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Speaker mount 1/4” = 6mm?

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Speaker mount 1/4” = 6mm?

Postby BillB » Fri Apr 17, 2020 8:57 am

Hi folks

I want to wall-mount my Blue Sky Exo satellite speakers.
https://www.soundonsound.com/reviews/blue-sky-exo-21
The manual states that the speakers have 1/4" x20" threaded inserts

I am wondering whether this kenable bracket would fit the thread

https://www.kenable.co.uk/en/accessorie ... 26509.html

It describes the mounting bolt as 6mm. 1/4” is of course 6.35mm, so will it be almost but not quite entirely wrong, or just wrong?

Or is there some weird convention in speaker mounting systems that 1/4” = 6mm?
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Re: Speaker mount 1/4” = 6mm?

Postby Kwackman » Fri Apr 17, 2020 9:19 am

BillB wrote:The manual states that the speakers have 1/4" x20" threaded inserts

It can't be 20", surely?

Anyway, if they are giving the dimensions in imperial rather than metric, apart from any difference in diameter, it's the pitch of the thread that may give you more problems. They are different, and even if you get the diameters the same, a metric thread isn't going to work in an imperial thread.

Edit - Just a thought I wonder if the manual means 20mm (which seems a reasonable length for an insert).
If you know anyone with a selection of bolts or screws, ask them for an M6 bolt (metric) and a 1/4" bolt and see if which screws into your insert.
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Re: Speaker mount 1/4” = 6mm?

Postby Wonks » Fri Apr 17, 2020 9:41 am

Blue Sky are American, where they staunchly continue to use Imperial size threads when almost everyone else now uses metric.

These are the current versions of the speaker mounts that Blue Sky recommends to use with the Exo system.

https://www.amazon.co.uk/B-Tech-BT332-C ... B002LK2DIE
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Re: Speaker mount 1/4” = 6mm?

Postby Kwackman » Fri Apr 17, 2020 9:51 am

Wonks wrote:These are the current versions of the speaker mounts that Blue Sky recommends to use with the Exo system.

https://www.amazon.co.uk/B-Tech-BT332-C ... B002LK2DIE

Good spot Wonks..
"Suitable for speakers using M5, M6, UNC 1/4" and wood screws"
That'll cover all options- "wood screws" - nice back up!
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Re: Speaker mount 1/4” = 6mm?

Postby Wonks » Fri Apr 17, 2020 10:00 am

It basically has a hole big enough to fit all those screw sizes through and with a suitable washer, stop the nut from pulling through the hole. Relatively expensive, but it does look sturdier than the 6mm dia universal mount ones.
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Re: Speaker mount 1/4” = 6mm?

Postby Rob Kirkwood » Fri Apr 17, 2020 10:14 am

Just to add that 1/4" x 20 is the most common camera mount thread found on tripods & other camera mounting hardware. 1/4" is the diameter, & 20 is the number of threads per inch.

There is also a larger camera-related one that's 3/8" x 16.

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Re: Speaker mount 1/4” = 6mm?

Postby BillB » Fri Apr 17, 2020 10:18 am

Thanks, folks.

The manual (http://abluesky.com/wp-content/uploads/exomanualc.pdf)
does indeed say 1/4" x 20" in the diagram on P12 - good catch, Kwackman. Elsewhere just referred to a 1/4" x 20, so presumably 20mm.

I think you are right, Wonks, better to go for the B-Tech mounts with the full range of bolts to fit the system.

Fastest tech support in the universe - thank you! :clap: :D
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Re: Speaker mount 1/4” = 6mm?

Postby Kwackman » Fri Apr 17, 2020 10:19 am

Rob Kirkwood wrote:Just to add that 1/4" x 20 is the most common camera mount thread found on tripods & other camera mounting hardware. 1/4" is the diameter, & 20 is the number of threads per inch.

Thanks Rob, I couldn't understand the "20" part of the spec, now it makes sense.
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Re: Speaker mount 1/4” = 6mm?

Postby BillB » Fri Apr 17, 2020 10:30 am

Rob Kirkwood wrote:Just to add that 1/4" x 20 is the most common camera mount thread found on tripods & other camera mounting hardware. 1/4" is the diameter, & 20 is the number of threads per inch.

Yes - thanks for that!
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Re: Speaker mount 1/4” = 6mm?

Postby Sam Spoons » Fri Apr 17, 2020 9:55 pm

Just to chuck a metaphorical spanner in the works ¼" x 20tpi could be BSW or UNC. Being American I'd guess it's UNC but, while the size and TPI is the same the thread form is different so they won't necessarily be interchangeable.

I've just being trying to ascertain what the threads in the tailstock hand wheel on the lathe is, in this case it's BSW, that's the only reason I could answer in such detail :blush:
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Re: Speaker mount 1/4” = 6mm?

Postby BillB » Sat Apr 18, 2020 12:05 am

Sam Spoons wrote:Just to chuck a metaphorical spanner in the works ¼" x 20tpi could be BSW or UNC. Being American I'd guess it's UNC

Well I hope so because 1/4” UNC will match the BTech wall mount I ordered earlier...
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Re: Speaker mount 1/4” = 6mm?

Postby ef37a » Sat Apr 18, 2020 7:19 am

Judging by how coarse it is I think a camera thread is a Witworth?

FYI some American rack cases use '10 UNF' and that is almost the same as M5 coarse but not close enough for any high load duty. But I am no mechanical engineer, just stuff I have picked up along the way.

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Re: Speaker mount 1/4” = 6mm?

Postby Sam Spoons » Sat Apr 18, 2020 10:06 am

The difference is the thread profile. UNC and Whitworth (BSW) share the same pitch and diameter (¼" is 20 TPI, 5/16" is 18 TPI and so on) but UNC (and metric) threads are cut with a face angle of 60º, Whitworth have a 55º face angle making them incompatible*.

* I'm guessing but a UNC nut would probably go onto a BSW screw but not vice versa and strength would be compromised.
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Re: Speaker mount 1/4” = 6mm?

Postby Rob Kirkwood » Sat Apr 18, 2020 11:18 am

Sam Spoons wrote:The difference is the thread profile. UNC and Whitworth (BSW) share the same pitch and diameter (¼" is 20 TPI, 5/16" is 18 TPI and so on) but UNC (and metric) threads are cut with a face angle of 60º, Whitworth have a 55º face angle making them incompatible*.

* I'm guessing but a UNC nut would probably go onto a BSW screw but not vice versa and strength would be compromised.

I've been 'mucking about' with cameras for nearly as long as I've been playing guitar (~60 years). Generally speaking, older cameras/tripods use 1/4" 20 BSW, but newer stuff uses 1/4" 20 UNC - which is also what the USA chose to use from the beginning (whereas Royal Photographic Society chose BSW unsurprisingly).

However, in this specific case (i.e. 1/4" 20) while the thread angles are different, in practice it doesn't matter - new cameras with UNC will fit old tripods/mounts with BSW & old cameras with BSW will also fit new tripods with UNC - it really is a non-issue for this specific thread size & usage (which is why I didn't mention it before) ...& bear in mind some high-end camera/lens combinations are pretty hefty (& expensive) things to be hanging off the 'wrong' 1/4" 20 thread - but they work fine & securely.

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Re: Speaker mount 1/4” = 6mm?

Postby BillB » Mon May 11, 2020 11:16 am

Just wanted to wrap this up by saying that the B-Tech wall-mount stands were fine. Very adaptable as to fittings and to setting-up. The closest bolt sizes, to fit the threaded inserts to the Exo satellite speakers, were not a perfect fit - very slightly loose. But no cross-threading, and when fully tightened against the bracket, aboslutely no movement.

I am happy with the height and position of the speakers, which reflect the fact that I spend far more time stood in front of keyboards than I do sat at a PC.
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