Yes, the inside got 3 coats of PU lacquer to seal the wood. The outside had 6 coats of the same lacquer for a mirror finish plus a stain was applied underneath (not on the inside).
It did not keep this tall of an enclosure from developing cracks due to expanding/contracting. The moisture trapped inside the wood apparently was enough to cause this much movement/force.
At the time I applied epoxy, the inside was painted with epoxy as well, with a white pigment added instead of the black on the outside. The outside has 2 layers of black boat paint to protect it from UV degradation.
It did not keep this tall of an enclosure from developing cracks due to expanding/contracting. The moisture trapped inside the wood apparently was enough to cause this much movement/force.
At the time I applied epoxy, the inside was painted with epoxy as well, with a white pigment added instead of the black on the outside. The outside has 2 layers of black boat paint to protect it from UV degradation.
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Looking to make a six sided sub, so it just makes sense to use slices.
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Looking at it, yes, I can imagine why you would think of that type of construction. However due to being a closed shape the amount of waste material would be huge.
With my "U" shaped profile I could interlock them to reduce this waste.
I do see options of building this without using translam construction though.
With my "U" shaped profile I could interlock them to reduce this waste.
I do see options of building this without using translam construction though.
Easier is a relative term when you own a CNC... I know I can't cut with the repeated precision equal to the pushing a button.
but I've cut bevels on a CNC. You can get large enough Vbits for standard angles and cut them quickly, and, if you aren't paying by the hour for machine time, you can do arbitrary angles with repeated passes of a small ball nose bit and spread sheet math to figure out the toolpaths. but that is OK. Do what you want, its your design. If I owned a CNC, I'd probably be doing something with glue lam technique.
Is that one sub with two passive radiators, looks interesting.
Is that one sub with two passive radiators, looks interesting.
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Yes 18" plus two 18" PRs.
I don't deny it could be done the traditional way on the CNC with relative ease. But I guess like the OP I am just looking to do something a little different.
What I am concerned about is... Is my desire to push boundaries and doing things different going to be at the determent of the box? I have seen this method used plenty of times before but none have reported issues, that doesn't mean they didn't have them, but they probably didn't document the build like the OP for it to show up.
I don't deny it could be done the traditional way on the CNC with relative ease. But I guess like the OP I am just looking to do something a little different.
What I am concerned about is... Is my desire to push boundaries and doing things different going to be at the determent of the box? I have seen this method used plenty of times before but none have reported issues, that doesn't mean they didn't have them, but they probably didn't document the build like the OP for it to show up.
I think the box will be fine without anything fighting normal expansion and contraction in the orthogonal to the plane of the slices direction. Then it should expand/contract as a unit w/o stress. You have full freedom to thicken it where needed to support the drivers and resist vibration and can incorporate braces in the layers. Too bad a lot of wood will be wasted but it is in a good cause. Wesayso just had extra challenges due to the height.
Think of the great looking wooden horns you could make this way if CNC time is unlimited!
Think of the great looking wooden horns you could make this way if CNC time is unlimited!
I hate to admit it but doing it the conventional way with a 60 degree V bit does make more sense on this particular project. I would lose my rolled over corners, but since I am not doing the wave inside (make no difference at very low frequencies) I can leave this technique for the rear speakers where I was planning to use the inside wave and more shapely cabinet.
The only difficulty might be in trying to put two layers over the top of each other.
The only difficulty might be in trying to put two layers over the top of each other.
Oh I have I plans to change my OB woofers to a cabinet in the near future. So that could be some interesting cabinets right there. I built the CNC specifically to make my own speakers.
Tell me about it, I have about 30 drivers still in boxes waiting for new homes.
About half way this thread (*), when I reported my misfortune, quite a few others came forward with similar stories.
I figured it would be more helpful to others if I reported about the cracks, it might give readers input to think about with their own plans for similar constructions.
Looking for cracked translam and pictures in Google does give a hint that it has happened to others, even in constructions way less tall than mine.
~ Yes, my thread is in there too
~The height of my stack certainly has had an influence. But for the plans you have, more conventional methods might be more sane. I can tell you, it was no fun! Though it was a valuable lesson and has been set right in the end.
You can still put the CNC to good use by using an interlocking construction for the corners.
(*) it used to feel like half way, but as this thread has become enormous, it's actually at the beginning now (lol).
Looking for cracked translam and pictures in Google does give a hint that it has happened to others, even in constructions way less tall than mine.
~ Yes, my thread is in there too
You can still put the CNC to good use by using an interlocking construction for the corners.
I did a bit of a search and like you say it isn't an isolated incident. Glad I spotted this thread before I spent $1000 on wood.
Would need to give it some serious thought how to interlock the corners.
I did a lay out and I can do it, but will need to lose 50mm off the width no real biggy as I can just add 50mm to the height to roughly compensate.
I also have a big table saw I bought about 7 years ago but never put together. That is an option for the angled cuts.
If I did two 25mm layers I could screw all the internal bracing in with long screws, and use the second layer to cover all the screw heads.
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Too bad even shorter translams have cracking issues.
re' big table saw:
pay special attention to the fence and alignment. If you have a fence that locks down square to the blade then the mitre cuts are relatively routine. Get a digital angle gauge to set the angle and go for it. I used this for the angles in my horn for which I couldn't get Vbits. The hard part is starting the angled cut exactly on the desired line but, working in wood, its not as critical as a perfectionist tends to think. But if you are cutting by hand you can always start slightly oversize and then shave the edge down until it fits
You can get router bits for interlocked corners. I've never tried them on a CNC or otherwise but they look like they would work.
re' big table saw:
pay special attention to the fence and alignment. If you have a fence that locks down square to the blade then the mitre cuts are relatively routine. Get a digital angle gauge to set the angle and go for it. I used this for the angles in my horn for which I couldn't get Vbits. The hard part is starting the angled cut exactly on the desired line but, working in wood, its not as critical as a perfectionist tends to think. But if you are cutting by hand you can always start slightly oversize and then shave the edge down until it fits
You can get router bits for interlocked corners. I've never tried them on a CNC or otherwise but they look like they would work.
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The question is whether its worth the trouble. I think it is. Once you go CNC, you can cut wood more accurately than you can hold it in position for gluing, especially when angles other than 90 degrees are involved. This behooves you to design so that parts self-align. Dados, interlocking corners and so forth. Dadoes have always been problematic for me. They often come out too tight or too loose depending upon how close a particular piece of plywood is to nominal thickness. I've resolved to do my final drawings and toolpaths based on the measured thickness of the acclimated actual sheet of plywood but this doesn't work out.
As a CNC owner instead of occasional user, how do you deal with this?
Rather than hijack the OP post, we can continue discussion over on my build thread here The mother of all subwoofers build
Thanks wesayso for your very valuable input.
Thanks wesayso for your very valuable input.
Metaplugin looks a great tool or swiss knife that said for free think its still possible get a single or multible or even multible of same VST work on up to 6 channels (three stereo sets), in the serial tree place the first L/R VST most upstream then a PEQ container including one or more "Mix channels" to get the job done so that L/R are swapped around with other channels, then the second L/R VST and now a second PEQ container that swap channels before the final and third L/R VST plugin. Probably it will mean swap of what channel really comes out on what physical output jack down stream onto soundcard but that should be to easy to find out. To use same VST and have it show up more than once in the serial tree is doable in make some more physical copies of VST dll-file and add for example a number two three four etc to file name, then install them copyes as a new VST plugin as many times as wanted, license from the first one will work on the rest of them. Should it happen routing politic inside those "Mix channels" starts a scary endless feedback loop then use multiple "mix channels" to get the right policy done, for example for various exercises i often need to route L/R stereo signal to both channels and it involves 4 times "Mix channel" adds over to AUX busses U1/U2 and then 2 times "Mix channels" move back again to L/R buss plus empty of those AUX busses.
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I'm just glad I found Metaplugin, as the above had crossed my mind, but the Metaplugin VST is way easier for me in day to day use. 
It can load multiple instances of VST plugins without trickery, you get a visual (I like that!) of the routing you do... with 6 channels in use now, moving to 8 channels very soon, I'd be scared to loose my way. Do I make Stereo listening too complicated?
It can load multiple instances of VST plugins without trickery, you get a visual (I like that!) of the routing you do... with 6 channels in use now, moving to 8 channels very soon, I'd be scared to loose my way. Do I make Stereo listening too complicated?