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The Mainline => Scratchbuilding => Topic started by: ACL1504 on December 27, 2015, 12:11:33 PM

Title: Casting a resin speaker box using RTV.
Post by: ACL1504 on December 27, 2015, 12:11:33 PM
I was taking inventory of my speakers and found that I needed three QSI speaker boxes. I have three of the Mini-Oval Speakers by QSI but no boxes. Heck, I don't even know if QSI is still in business. The Mini-Oval Speakler is an 8 Ohm 1.0 Watt speaker. It measures .56" X 1" or 14X25 mm.

Here is what the speaker looks like.

(https://modelersforum.com/gallery/24-271215120422.jpeg)

It is small but sounds great in smaller locos with DCC sound.

I have one speaker box that fits the speaker and decided to change gears for a few hours. I took the speaker box/enclosure and placed it in a small plastic box. It was a perfect fit.

(https://modelersforum.com/gallery/24-271215120433.jpeg)

Continued in a few.
Title: Re: Casting a resin speaker box using RTV.
Post by: ACL1504 on December 27, 2015, 12:23:04 PM
I then used Baby Powder to lightly cover the speaker box and the inside of the plastic box. This reduces the friction in the demolding process.

(https://modelersforum.com/gallery/24-271215120444.jpeg)

I used the RTV (Room Temperature Vulcanizing) from Micro-Mark. It's the 1 to 1 rapid 4-hour cure Silicone Mold Rubber.

I used a round dowel to thoroughly mix Part A and Part B.

(https://modelersforum.com/gallery/24-271215120456.jpeg)

Continued in a few.
Title: Re: Casting a resin speaker box using RTV.
Post by: ACL1504 on December 27, 2015, 12:29:53 PM
I like using the small Dixie Cups for mixing. They have lines and other patterns on the cups. I use these lines to determine how much rubber mold compound and resin mix to use.

(https://modelersforum.com/gallery/24-271215120512.jpeg)

I used equal parts of A and B and mixed thoroughly. I then carefully poured the RTV into the plastic tray/box.

(https://modelersforum.com/gallery/24-271215120524.jpeg)

The completed mold was ready to remove after four hours but I let it sit overnight.

Continued in a few.




Title: Re: Casting a resin speaker box using RTV.
Post by: ACL1504 on December 27, 2015, 12:34:39 PM
This morning I used a #11 Xacto knife to pry the mold out of the small plastic box.

(https://modelersforum.com/gallery/24-271215120607.jpeg)

After removing the silicone rubber mold, I removed the speaker box/enclosure.

(https://modelersforum.com/gallery/24-271215120634.jpeg)

The original speaker was then placed back into the mold for your viewing of how it looks when it is ready to be removed.

(https://modelersforum.com/gallery/24-271215120620.jpeg)

Continued in a few.
Title: Re: Casting a resin speaker box using RTV.
Post by: ACL1504 on December 27, 2015, 12:47:53 PM
Here is a better view of the Dixie Cup.

(https://modelersforum.com/gallery/24-271215120646.jpeg)

I then mixed Part A and Part B of the casting Resin. I used the Micro_Mark CR-600 High Performance Casting Resin. After thoroughly mixing the two parts, I poured the resin mix into the rubber mold and let it harden.

(https://modelersforum.com/gallery/24-271215120656.jpeg)

NOTE: You have about two minutes to make the pour after mixing the two parts.

You can remove the new part after 30 to 60 minutes. I let it sit for about two hours as I was working on something else.


The mixture is clear but will dry to a milky white.

Continued in a few.






Title: Re: Casting a resin speaker box using RTV.
Post by: ACL1504 on December 27, 2015, 12:51:35 PM
The new resin speaker box is white and hard.

(https://modelersforum.com/gallery/24-271215120709.jpeg)

The speaker fits into the new part with no problem. This was an easy fix to get the speaker enclosures I needed. I've made four just in case. But I'll have the rubber mold for quit some time.

(https://modelersforum.com/gallery/24-271215120723.jpeg)

Tom ;D
Title: Re: Casting a resin speaker box using RTV.
Post by: donatode on December 27, 2015, 01:14:44 PM
Nice Job....and neat too!!!!



Title: Re: Casting a resin speaker box using RTV.
Post by: jimmillho on December 27, 2015, 01:40:50 PM
Is that speaker similar to the ones from Digikey ?

Jim
Title: Re: Casting a resin speaker box using RTV.
Post by: ACL1504 on December 27, 2015, 01:44:02 PM
Quote from: Donato on December 27, 2015, 01:14:44 PM
Nice Job....and neat too!!!!


Donato,

Thanks, much appreciated. This was an easy task and the RTV is great for making spare parts.

Tom ;D
Title: Re: Casting a resin speaker box using RTV.
Post by: ACL1504 on December 27, 2015, 01:45:58 PM
Quote from: jimmillho on December 27, 2015, 01:40:50 PM
Is that speaker similar to the ones from Digikey ?

Jim


Jim,

Thanks for stopping by. I'm not familiar with the Digikey. It is a Digitrax product? I haven't found anything else the small QSI speaker will fit into other than the QSI speaker enclosure.

Tom ;D
Title: Re: Casting a resin speaker box using RTV.
Post by: GPdemayo on December 27, 2015, 02:07:50 PM
Great job Tom.....does the sound system for the C&O J-3 need one of these super special custom built speaker boxes?  ;)
Title: Re: Casting a resin speaker box using RTV.
Post by: ACL1504 on December 27, 2015, 02:41:40 PM
Quote from: GPdemayo on December 27, 2015, 02:07:50 PM
Great job Tom.....does the sound system for the C&O J-3 need one of these super special custom built speaker boxes?  ;)


Greg,

Thanks, much appreciated. No, your C&O J-3 will have a mack daddy speaker in it! No enclosure needed. The brass tender will act as the box. Some foam around the speaker will do the trick. 8)

Tom ;D
Title: Re: Casting a resin speaker box using RTV.
Post by: jimmillho on December 27, 2015, 04:04:36 PM
Tom,
Digikey is the Electronics Co that had the small speakers we used for the PFM System.

Jim
Title: Re: Casting a resin speaker box using RTV.
Post by: ACL1504 on December 27, 2015, 04:52:16 PM
Quote from: jimmillho on December 27, 2015, 04:04:36 PM
Tom,
Digikey is the Electronics Co that had the small speakers we used for the PFM System.

Jim


Jim,

I don't remember the name. However, I've only used the PFM 1.5" 8 Ohm speakers from PFM/PBL. PFM is marked on the top of the speaker. This is what happens when one gets old, I just don't remember.

Tom ;D




Title: Re: Casting a resin speaker box using RTV.
Post by: GPdemayo on December 28, 2015, 08:43:52 AM
Quote from: ACL1504 on December 27, 2015, 02:41:40 PM
Quote from: GPdemayo on December 27, 2015, 02:07:50 PM
Great job Tom.....does the sound system for the C&O J-3 need one of these super special custom built speaker boxes?  ;)


Greg,

Thanks, much appreciated. No, your C&O J-3 will have a mack daddy speaker in it! No enclosure needed. The brass tender will act as the box. Some foam around the speaker will do the trick. 8)

Tom ;D


Mack daddy.....that sounds even more super dulexee !  ;D ;D ;D
Title: Re: Casting a resin speaker box using RTV.
Post by: ReadingBob on December 28, 2015, 08:53:54 AM
Now that's a really creative solution to a problem.  Creating molds and making castings of stuff is one of those things I haven't tried but intend to (someday).   
Title: Re: Casting a resin speaker box using RTV.
Post by: ACL1504 on December 28, 2015, 11:11:27 AM
Quote from: GPdemayo on December 28, 2015, 08:43:52 AM
Quote from: ACL1504 on December 27, 2015, 02:41:40 PM
Quote from: GPdemayo on December 27, 2015, 02:07:50 PM
Great job Tom.....does the sound system for the C&O J-3 need one of these super special custom built speaker boxes?  ;)


Greg,

Thanks, much appreciated. No, your C&O J-3 will have a mack daddy speaker in it! No enclosure needed. The brass tender will act as the box. Some foam around the speaker will do the trick. 8)

Tom ;D


Mack daddy.....that sounds even more super dulexee !  ;D ;D ;D


Greg,

The larger speaker in a large tender has great sound.

Tom ;D