Jack 15 and SLA Build - A First Time Experience

[Traijin]

Hello all,

I have written a few posts for what was my beginning project. Here is how things have transpired.

I started out wanting to build a pair of Jack 15s for PA's. I purchased 4 sheets of Baltic Birch and started cutting. As of now I have access to a Grizzly 10" table saw with a full shop built saw table and a 20' miter station. This easily took care of the panel cuts.

I already owned a decent jig saw and several bar clamps. The Jack baffles are cut out and the duct and throat panels are glued in place. The reflectors and bases have been cut as well as the tops, sides, and braces. They all need to be fitted, but belt sander makes that easy.

So, I have to still cut the backs, the mouth panels, plug discs, and rings. I have since purchased a router and both jasper jigs to cut the radius stuff. Obviously this was a significant expense. Given the fact that I will have an extra sheet of birch, I decided to further justify the jigs and router by building a second pair of speakers. So SLA away.

These will be home speakers. If I am going to put this much effort into the build, then I want something that looks excellent. So, my intent is to 45 miter the baltic for the cab top, bottom, sides, and back as to hide and endgrain. Then pore fill all the plywood and continue on with a deep piano black finish. The baffle will be Curly Maple. I have already picked up the 4/4 X 9" board X 9'... it is beautiful.

I have a brand new blade to rip the maple and new 2 flute 1/4" straight bits, flush cut bits, 1/4" round off and 1/2" round off bits. Since the maple is so hard and prone to burning, I will postpone any more assembly on the Jacks to cut the maple with as sharp a tool as I can.

It is amazing how it was just a matter of logic to double the size of my project, but I imagine that is not uncommon around here.

I will post pictures as I can.

Traijin

[Tom Smit]

It is amazing how it was just a matter of logic to double the size of my project, but I imagine that is not uncommon around here.

...and the addiction starts.....

[ewetho]

Can't wait to see your SLA's. Are you gonna do the center channel too?

It is addicting.

[Traijin]

I will do a center channel eventually, but that is a few projects back in line.

I got the Jack reflectors placed and the braces placed this weekend.

I also got the SLA Front Baffle ripped, and all holes opened. I also built up the SLA Baltic Birch back cabinets.

As previously stated, I was a rough/form carpenter years ago. My idea of accuracy revolved around 1/8", That doesn't cut the butter in this world, more like 1/32" or 1/64" here.

Here are some of the lessons learned so far:

1) A router is critical, I picked up a basic Craftsman plunge/fixed base for just over $100.00. I also bought a two flute 1/4" straight and flush cut 1/2" shank bits and a 1/4" and 1/2" round over bits.

2) I bought a Jasper Jig for circle cutting... spend the money here, especially for an SLA. This was crucial for a perfect layout.

3) Curly Maple is some hard wood. Don't sand over 120 grit or you run the risk of burnishing the wood, not good for finishing. Also, after cutting all 30 holes with the new 1/4" bit, the bit is cooked. I can still cut pine or birch, but if I were to do another SLA, a new 1/4" bit would be in order. VERY hard wood.

4) Layout, although not difficult to do, somethings take experience. I layout the two SLAs and cut the holes. It was time to sand so I layed out the baffles next to one and other. I screwed up. Since the speakers are not bi-laterally symmetrical, than they should have been mirrored... instead they are identical. I now have to use a face of the wood that I never intended to show the world. Live and learn.

5) I had intended on altering the design of the SLA and mitering all the corners. After assembling most of one cabinet, I had to abandon the idea. I do not have access to a panel saw or other precision equipment needed to cut a perfect length and square to the world cabinet. I can and did, jig up the rest of the panels in a butt joint condition. Take the time to build jigs. It is worth the effort. Corner clamps are also very helpful for holding a 90.

6) I did extend the cabinet height to 38-1/2". I want to display more of the maple. The cabinet will have a sealed bulkhead where the design shows the height of the cabinet to be. This also gives me floor standing speakers at the height I like.

7) The maple was warping after I ripped and cross cut. I was concerned until I cut the holes. That stress relieved the material and it sat back down. Store wood like this on a flat surface, not leaning against the wall. (FYI)

Buy a box of rubber gloves. This glue takes 2-4 days to wear off your fingers.

9) A Senco 18 gauge pin nailer is a blessed device. This has helped to pin the long cabinets flush and square. Huge advantage.

10) I ended up have four different sanders plugged in at the shop table. A palm sander with 40 grit for shaping and heavy, heavy material removal, a palm with 120 grit, an orbital with 150 for the birch, and a mouse with 120 for the detail.

I will try to post some pictures this week. This coming weekend I have to sand the SLA cabinets, flush cut the SLA baffle and mount the Jack baffle assembly on the bottom Jack panel.

[KeithHeadley]

Hi Traijin

I had a project I did (in aluminium) where we had the "mirror image" error . . .


Most annoying . . .

Sounds good sofar! Good luck and we look forward to pics!

[Traijin]

I have skim coated the SLA cabinets with body filler which also filled any inconsistant joints and pin nail holes. I ordered the Speaker components from Speaker Hardware yesterday, when they arrive I can test fit the baffle then run the flush cut on the baffle.

This is an interesting build, an odyssey is the right terminology. Started to think about the finishing coatings and went back to my high end wood working supply store. When I decribed a piano finish, the guy looked at me like I had lobsters crawling out of my ears. He couldn't tell me anything about pore fillers or hand rub finishes.

So I went to the Sherwin Williams store. They were unable to help me either since this was a wood work finish, not commercial or house paint. He did give me a number for their industrial coatings branch. So, I gave them a shout this morning. Sherwin William acquired a company called Sayerlack about a year ago. Sayerlack manufactures a rubbable polyurethane finish that is meant for musical instruments. I am having the rep put together a prime, base coat, and clear coat system for the piano finish. Next step is the pricing, I will find out how much they protect their dealers. If the cost is ridiculous, I'll call in a favor from one of my painting subcontractors to get the coatings picked up at a fair market price. We shall see.

[Gregory East]

If you set the site search engine on "piano finish" you'll find a T18 iirc , gobsmackingly beautiful. There was a bit of a how-to with it.

[Traijin]

Yeah, I saw that post along with a few others on this site for piano style finishes. I see the need for supreme prep work, much like painting a car body, This procedure reminds me of painting my 1970 Chevelle. Lots of patience and block sanding. The finish system I have found is a two part base coat and top coat. Both paints are a two part catalyst system. The top coat is a urethane high build, flexible clear coat that can be buffed.

Most of the information I have found on the net for a piano finish revolve around the hand rubbing aspect, but tell little about the products used. The paint rep has answered all my questions and I have setteled on a Sayerlack product. The TU0202/22 is a black basecoat, and the TZ7090/00 is the clear topcoat. The top coat has a sheen value of 90, this will require the least amount of buffing and polishing. The store will sell to the general public, lead time is about a week to stock the paint and it runs about $60.00 per gallon for each component plus the catalyst.

Soon it will be time to break out the HVLP gun, but I still have a lot of sanding and fitting to do and some pictures to take.

I will have plenty of finish left over... enough for a Table Tuba perhaps... This is a sickness.

[Traijin]

So, I looked into what it will take to use my basic HVLP gun. I have not used this in a decade and no longer have access to the paint shop and compressor I used to. I own a basic pancake compressor, which will not make the cut it for volume. I have access to a beat up 220 volt 30 gallon compressor which will likely create the volume I need. There is some market ambiguity for measurement of the volume of air produced. In the construction world we operate off of cubic feet per minute, this makes sense regarding volume, however the HVLP guns typically rate needed volume in SCFM. I would guess that would mean square feet per minute, which makes little sense for volume.

Regardless, the compressor I can use is 220 volt which limits where I can use it and it needs some help. I have no idea when the last time the tank was drained, it could be rusty. I also have no idea when the last time it was oiled or if it even needs oil. All this adds up to a PITA, not to mention the gun I have is very basic and its rubber seals are probably junk.

So, I explored other options. I am strongly considering picking up this finish kit.

http://www.earlex.com/hv5000.php

No more problems with water from compressed air, 110 volt, can hadle any finish type, multiple options for needle and seat, and its portable. I found it new for about $265.00 delivered. The finish is turning out to be very expensive, but furniture style finish cannot be done on the cheap. I need to find the specific gravities and viscosity of duratex to see how far I can thin it out while still maintaining the finish appearance. It would be nice to know if I can get a needle and seat size large enough (2mm?). I would love to spray apply the durtex on my Jack 115's. I will do some more research.

[Bill Fitzmaurice]

I would love to spray apply the durtex on my Jack 115's.

This is what works best for that:

http://www.harborfreight.com/air-tools/ ... 66103.html

[Traijin]

Thanks Bill,

I figured that may very well be the case. Those orifice options are huge compare to what I can do with the turbine system. Well, I had origanally intended on rolling the Jack finish anyway. I still have to spray a high temp paint on my pig cooker, so this system still makes sense in the long run for the thinner finish types. I have even seen videos of a guy shooting latex with this setup. Still weighing my options. Long day of sanding tomorrow to look forward to...

[Traijin]

I received my tweeters, woofers, and crossovers from Speaker Hardware today for the SLAs.

When I routed the holes for the SLA baffles I started on the larger holes. I had intended on installing the woofers on the surface and the tweeters on the back just as the drawings. I had assumed the speakers I would be receiving would be the same as shown in the drawings. They are not or have been through a design revision. These speakers look to be better suited for back mount. I have read plenty of posts on here for adding gasket tape and surface mounting, can this be done in a manner which will be hidden from the eye? I ask because I was still on the learning curve with the jasper jig. The user must apply slight inward pressure on the final pass to insure the edge of the hole does not get nicked by the bit when the center of the whole is cut free. I have two holes that have a minor nick, but had fixed my technique by the time I set the tweeter holes. The other eyesore would be a knot/stick in the wood that I have to drill out an epoxy to avoid a failure point. This simply will no look good in a back mount situation. Do I have to go with "speaker gasket" or can I use some 1/4 inch high density foam tape?




1) Tweeter
2,3) The Stick/knot problem I have to cut out and epoxy or it will fail.
4)Woofer
5) A few speakers in place, I still intend on back mounting the tweeter.

[LelandCrooks]

The other two drivers are on the way. Came in today, will ship tomorrow.

[Chris_Allen]

You could always remove the gasket to make them look better with a front mount.

I would agree that would look better as a rear mount in current form. The correct router bit would allow you to slightly recess the drivers for a front mount and a flush finish. If you are feeling brave, recess a little deeper and apply a very thin, almost veneered, wood ring on top.

[DJPhatman]

My vote is round over the front of the woofer baffle holes and rear mount the drivers. I would also rear mount the tweeters, letting the fine finish of the baffle wood shine through.

Unless they are already loose, don't mess with the knots. They give the wood "character", and add to the warm look of the wood.