Introduction: CD Polisher

By
About: I ain't no physicist, but I knows what matters.
You must remember this
A nick is just a nick, a scratch is just a scratch
The fundamental things apply
As CD's die
(forgive me Warner Bros)

So you went to the local library & got a DVD movie to watch with your honey. Guess what? It won't play!
That little tramp who returned it yesterday carried it in her purse for three days with no jewel case!

Run it through this CD Polisher for five minutes & it will play like new.

I store my data archives on DVD-RW. If one bit is misread, the whole file is trash. A data disk must be exactly written & verified.

This machine can be used to repair disks that have become unreadable. There is a very good chance that the files can be recovered.

When putting together the parts for this project, use my mantra 'Goodwill, Goodwill'. If you shop well (or have a big stash of parts) the machine will cost under twenty dollars to build.

Before we start, let me apologize for my lack of describing how to accomplish each and every step. I am assuming that a project meister who chooses to build this machine can infer much info from the pictures.

It's my dad's fault. He taught me by doing, not by lecturing.

So, in memory of my father, I will not give a list of tools, materials, or skills needed to complete this project.

Thanks dad

Well, if you see that the machine actually runs, you might get to step 3. Or 4. 5 is a good one, too.

Here's a video of the thing in action:
http://www.youtube.com/watch?v=kpkhOUs6nFg&feature=plcp

Step 1: The Bearings

Find a  pair of junk rollerblades at Goodwill. For two bucks you will get sixteen bearings, axles, bushings.

At the home center I found 3/4in CPVC (not PVC) fittings. The bearings are a perfect slip fit. The tube stub is cut off & cemented to lock the bearing in the housing.

1/4-20 hardware is used to create the axle. The bushing flange is cut off (shorter than the bearing width) to center the axle.

We need two of these.

Step 2: Turntable

Thrift stores are my first stop when I need material. Floppy disk storage box. Fifty cents. Great source of plastic sheet.
By the way...what's a floppy disk?

While you're there browse the wood things section and get pieces for the rest. Look for shelves, curio cabinets, hat racks.

The center nubbin is a piece of 9/16in OD nylon tubing. Press fit into the platter.

The pad is cut from a rubberized place mat.

Attach the platter to the bearing assembly with #4 wood screws.

Step 3: Alignment

This shows the position of the pad upon the disk.

The buffing pad front edge must cross the disk as close to perpendicular as possible.

Keep this in mind while positioning the disk platter and the buff motor assembly.

Note from author: 20 years ago I fixed a Jimmy Buffet CD that skipped. Instructions at the time said use toothpaste, a damp cloth, and scrub across the disk perpendicular to the tracks. The method has not changed. Any polish lines that are not perpendicular to the track will scatter the light and make the track unreadable. Or I may be full of shit. Further research required.

Step 4: Base

The platter motor is a 5 rpm microwave oven turntable drive. I found a junk oven in my alley.
A short length of tubing on the shaft gives good traction.

(Note from author: If you haven't figured yet, I've got a sh*t-load of parts I've collected just waiting for worthy projects.)

The drive belt is from an upright vacuum cleaner. Use a sharp utility knife to split it into two belts. This is (was) a Hoover 'Y' belt.
Maybe you can buy a 2-pack for your home vacuum, then sacrifice one for the cause.

Mounting locations depend on the belt length and the buffer motor configuration. Make some sketches and figure out approximate positions.

Ponder this step until the buff motor assembly is finished.



Step 5: Buff Wheel

The plastic backing pad is thin (.050in) flexible plastic cut from a Sterilite storage container lid. Diameter is 3 inches. The center hole allows access to screw head for height adjustment.

I drew six quadrants on the buff pad to use as a guide.

The buff material is 1/2in wide felt weatherstrip with adhesive backing.

Use six separate pieces to keep the pad flexible. Cut to fit, peel backing to attach, then trim with scissors. 

Step 6: Buff Motor

My motor is from a B&D 12v cordless drill. Goodwill. 2 bucks.

I extended the shaft with a length of brass tubing, staked it, then added a piece of plastic tubing to help grip the belt.

Google your motor part number. My 12v motor is rated for 24v. I run it at 18v with PWM speed control. More power. Higher rpm. Yessss.

Mount the drive belt without stretching, but with solid contact.

Step 7: Buff Motor Assembly

1/8in brass pins mount the buff motor assembly to the base so that it swings freely. Gravity creates the working pressure.

If the drive motor can handle it, add weights for more pressure.

I needed to add a cage to keep the belt centered on the motor shaft. It is made from 1/16in brass rod and pressed into drilled holes.


Step 8: Setup

The pad position?
Passed: Well within Specs.

The back view shows the angle of attack between the pad and the disk. The front of the pad is doing the work. The back of the pad makes no contact.

Move the platter up or down to adjust the angle.

Step 9: Controller (waaaay Optional)

I built this with a PWM speed controller based on the LM324, and a relay to supply AC to the platter motor.

Power comes from a separate 18vdc 5 amp power supply.

You see in the video that the buff motor I use goes damn fast (my guess >12,000 rpm). Better to start at slower speed or else the whole area gets a shower. If you start at full speed, build a shower curtain.

These little motors suck 3+ amps, more at stall. Choose a power source that can handle the current.

Pardon my lacing tape, I've worked in aerospace and can't help myself.

Step 10: Let's Run It

Use plastic polish for polycarbonate (auto headlight lenses). Expensive but it works great.

NFG is techspeak for 'could not find disk'.

Saturate the felt with water, then rub in a small amount of polish.

Run for five or ten (or twenty) minutes. Add polish to the buff pad every few minutes. Keep the disk surface oily.

Result from this run: Couldn't save this one as a data disk. Status went from unreadable to recordable, with errors. Still good for movies or music. (Do not buy cheap disks for archives.)

Note to builder: No operating instructions are available. This is your new toy. Tweak the shaft positions & angles & weights & fluids until you get the results you want. Mine works great, but took a little fine tuning.

And don't tell the librarian you fixed her DVD. She would not understand.

Thanks for looking at my baby
wotboa