myn's Tuba HT Build Thread

[WB]

I prefer to have as little contact as possible between the PL and paint and Duratex. Especially Duratex since it won't stick to PL at all. It would take roughly a minute to remove with a long bladed exacto knife.

[myn]

[== 08/09/2009 ==]

I went out to Home Depot today and had them mix me up a gallon of some flat black interior latex (Glidden brand).

Sanding BEFORE Applying Latex Paint?

I see many people are using the flat latex as a primer before the Duratex. Should I sand the wood BEFORE applying the latex paint? I see some posts saying use "40 - 60 grit" but perhaps that's just if you're going straight to Duratex and not priming with latex?



Sanding AFTER applying Latex Paint?

I see that most of the people that do primer with latex don't sand AFTER applying and just put the Duratex on immediately after. Here lies the confusion for me. I found a DuraTex PDF that states the following: "No primer is needed on bare wood or on well sanded latex paint as DuraTex is self-priming and has great adhesion". But in all of the cases on this forum I have found where people use latex before applying Duratex, no one sands the latex paint. Maybe I am missing something?


Any help in explaining the steps would be greatly appreciated.

[maxmercy]

I would fill the wood, sand the wood (pretty rough, 60-100 grit should be fine, best with 60 grit followed by 100 grit), paint with latex, let FULLY dry, sand with 150 or so, and have at it with the duratex. I ALWAYS sand before coating something. It not only removes any contaminants that may be on there (think oily handprints), but it gives 'tooth' for the next coat to go on, PLUS, smooths the surface for the next coat. There are no downsides to sanding.....except sanding through...avoid power sanders (unless you know what you are doing) and you should have no problems, be careful on the rounded corners...

Oh, and NO STEARATED SANDPAPER. I have had multiple coating adhesion issues in the past with it (mainly with epoxy coatings)...I no longer take chances and use plain, untreated garnet or silicon carbide papers.

JSS

[WB]

I found a DuraTex PDF that states the following: "No primer is needed on bare wood or on well sanded latex paint as DuraTex is self-priming and has great adhesion". But in all of the cases on this forum I have found where people use latex before applying Duratex, no one sands the latex paint. Maybe I am missing something?


Any help in explaining the steps would be greatly appreciated.

Duratex has great adhesion to wood but none to PL. I never sand after a latex primer coat. The latex paint seems to stick to the PL ok.

[LelandCrooks]

Applying a black primer saves duratex. It's a whole lot easier to get even coverage. I generally only primer anyplace there's pl, body filler, or is very hard to access. A really dense foam nap roller will apply duratex like paint, very thin, which is what I do for my first coat.

Primer and paint do 2 very different jobs. I always primer everything when I paint. Duratex is neither, it's an elastomeric coating, derived from roof coatings. It really doesn't require primer, except on the above exceptions. I used Acrytech's elastomerics on my roof and they are the best I've ever used. Fixed leaks I'd been fighting for 5 years.

[myn]

Is there something wrong with the forums? I can't post anything with an img without it timing out. Tried last night 3 times and once this morning.

[myn]

[== 8/11/2009 ==]

Yesterday the Duratex arrived with the numerous textured rollers. Leland, I really wanted to buy the Duratex from you because I believe supporting our local BFM alum is important. I ended up having to buying from Acrytech because I needed the rollers which apparently they only sell.

Tonight I drilled more holes than I care to count, 4 or so inches apart. I also prefit the side panel and tested the screw registration points confirming the panel could float above the panel edges once PL is on them. As you can see by the pics this method worked out well. Now all I need is balls to do the securing with PL..

As I am planning on unscrewing all of the external screws once the top panel is on and fill it with something (Bondo or Wood Filler). I was wondering, when I route the edges with a roundover bit and its close or ontop of the filler, will the router chew the filler up? (example below)

[WB]

I was wondering, when I route the edges with a roundover bit and its close or ontop of the filler, will the router chew the filler up?

No, because the bit spins inside a bearing, the outer race of the bearing is stationary against the contact surface.

[Scott Brochu]

Before you round over on this beautiful cabinet, don't forget to use a straight bit to true up the edges. All that overhanging plywood will not be fun if you leave it. The router will follow straight only if what the bearing on the bit is gliding on is.
But if your using a straight edge with no ball bearing on the router bit I think it'll be ok. It'll plow through anything.

Just in case you didn't know.

[LelandCrooks]

No biggie. I just got rollers from from acrytech w my last order. After I try them I'll probably add them to the site. I don't sell anything I haven't used myself.

[myn]

I was wondering, when I route the edges with a roundover bit and its close or ontop of the filler, will the router chew the filler up?

No, because the bit spins inside a bearing, the outer race of the bearing is stationary against the contact surface.

Sorry I didn't convey this right.

In the picture below, if I was to put a roundover on the vertical surface where the screw is, wouldn't the router bit chew up the filled hole and create a crator? Like you said, I think I'd be fine if I was doing the horizontal surface as the bearing would ride along the edge smoothly.

[maxmercy]

if you use good filler that is fully cured/dried, the router bit will turn it to dust, leaving you with a nice roundover...it works very well.

So, has the side gotten glued on yet?

JSS

[myn]

Would 2 part Bondo constitute as "good filer"?

I am planning on closing the coffin tomorrow morning pending some black latex painting of the horn mouth tonight.

[David Carter]

Would 2 part Bondo constitute as "good filer"?

I am planning on closing the coffin tomorrow morning pending some black latex painting of the horn mouth tonight.

I've used Bondo to fill the screw holes on all my BFM builds, and I've never had any problem with my roundover bits messing up the filler. Just make sure you let it dry well first.

[maxmercy]

Would 2 part Bondo constitute as "good filer"?

Yes. It is very good, and cures very fast. You can sand in around a half hour, but for the router I'd give it a little longer. It's essentially polyester resin and silicon microspheres. So wear a respirator when you sand/rout the stuff (you should always anyway).

JSS