[BadgerMcBadger]

how do i keep the canal from becoming entirely solid when hardening the fotoplast? can i poke it with tweezers to check or will that mess up the shell?

 

[citiesandshapes]

how do i keep the canal from becoming entirely solid when hardening the fotoplast? can i poke it with tweezers to check or will that mess up the shell?

Typically what’s recommended is that you cure the mold with the opening facing up long enough to get your desired shell thickness (usually 1.5-3 mm). Then you’ll turn the mold upside down to finishing curing. This lets the incited fotoplast flow down and out of the canal and keeps it from becoming solid

 

[BadgerMcBadger]

Typically what’s recommended is that you cure the mold with the opening facing up long enough to get your desired shell thickness (usually 1.5-3 mm). Then you’ll turn the mold upside down to finishing curing. This lets the incited fotoplast flow down and out of the canal and keeps it from becoming solid

how do i know i reached desired shell thickness? also which negative mold material should i use? i tried the gelatine glycerin mix and it didnt end well

 

[citiesandshapes]

For me it was a lot of trial and error to get desired thickness. Cure time depends on your material, strength of your UV light, etc, so you’ve got to play around with if. Even just a couple seconds can make a significant difference.
I use mold making silicon for my molds. It’s more expensive than glycerin, but I got better results and the molds are quite tough so can be used repeatedly

 

[BadgerMcBadger]

For me it was a lot of trial and error to get desired thickness. Cure time depends on your material, strength of your UV light, etc, so you’ve got to play around with if. Even just a couple seconds can make a significant difference.
I use mold making silicon for my molds. It’s more expensive than glycerin, but I got better results and the molds are quite tough so can be used repeatedly

can i poke the sides with a dental tool or will that ruin the shell? also, thanks for the answer

 

[BadgerMcBadger]

also, which mold sillicone do you use?

 

[citiesandshapes]

also, which mold sillicone do you use?

I’ve use this and it has worked well. It’s mixed 1:1 by weight, so a kitchen scale is helpful
https://a.co/d/6sqCnPm

As far as poking the shell, I’d avoid that. When you do the initial cure it will still be somewhat flexible. You should be able to eyeball the thickness by looking at the edges of the top of the mold.

My process is usually pour —> initial cure —> cure upside down —> remove from mold —> final cure for several minutes in glycerin to avoid the sticky inhibition layer

 

[BadgerMcBadger]

I’ve use this and it has worked well. It’s mixed 1:1 by weight, so a kitchen scale is helpful
https://a.co/d/6sqCnPm

As far as poking the shell, I’d avoid that. When you do the initial cure it will still be somewhat flexible. You should be able to eyeball the thickness by looking at the edges of the top of the mold.

My process is usually pour —> initial cure —> cure upside down —> remove from mold —> final cure for several minutes in glycerin to avoid the sticky inhibition layer

since the bottles seem the same size and have the same weight i can just mix them by volume right?

 

[citiesandshapes]

since the bottles seem the same size and have the same weight i can just mix them by volume right?

Should be able to-I use a scale just to be double sure because it’s important to the silicone curing correctly

 

[BadgerMcBadger]

how do i keep the paraffin wax from sticking to the negative mold?

 

[BadgerMcBadger]

how do i keep the paraffin wax from sticking to the negative mold?

Should be able to-I use a scale just to be double sure because it’s important to the silicone curing correctly

i dont have a scale sadly. did you ever notice if the volume ratio is much different than the weight ratio?

 

[citiesandshapes]

how do i keep the paraffin wax from sticking to the negative mold?

i dont have a scale sadly. did you ever notice if the volume ratio is much different than the weight ratio?

So the paraffin won’t stick to the silicone as they don’t interact with each other. After the mold is cured you be able to carefully pick out any bits that stuck. Though for waxing I’d recommend this
https://a.co/d/2OhJAUo

It’s a slightly thicker, more flexible wax and I got smoother molds and less flaking vs pure paraffin

For measuring the silicon, appears the weight/volume is the same so they’re the same density. You should be able to measure 1:1 by volume and be ok

 

[BadgerMcBadger]

So the paraffin won’t stick to the silicone as they don’t interact with each other. After the mold is cured you be able to carefully pick out any bits that stuck. Though for waxing I’d recommend this
https://a.co/d/2OhJAUo

It’s a slightly thicker, more flexible wax and I got smoother molds and less flaking vs pure paraffin

For measuring the silicon, appears the weight/volume is the same so they’re the same density. You should be able to measure 1:1 by volume and be ok

thanks. sadly i already bought a bunch of parrafin because shipment is expensive and i wasnt expecting having to order new mold materials. thanks for the help though

 

[swtnate]

thanks. sadly i already bought a bunch of parrafin because shipment is expensive and i wasnt expecting having to order new mold materials. thanks for the help though

The issue with silicone for molds is the transparency causes the shell to flash cure sometimes and you get some ridges and stress lines on the external layer you will have to contend with.

 

[piotrus-g]

When going to shorter tube lengths, keep in mind that THD increases when you being the drivers closer to sound bore. I would recommend nothing shorter than 12 mm.

THD is not really a concern with BA for high frequencies, anything above 2-3kHz 99% BAs handle well, unless you are stressing over 0,03% vs 0,028% ...but then there are bigger variations between BAs themselves

Hi guys, I've decided to go with a simple GK build this time, starting with the green damper on TWFK and red on the CI, as a start point.
I'm more interested in tubing size and what's worked well for others, before experimenting too much.
Most of the tutorials I've found online seem to go with the first option that in the pic that I've added below, but wouldn't having a 1mm ID be less than ideal for the high's of the TWFK?
I can fit 2mm ID tubing (like option 2) inside my custom shells, but it's been a crazy tight squeeze in previous builds.
Would option 3 be a good compromise with the 1.5mm ID tubing? Or a mixture of the three options?

What's been everyone's tubing method with any simple GK builds?

I would not listen to anyone who recommends option 1.
Do not use anything smaller than 2mm ID for TWFK otherwise you will kill all usable high frequencies and with 1mm ID you'll move first peak to honky 1,5kHz it will sound like a low quality radio.
For CI use any of the above options, but TWFK 2mm ID is necessary unless you are going for something like a horn with combination of 1mm or 1.5mm and 2mm.
You didn't specify lengths of tubing you plan to use. My recommendation would be anything between 12 and 18mm.

How could I confirm that should I Reverse CI/3300 when using WBFK from TWFK or single WBFK? I have tried both way to connect the driver, I feel like when I connect all of them in normal +/- way, sound of wbfk is gone. When I connect it reversed, it sound more "". Thanks

When it sounds more - then it's the correct polarity

Has anyone tried Knowles RDU? Seems to be a dual version of RAU. Would two RAUs be beneficial or is one good enough?

Check a few (maybe 20) pages back, I think there was a discussion about RAU/RDU already