DIY Disc Changer

[MattRX]

Hi All

I ripped my CD collection to MP3 files a little over 20 years ago.

Back then storage was expensive and processors were slow. Like everybody else I used 128k encoding with ID3 (no v anything) tags. Tagging metadata has improved out of site in more recent times and I have manually updated the tags with more data (like track number) when that became possible.

Time has moved on and I feel its time to rip my collection again this time using FLAC.

Last time I ripped my collection I moved my PC into the lounge and loaded CD's as I watched TV in the evening and typed in metadata over lunch. Now days I have kids and leaving piles of CD's around the house will end in disaster.

So what to do? I have limited available funds so purchasing a CD autochanger for a one off use is out of the question and I'm lazy so loading a few hundred CD's again just isn't going to happen.

Last time I used EAC to perform the ripping and as it worked quite well so I didn't see any reason to change. EAC has an auto mode where on insertion it will load the CD, collect metadata, rip, encode and eject on completion. I figured building a robot arm and triggering it on CD eject would not be that difficult.

Enter Rip-O Mk1

https://youtu.be/WEzof_5XjsA

Rip-O Mk1 worked quite well. It uses radio control servos to move the arm and vacuum to grab the disc. Servos are reasonably accurate but when driving a 200mm long arm not accurate enough. The arm would get the CD into the drawer 95% of the time, but sometimes it would miss and the drawer would try to close on a disc not quite seated properly. EAC also has an issue in auto mode where unless the disc has been previously inserted the metadata is downloaded after extraction has commenced and everything is saved as unknown artist/unknown...

After finding DBPoweramp I decided to design a new autochanger and have it mimic a commercial product.

This changer will again use vacuum to grab the disc. It has in input stack, an accept stack and a reject stack and accepts the same serial commands as the MF Ripstation.

I have pretty much finished the design and have manufactured most of the parts. With luck I will get it assembled and the controller programmed over the coming weeks and have it busy ripping early next year.

Matt

[linkman]

Re: DIY Disc Changer

Nice work. You mention that you are lazy but I need to counter that argument with the fact that you probably put in quite a bit of work to create and get that robot arm working. How much money and time did you think you put into it/them?

[MattRX]

Re: DIY Disc Changer

Hi Linkman

Sorry for the tardy reply. As I said Lazy!

I'm not sure what the parts cost would be. I get all the plastics from work, all I have to buy is the electronics and most of that I had lying around. I would guess without the plastics it would be well less than $100.

I managed to get it all assembled, but the dodgy vertical slide I made either has to be too tight for the motor or very sloppy. I have shared a couple of photos here (hopefully).

https://photos.app.goo.gl/tzeyKcW6cwZA76K03

I have ordered some linear bearings and will mill it up soon-ish.

Stay tuned for the next exciting adventure.

Matt

[MattRX]

Re: DIY Disc Changer

Well its been quite a while, in fact its late next year.

Not long after I started this thread I managed to injure my back and sitting down in front of a computer suddenly became very low on my priority list.

So how far have I progressed... Not very. I tried using an oval shaped curtain rod for my linear stage and to get it tight enough to not be sloppy it was so tight my little stepper driving it could not cope.

I since built a real linear stage using 10mm ground rod with bearing rollers and my vertical stage now works a treat.


I'm using 28BYJ-48 steppers like this one https://www.ebay.com.au/itm/2pcs-28B...C~B:rk:12:pf:0

These motors have in internal reduction gearbox, unfortunately you don't get a lot for a couple of bucks and the gearbox is a bit sloppy. This slop causes the arm that rotates between the cd drive and the spindles to not always be where I want. To solve this I machined a new gear section on the arm that has a few little detents in it that a roller micro switch runs in.

At the moment I am not using the micro switch to detect arm movement, but I might change that as it is there and working so why not?

I have written the software to drive the whole thing using an Arduino microcontroller. At the moment the code is absolutely horrible. I will slowly work on a mostly rewrite and see if I and just reduce it to horrible. I was driving the motor controllers incorrectly and as soon as I fixed that my movements were all wrong. I'm working on fixing that and then I need to get all the exceptions programmed in so that if something does not go quite right it can either recover or stop and wait for help. I'm planning on starting this thing and leaving it to its own devices until the job is done s I need some faith that it will not be destroying all my cd's. Software is not my thing so we will see how I go. It's all a learning experience.


As you can see the wiring is all very messy, but as it has been changed fairly regularly I have not gotten around to neatening it yet. The only real interesting thing here is that I am using a pair of Pololu DRV8255 stepper drivers to drive my motors. The motors I'm using have a common center tap and apparently what I'm doing just isn't possible. Luckily for me it is and by using these driver I can get a lot more speed and power from these little motors. Having said that they are still really slow. In the coming weeks I will hopefully get it all running again and then I can post up a video.

Anyway here it is in all its glory. Stay tuned for the next exciting adventure.

Matt

[linkman]

Re: DIY Disc Changer

At the moment I am not using the micro switch to detect arm movement, but I might change that as it is there and working so why not?

It can be used for error detection I would imagine.

I have written the software to drive the whole thing using an Arduino microcontroller. At the moment the code is absolutely horrible. I will slowly work on a mostly rewrite and see if I and just reduce it to horrible. I was driving the motor controllers incorrectly and as soon as I fixed that my movements were all wrong. I'm working on fixing that and then I need to get all the exceptions programmed in so that if something does not go quite right it can either recover or stop and wait for help. I'm planning on starting this thing and leaving it to its own devices until the job is done s I need some faith that it will not be destroying all my cd's. Software is not my thing so we will see how I go. It's all a learning experience.

Use some old CDs that you really don't care about anymore! Or ones that you have already ripped to high quality. As for the code, you are either going to be really good with hardware, really good with software, or somewhere in between. Almost nobody is great with both.

As you can see the wiring is all very messy, but as it has been changed fairly regularly I have not gotten around to neatening it yet. The only real interesting thing here is that I am using a pair of Pololu DRV8255 stepper drivers to drive my motors. The motors I'm using have a common center tap and apparently what I'm doing just isn't possible. Luckily for me it is and by using these driver I can get a lot more speed and power from these little motors. Having said that they are still really slow. In the coming weeks I will hopefully get it all running again and then I can post up a video.

Anyway here it is in all its glory. Stay tuned for the next exciting adventure.

A bit messy on the wiring, but you aren't producing a production model that is for sale. Messy but functional is the best case. I would definitely like to see some video of it in action once you get finished (or close to it).

[MattRX]

Re: DIY Disc Changer

Hi Guys

Just thought I would re-appear and report on my progress.

Well... there hasn't been any. I have been getting a car ready for a display at a historic racing event and everything else has been put aside.

That's done so hopefully sometime soon I'll get back to wherever I was.

Matt