# Which Should I Do First?



## jlk103144 (Mar 26, 2012)

Some time ago I made a pair of hexagon speaker cabinets. I got stuck on the top sound diffusion lenses, but that's a whole other story. In this case, I did not run into any important problems putting the boxes together. here is the pair.



The sap wood made the walnut heart wood really stand out. Here are some pics.







My biggest mistake then was that I put the cabinets together first, and added the veneer second. The result was a lack of perfectly veneered joints. 

I'm seriously thinking about making a second set, and giving my grandson these, as soon as I get the lense making down pat. Naturally, I want to do the next one correctly. 

So here is my question: Prior to putting the veneered sides together, should I put some form of finish on them, so as to keep glue from becoming a real problem later when I need to finish them? Oh, regardless the finish, I will be using shellac as a sealer. 

And lets say I don't finish the veneer until after I put the cabinets together, how would I thoroughly remove any glue that would make a mess of the veneer edges?


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## Marco (Feb 21, 2009)

Well John the speakers look great. I love hexagons and walnut. The only help I can give you is the glueing. I beleive it was BobJ3 who had suggested for me to try vinegar and water at a half anf half mix in a spray bottle to clean up the glue while fitting the wood. It works really good for me. As a personal preference I prefer to finish after glue up however I have read that some in certain circumstances finish before hand making sure to not have the finish spread on to the joint.


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## jlk103144 (Mar 26, 2012)

Right now, I am having one terrible time making a two piece diffraction lense out of urethane. The first time I tried, I ordered too little silicone(one quart total) for both pieces of the ceramic 'blank' I had made on a potters wheel. Then I took the plaster I had, and tried to make an outer 'mother' mold as a solid backing for the silicone. What a disaster. I've had it made for two weeks now, and it still feels as wet as the next day after I poured it. Plus it's unbelievably heavy. Here is a hand made picture of the original idea(on the right), and what I have changed it to now(on the left). Obviously the left example has more balance. Also, both renderings are scaled.
Pardon the primitive nature, but I still have not learned my copy of SketchUp, or any drawing program. 
 

So, I'm taking a different approach to using the mold and making the urethane lense. First, here are what the two ceramic pieces look like.





The top one was what I was originally going to use on the bottom, to be topped with a slightly rounded top. But I never really scaled it out. When I did scale both possibilities, clearly the left one is the best looking, in my opinion. So that is what I am going to switch to. 

Also, the bottom picture was just a spare piece to be used on a smaller hexagon cabinet, should I wish. I had it sitting in the bedroom walk-in closet. I am going to incorporate it into this project. The original sample(upper pic), is larger than the new sample(lower pic), and will be the top half, facing upward. The smaller sample, which is smaller in diameter and height, will be used on the bottom half, facing downward. 

I'm doing this because I will need to make the total diameter of the finished lense assembly about 2.5 inches bigger in diameter. That would make the lense 16 inches, which is the distance from corner to opposite corner of the hexagon cabinet. 

I can take cabinet grade 3/8 inch plywood, and cut an exact opening of the bottom lense(for the inside), and route out an exact circle for the outer edge. I will do the same thing with the larger lense, which will make the edge of the urethane lense assembly right at 3/4 inch thick, and with a little filling, can make the assembly flow together. 

However, the bottom outer portion of the plywood, will sit under the outer edge of the top lense, and support the entire assembly. Let me see if I can find an image showing how this would work. 

Here is one:










If you closely examine the top lense of this drawing you can see that the bottom half of the black outer section, sits under the top part, and thus acts as a support, while it is held up by the outer metal tubes. But I will not really need a second lense assembly. What it is there for is mainly to add symmetry and balance for the opening with relation to the lower and upper cabinet parts. Besides, if you are going to charge around $40,000 for a pair, you need to add as many trimmings as possible, right?

You might be tempted to say that the easiest thing to do would be to turn two halves, times two, on a large lathe. But I tried that, and even took a special lathe class in order to make two pair. All I did was practically ruin the instructors favorite all carbide turning tool, by completely dulling it. Here is what one of the 'blanks' looked like, and one half of one of the turned pieces taking shape before dulling the turning too..





There was still a lot of work to do on just that one half of one lense assembly, but not worth ruining several turning tools. That's why I went with the potters wheel, and made those samples for a possible mold. 

Anyway, I got very frustrated, and just walked away from the project, hoping to resume later. But "later" was slow in coming, until I finally got sick of looking at my unfinished job every time I went into the basement shop where I work to make custom items for the interior design business. I finally figured I would have to either throw them out in order to just get them out of my sight, or give it one more go. So I'm giving it one more go. 
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And when I finish the critters, I am going to give them to my grandson for his birthday come July. If I don't have the finished by then, I will never finish them. And you know what? I don't even like walnut. It's just too dark and dreary for my taste. And the only reason why I used the walnut was because I had fallen in love with a beautiful example of a pair of hexagon speakers skinned in a totally unique pattern of Santos Rosewood. But I couldn't find any Santos remotely like what I fell in love with. So I finally settled for the walnut, with the sap wood as accent. If I get this pair finished, I will apply my lessons learned and use something like Black Limba. Something that has life, and grabs one's attention.
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But this time, I'm going to make a good mold, with silicon for the inner part, and brushed on urethane for the mother mold outer shell. That way I can make the urethane mold parts, and let the silicone allow me to remove it, without damaging anything, allowing me to reuse it as many times as I like. 

After I finish the silicone part, and the mother mold, I'm going to trim the edge, and use a sealed and painted piece of plywood for the 'lid'. I can turn the mold upside down and attach the lid to the first half of the mold. Oh, and the lid will have a fairly good size hole in the middle, which will allow me to pour in a special mix of urethane, and pecan shell powder. This coat will be applied to the entire mold, so the lense will have a wood look. Once that has had a chance to set, I'll apply a couple more heavy coats of regular urethane, in order to give the shell enough thickness as to be very solid. And once that has set, I'll use a urethane solid foam mixture, in order to fill in the hollow piece portion and help deaden the entire lense.

I'll repeat the same thing to the other half of the lense assembly and when they have thoroughly cured, I'll fuse, or glue, the two parts together, and have one piece. And all the drilling will be done on the plywood outer shell, which I will finish.

It all sounds so easy, but I am completely new to the art of pouring urethane resins, so I am going to be learning as I go. So I'm going to order enough urethane to practice a couple of times until I get the procedure down fairly straight. 

Woodworking is something I can handle, with the right tools. After all, I was able to put the two hexagons together fairly well. But working with molds and resins is a whole other animal. You wouldn't believe the number of videos I have watched on some of the resin maker sites, as well as YouTube. I can go over them in my sleep, but doing something for the first time is still a daunting process. 

Sorry for the extra long post, but it is not anywhere as detailed as this project. And the more I think of it all, the more I realize that I have bitten off more than I can easily chew. Let's hope I can get the monsters finished. 

But getting back to the assembly of the next pair of speakers, I think I am going to use double the inner bracing, since I used brad nails the first time, and cannot do it the next. I'll have to rely on an almost perfect gluing and plenty of inner support bracing, like the picture in my first post, in order to keep it all together. 

I'll find some way to add plenty of bracing all around since I can't use a 30 degree angle routing bit. That is why I am worried about the glue. And that is why I will most likely rub in several applications of untinted shellac, to act as a finisher/sealer. The wonderful thing about shellac is that you can apply other things over it, or just use it for a finish, once you build it up.


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