Kevin's Curved Core Two Way Speakers

[kevinm]

Howdy all,

While (im)patiently waiting for my car to be built, I am finding anything I can do to keep me distracted. I had most of the parts for Paul Carmody's Core 2 Way speakers, so I am building a pair in curved cabinets to prep for re-doing my main channels (gotta keep myself REAL busy while I wait).

Finishing
I have some beautiful Hickory veneer I plan to finish these in. Will most likely keep it natural. Haven't landed on this quite yet. Open to ideas!

I've taken some pics of how I built the skeleton. Nothing ground breaking nor will I win any engineering awards, but better than my usual craftsmanship. I am improving about +1.5% each cabinet. Hehe.

After I made my template for the curve/shape of my cabinets, I cut out a ton of square braces/tops/bottoms. I trimmed some waste before heading to the router table (couldn't talk the fiance into a band saw for this project after ordering the car, so chop saw had to do).



Once I trimmed some waste, I brad nailed the template to my tops/braces/bottoms and headed to the router table for flush trimming.



For the braces, I traced 1in around the edge. Then drilled holes in the 4 corners and busted out the jig saw.



After the insides were cut out, I took them to the router table and applied round overs. Looking pretty good compared to my usual work



Because my rear baffle/rear board will need to fit flush with the curve of the sides, I needed to calculate what angle I needed to cut them at. I busted out this handy digital tool to calculate what angle I needed to cut. To find out what angle I needed to set my track saw at, I subtracted 90 from 105.3. So I set my saw at 15.3 degrees.



I was smarter than normal here - I cut one section 3/4 BB ply the height of my cabinets. I then cut dados that my tops/braces/bottom will fit into. I Then cut my front and rear baffles out of that. This made sure all of my dados were at the same height.

Cutting my rear baffle at 15.3 degrees.



I wanted a removed bottom, so I have a brace at the bottom that my access door will bolt into. Since my floor spikes will be in the bottom access door, I needed it think. Test fitting below. So far so good.



Test fitting after all the baffles cut. Looking good



Quick pro tip before assembly. Lay out your tops/braces/bottoms and mark "top" on the tops of each one so you can easily keep track of their order.



Gluing up the skeleton



Adding rear baffle



Gluing the the first layer of the first side on. Nothing ground breaking here. I just repeated this step 3 more times for each side on each cabinet. I skipped the pics



Current status as of today

I've wrapped the entire cabinet in the 1/8in HDF and cut out the driver holes. Almost ready for finishing

[kevinm]

So I've ironed on veneer and cold pressed. Interested in trying contact cement. My veneer is paper backed. Which contact cement does everyone recommend?

[Jim Holtz]

So I've ironed on veneer and cold pressed. Interested in trying contact cement. My veneer is paper backed. Which contact cement does everyone recommend?

Hi Kevin,

I've used different brands over the years but Titan DX from Veneer Supplies is the one I like the best. It's easy to use and bonds extremely well.

HTH

Jim

[dar47]

Nice work! good idea with the 1/8" board it provides great corners.

Not a fan of contact cement as any little bubbling is more inconsistent to get it to lay down some times days after you put it on. Iron on is more consistent and PSA paper backed beats both. Most would say contact is for sub-straight applications like counter top or large paneling. With your curved application Tight Bond or heat lock iron on would be easier. If you haven't got your veneer yet and you can afford, try PSA. With PSA backed the veneer it can shrink back a bit so don't trim flush for at least a day and you will have tight joints. If you go with the contact show us your progress we may learn a thing or to!

[JonMarsh]

Nice work! good idea with the 1/8" board it provides great corners.

Not a fan of contact cement as any little bubbling is more inconsistent to get it to lay down some times days after you put it on. Iron on is more consistent and PSA paper backed beats both. Most would say contact is for sub-straight applications like counter top or large paneling. With your curved application Tight Bond or heat lock iron on would be easier. If you haven't got your veneer yet and you can afford, try PSA. With PSA backed the veneer it can shrink back a bit so don't trim flush for at least a day and you will have tight joints. If you go with the contact show us your progress we may learn a thing or to!

++1

I'm with Darrel on this...

[kevinm]

Thanks for the suggestions guys.

I've tried iron on about 6-8 cabinets with titebond 1 and I've never been able to get extremely reliable results. Always fought bubbles (probably moving too fast). Do you think heat lock would yield different results?

I'm in the mood for something new, so I am leaning towards trying contact cement on the sides and cold press on the flat parts. If I have bubbling, I can go back to iron on for my HT speakers that I am building next (another curved build).

Darrel - u fortunately I already have my veneer. It was a sale opfrom eBay seller, so didn't get the chance to try PSA. Hopefully I can get it for the next build - I've wanted to try it.

[dar47]

The problem with titebond 1&2, heatlock and contact cement is getting consistent layer across the whole surface. The titebond needs to be thinned a bit and mixed real well. I found 2 thin coats on the 1/8" hardboard and 1 on the veneer works best (small tight foam roller to apply). Yes it is less consistent when applied to MDF but worked well for me on the hard board. Heatlock is suppose to be applied unthinned and has a shorter re-reaction time as it is cross linked, again kind of thick. Contact cement is harder to get a consistent coat thickness across the hole surface and seams to absorb unevenly. It was developed for hard veneers like Arberite and plastic laminates and not idea for soft veneer woods. I tried it on 2 builds with the both coming out as my poorest work.

[Jim Holtz]

My experience is the same as Kevin's. I've used paper backed veneer with Titebond 1 iron on method and have always had to fight with bubbles. Titan DX applied per directions lays flat and sticks tight. I have several speakers including my line arrays going back 12 years using contact cement with no issues.

Just my experience.

Jim

[blue934]

I'm in Jim's camp. Have never been satisfied with iron on results but I've been using water based contact cement for over a decade without a single problem. I guess each to his own. I use 3M in a five gallon pail but the glue Jim linked looks excellent.

David

[Hank]

I'm not building speakers these days, but did for 10 years, using lots of paper-backed veneers (favorite is still Rosewood) and contact cement. Never a problem with contact cement - just carefully rolled on with a tight pore foam roller (as Darrel mentioned).
I tried Heat-Lock ~4 years ago and didn't like it very much - less even app than contact cement, but that may have been my being a newbie with it. Try PSA-backed - it will likely be 3M adhesive (I gotta quit shilling one of these daysops

[TEK]

I have tried contact cement on a couple of occuations, but I have never got it to work.
My problem is that the contact cement that I have tried is way to thick so it is impossible to lay it out evenly - so I'm unable to get a good even surface on the thin top layer beeing glued too the substrate.
I was told to try thinning it with aceton. That for sure did not work. If I just had a tiny bit too much aceton the glue would just separate and be usless (and that happens long before the contact cement was possible to rolle out in a thin even film)

Do NOT use this stuff:

http://www.casco.eu/no/casco-produkter-1/?pc=138&p=1012

(or if you do, at least get the proper thinner - aceton does not work...)

[JonP]

Don't know how many of the iron on crowd know about the supposed differences between the Titebond glue types. This has been around for a long time: http://www.webherrera.com/blog/2009/...-instructions/ and supposedly outlines the time you can do the heat reactivation after it dries. Basically, white glue, forever, TB1, 7 days, TB2 and TB3, 12hrs.

I've heard of a few folks having bad results, that realized they waited longer than the suggested time.

Personally, my few projects doing iron on seemed to go better when I had a good coat on both surfaces.

I've used the very thick, danger no smoking, contact cement... and also had trouble spreading it well. Haven't tried water based.

The cabs are looking nice.... can't wait to see them with veneer on!

[Face]

Never tried the iron on method, but have used contact cement and cold press method with TB3 successfully. The veneer on those builds has been stable for 5-10 years+

[Steve Manning]

I have used the Heatlock on several projects, with mostly good results. I say mostly because I have had a couple of issues that I believe were due to surface prep. I would advise reading through all the information on Joe Woodworkers site before giving it a try. I found this note most useful ......

"What kind of substrate can I use for my panel?
Heat Lock will work with a variety of substrate materials such as wood, plywood, MDF and particle board. Make sure the substrate is clean and porous. Some substrates can be made more porous by scuff sanding with 100 grit sandpaper. You can test the porosity of the substrate by placing a few drops of water on the substrate. If the water is not absorbed by the substrate within 10 seconds, you may find that the Heat Lock glue will not work."

This also applies to the veneer if it's paper backed ...... I believe this is where I ran into issues.

[flamethrower1]

I have also used heatloc on all of my builds and never had any issues.
As long as you apply a nice even coat with a hard rubber roller, I think it is very forgiving.
If you do have a bubble, simply go over it again with an iron and reactivate the adhesive.
My original Mini Statements are probably 8 years old now and look just as nice as the day I built them

[kevinm]

Booo...well, I wasnt able to finish these up before the car came. I had to re-prioritize a length garage project in preparation for the car that delayed me until about 2 weeks ago. The car came in on Friday, Good news is it's more beautiful than I even imagined. The smiles per mile with this beast are wild. We are having a blast.





I am hoping to get back to the cabinets soon - another week or so. I'm planning on wrapping them in Hickory veneer. I would like to do a smooth, satin finish. Something not really shiny. I'd just like a really smooth (grain-filled), satin finish that's fairly durable. Anyone have any pointers?

[flamethrower1]

That is a nice ride, love the color too

[JonMarsh]

Great color, Kevin- hope it turns out to be everything you expect! :T

[dar47]

Nice Cobra, are you brushing or spraying the finish?

If you brushing, I have had great results with filling the grain with sanding sealer, then an oil based varathan gloss 5 to 10 coats with sanding between coats to level. Remember varathan doesn't stick to it self without sanding between coats very well, 400 grit wet sanding takes care of this. Gloss is used for the build as there is no flatteners to dull the look through of the finish. When the finish is built up enough then 2 to 3 coats of satin is applied and can then be rubbed out. As you are using Hickory the oil base has an amber tint to it which should darken the wood a bit but would add some warmth to the finish. With a wood like Hickory you can use oil based as I have had issues with water based varathan delaminating if each coat is not thoroughly cured before sanding.

[JonMarsh]

Nice Cobra, are you brushing or spraying the finish?

If you brushing, I have had great results with filling the grain with sanding sealer, then an oil based varathan gloss 5 to 10 coats with sanding between coats to level. Remember varathan doesn't stick to it self without sanding between coats very well, 400 grit wet sanding takes care of this. Gloss is used for the build as there is no flatteners to dull the look through of the finish. When the finish is built up enough then 2 to 3 coats of satin is applied and can then be rubbed out. As you are using Hickory the oil base has an amber tint to it which should darken the wood a bit but would add some warmth to the finish. With a wood like Hickory you can use oil based as I have had issues with water based varathan delaminating if each coat is not thoroughly cured before sanding.

Listen to the man... he's obviously a serious finisher rather than just an amateur like me! :T

[kevinm]

Thanks guys! If the first week of ownership is anything to tell by, it's everything I coul dhave imagine. It's 50% classic muscle, 50% sports car and 100% hooligan machine. That 5.2l, 8,250RPM Voodoo V8 definitely brings out the hooligan in ya'.

Darrel, that sounds like just the ticket. I have the ability to spray, but it doesnt seem like the best way to achieve the finish I am looking for. I prefer a brush on (not wipe on?) method given the state of my workshop right now anyways. What do you recommend for a grain filler?

[dar47]

I like General Finishes it is water based but if you allow 2 days for cure it is an excellent base and grain filler and you can go oil based Varathane over it.

[kevinm]

O.K. Just so I am clear on the finishing process:

1. Final sanding on veneer
2. Build up coats of GF water-based to fill in the grain (are you talking about the Enduro stuff? https://generalfinishes.com/retail-p...r#.WB7eYeErLVo)
3. Once grain is filled, then switch to an oil-based Verathane (gloss) and do 5-10 coats with wet sanding between each coat
4. After sufficient depth is built, switch to satin do another 2-3 coats
5. Rub out finish with sanding paper and then 0000 steel wool

Does that sounds about right?

[dar47]

That's the stuff, you can use 400 grit wet sand between coats to your final rub out which I go up to 1000 grit then use a rubbing compound something like Turtle Wax rubbing compound. Not a fan of steel wool as you can leave debris in the finish. A satin finish is not as rigorous as a high gloss finish. When you get to 1000 grit let the finish fully cure maybe a week then rub out with the rubbing compound and wax.

An example of rubbed out satin, not glossy looking straight on but nice and flat and shinny looking across the surface.