BD's Mechanical Disk Recorder Build

[Bahndahn]

Today I have started fabrication of my personal mechanical disc recorder. This thread will loosely document the process for the enjoyment of those interested.

Here are some photos from the process so far, more to come as a work on the device this week:

[tragwag]

cool! looks kinda like the Vinyl Recorder.
best of luck!

[ROLANDJAYS]

look like mine

[opcode66]

I only see one motor. Same with the DRC. This is problematic. You want two for pitch with a gear box. One for normal pitch and the other (fast motor) for track spacers, lead in and lead out.

[dubcutter89]

Two motors was the way in the 50-70ies, today there is more options on motors and more important electronics... (vinylium, vms80, capps pitch??)
And then there is still old school hand crank lead in, mark, lead out... for those who like to craft records rather then click mouse buttons...

@RD + BD - great work!

Lukas

[Bahndahn]

@tragwag Definitely inspired by the VR, yet Souri's master design could certainly put mine to shame through the right eyes. I still don't really understand how his suspension and overhead cross-beam are connected on it.

@ROLANDJAYS Nice work! Your machine looks very robust. Nice components, you've clearly gone for the 'best' options. My build is a little more 'budget'.

That geared DC motor may be just fine for both pitch and L-in L-out. Depends what the rpm range is, better to have only one motor that can do both I'd say.

Last night I cut the aluminium and worked some drilling and tapping. Wednesday, Thursday and Friday will be machining and completion days for the main structure. I will continue to update here daily if possible.

Pics:

[budharpey]

very nice project! It seems to me that there are many projects on building cutterheads, but very little on building a proper overhead lathe. Especially with spring+oil damping - I could not clearly see it on your pictures - will you build with oil damping? I must admit that I have not completely understood how oil damping in a lathe actually works, due to the lack of a good lathe (I built only a "bad" diy lathe myself and do not possess and have not had the chance to use anything like a Presto or better...). Though I would like to build a better (presto quality like) diy lathe since a long time.
It would be very nice if you keep posting your progress, so that we can learn with you:)

[chaosbc]

Are you happy with your stepper motor? I have read it can be the cause of bad vibrations....

[opcode66]

The problem is the transition from a fast to slow or slow to fast speed. If not graceful, the stylus will hop out of the groove on playback.

Stepper motors can't be used for a pitch system. Unless you like hearing the stepper motor functioning in unmodulated grooves. If you can see anything other than a smooth curve to the grooves under the scope, then you're going to hear it too.

[SingleCut]

look like mine

Is this the DUAL DTJ 301 USB?

[ROLANDJAYS]

What are you asking?
Its a technic table, and I built the over head .custom parts.....

[SingleCut]

.. sorry, was asking about the turntable.
looks like the DUAL.

[opcode66]

That is a technics 1200 if I eve saw one....

[EpicenterBryan]

Stepper motors can't be used for a pitch system. Unless you like hearing the stepper motor functioning in unmodulated grooves.

I don't agree. But there are a few things he will need to do.
1). Start with a fine pitch leadscrew.
2). Microstep the motor - I would go 50,000 steps per rev.
3). Use a belt drive between the motor and leadscrew.
4). Issolate the motor mount from the overhead.

Some Details...
a). Leadscrew - an easy one to find on E-bay is an 8MM 1.25mm pitch that works out to 0.0492126" per rev. I have one, it's nice quality. The guy who sells it is in Cyprus.
b). Microstep drive. Stay away from the common drives that only go to 1/16th microstep. With a 200 step per motor that's only 3200 steps per rev. You can find Chinese ones that will run at 50,000 steps per rev but you can also get an old school Compumotor S6 drive used for the same or less and the power supply is built in and high voltage so you can get really high Rev's per second if you want. And you don't need to buy a power supply.
c). Adding a pully / belt drive between the motor and leadscrew also helps issolate. But he could also do a reduction giving more steps per turn of the lead screw.


An example:
Running at 200LPI is 0.005" between grooves. So lets pretend we do this:

We use the leadscrew noted above, and a 10:1 belt drive reduction. If we had the motor running at 50,000 steps per rev, and turned it 1 Rev the leadscrew would move 0.00492126" which works out to 203.2 LPI. Using the same steps per rev but running 2 Rev per second we would have 101.6 LPI, and at 1/2 Rev per second we would have 404.4 LPI.

The point is over the range of 100 to 400 LPI and 25,000 to 100,000 pulses per second using a stepper isn't going to bother anyone except your dog. But again, issolate the motor mount from the overhead.

[opcode66]

Or.....

Use a DC Motor/BLDC Motor with an optical rotary encoder and a descent motor control circuit that can be speed controlled via PWM. Then, put together a PWM circuit with a knob control. Done and done. You can couple the motor directly to your feedscrew. Or, indirectly via a gear box for two motors (fast and normal as in Neumann). You would additionally need another circuit to translate the rotary encoder output into LPI for readout on a meter (which would include a trimmer for calibration).

I have plenty of Neumann clone halfnuts for anyone making an overhead that wants to use the same halfnut. You may not like the price however.

[Bahndahn]

It has been a long three days of working with a precision mill [to the 0.0001"] to obtain the parts drawn on the computer in aluminium from various stock rods/bars. Tomorrow I will tap like crazy and get things put together, more photos to come. Here are some of the parts machined and the mill used:

[Bahndahn]

The mill isn't available to me until January 5th so my progression will slow quite a lot until then. I have been slowly test-assembling the unit and noting any extra parts I will need to machine.

Here is a photo of my test assembly. the backbone of my cutter head with the drivers attached is also visible.

[budharpey]

looks great!!

[Bahndahn]

More updates will follow soon regarding my build.

For now, I am looking for someone who is willing to sell [or gift] me a shot diamond or sapphire for early embossing testing. I have various metal embossing styli lined up for eventual testing but among them I would benefit from a crystal of some sort.

PM me if you are interested in helping out in this regard.

[Bahndahn]

Here is a brief photo update of the cutterhead portion of my build. Details will come when some more of my time opens up.

For now, I have a question for y'all: what experience do you have with pushrod [transducer-coupling rod] material options? Those of you who have 3d printed them, how are your results? Have flexible materials like plastic worked out? Would aluminium work? Why do many designs feature steel pushrods over aluminium? Has anyone used nylon with any degree of success? Other suggestions?