Horns and Compression Drivers - Screw thread too tight - diyAudio
Go Back   Home > Forums > Design & Build > Construction Tips

Construction Tips Construction techniques and tips

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 3rd March 2012, 11:46 PM   #1
diyAudio Member
 
blakkshepeaudio's Avatar
 
Join Date: Sep 2010
Location: Country Victoria Australia
Unhappy Horns and Compression Drivers - Screw thread too tight

Greetings.

A while ago I bought some horn flares with 1 3/8 inch screw threads. They were cheap and I thought they might come in handy.

Today I bought some cheap piezo drivers (3 different kinds to play with) planning to screw them into the flares and take some measurements to see if they were any good. Party speakers maybe.

Well, the threads are so tight that I could only screw the first one in about half way. The effort required to UNscrew it was so great the body of the piezo driver broke off in my hand. One driver down and a horn flare with half a tweeter jammed permanently into it. Boo.

So I tried a different driver, very carefully, in another horn. Same deal. So I carefully unscrewed it, applied some vaseline and tried again. Went in easily, about half way, then stopped. Very carefully unscrewed it again, with much effort.

I have now tried half a dozen driver / flare combinations, all the same.

There are no obvious defects in the threads of the drivers or the flares.

Can an experienced soul tell me if this is par for the course (plastic driver thread into plastic horn thread) and if so, what's the trick to getting them in and out.

If this is unusual, perhaps someone might suggest a fix.
Perhaps I just bought dud flares, which is pretty sad because I have dozens of them.

Any advice gratefully received.

Thanks,
blakk
  Reply With Quote
Old 4th March 2012, 02:29 AM   #2
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
maybe you are experiencing some sort of metric vs the neanderthals issue? =D
  Reply With Quote
Old 4th March 2012, 04:08 AM   #3
diyAudio Member
 
blakkshepeaudio's Avatar
 
Join Date: Sep 2010
Location: Country Victoria Australia
Quote:
Originally Posted by qusp View Post
maybe you are experiencing some sort of metric vs the neanderthals issue? =D
If that's the case, it looks like the Neanderthals have got this one in the bag......
  Reply With Quote
Old 4th March 2012, 04:59 AM   #4
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
damn throwbacks

seriously though, i reckon thats your problem as thats how it goes with using for example M3 into a 4/40 thread, it'll go in a bit if you force it, but never all the way and you ruin the thread in the process
  Reply With Quote
Old 4th March 2012, 05:21 AM   #5
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
Are all units using 1.375"x18 thread?
  Reply With Quote
Old 4th March 2012, 05:56 AM   #6
diyAudio Member
 
blakkshepeaudio's Avatar
 
Join Date: Sep 2010
Location: Country Victoria Australia
Quote:
Originally Posted by 454Casull View Post
Are all units using 1.375"x18 thread?
Uh-oh. In my ignorance I was unaware that there was more than one standard. This would explain my dilemma but surely there aren't multiple TPIs in use in this horn / driver application - that would be completely insane.

Please tell me it isn't so.....
  Reply With Quote
Old 4th March 2012, 06:33 AM   #7
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
They should be.

Problem is, nobody makes a tap and die in that size in case you wanted to clean up the threads.
  Reply With Quote
Old 4th March 2012, 06:40 AM   #8
diyAudio Member
 
Join Date: Jan 2010
Location: Manitoba
Hi, Blakk:
Hmmm, maybe the plastic horn flares were cheap for a reason? If the threads are moulded instead of cut (machined) I could see plastic - or "Resin" as it's fashionably called nowadays by marketing types - shrinkage being the cause of your problem. I got myself a Go/No-Go plug gauge for 1-3/8-18 UNEF threads, and it runs easily into any threaded horn that I've tried it on. I've never come across a tapered variant of that thread, and don't know of any standard to that effect either.

If you can get a couple of threads engagement before it binds, why not just make up a spacer you can drop into the threaded hole, thick enough to let the driver's end face butt up against it before the threads bind up? I've seen cork or rubber washers typically used in that location, or maybe you could find a bit of hard plastic tubing of the right ID/OD and just measure and cut the required length.

Hope this helps!
Wilf
  Reply With Quote
Old 4th March 2012, 07:57 AM   #9
diyAudio Member
 
blakkshepeaudio's Avatar
 
Join Date: Sep 2010
Location: Country Victoria Australia
Thanks Wilf, that is an ingenious suggestion! Not sure how it might affect performance though.

454Casull, damn, that was my next idea, buy a tap and die and tidy up the threads that way. Sounds like that's out, although I might try some machinery suppliers just on the off chance.

I am thinking of buying some new flares and making an outdoor water scuplture out of these....


Waddya think?

Cherrs
el Blakko
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
FS: 18 Sound Compression Drivers and Horns sunandmoon Swap Meet 1 13th September 2011 04:05 PM
Compression drivers in horns or waveguides 454Casull Multi-Way 6 1st December 2008 12:41 PM
Compression Drivers without Horns? NV&H Multi-Way 17 15th August 2007 06:03 PM
WANTED: Horns & Compression Drivers Carl_Huff Swap Meet 5 14th May 2007 07:43 PM


New To Site? Need Help?

All times are GMT. The time now is 08:29 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2