bending cast driver baskets

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Tom,

Depends upon how bent and where bent... and more to the point how determined you are to repair. IF it's damaged to the point where you have nothing to lose... then your options are unlimited.

Lets look at worst case and perhaps silly scenario; take it all apart... cut, fixture the pieces and tig weld the frame back together.... re-machine as required.

Heck, I know guys that rescued an airplane which had crashed and lay forgotten for 50+ years in the jungles of Borneo. After that a speaker basket seems kinda easy.

Much is possible if you are willing to throw caution to the wind... and you can find someone who wants a task more for the thrill than the money.

Cyclotronguy
 
I think it might be magnesium.
Sorry about the picture but I had to crop it to get it's size down.
 

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In your pictures, am I seeing where it is actually bend, of am I seeing the result of a bend in a different location?

If one of the legs of the speaker frame was bent, then that would show up as a warp on the mounting surface of the speaker, which seem to be what you are showing us.

I agree with others, it seems odd that a CAST frame would bend rather than break.

I also agree with others that the 'whack it with a hammer' is probably not going to work. That means, as indicated by others, completely dismantling the speaker then trying to bend it straight by whatever means, then reassembling the speaker and hoping that you do it right.

What is the speaker worth? And what is the cost in time, effort, and external expenses to fix it. I suspect a new speaker would be cheaper than trying to fix this one.

Still, I'm a bit of a pack-rat myself, I hate to throw anything away if it looks like it could be used for something. Though usually, this 'precious object' just sits around gathering dust of decades. By the time I need it, I've forgotten I have it, and just go out and buy a new one.

Steve/BlueWizard
 
None of the ribs look bent.
The pictures show me holding a flat round 1/4" thick plywood circle against the bent section. The air gap shows how bent it is.
Basically half of the outer rim is bent about 1/4-3/8 ths of an inch.
It's worth about $4k. They don't make them anymore.
 
Tom, I think Cal's on the right track. First thing is to notify the ins co, and send pics. Explain you want to repair the speaker, before claiming the full amount.

An engineering shop with a large hydraulic press with a sturdy table with clamping slots may be able to align the basket. They will probably want you to indemnify them should it crack. They may want to heat it to make it more maliable. (softer)

You will have to dismantle down to the frame. The worse thing that can happen is the VC jamming in the air gap.

I hope it works out OK. Geoff
 
Geoff H said:
They may want to heat it to make it more maliable. (softer)

You will have to dismantle down to the frame. The worse thing that can happen is the VC jamming in the air gap.

I hope it works out OK. Geoff

I'd say the worst thing would be them taking an oxy torch to a magnesuim chassis. Better take a small sliver off the side and see if it burns.

Good luck. It would be a shame to see a piece of history go in the bin.
 
Cast driver bent

This may be one of the ZAMAC alloys used for everything from pulleys and machine shop gearing to speaker frames and lawn ornaments... an alloy of zinc, aluminum, magnesium, and copper.

If it is (or is aluminum pot metal) be gentle on the heating end, as all of these alloys melt at pretty low temps and have a limited range of ductility...

Ideally, I'd want to heat it in a press with a conforming steel frame beneath of the final shape you're hoping to achieve... essentially re-cast it to it's original shape by pressing it while heated into an annular ring with a machuined groove to match the unbent flange configuration.
 
Hi,

You could try :

bolting the driver securely clear of rigid surface by 3 of the holes,
using a spacer of something simlar, and then using another bolt
through the hole or side clamps slowly bend it back to position.

Ideally you would use a steel ring or similar for load spreading.

:)/sreten.
 
sreten said:
Hi,

You could try :

bolting the driver securely clear of rigid surface by 3 of the holes,
using a spacer of something simlar, and then using another bolt
through the hole or side clamps slowly bend it back to position.

Ideally you would use a steel ring or similar for load spreading.

:)/sreten.

I am in the process of doing this slowly. It seems to be working so far.
I will report back the results.
 
Is the frame of the Monitor Black the same as the later types (Red, Silver, Gold) - I can't remember for the moment?
If so, it might be best to pick up a defunct one of these and use the chassis to rebuild the black. I know it wouldn't be absolutely original, but I'd personally prefer that option to a repaired frame.
Most old Tannoys benefit from a strip and rebuild anyway, particularly a good clean of the waveguide, and they're not difficult to do.
 
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