QUESTION on Dictaphone Shaver

[Curt A]

This is an unusual request, but I really need an answer:

Does anyone know the number of threads per inch on the feedscrew of a Dictaphone shaver? More importantly, is it the same as the threads per inch used for playback on cylinder machines?

I am making an electronic "cylinder turntable" using a Dictaphone bedplate and mandrel as the basis. I need to know if I need to match the thread pitch on a cylinder player to get the correct tracking for playback... If necessary, I can probably adapt an Edison Home feedscrew and half nut to fit the Dictaphone, but would rather use the existing parts if they are compatible. The tonearm and cartridge will be mounted to the traveling shaver arm, so it will be important to have it track correctly...

I plan to use a variable speed stepper motor and driver to control the mandrel, but the mandrel and feedscrew need to synch to make it work properly.

Thanks for any help or ideas...

[Victrolaboy]

Dictaphones track at 160 threads per inch. 2minute cylinder machines track at 100 threads per inch and 4minute is 200 threads per inch.

[Curt A]

Nick, I appreciate the info, but still have one question. Does a Dictaphone "shaver only" machine track the same as a Dictaphone recorder?

[Victrolaboy]

Curt,
I'm not sure but I will check when I get home tomorrow.

[welshfield]

My Edison electric shaver runs across the cylinder in seconds, nowhere near the slower tracking of a cylinder player.
John

[saxymojo]

That's because they run at about 1600 rpm, well my Dictaphone shaver does. Gives a beautifull finish at this speed.

[Chuck]

The only way to know for sure the answer to a
question such as this is to make your own measurements.

That way, you will have the required data for your
specific application.

The mandrel can be turned slowly by hand, counting each
turn. Meanwhile the distance that the carriage has moved
can be measured using a dial calipers accurate down
to plus or minus .0005 inches.

Then, after you have that data collected and verified
by not just doing it once, but several times to make
sure it comes out the same each time, then whip out
the calculator and do whatever math is required to
put those numbers to work to answer your original question.

You may also have to count all the gear teeth of
each gear involved so that the ratios can be
calculated. Once that is done, then the feedscrew
pitch can be calculated once all the other items
are known. In the case of a shaver, the feedscrew
drive pulley diameters need to be measured so that
that ratio can be known.

That method is the only way I know of to find these
sorts of answers.

Chuck

[phonogfp]

Well, I wasn't going to ask this question for fear of looking stupid, but I suppose that ship has sailed...

Why would the pitch of a shaving machine matter if the end result is a perfectly smooth surface? The blades I've seen are wide enough to span several revolutions of the groove, so what would be the difference between 150 tpi or 160 tpi when shaving?

I'm prepared for public humiliation...

George P.

[Curt A]

Thanks for all the answers.

George, to answer your question, I am making an electronic "cylinder turntable" for dedicated use with an amplifier or computer. The feedscrew pitch seemed problematic since the mandrel and feedscrew turn at different speeds. Using a shaver mandrel and bed plate seemed perfect for the project but the feedscrew on a shaver is driven by a belt and not a gear train. I have solved the problem by using two separate stepping motors - one for the mandrel and one for the feedscrew so they operate independently from each other. Once the project is completed, I will post pictures (if it's successful).

[phonogfp]

Thanks for all the answers.

George, to answer your question, I am making an electronic "cylinder turntable" for dedicated use with an amplifier or computer. The feedscrew pitch seemed problematic since the mandrel and feedscrew turn at different speeds. Using a shaver mandrel and bed plate seemed perfect for the project but the feedscrew on a shaver is driven by a belt and not a gear train. I have solved the problem by using two separate stepping motors - one for the mandrel and one for the feedscrew so they operate independently from each other. Once the project is completed, I will post pictures (if it's successful).

Now I see that if I had only re-read the initial post, my question would have been answered! Evidently, I don't remember posts over two weeks old... And I thought short-term memory was the first to go...

Sorry...!

George P.