OTop12 Build Thread

[AntonZ]

Move the tweet over to Slot #2. Note that the previously cut side is against the fence


And that's how you trim the top and bottom of the tweeters.

Cute little jig
How do you keep the pizzers in place while cutting? Do you manually hold them in place? I would advise to have some sort of blocking stick or something that holds it in place so you can leave your hands well away from the spinning blade. Other than that, great progress and thanks for sharing.

[Bas Gooiker]

You are probably done by now. But this thread has some clever piezo cutting solutions.
http://billfitzmaurice.info/forum/viewt ... ting+piezo

[miked]

Thanks, Bas. I looked at that thread and while it's got great safety tips, there's nothing in there relating to proper trimming of the top/bottom tweets in the melded array. If I don't get some clarity by tonight, I'm just going to cut the 45 first, then decide which top/bottom frame to cut.

I still need to build the gluing jigs. For the straight arrays, I think I'm going to build something similar looking to the actual array braces on the speaker. The two strips of wood hold the array nice and flat...perfect for gluing.

[miked]

Move the tweet over to Slot #2. Note that the previously cut side is against the fence


And that's how you trim the top and bottom of the tweeters.

Cute little jig
How do you keep the pizzers in place while cutting? Do you manually hold them in place? I would advise to have some sort of blocking stick or something that holds it in place so you can leave your hands well away from the spinning blade. Other than that, great progress and thanks for sharing.

I was using a block of wood. Not as elegant as the clamping mechanisms the pro guys have built. If I was making arrays in quantities, I'd build a bigass multi-slot jig like Harley's. Now THAT is slick.

[miked]

Sorry Grant; didn't see this on the previous page. This helps a lot. Thanks for taking the time to type it up!

I also cut the 16 tweets (top and bottom) for the 2 melded arrays I'm building, but I stopped there b/c I'm confused about the top and bottom tweets of the melded array. The plans say "cut the bottom frame off one, the top off the other." I'm confused b/c the tweets are symmetrical. If I cut the "top" frame off one, I can just flip that upside down, and now I've cut "the bottom frame" off, no? Is the "top off one, bottom off the other" b/c after you cut the 45, you have to flip one tweet to get it to meet the other at the 45-degree angle? I think I get it...there's a little clarity there, but I'm still not sure.

I am thinking it might be best to cut all the top/bottom tweets at the 45, and then determine which edge to cut off. I have 3 spares, but would rather not have to use them.

I don't want to screw this up. Would someone please expain the process of cutting the top and bottom tweets? Thanks.

Ok, I'll try lol

For each melded array, there needs to be 4 of the piezo's done with cut no1 only.

The uncut edge forms the very top (2 piezo's) and the very bottom (2 piezo's) of the melded array. Much the same as the flat array.

All piezo's inbetween have cuts 1 and 2.
Then all piezo's have the 45 degree cut, but pay particular attention to the orientation of the piezo you are cutting, especially for the top and bottom ones.

Remember, you're working upside down now, so, for the piezo that ends up being top left of the array when completed, the uncut edge is furthest away from you on your cutting sled/jig, but gets placed on the right hand side of your assembly jig.
The other top piezo is cut at 45 degree with the uncut edge nearest to you on the sled/jig, but rotated to place on the left side of the assembly jig with the uncut edge uppermost.

For the bottom piezo's, it opposite, so
Uncut edge nearest to you, goes on the right hand side of the assembly jig.
Uncut edge farthest away from you, rotate to place on left hand side of the assembly jig.

All the piezo's inbetween can just be run through, rotating every second one to place on the left of the assembly jig.

Hope this helps...

[miked]

New question: What size roundover do I use for the small, plastic chevron corners? I know it's either 3/8" or 1/2" but cannot remember which.

[AntonZ]

I'd say run both bits over a block of scrap wood and see which fits your corners best.

Good to see you used a block to keep your fingers away from the blade. I fear that blade when it is running. I had an uncle who had been a carpenter all his life. He lost a finger to the big ass table saw in his workshop well after his retirement. It made quite an impression on me. And Harley is quite the jigmaster indeed.

[Bruce Weldy]

New question: What size roundover do I use for the small, plastic chevron corners? I know it's either 3/8" or 1/2" but cannot remember which.

Pretty sure that I did the 3/8" on mine....I think the 1/2 is a tighter fit, but I didn't want to take off that much of the joint...and they fit just fine. Plus, it keeps you a little farther away from any brad nails that you shot in there.

[miked]

I'm very happy to say that I am DONE cutting piezos and still have all my digits. Now I have a clue why Leland charges what he does for a built array. Cutting these things simply sucks...and I haven't started gluing yet. LOL! I only screwed up ONE tweet and cut it on the wrong side. Glad I bought spares.

Two pics, then I'm back to work.




The other 45-degree tweets with the straight cuts are just fine too.

Thanks for the helpful hints on cutting these; they were a tense part of this build.

Think rather than glue them up (haven't built that jig yet), I'll get back to the cabs themselves. They need some lovin'.

[miked]

New question: What size roundover do I use for the small, plastic chevron corners? I know it's either 3/8" or 1/2" but cannot remember which.

Pretty sure that I did the 3/8" on mine....I think the 1/2 is a tighter fit, but I didn't want to take off that much of the joint...and they fit just fine. Plus, it keeps you a little farther away from any brad nails that you shot in there.

Yup. And in my slopiness, I've got plenty of brads within about 1/8" from the edge. Thanks for the tip.

[bmf]

One quick comment: Don't use body filler if you are using a latex based coating such as duratex. The off gassing of styrene and peroxide will not play nice with the latex. You may not have a problem, especially if it sits a long time before coating, but not worth the risk in my book. Light fill spackle will sand easier and is what duratex recommends under their product. I've been following this thread and would hate to see your cabinets peel in the sun after all the care you have put into them.
Great looking build and excellent documentation by the way.

[Bruce Weldy]

One quick comment: Don't use body filler if you are using a latex based coating such as duratex. The off gassing of styrene and peroxide will not play nice with the latex. You may not have a problem, especially if it sits a long time before coating, but not worth the risk in my book. Light fill spackle will sand easier and is what duratex recommends under their product. I've been following this thread and would hate to see your cabinets peel in the sun after all the care you have put into them.
Great looking build and excellent documentation by the way.

I used bondo, then flat black latex paint, then duratex... no problem at all. And they've been in the hot Texas sun.

I however, do indeed start off-gassing in those conditions.

[miked]

One quick comment: Don't use body filler if you are using a latex based coating such as duratex. The off gassing of styrene and peroxide will not play nice with the latex. You may not have a problem, especially if it sits a long time before coating, but not worth the risk in my book. Light fill spackle will sand easier and is what duratex recommends under their product. I've been following this thread and would hate to see your cabinets peel in the sun after all the care you have put into them.
Great looking build and excellent documentation by the way.

Thank you, bmf. I will have to read up some more on this. I know zip about Bondo and peroxide and gasses. I do know that lots of folks like Bruce have used it and had no problems. I will peruse Acryltec's website and see what I can find. Thanks for the kind words too.

*edit*
Hmm. In this Duratex video, they say "Spackle or Drywall Compound does a great job."
http://www.youtube.com/watch?v=Y5N_CND233M

They don't specifically say "Don't use Bondo." So I emailed the company and specifically asked about Bondo. We'll see what they say. Better safe than sorry, ESPECIALLY at this point. I used Duratex once before on my bass cab...I think I used wood putty to patch the holes...pretty sure I did. But that was one large cab with not a lot to patch. Not 4 medium cabs with a ton of stuff to hide...er...pretty up.

Holy crap. For grins, put this stuff on your cab and never worry about anything again! http://www.youtube.com/watch?v=lAsoTOxwAGI

[biggerrigger]

Bottom line with Duratex and Bondo is on the same cab with a scratch say from a small pebble or a screw head in a trailer floor ect. The area with,
Dtex and bare wood= No problem.
Dtex and Bondo= You will re-Dtex that area.
Black paint+Dtex= I don't know as I have just used Dtex on wood with no paint as a bottom coat.
The very few scratches that I do have on my cabs that show any color other that the black Duratex are directly over a area that had Bondo applied and it did not adhere no where as well as the areas that had the Dtex applied to the bare wood. The areas that received the coating to bare wood are very durable(No pun intended) and are holding up very well. The same cannot be said about Dtex over Bondo or the spot puddy for that matter.
Just for reference I used brand new containers of Bondo Gold and Bondo Glassing Puddy on my builds and have used them both several times over several years and I am very familiar with these products and how they work under an automotive finish.
Just to recap.
Duratex over bare wood= Awesome product,Very tough,Very durable.
Duratex over anything else= Use caution with handling.
This has been my findings on BB built cabs.

[miked]

Very informative, biggerrigger. I really appreciate you sharing your considerable experience with Duratexed cabs. I've only Duratexed one cab and it rarely leaves the house, and when it does, I'm the only one who moves it and I'm very careful not to ding it up. It is two coats of Duratex over bare wood.

I got the tweet glueup jig built too. I made mine 28" long so I could do two arrays at once. Bit of a PITA getting the ledges the tweets sit on totally even side to side. AFterall, we're talking about 1/32" making a noticeable difference in how the tweets meet up. That took me the better part of the evening.

In other news, I'm disgusted with the cab backs I made. You may recall from a few pages back that basically, they are a 1/4" to 5/8" short in both dimensions (partially my fault as they were 1/8" too narrow to begin with) AND I've already predrilled all the mounting holes at 1/2" up from the edge. Yes; I could fill them and drill new holes but it wouldn't look right. As the panels currently sit, there really isn't a way to ensure that all the mounting screws get good purchase; some will sit right, some would probably bust thru the inner edge of the panel braces. So, I'm redoing the back panels. This will also give me a chance to make the recesses the correct size for the proper cab mounted Speakons. Talking about this:



So I'm cutting new backs tomorrow. They will be 13 7/8" x 20 7/8". And I wont' cut them short this time. My cabs are not square, so there might be a little hand-fitting of each panel, but not too much sanding will be needed. I will cut up the old backs and get my new back panel braces out of them...at least I'm thinking ahead.

Why screw it up now by settling?