Fixing a Recorder

[winsleydale]

I just came into possession of a lovely Standard D from our friend Jerry, and with it came a recorder. The cutting stylus is good, but it looks like the diaphragm might be cracked, and the stylus bar is facing the opposite direction from how it should face. How does one go about correcting this?

[Lucius1958]

First off: you can remove the stylus holder by carefully brushing alcohol around it (I believe they used some form of shellac as an adhesive).

Next, scrape off the wax holding the diaphragm, and carefully pick it out. Check to see whether the gasket underneath is still good: if not, replace it (it should likely be the same diameter as a reproducer gasket - please correct me if I am wrong).

With a good micrometer, find out the thickness of the diaphragm. Look for something of the same thickness and diameter from a reputable supplier.

Replace the inner gasket; lay the diaphragm on it; lay a thin ring of beeswax around the edge, and melt it with a hot metal point.

Finally, align the stylus holder in the correct position, and fix it down with an appropriate adhesive (as noted above, a form of thickened or 'burnt' shellac was likely used, but something like hot hide glue may work).

Bill

[winsleydale]

Thank you!

[De Soto Frank]

I took a quick look at my original / unmolested Edison recorder, patent date on box lid is May 1905.


Diaphragm is sealed with "white" bees-wax, stylus bar appears to be anchored with brown stick-shellac.


I think the stick-shellac is a littler easier to work-with than hide-glue: just heat the end of the stick, then drag the sylus bar across it to pick-up some shellac, then place on the diaphragm, and apply a dry soldering iron to re-melt the shellac, and finally position the stylus bar accordingly.

[Chuck]

As Bill points out, you need a few of the proper
tools.

Proper adhesives are a very helpful as well.

In my experiences with recorders, the sapphire cutting
stylus is held into the copper holder with shellac.
When mounting one, the stylus just slips into the
end of the copper with about .04 inches (one diameter)
of stylus poking out past the copper. Then the whole
works is held in an alcohol flame and heated up and a
flake of shellac is touched where the copper and
the sapphire meet. The shellac then melts and wicks its
way down between them much the same as making a solder
joint.

The assembly consisting of of the copper holder that
has the stylus held in with the shellac then gets
glued down to the diaphragm using stratena glue.

Peter Wall makes and sells new bottles of stratena
on ebay for a few bucks each. It's worth it! It's
the proper glue and it works great! Stratena is
a gelatin-based glue, it comes loose nicely after
about half an hour when wetted with a moist Q-tip.

Stratena is known as a reversible adhesive because
it comes loose easily. This is very handy when rebuilding recorders because quite often something
has to be taken apart a few times and moved around
and then fastened down again.

The beeswax around the perimeter of the diaphragm
must be sealed air tight. It also helps to have
a 2nd gasket on the top of the diaphragm which
then gets beeswaxed on there along with the bead
of beeswax all around.

I've rebuilt 9 recorders now and have found that
the ones with the 2nd gasket talk up much louder
and clearer than the ones with only the beeswax bead.

Typical mica Edison recorder diaphragms are .002 inches
thick. Beware of mica diaphragms for sale most
places now. They are typically a LOT thicker such
as .007 inches. They are usually a darker grey color
not clear like the original .002 Edison ones.
.007 inches in my opinion is WAY too thick to
be sensitive enough to record well.

If your .002 inch thick mica is in even close
to reasonable shape, by all means try using it.

You can always change it later.

I usually take a recorder like you have all apart
and make sure the swinging weight pivots freely
without any side play. Polish the inside of the
sound tube and make sure that the sliding tube inside
which has the ball and socket joint slides freely.

Make sure all the old beeswax is removed from around
the rim edge of the round weight.

Clean the gasket if you can get it out in one piece.
I'll usually gently scrape those gaskets using
a semi-dull old pocket knife to get the old
beeswax off. For your's, I'd cut a new top
gasket out of some .014 inch thick cardboard.

The gasket under the diaphragm is typically .019 to .021
inch thick. The top gasket is a bit thinner, in the
range of .014 to .015 inch thick. The typical width
of them is .052 inch. I've used cardboard to make
these gaskets with great success. Manilla-folder
cardboard is about the correct thickness for the top
gasket. The thicker cardboard for the bottom gasket
is a bit more difficult to run across. I found some
of that thickness of cardboard and cut it out from
the side of a box which originally contained paper
envelopes.

Once these gaskets are cut out, they should be boiled
in a boiling spoonful of beeswax over an alcohol lamp.
This impregnates the cardboard with the beeswax, it really soaks in there and makes a nice gasket.
After cooling and hardening, then scrape off the excess
beeswax off of both sides of the new gaskets using
a rather dull knife such as an old pocketknife.
They must be smooth and even.

Use the old bottom gasket as a template.

To do it properly, you'll need a high quality
drafting compass to lay out the circles. Then cut
with sharp exacto knife under bright light.

Once it's all glued up, be sure to wait a full 24
hours before testing.

To test: Put on a high diameter blank that's
about 2.196 inch diameter. Gently install the
recorder. Gently set the recorder down while holding
the weight up. Look carefully for some clearance.
There should be some clearance between the cutter
and the blank. If there is some small bit of
clearance, it is good to go. Do some recording
tests and then clean off the blank, put in the
reproducer and see how it sounds.

If it is muffled or low volume, check the beeswax
seal around the diaphragm. When a 2nd "top" gasket
is used, it's most important to flow the beeswax off
of the gasket, out onto the diaphragm a little ways.

That makes it air tight. Everything must be air tight.

A good test is hold the recorder upright next to
your ear and move the weight up and let it down
against the limit loop. The recorder should make
a very distinctive resonating sort of "ring-pop"
sound. If it only makes a dull thud, it still needs
more sealing work.

Have fun and get some stratena from Peter Wall.

Also it helps a lot to make yourself some little
handy beeswax working tools out of thin sheetmetal.
Make one shaped like a flat wooden toothpick, that one
is very handy because it can be curved and bent
to do whatever you need it to do.

Get or make an alcohol lamp.

Clean diaphragm and stylus mount thoroughly with
acetone or denatured alcohol and dry and don't touch
before applying the stratena.

Get a dial calipers or a micrometer or both.
Get some small handheld magnifiers such as various
power loupes.

Work under the brightest light you can find.
Be patient. Do lots of tests. Ask lots of questions.

Chuck

[Bruce]

It is always a pleasure when Chuck offers up advice. It is detailed, complete and very informative - almost to the point that some day I think I will take on the challenge of recording my own blanks. Likely that will have to wait until I retire

As for the legal advice, I agree if you receive an item which is not as described then certainly return it. The reality is that we are dealing with 100 to 125 yr old items, many of which worked hard in their earlier lives. The vast majority of us look for and expect that the items we buy are not in pristine shape. Many look forward to the challenge of restoring these items to working order.

As for Dealing with Jerry as a seller I have nothing but positive comments to say about how he presents his items for sale and how fairly he deals with his customers.

Bruce

[Chuck]

Bruce, you have the ideal machine to do it with too!
Your Class M machine will make some wonderful recordings!

I did go back and edited my previous post with more
detail about making the gaskets.

During the last few years I've found a way to make
new copper cutting-stylus holders from scratch.
I've been using .005 inch thick copper sheet which is
a bit thinner than the original .010 inch thick copper
that the original Edison holders are made from.

But with enough time and patience, these holders
work every bit as well as an original.

For those who want to consider making these, get ready
to spend the time it takes to do it.

I have not yet been able to get one made and all adjusted and straight in any less than 8 hours
of work, and most often it ends up a lot more
time than that before the recorder is fully working
right. Most often when making the holder, the recorder
must be all glued up, tested, then taken back apart
and the holder height adjusted. Sometimes both the
height and the angle must be adjusted not once, but
a few times before it all works the way it's supposed
to. Those times are when Peter's stratena really
proves itself!

Chuck

[winsleydale]

So I was bored and I decided to try my hand at a diaphragm for the recorder. I took the mica from a crappy Edison-to-78 adapter that I had lying around (literally, this thing was unfixable - the more stuff you fixed, eg gaskets, pivot, etc, the worse it got. I understand why they never sold well.) and split the layers until I got something very (but not too) thin, which I think will work well. My next challenge is getting it to be the correct diameter. How do you cut mica?

[Mr Grumpy]

How do you cut mica?

I use scissors.

[winsleydale]

Really? It doesn't screw the layers up at the edge??