[HT cOz]

I’ll be sharing my build of Rick’s Ceramica kit.  Let me first start by thanking a few people who have been very helpful bringing this project to realization.  First thanks to Rick for creating a great kit and making it available to DIY customers.  Rick has been great to work with on this project.  I also need to thank Ivica who goes by Bassivus on DIYAudio.  Ivica is a very talented artist whose speaker project on diyaudio caught my eye and has graciously agreed to help me design the Translam Cabinet. 

Now a confession, I’m not sure I’ll be able to complete this project as it is greater is scope than any of my previous builds or work.  I’m willing to try and maybe even fail but am happy to be on the journey and share my learnings in this thread.  To make it even more challenging, I’m living in India and wil be working this project in a culture vastly different than the USA and in languages which I’m not familiar.  However, India also has its advantage in great craftsmen, technology, and lower costs than back home.

So with that let it begin..

[HT cOz]

I received my first teaser rendering from Ivica this morning and I’m already really excited.  I like the scale and shape of the design.  It looks great to me. 

I’m also checking dimensions by Primary school method.  Better safe than sorry when it comes to a project like this.  I’m also going out today to check out what kind of wood is available.  I’ll try to snap some pics to give you an idea of what its like to navigate a project like this in India. 

Here are a few photos...

First look...


Checking future cuts


Lined up CNC shop today





Front baffle will be two 18mm sheets of Baltic Burch laminated together.  The bass port will be shaped during the CNC process








Continue to work on the shape of the internal surfaces and the overall shape.  The internal shape is sculpted to reduce standing waves and reflective surfaces.





A few pics of the work on the midrange box.






More eye candy


























Thanks for following...

[steve1580]

Similar footprint to what I am working on now, with Rick's Essenza kit.  Great start, looks to be a great project!

[Nick77]

Looks awesome! Subscribed..........   

[HT cOz]

Similar footprint to what I am working on now, with Rick's Essenza kit.  Great start, looks to be a great project!

Your build is going awesome, it’s like the big brother!

[HT cOz]

Design work continues on the front baffle.  It is fairly thick at 36mm and we need consider the back wave of the driver and how a thick baffle can be made without negativel impacting the sound of the speaker.  Here is an example of techniques that work and don’t work.

[gab]

Design work continues on the front baffle.  It is fairly thick at 36mm and we need consider the back wave of the driver and how a thick baffle can be made without negativel impacting the sound of the speaker.  Here is an example of techniques that work and don’t work.

from http://www.troelsgravesen.dk/chamfer.htm

[bassivus]

Hi everybody! Just want to say hello to everyone here. I'm helping @ HT cOz on design of the box. Really enjoying this stuff 

[Tyson]

That speaker is going to be a work of art!

[Norman Tracy]

Hello HT cOz and welcome to AudioCircle Ivica who goes by Bassivus.

As a builder of several translam projects and follower of many more I have a bit of advice I want to share while the design remains in CAD before the sawdust flies and glue is uncapped.

Allow some mechanism for compliance between the baffle (grey in your renders) and speaker body (red in render above). As the baffle and speaker body undergo changes in temperature and humidity the wood or MDF will grow and contract. I have seen translams fail when the baffle moves in the up/down direction and when solidly glued to the laminated body pull open the layers causing cracks. Like this sad case http://www.htguide.com/forum/showthread.php?42594-My-first-project-is-a-4-way-speaker.

From page 12 of the above linked thread:



It is like the furniture making issue of attaching a table top or cabinet top to its legs or base. Its wood and they are going to move, at different rates. For furniture slotted screw clamps are favored. For a speaker like this I would use a bolt on baffle or glue it on with an adhesive that retains some flexibility like RTV.

When the entire speaker is translam like my FA120A build seen below this is not an issue. The trade off is the high stress time when machining the driver and other holes when one slip writes off the entire box!

[steve1580]

Hello HT cOz and welcome to AudioCircle Ivica who goes by Bassivus.

As a builder of several translam projects and follower of many more I have a bit of advice I want to share while the design remains in CAD before the sawdust flies and glue is uncapped.

Allow some mechanism for compliance between the baffle (grey in your renders) and speaker body (red in render above). As the baffle and speaker body undergo changes in temperature and humidity the wood or MDF will grow and contract. I have seen translams fail when the baffle moves in the up/down direction and when solidly glued to the laminated body pull open the layers causing cracks. Like this sad case http://www.htguide.com/forum/showthread.php?42594-My-first-project-is-a-4-way-speaker.

From page 12 of the above linked thread:



It is like the furniture making issue of attaching a table top or cabinet top to its legs or base. Its wood and they are going to move, at different rates. For furniture slotted screw clamps are favored. For a speaker like this I would use a bolt on baffle or glue it on with an adhesive that retains some flexibility like RTV.

When the entire speaker is translam like my FA120A build seen below this is not an issue. The trade off is the high stress time when machining the driver and other holes when one slip writes off the entire box!

As an amateur but somewhat experienced woodwooker I have to ask about the separation of the joint you've shown.  To me it looks like a glue separation problem and not something you could attribute to wood expansion.  Just curious?

[HT cOz]

Hi everybody! Just want to say hello to everyone here. I'm helping @ HT cOz on design of the box. Really enjoying this stuff 

Bassivus welcome to AudioCircle we are lucky to have you here.  Your work so far is inspiring and its as if you read my mind of what this build could be!

[HT cOz]

Hello HT cOz and welcome to AudioCircle Ivica who goes by Bassivus.

As a builder of several translam projects and follower of many more I have a bit of advice I want to share while the design remains in CAD before the sawdust flies and glue is uncapped.

Allow some mechanism for compliance between the baffle (grey in your renders) and speaker body (red in render above). As the baffle and speaker body undergo changes in temperature and humidity the wood or MDF will grow and contract. I have seen translams fail when the baffle moves in the up/down direction and when solidly glued to the laminated body pull open the layers causing cracks. Like this sad case http://www.htguide.com/forum/showthread.php?42594-My-first-project-is-a-4-way-speaker.

From page 12 of the above linked thread:



It is like the furniture making issue of attaching a table top or cabinet top to its legs or base. Its wood and they are going to move, at different rates. For furniture slotted screw clamps are favored. For a speaker like this I would use a bolt on baffle or glue it on with an adhesive that retains some flexibility like RTV.

When the entire speaker is translam like my FA120A build seen below this is not an issue. The trade off is the high stress time when machining the driver and other holes when one slip writes off the entire box!

Norman thanks for stopping by and sharing your experience.  It's valuable to have real world advice on this because it is basically an expensive time consuming experiment.  However, I've looked at Translam builds for years in admiration and always wanted to give one a go. 

Its like you read our minds... Bassivus and I spent a lot of last night discussing this very post and coming up with a mitigation strategy.  So far we are thinking the following:
1). Lots of glue and not excessive force while clamping
2). Seal cabinet inside and out with Bitumen Paint or Glue
3). We changed to 360 style cutouts which will consume more wood but should also be stronger
4). We are floating the front baffle with 3 inside screws and 3 outside screws (six total per side)

We are still thinking about a thin layer of Sorbathane to further isolate the baffle and allow movement.  Not sure yet on this.  I need to check out RTV glue.  I think we might make the baffle removable.  You can see some of the change in thinking in these renderings.

Now 360 parts instead of C style


Speaker view without floating baffle attached


Target look



If you guys have any hints or tips, we are all ears.  As you say changes in the digital realm are quick and easy, once the sawdust if flying changes become painful. 





   

[HT cOz]

As an amateur but somewhat experienced woodwooker I have to ask about the separation of the joint you've shown.  To me it looks like a glue separation problem and not something you could attribute to wood expansion.  Just curious?

Steve in reading the thread it was a bit of mystery, but the final consensus is that the cabinet shrank in low humidity and the baffle didn't.  That shrinkage forced the crack. 

[steve1580]

Steve in reading the thread it was a bit of mystery, but the final consensus is that the cabinet shrank in low humidity and the baffle didn't.  That shrinkage forced the crack.

I think I understand, but what is confusing is a glued joint is much stronger than the wood plys themselves, so to see such a clean separation suggests to me a problem with the glue joint. 

[EdRo]

This does look very sweet! Great job!!!

[bassivus]

Hello HT cOz and welcome to AudioCircle Ivica who goes by Bassivus.

As a builder of several translam projects and follower of many more I have a bit of advice I want to share while the design remains in CAD before the sawdust flies and glue is uncapped.

Allow some mechanism for compliance between the baffle (grey in your renders) and speaker body (red in render above). As the baffle and speaker body undergo changes in temperature and humidity the wood or MDF will grow and contract. I have seen translams fail when the baffle moves in the up/down direction and when solidly glued to the laminated body pull open the layers causing cracks. Like this sad case http://www.htguide.com/forum/showthread.php?42594-My-first-project-is-a-4-way-speaker.

From page 12 of the above linked thread:



It is like the furniture making issue of attaching a table top or cabinet top to its legs or base. Its wood and they are going to move, at different rates. For furniture slotted screw clamps are favored. For a speaker like this I would use a bolt on baffle or glue it on with an adhesive that retains some flexibility like RTV.

When the entire speaker is translam like my FA120A build seen below this is not an issue. The trade off is the high stress time when machining the driver and other holes when one slip writes off the entire box!

Hello, Thanks for the welcome and for valuable building experience info!
I have some building experience also and I'm quite aware of the climate/ temperature/ humidity issues. I'm fighting that with my instrument - 150 year old Double Bass, whole my life and have read a lot on the subject. Plywood shrinks the most on the material thickness side and that multiplied with layer count makes the problem above.
Those things must be taken  into consideration when doing the design, so Robert and me changed the design as he already reported.

We welcome all the opinions and advice!
 

[HT cOz]

Hi everybody! Just want to say hello to everyone here. I'm helping @ HT cOz on design of the box. Really enjoying this stuff 

I continued to be amazed at how well you are realizing the concept!!!







Saw dust coming soon...

[Steidl Guitars]

I think I understand, but what is confusing is a glued joint is much stronger than the wood plys themselves, so to see such a clean separation suggests to me a problem with the glue joint.

I'll second this.

[Norman Tracy]

I'll second this.

Steidl and steve1580,

The failure photo I posted was from a project by Steve Manning who frequents the htguide.com Mission Possible DIY forum.

Here is one of Steve Manning’s builds in partnership with JonMarsh. These are laminated bamboo plywood picture from page 24 of the long detailed build thread. http://www.htguide.com/forum/showthread.php?43049-Minerva-Monitor-quot-Patience-my-ass-I-m-going-to-go-build-something-quot



Steve wrote about the failure he suffered in a previous project:

“Hey Ryan ..... after I had mine crack I did a lot of research online into the issue. First, I was rather surprised by how much the BB actually moves over time, I thought it was a lot more stable. That being said, sealing it helps but will not stop it it completely. I think the biggest part is learning to work with it and not constrain the layers from moving. What I found in most cases where these projects crack and what I did myself, is we glue the baffles, backs, sides, what ever, in place across the lamination's. This "try's" to prevent the wood from moving ....... not.

If you look at say what Magico did when they used BB with the aluminum baffles and backs for their cabinets ..... they had o-rings in the baffles and backs and the two were bolted together as a unit. That way they floated independent to the wood portion of the cabinet. That way the BB could breath as needed without cracking.

This is of course all conjecture on my part, but I don't think I'm too far off.

Steve”


So restating what I read Steve saying and the opinion I have is yes “a glued joint is much stronger than the wood plys themselves” and that is exactly the issue. The baffle glued at a right angle to the laminated buildup moves most along its length and when solidly glued to the plywood or MDF stackup that movement can cause a failure. HT cOz gets it and now has in his design an air tight interface between the horizontal laminated sections and vertical baffle.

Here are a couple of pics of my last translam design, the baffle is glued using RTV with ~1/16” ~2mm clearance space all around between horizontal laminated plywood layers and vertical baffle.





Another hint/encouragement to HT cOz is I see in the renders holes I presume are for alignment. Good! Aligning the layers during the glue-up is vital unless you enjoy descending into sanding purgatory where time stands still as innumerable sanding sheets clog and sanders’ motors expire. I have tried the following alignment methods:

• All-thread metal rods. The idea was to get both alignment and clamping. Big fail, if the alignment holes are large enough to get the plywood down the all-thread the layers do not align with sufficient tolerance. Also a builder on DIYaudio.com who did a six foot tall translam line array and left the metal rods in suffered cracks when the differences in the thermal expansion characteristics of wood vs metal happened.
• While gluing manually align each layer and pin with brad nails. Better but makes gluing (even more) slow and tedious and is still prone to misalignment.
• Use wood dowels in holes as in your render. Best solution I have used, my speaker shown above used ¼” dowels in ¼” holes and the layers were very well aligned after glueup. I used the short dowels one can buy precut for making doweled wood joints. I would not use long dowels, they will bind up as you try and slide the layers down them. I had extra alignment holes so when layers 1 & 2 filled a hole I moved over to the adjacent hole for layer 2 & 3. Then the original hole is available again. Or you could custom cut dowels long enough to align but short enough not to fill the hole so it remains available for the next layer. In your renders I see 8 alignment holes. In my experience 4 is plenty so you could alternate which four you use as the layers are added. Final doweling hint is if like me you only drill the alignment holes partly through the top and bottom layers check the dowel length protruding to align that top plate. I almost cracked one when the alignment dowel bottomed in its hole.