The PVA would be used to fix down the cone to the basket, so there shouldn't be any flexing there.

I woud prefer a glue for fixing down the cone to the basket that would stand normal usage, but be able if necessary to be lifted without damaging the cone. Same for the corrugated spider gued to its support. As it is gueing these down is pretty final if lthere turns out to be poling after all. But people are successful by following a procedure and being careful. So onward!

I have rebuilt many speakers from 500 watt 15" 'grunters' down to valve radio 5" types.
The essential thing in the end is the voice coil runs centred on the pole and at the correct height..
Everything else flows from that.
Assuming the voice coil is round with parallel sides, the first thing to do is use, or make, is a tool to accurately center the coil on the pole.
Then, the cone, the suspension discs are mounted onto their mating surfaces and without any strain.
A lot of that assumes the magnet, frame, basket are all concentric and parallel!!
That means all the engineering fundamentals are correct.
Of course that never quite happens, so you do your best and choose appropriate adhesives for each surface.
Only experience tells you what to do. Keeping in mind all the time that the voice coil sitting on the pole and centred by the tool you made must not have any tilting or twisting torque applied by the way you glue the rest down!
A lot depends also on whether you are just fitting a re-cone kit or trying to rebuild a wreck with the original or materials you fabricate your self.
I tended to epoxy the join from a voice coil to a cone. The suspension discs can be mated to a bed of silastic so as not to torue the coil alinement.
Moth eaten cones can be repaired with "Latex" the water base stuff that turns clear when it cures.
Someone can correct me on the word latex, I use a bottle of white stuff I got from the speaker suppliers about 20 years ago.
There was no chemical analysis given, just "use this"!
Once every thing is bedded down and cured you can remove the aligning tool, the cone does not pop to one side (aaaaargh) and all is go.
There are a lot of side issues like installing new flex braids to the coil, rewinding coils (if you are desperate) but its all really just rebuilding vintage motors.

Fred.

Latex adhesive is natural rubber in a chemical cocktail including Ammonia. The Material Safety Data Sheet for the Shearers stuff is quite scary, as are the warnings on it.

Not something to get on you, or use in a confined space. Shearers stuff is soluble in water.

Thanks for this good advice. I successfully rebuilt this speaker in 1989 so should be able to do it again. This time though I have had to build and wind the voice coil and replace the spider and cone. I have lately replaced the suspensions on two subwoofer speakers so that gives me some confidence too.

The voice coil was wound on a paper former on a socket built up to the right diameter with tape. The socket had the advantage of having slightly lower diameter at the spanner end so that using wet paper I got the step required in the profile to clear the voice coil wires as they run up to the edge of the former. Very fiddly requiring much fettling to remove excess adhesive.

Hi STC great work on winding a voice coil.
Can be one hell of a job and like you say 'fiddly'!!
Thats engineering!

MarcC this white stuff I got from the speaker supplier is very neutral in smell.
It thins with water, soaks into old crackly cone material well.
Thinned out its great to freshen the cone and brushed on thick will 'replace' an outer suspension ring.
Or fill up an inner suspension.
It is creamy white but dries clear and is a '1 product does it all' cure for old speakers!
I have no way of finding out what it is, but it works well.
Fred.

Working in polymer chemistry one becomes a bit like the perfumery "Nose" and can identify many chemicals by their smell. PVA is pretty straight forward, Based on Vinyl Acetate monomer to form Poly Vinyl Acetate. Which, in that form is a wood & paper glue.

The acrylic binders which I use & have made tend to be tailored to their end use and the acetate monomers are blended accordingly. These tend to remain tacky and do not "dry" as such, which is why I used them for their flexibility and why, due to their remaining tacky, requires talc to stop the stuff binding onto the rest of the pages when used for book binding. It will form a flexible repair but I use Micropore as a strengthener.

I used white glue from a Sydney speaker repair supplier several years ago. This didn't have much smell either. Expensive and a tiny bottle, but didn't want to take a chance fixing subwoofer cones. It worked OK and was repositionable as advertised.

The PVA craft glue for this job claims to be non acidic and repositionable.

Having made Adhesives, I do wonder at some claims. On paper if the PVA has done its job and soaked into the paper and set semi rigid, I would expect it to destroy the paper trying to separate it. Repositioning while its still wet I would believe.

With some of the tacky glues, a miscalculation can be a disaster, as once they have grabbed & bonded, that's the end of it. The last time I had to align a cone & voice coil tube I cut a cone on a wood offcut with a spigot to hold the tube straight. Lathes can be useful for repairing radios

One of course realises that if you can get access to a laser engraver, you can cut gaskets and that central spider, given the right material.

Wet repositioning is what I mean.

Drying hard makes then process more unreversible if you get it wrong. If the glue has to be tacky to make the process reversible then the quality of repositioning is lost. Repositioning is essential to getting alignment of the speaker cone without any strain and hence distortion being built in, which might push the voicecoil out and cause poling.

If I hadn't found the right size corrugated spider with regard to outer diameter and voicecoil hole I might have had a go at making the normal sort of spider. Would have used the right thickness craft paper strenthened with a smear of epoxy.

That it why I turned the cone & spigot. The only thing that was liable to cause an issue was failing to protect the union from sticking to the wooden cone used as a former & alignment tool. That is the point where a rigid adhesive was required to prevent the VC tube from moving, giving a greater chance to the spider of avoiding poling.

Somethings you just have to be fastidious with, to get it right.

My intention is to put the voicecoil in place with a spacer between it and the magnet pole. Then put the spider in place over that and glue it to its support. Then once the glue is set, epoxy the spider to the voicecoil after checking that the vc is at the right height with respect to the magnet plate. That way strain that could uncentre the vc should be minimised.

Once wired up, strictly that makes a speaker totally devoid of bass so should be able to plug it in.

Some use toothpicks as centring. There are a few on the American Antique Radio forum that do that as cones are easier to get in USA.

Do not forget to mark the polarity. Feeding it with a transformer has no DC component, however, if it is used, say, in the collector circuit of a transistor, then polarity is seriously important. I have seen some rather expensive speakers destroyed by reverse polarisation.

When fed DC, the polarity is correct when the cone is repelled. The voice coil is an electromagnet.

I got my cone from, of all places, Ukraine. Good price too. Only place with a 12" cone with a 25mm centre hole.

The spacer is plastic sheet, but the vc moves if you are not careful. Tooth picks might be useful to lock the vc in place wile putting the spider in place.

I have been very careful with wiring and winding direction of the voicecoil. So hopefully OK. If I get hum, reverse the polarity.

Hum can be very entertaining & frustrating, as there a so many places it can creep in. Often it is a case of firing up an oscilloscope to try to spot the source. One of the best I have seen, is in American sets where there is or, cannot be a ground & relying on neutral as the ground.

In most cases neutral is at ground potential so putting a line capacitor to chassis or to the chassis on a hot set is fine, but falls apart when the plug is reverses & active ends up on ground. Their 2 pin plugs can be reversed, thereby putting AC onto the chassis.

If you have a transformer set, I usually ground them, if it has a shielded transformer, definitely ground it, as that type of transformer puts a charge on the chassis. Grounding gives abetter RF path to ground on sets requiring a separate antenna.