I absolutely agree that $80 per is a bit steep- it's a lump more than I thought it would be, given that the off-the-shelf gear is about $18.... but this one is especially thin & has this large aperture in the centre, making it difficult for them to machine. I'm told.

on the other hand, if it works.... your unuseable machine becomes useable for a lot less than the price of a new one. for me, the important one to restore is the D3.

I'm a fan especially of recording machines, & most of my 40 walkthings are recorders, from the aiwa HS-F1 (I have a mint one, never used), sony 370 & 430, through the mighty D6C to the GX670 20th anniversary special, alongside panasonics, fishers....

I ought to put some pictures up, I suppose...

anyway... I plan to fix the DDII, & take lots of pictures & a video. I'll then run the thing while I commute (= 2-3 hours/day) for a month, & then re-examine it for signs of deterioration at the plastic parts. an important part of this test is to let the cassettes run out whilst in play & fast-wind modes, as this places extra stress on the main gears.

after this, we'll know. fingers crossed!

d.

The company I had contacted in Florida were willing to make replicas of the whole gear out of steel. With an order of 10, cost per gear was around $30 I believe. It was just a rough estimate they gave from the pictures. I was planning to mail them the gear to inspect it but changed my mind. The reason I bring that up is that if you can send me the measurements and the material specs, I can find out how much they would charge for one or 10...after you have tested the fix and the plan succeeds (fingers crossed). It will probably be cheaper than $30.

that's a very good price- & this was for the whole thing?

it wasn't just the cost that put me off from getting the whole thing built, but the difficulty of replicating the fit & feel of the whole thing; I have mentioned that japanese mechanisms mix materials, often with little regard for the properties of those materials over time, but they do somehow make the work. I'd be worried, in this case, about upsetting the balance of the magnetic clutch by changing the type or amount of steel in the finished thing.

but so anyway, if they could make the gear part on its own.... do you think they'd be able to do it in copper?

the details- 120 teeth at M0.3 pitch (gives overall diameter of roughly 37mm), with no hub & a "bore" of 24mm. it should be no more than 1mm thick.

I chose copper because it's stiff & won't shear as easily as plastic, it can be soldered to the steel inner, & it won't upset the rest of the mechanism.

see what they say.

d.

PS if they want a drawing or picture, I can do something...

I have sent them the specs. I am waiting to hear back.

brass will be fine too. I just thought copper would be a bit easier to machine, & slightly easier to solder in place.

as it turns out, I had to order five of the things to get the price, so I will have enough to fix my dd33, d3 & this dd10II, + whatever else comes along. I will watch the 'bay for suitable patients. you've got a good deal there... I'm guessing that before too long (& after we've both posted success stories, obvsly) other list members will be volunteering their machines for surgery, whether or not they've managed to glue the old gears shut.

are you going to go for it then?

d.

Hi! May be my DD gear repair tip will be useful to others. I think the main problem with this part is a huge residual tension after nylon part was hot-pressed around steel base - it's impossible to remove gap between crack sides when trying to repair gear with the clue. But you can make it much more simplier by precisely grind off a thin portion of steel from the outer base diameter, so original nylon gear can be glued back without problems. I successfully bring back to life two WM-DD33 using this method.

I have never actually attempted to fix the gear. I get the basic idea and it sounds simple but it would be great if you could provide some pictures of the repair that show how you fitted the new gear and where you soldered it. This sounds very exciting and I am waiting to hear the results of your repairs after your testing. It seems like there's finally a good solution to this problem.

Your idea sounds good too. Thanks for sharing. I have a few questions.

1) Did grinding a portion of the steel part have any affect on the playback speed?

2) What type of glue did you use?

3) How long have you had this repair and used the Walkman?

No, speed is not affected (device uses capstan tacho and quartz phase lock servo so average motor speed is rock stable), but vertical and radial symmetry of this gear must be good enough for correct transport function, especially in fast forward/rewind modes. Big assymmetry can also cause additional wow and flutter and weird transport noise.

I use 3M automotive superglue and а tiny n-shaped copper wire for additional nylon bonding.

I don't use these devices on a regular basis, but can say that after ~100 played hours gear is still working.

P.S.: consumer DD series transport is a strange combination of the perfect capstan servo part and the messy gear part (unlike professional grade devices, e.g. WM-D6C was built far-far better), it is really a pity.

Did the gear repair die the death? With 3 D Printing now this should easily be tackled? I've a machinist that may help us but we 'd need a decent copy to start with? Any one interested?

It's a really complicated gear to fabricate without the proper moldings and presses. I tried to make a repro with help of a laser cutter, but ended up with a way to complicated construction that needed a lot of extra handcraft to put together and figured out it was easier to repair a broken gear.

Don't think 3D printers are capable to make one at the moment too. Looks like it isn't a populair subject anyway, havent heard about it for months.