It is currently Fri Jul 19, 2019 12:37 am

All times are UTC - 6 hours




Post new topic Reply to topic  [ 20 posts ]  Go to page Previous  1, 2
Author Message
 
PostPosted: Tue Jul 02, 2019 1:14 pm 
Offline
User avatar

Joined: Thu Sep 10, 2015 2:59 am
Posts: 75
Location: Coventry, England
One factor I (and I suppose "we") don't know is how hot/warm the plastic heads are when the are put onto the brass tubes.

_________________
Andrew Wigglesworth
http://www.greenmanrising.co.uk


Top
 Profile  
Reply with quote  
 
PostPosted: Tue Jul 02, 2019 3:07 pm 
Offline
User avatar

Joined: Fri Jan 27, 2012 10:15 pm
Posts: 587
Location: Seattle, WA
ecadre wrote:
Steve Bliven wrote:
I was wondering whether the expansion of the plastic head would make it grip the tube more tightly...

Best wishes.

Steve


It's a common misconception, but, no, it doesn't work like that. When you heat a ring of solid brass or ABS plastic, the diameter increases. The diameter of the ABS plastic ring/sleeve will increase when heated, and since it has a higher expansion coefficient (4 to 5 times) than brass, its grip on the brass tube will lessen.


Hmm. I recall a demonstration at school where we were challenged to determine if a slightly oversized ball could fit through a thick metal ring, if the ring was heated (when cold it could not). It was a trick question of course, all of us knew hot things expand, but the point of the question was to show us that expansion is equal interior and exterior, so the ball still could not pass through (i.e. yes, the outer diameter increases, but the interior diameter decreases). If anything, freezing it would be the better option, but the risk of cracking may not make this worthwhile.

Perhaps plastic is different, but I think the temperature of the head only affects the glue present on other whistles.


Top
 Profile  
Reply with quote  
 
PostPosted: Tue Jul 02, 2019 3:41 pm 
Offline
User avatar

Joined: Thu Sep 10, 2015 2:59 am
Posts: 75
Location: Coventry, England
MadmanWithaWhistle wrote:
ecadre wrote:
Steve Bliven wrote:
I was wondering whether the expansion of the plastic head would make it grip the tube more tightly...

Best wishes.

Steve


It's a common misconception, but, no, it doesn't work like that. When you heat a ring of solid brass or ABS plastic, the diameter increases. The diameter of the ABS plastic ring/sleeve will increase when heated, and since it has a higher expansion coefficient (4 to 5 times) than brass, its grip on the brass tube will lessen.


Hmm. I recall a demonstration at school where we were challenged to determine if a slightly oversized ball could fit through a thick metal ring, if the ring was heated (when cold it could not). It was a trick question of course, all of us knew hot things expand, but the point of the question was to show us that expansion is equal interior and exterior, so the ball still could not pass through (i.e. yes, the outer diameter increases, but the interior diameter decreases). If anything, freezing it would be the better option, but the risk of cracking may not make this worthwhile.

Perhaps plastic is different, but I think the temperature of the head only affects the glue present on other whistles.


Sorry, but you're wrong. The internal diameter of a metal ring will get larger when it is heated. Every arc of the internal face of the ring will increase in length. You have misremembered the lesson, because what you propose is that metals shrink when heated, which is precisely the opposite of what actually happens. ABS plastic also expands when heated, and like metals, this does not decrease the internal diameter.

What I was wondering was how warm the heads are when put onto the tubes, if warm then they would shrink onto the tube. I know it's commonly stated, but, personally, I've never experienced Generation whistle heads being glued (tubes lacquered, yes), and I seem to remember Jerry Freeman at some point saying that they're not glued.

(Just removed a couple of heads ... lacquer, but no evidence of glue).

_________________
Andrew Wigglesworth
http://www.greenmanrising.co.uk


Top
 Profile  
Reply with quote  
 
PostPosted: Tue Jul 02, 2019 4:07 pm 
Offline
User avatar

Joined: Sun Sep 13, 2009 10:06 pm
Posts: 1462
Location: just outside Xanadu
Fun, totally irrelevant story. We had to fit a nickel 5 inch bearing into a stainless steel housing. The bearing, about 7.5 by 18 inch outer diameter was machined to an interference fit to the housing. That is the outer bearing diameter was too large to fit into the bearing housing/sleeve. I cannot remember the exact interference, but greater, I think than 0.040 inches. We dunked the bearing in a pail filled with liquid nitrogen. We topped up the pail a couple of times as the nitrogen furiously boiled off. We slathered up the interior of the bearing-housing with Syl-Glyde lubricant and played a propane torch on it until the housing/sleeve started to smoke. Using a crane, standing well back, we lifted and then slipped the bearing into the housing. It readily slid into place. It stood in the corner of the shop, loudly 'singing' and groaning for several hours while the temperatures equalized and the two pieces 'married'.

:D Bob

_________________
Not everything you can count, counts. And not everything that counts, can be counted

The Expert's Mind has few possibilities.
The Beginner's mind has endless possibilities.
Shunryu Suzuki, Roshi


Top
 Profile  
Reply with quote  
 
PostPosted: Fri Jul 05, 2019 10:30 pm 
Offline
User avatar

Joined: Sun Sep 13, 2009 10:06 pm
Posts: 1462
Location: just outside Xanadu
As an update on removing the head on a Clare two-piece whistle. I just firmly grasped the head and the upper tube and twisted. Came right off. Note to Steve Bliven: You might try using 'gripper gloves' or, since I'm a geezer and have them on hand, a couple of those rubber thingies to grip and loosen stubborn twist bottle caps.
Now you must understand I am not a tremendous fan of the sound of the Clare fipple head. Just a little too unfocused and airy. But I did have a Freeman Tweaked Eb that I cut down and tweaked into an E whistle. I think it was a Blackbird whistle head, but at any rate it was black. Since it was sized to an Eb brass tube, it was a perfect fit for the upper tube of the Clare Whistle, and I now have a delightful addition to my whistle quiver: A Freeman Tweaked two piece D pocket whistle. :D :D :D

Bob

_________________
Not everything you can count, counts. And not everything that counts, can be counted

The Expert's Mind has few possibilities.
The Beginner's mind has endless possibilities.
Shunryu Suzuki, Roshi


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 20 posts ]  Go to page Previous  1, 2

All times are UTC - 6 hours


Who is online

Users browsing this forum: Google and 16 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group
[ Time : 0.163s | 12 Queries | GZIP : On ]
(dh)