My first project is a 4 way speaker...

[JonMarsh]

Pretty small differences... the soft of thing that can be swamped out or changed by diffraction effects...

And best of luck with the crack repair...

[cochinada]

This gives an idea of how small or how big, depending on the point of view, the old and the new spike pads are.
Now if I could only remember where I put my anti-gravity device...

[Steve Manning]

This gives an idea of how small or how big, depending on the point of view, the old and the new spike pads are.
Now if I could only remember where I put my anti-gravity device...

Image not available

Big difference there ..... I'm with you, I wish Via Blue's were a little bigger to begin with.

[JonMarsh]

Now THOSE are MANLY support pads! Where did you get these new ones?

[cochinada]

Now THOSE are MANLY support pads! Where did you get these new ones?

Indeed . I got it on eBay here. They come in two sizes and I got the most beefed ones.

[JonMarsh]

Indeed . I got it on eBay here. They come in two sizes and I got the most beefed ones.

Thanks for the link. Ordered, on ET's behalf...

[cochinada]

Much better with these MANLY pads as Jon calls them. In fact so much better that now I can easily slide the speakers around the floor. :banana:




I've also applied the epoxy with a spatula although I didn't bother to lay the speakers on their sides. It was much harder than I anticipated as I only had 90s to apply the stuff on both speakers and I'm not at all pleased with the result. I didn't have enough epoxy to start with. Anyway, for the moment I'm letting it dry before I try to sand it a little. :roll:

I've learned one lesson: for speakers this size if you want a flawless finishing you better paint them. As all of you who followed this thread know I had them built and the final result came out way short of my expectations that were very high. The worst part is since I had to fight with these issues of the CNC not being calibrated the wholes are not perfectly round. They seem more like an elipse. So even if I wanted to paint it now I'm afraid I simply can't because with the thickness of the paint my drivers would not fit the holes any more. In fact my new tweeters were a little larger than the previous ones and I had to sand the holes a little to be able to fit them.

[Steve Manning]

Much better with these MANLY pads as Jon calls them. In fact so much better that now I can easily slide the speakers around the floor. :banana:

Image not available

Image not available

I've also applied the epoxy with a spatula although I didn't bother to lay the speakers on their sides. It was much harder than I anticipated as I only had 90s to apply the stuff on both speakers and I'm not at all pleased with the result. I didn't have enough epoxy to start with. Anyway, for the moment I'm letting it dry before I try to sand it a little. :roll:

I've learned one lesson: for speakers this size if you want a flawless finishing you better paint them. As all of you who followed this thread know I had them built and the final result came out way short of my expectations that were very high. The worst part is since I had to fight with these issues of the CNC not being calibrated the wholes are not perfectly round. They seem more like an elipse. So even if I wanted to paint it now I'm afraid I simply can't because with the thickness of the paint my drivers would not fit the holes any more. In fact my new tweeters were a little larger than the previous ones and I had to sand the holes a little to be able to fit them.

New discs are looking good. By the way even with the out of calibration cnc these still turned out very nice. I think you will find that your expectations are always higher than what you get. Perfection is more of a goal than actually something you can obtain. At least that's what I have found .... if you take the lessons you learn for each project and apply them in the future, each will be better than the last.

I also think you might find painting will be less tolerant of surface imperfections than a natural finish like you did here ...... Ron would be the one to ask on that though.

Also if you have a small scrapper you might find that will give you a better finish than sanding the epoxy. That's what I used when I had to do the same repair and it worked rather well.

[cochinada]

This is way beyond perfectionism in my book. The image speaks for itself: just look at the baffles. They are not aligned with the respective sides of the boxes. Clearly something went wrong with the measurements as we are talking about 5mm! To be honest I must add that this is much worse now than it was one Year ago and I suspect the wood have been expanding or contracting during this time. Take your pick.

Anyway, this is what I suspect to be the reason why I have the huge lateral gap between the top box and the MTM as the taller baffle pushes against the MTM raising the top box way above what it should. On the other hand the MTM baffle came out shorter. How does one fix that? If these were to be painted I reckon that with a lot of sanding and filling it would be possible to align both baffles but with this natural finishing I don't know...

Image not available

[Steve Manning]

Amazing how much wood can move over time isn't it. 8O You are right about being able to resolve some issues with filler and painting it over though. A bit more forgiving over all.

[cochinada]

Amazing how much wood can move over time isn't it. 8O You are right about being able to resolve some issues with filler and painting it over though. A bit more forgiving over all.

Yes indeed and it is why I believe that with proper isolation, stabilization and painting this wouldn't have happened.

[TEK]

I'm not to sure about that. I suspect that the cause here is the combination of two different materials that has different attributes regarding how moist affects the lenght.
Having all materials stabilized a looong time before assembly might have helped, but the risk is that it would change anyway if you later on moved them to a location with a different moist level.

For this design it might have been better to separate the baffel from tha rest and have it attached using screws and a gasket. At the same time having a design where the baffel and sides was not aligned closely so that relative lenght changes is not very visible.

However, this does not help you with your current issue.
But you should be aware that the changes you are seeing might be caused by season climate changes. Making them perfect now might not make them perfect in 1/2 year...

[cochinada]

I'm not to sure about that. I suspect that the cause here is the combination of two different materials that has different attributes regarding how moist affects the lenght.
Having all materials stabilized a looong time before assembly might have helped, but the risk is that it would change anyway if you later on moved them to a location with a different moist level.

For this design it might have been better to separate the baffel from tha rest and have it attached using screws and a gasket. At the same time having a design where the baffel and sides was not aligned closely so that relative lenght changes is not very visible.

However, this does not help you with your current issue.
But you should be aware that the changes you are seeing might be caused by season climate changes. Making them perfect now might not make them perfect in 1/2 year...

But I'm using only Baltic birch. Unless by saying "two different materials" you mean that it's a translam construction on the round sides whereas the baffle and all the other panels are not. This is true.

We have a moderate climate on Winter and hot Summers but luckily my home is not humid at all so I have difficulties blaming the weather as the culprit. What I notice is that right at the beginning the panels, specially the baffles, were not so well aligned like I wrote at the time and this has become worse and worse due to these strange phenomenons with the wood. I summoned my carpenter to come and evaluate the situation and I'm expecting him today so let's see what he thinks.

[Steve Manning]

I think allowing the baffle to "float" relative to the rest of cabinet would have done the trick. I did the same thing as you and glued and doweled my baffle in place, I got cracks. If you look at what Magico did with the Mini as well as other models with BB and aluminum, the baffles and backs were connected as a unit with long bolts. This allowed them to move independently to the stacked lamination's in the rest of the cabinet. I found that out after the I had built mine.

[cochinada]

I think allowing the baffle to "float" relative to the rest of cabinet would have done the trick. I did the same thing as you and glued and doweled my baffle in place, I got cracks. If you look at what Magico did with the Mini as well as other models with BB and aluminum, the baffles and backs were connected as a unit with long bolts. This allowed them to move independently to the stacked lamination's in the rest of the cabinet. I found that out after the I had built mine.

Yes, I agree with that approach as it makes perfect sense but only to avoid cracks. However even so, I reckon one would still see gaps appearing as the wood expands or contracts. For instance, imagine the baffle would contract. Then you would have gaps around it or isn't so?
In my case it's too late to think of such a solution anyway...

[Steve Manning]

Yes, I agree with that approach as it makes perfect sense but only to avoid cracks. However even so, I reckon one would still see gaps appearing as the wood expands or contracts. For instance, imagine the baffle would contract. Then you would have gaps around it or isn't so?
In my case it's too late to think of such a solution anyway...

I would think you see gaps coming and going, though I sure you could design things to minimize to a point it's not noticeable. Your certainly right about that being an option for you at his point, unless your looking for something to do ....... a major cabinet rework would certainly fit the bill.

[TEK]

Even if it's all baltic birch, a translam construction and your baffel will contract and expand very differently. The direction of the wood have a lot of inpact and how it will behave. The point is to take this into account in the design.
Regarding a mount on baffel and visible gaps. The clue would be to design it so that the changes would not bee visible.
For examle by having the baffel overshoot the cabinet by 1/2" on all sides - or other simular technics.
Ome possible option for you might be to add another baffel, say 18mm thick, on the outside of the baffel you have and let that overshoot the exising baffel and body on all sides - and integrate that into the current design.
Would not fix the cracks, but could fix the problem with edges not lining up...

[ergo]

On my Minerva-s I used a 45 degree chamfers on the edges around the flat front panel pieces. I figured that even if I do CNC most of the parts I probably will not get these parts to match so well that it will not show up a bit. I also added some same colour silicone filling to the gap. So far so good but it's been less that half a year.... (spitting over shoulder now 3x )

[cochinada]

Even if it's all baltic birch, a translam construction and your baffel will contract and expand very differently. The direction of the wood have a lot of inpact and how it will behave. The point is to take this into account in the design.
Regarding a mount on baffel and visible gaps. The clue would be to design it so that the changes would not bee visible.
For examle by having the baffel overshoot the cabinet by 1/2" on all sides - or other simular technics.
Ome possible option for you might be to add another baffel, say 18mm thick, on the outside of the baffel you have and let that overshoot the exising baffel and body on all sides - and integrate that into the current design.
Would not fix the cracks, but could fix the problem with edges not lining up...

Interesting option of a second baffle but I'm afraid that would cause diffraction issues due to the discontinuity in height and aesthetically I'm not found of the idea.

My carpenter has just left the building and he suggests the cracks are caused because of moisture that was trapped inside and is now trying to get out but due to the treatment he made it takes a long time to do so. He also confirmed that the baltic birch his supplier gave him is top grade. For instance, all layers are uniform with 1mm thickness each or so. We also discussed that it would have been much better to opt for curving enough layers of baltic birch to make the round sides instead of a translam as it is. Lesson learned.

Regarding the options he gave me two to fix the cracks on the sides:
1) cut the sides vertically and evenly spaced in order to insert two or three fillets to stabilize the whole thing.
2) make two holes and insert two huge or MANLY dowels from top to bottom on each side.

Option 1 would imply to paint the whole speakers as I don't want to see fillets interrupting the pattern I have right now on the sides.

As such I'm going to give option 2 a try. He will also fill the gaps with a special wax in the same color and hopefully everything will be much better.

From my side I'll have to dismount all the drivers, which is worrying me immensely because they are really really tight and I'm afraid some will not be easy to remove at all.

What do you think of this plan?

BTW, Tek I like the words on your signature.

[cochinada]

On my Minerva-s I used a 45 degree chamfers on the edges around the flat front panel pieces. I figured that even if I do CNC most of the parts I probably will not get these parts to match so well that it will not show up a bit. I also added some same colour silicone filling to the gap. So far so good but it's been less that half a year.... (spitting over shoulder now 3x )

[ATTACH=CONFIG]27078[/ATTACH]

Don't spit too much
But yes, that was very good thinking! :T

[Steve Manning]

An idea for you for removing the drivers ...... http://www.htguide.com/forum/showthr...highlight=1071, look at post 205. Now, even though I did this with drivers not installed, you can still get a flat ended tap and should be able to get things threaded, you only need to do a couple of holes. Just run the bolts in and the driver pops right out.

[cochinada]

An idea for you for removing the drivers ...... http://www.htguide.com/forum/showthr...highlight=1071, look at post 205. Now, even though I did this with drivers not installed, you can still get a flat ended tap and should be able to get things threaded, you only need to do a couple of holes. Just run the bolts in and the driver pops right out.

I also went ahead and threaded two holes on each of the mids and woofer drivers so I could easily lift them in and out of the cabinet. I had been debating on doing this, but with the paint build up issue it seemed like the prudent thing to do.

[ATTACH=CONFIG]22030[/ATTACH]

Once I get this straightened out I can hopefully get these things finished and making some music !!

Very clever but what is this strange tool on the right of the picture? Is this something specifically designed to make threads? Is it a manual tool or what?

[Steve Manning]

Very clever but what is this strange tool on the right of the picture? Is this something specifically designed to make threads? Is it a manual tool or what?

Yep, that's the tap to make the threads. It's just a tee handle that accepts different thread cutters. As I recall in this case 1/4-20 threads and yes this is a manual tool. This will give you an idea for what's available, https://www.mcmaster.com/#taps/=16s2nsn. Just Google how to use a tap and go slow with the drivers, you don't want to crack the frame. FYI you will not need any lubricant, which is sometimes required depending on the material.

[TEK]

Steve, your post was the first i thought about when I saw cochinada's worry.
A great tip that should work here as well.
Cochinada: You get tap's at most hardware stores. Get a cheep set as you will probably not be doing that mutch tapping (you can make threads in hardwood as well - it's pritty cool ;-))
Also, as you might apply some force to get these out you must be careful to put something between your tools and the speaker baffel to be sure not to hurt anything.

The MANLY solution sounds good :-)

[TEK]

Other solutions:
- Add a front cover, like on the picture below. Will not fix the problem, but it will not be visible any more.
- Add some kind of visual separation between the top, middel and bottom that prononces and covers the problematic areas. Like a gasket or something.

[cochinada]

Other solutions:
- Add a front cover, like on the picture below. Will not fix the problem, but it will not be visible any more.
- Add some kind of visual separation between the top, middel and bottom that prononces and covers the problematic areas. Like a gasket or something.

Those look like fillets of some kind of wood but the idea of some sort of gasket is interesting indeed.

BTW can you guys please show me some links of builds with curved faces not using translam but curved sheets? I'm searching here in the forum but can't find many examples.
It's too late for me but I'm curious and would like to study the subject and see if and how I could have built mine in a different way.

[Steve Manning]

Those look like fillets of some kind of wood but the idea of some sort of gasket is interesting indeed.

BTW can you guys please show me some links of builds with curved faces not using translam but curved sheets? I'm searching here in the forum but can't find many examples.
It's too late for me but I'm curious and would like to study the subject and see if and how I could have built mine in a different way.

If your looking at how to do curved surfaces, this site ought to give you some ideas. http://www.curvomatic.com/

[cochinada]

If your looking at how to do curved surfaces, this site ought to give you some ideas. http://www.curvomatic.com/

Thanks Steve. Very interesting! Any build threads to look around?

Picking up TEK's suggestion, I'm thinking about using some kind of gasket in order to disguise the joint between the boxes. For instance here in red:

Image not available

Since I'm going to order gasket foam for my drivers...

Image not available

...I was wondering if I should use the same stuff for this purpose or do you think that a rubber material would be more suitable? I'm thinking to apply it all around the MTM as below:

Image not available

[dar47]

You take printer toner cartage black ink powder mix with epoxy and slowly build up the gap. Use quick setting and let the epoxy thicken a lot so you can get thicker layer in the joint with one pass. Just put tape on either side of the joint. Granted it will take time.

Gives a subtle effect, see the joint between baffle and top and sides of this build. Makes the joint not even noticeable. You can use your gasket material between boxes.

Image not available

[Steve Manning]

Thanks Steve. Very interesting! Any build threads to look around?

Joaquim, if you look towards the bottom of the projects section on the site you will find something on speakers.

[CraigJ]

Hi Joaquim,

I've followed your initial build and sorry about the movement in your BB. Although I don't quite have the talent as some members, my experience with woodworking would say to follow Steve's advice here; http://www.htguide.com/forum/showthr...l=1#post618681 I started making reproduction antiques 40+ years ago, and some of the furniture is still moving today.

My guess is you will most likely have more gaps from expanding and contracting in the future, and you might as well keep it simple. Using epoxy will allow you to add filler and tint if you want and with time, and will look very similar to a thin layer of BB.

Craig

[cochinada]

You take printer toner cartage black ink powder mix with epoxy and slowly build up the gap. Use quick setting and let the epoxy thicken a lot so you can get thicker layer in the joint with one pass. Just put tape on either side of the joint. Granted it will take time.

Gives a subtle effect, see the joint between baffle and top and sides of this build. Makes the joint not even noticeable. You can use your gasket material between boxes.

Image not available

Thanks for the suggestion.

Joaquim, if you look towards the bottom of the projects section on the site you will find something on speakers.

I've navigated already to page 4 but with not much luck.

Hi Joaquim,

I've followed your initial build and sorry about the movement in your BB. Although I don't quite have the talent as some members, my experience with woodworking would say to follow Steve's advice here; http://www.htguide.com/forum/showthr...l=1#post618681 I started making reproduction antiques 40+ years ago, and some of the furniture is still moving today.

My guess is you will most likely have more gaps from expanding and contracting in the future, and you might as well keep it simple. Using epoxy will allow you to add filler and tint if you want and with time, and will look very similar to a thin layer of BB.

Craig

:E I sure hope this won't happen to me. Anyway my cracks were really nasty as they were not 'even'. As such my try with the epoxy didn't go very well. :cry:

I'm gonna take the chance now and enlarge the holes a bit in case I decide to go and paint the boxes. I'm using templates as someone already did elsewhere with very good results.

Image not available

[lusk]

Did you seal the plywood layers on the inside of the enclosure? Going back through your build pictures l can't see that
you sealed the wood on the inside. I have also built stacked ply layer and has not cracked in many years +5 just
made sure wood layers were sealed inside and out. Something to consider as it may continue to crack.

[cochinada]

Did you seal the plywood layers on the inside of the enclosure? Going back through your build pictures l can't see that
you sealed the wood on the inside. I have also built stacked ply layer and has not cracked in many years +5 just
made sure wood layers were sealed inside and out. Something to consider as it may continue to crack.

I don't think my carpenter did it

[JonMarsh]

Indeed . I got it on eBay here. They come in two sizes and I got the most beefed ones.

Got mine in yesterday! :T

[cochinada]

Got mine in yesterday! :T

First impressions?

[cochinada]

So, I have a feeling of déjà vu but the challenge is immense. I don't know if it is because the drivers are removed but now this vertical gap on the baffle looks huge! I don't know what is worse...
I'm waiting for my carpenter to come and pick up this box first.

The gap...


and the crack...

[roadrune]

Hi, first of all, sorry if this has been adressed earlier, i only joined the forum today, and have just skimmed through this entire thread.

The cracks is IMO natural and logig, because wood tend to move alot more one way then the other, lengthwise (thinking the way the three grows) it is shrinking very littl, but the other way it is moving alot, when you have built the speakers like you have with the baffle using the "length" of the wood and the cab sides the "width" of the wood they will shrink and expand differently, and eventually crack, even with plywood this will be true, just not as much as if you used hardwood.

My guess to fix this permanently would be to either get a perfectly constant humidity and temperature in the room (almost impossible) or cover all the wood inside and out with something 100% water and diffution proof like epoxy...

Really sad though, its a beautiful build.

[cochinada]

Thanks roadrune.

Yes that makes perfect sense. The most curious is that the crack happened exactly in the middle of one entire layer but not between two different layers. So the problem was not with the gluing but with the material itself which according to my carpenter was of the highest grade available here and this wasn't supposed to happen this way. I think it's also possible to see on the picture that half of the piece has cracked in one direction and the other half on the opposite direction. Weird stuff really...

Anyway, after much pondering I decided I'm going to paint them. I think, under the circumstances, that it is the best way to solve all these visual problems with the gaps and so on.

Unfortunately it's not possible anymore to cover the inside walls with epoxy or any kind of material as there is no access to most of it. This is even more the case since they are already completely filled with acoustic stuff and with the cables soldered to the rear terminals which I'm not going to remove. Just the thought of it makes me tired and anyway it wouldn't help. There was a chance perhaps to have done this before gluing the outer panels but now is too late I'm afraid.

For those who are curious I've decided to go with.... piano black. :P

Yes, I know it will reveal all minor imperfections if the preparation is not up to the higher standards but I'll give it a shot, mostly because the only color that I find in harmony with my living room would be some sort of metallic red dark tone but I already have a pair in red and I want something different.

[roadrune]

Nooooo, not black!

It would be a shame to hide all that nice wood...

[cochinada]

I'm afraid not hiding the wood means living with all the flaws and possibly becoming worse with time so...

Image not available

[LFM2]

I recommend you look into having them wrapped with 3M vinyl for cars. It is durable and will look as good as paint. It will expand and contract with humidity without splitting and can be removed and replaced quite easily. I would worry that paint will crack as the wood moves and then it will be difficult and expensive to repair. I would be tempted to just wrap them and wait a few years for them to stabilize. I would then unwrap them and if things hadn't deteriorated much then repair.

[Steve Manning]

I recommend you look into having them wrapped with 3M vinyl for cars. It is durable and will look as good as paint. It will expand and contract with humidity without splitting and can be removed and replaced quite easily. I would worry that paint will crack as the wood moves and then it will be difficult and expensive to repair. I would be tempted to just wrap them and wait a few years for them to stabilize. I would then unwrap them and if things hadn't deteriorated much then repair.

Good idea .... I agree, I don't think these cabinets are done moving around and putting time and money into a nice paint job will be a waste.

[Juhazi]

^^ and ^Wise advice!

[cochinada]

I recommend you look into having them wrapped with 3M vinyl for cars. It is durable and will look as good as paint. It will expand and contract with humidity without splitting and can be removed and replaced quite easily. I would worry that paint will crack as the wood moves and then it will be difficult and expensive to repair. I would be tempted to just wrap them and wait a few years for them to stabilize. I would then unwrap them and if things hadn't deteriorated much then repair.

I never thought about that but certainly sounds like a terrific option. I already saw come cars wrapped in vinyl and indeed they look like they were (very well) painted. Nevertheless I have to consider some points:

1 - My carpenter has now also a paint shop for which he will charge me nothing as this is a repair job according to him.
2 - I don't think he has ever used vinyl before and from what I've seen it still takes a considerable amount of skills to do a neat job. My experience in the area is none.
3 - Vinyl is a bit costly, specially when we talk about the material needed for a pair of speakers this size.
4 - And this is the big question: are these stabilized already after more than one year or not?

Anyway I've sent him an email with this possibility but he hasn't returned it yet.
Bottom line is that for now I have the option of painting basically for free but being subject to some future hazards. On the other hand if I go with vinyl this will cost me something right now.