BillFitzmaurice.info

Working through the throat and braces. Here's everything glued up at the moment:



I have developed much love for PL Premium. It forgives all sins, except for the sin of leaving it clamped for 24 hours. In that first half hour, it's complete freedom. As I was setting up the throat reflectors, I took the chance to "caulk" up seams which had expanded because I weighted the pieces down instead of clamping them. Rule 1 of PL - always clamp, unless you intentionally don't want to. It will expand and if you didn't want it to, your joint will be out of whack.

Rule 2 is cut open the tube at a narrow angle, it makes it easier to draw a bead over a joint. Latex gloves help too.

I had misaligned one of the throat panels so it was 1/4" off an edge of the baffle. Trimmed the overlap with the backsaw, and PL'd it to the other side. When I say "all sins", I mean "all sins".



Also found that isopropyl alcohol is good at cleaning off PL from the fingers. This was still within the half-hour window... don't know about if that works after it's had time to set.

Question on sanding prior to painting. How do I know if the surface is properly sanded? I'll be painting with Duratex.

Pre-paint with black latex paint which will stick to the PL. Duratex after that.

ian wrote:Question on sanding prior to painting. How do I know if the surface is properly sanded? I'll be painting with Duratex.

Sand with 40-60 grit, then clean off the dust. You are ready to Duratex.

BTW, thin a cup of Duratex with a 1/4 cup distilled and filtered water for primer, and allow drying to take place in a warm (80+ F), dry place.

Tom Smit wrote:Pre-paint with black latex paint which will stick to the PL. Duratex after that.

+1

Prime with flat black paint first. $15 a gallon vs. $50+ a gallon for duratex. You'll need less duratex to cover if you prime first. I actually did two coats of paint before the two coats of duratex. Looks great and have a lot left over for touch ups and more speakers.

My question on sanding arose because I hand-sanded the vent ducts with 60-grit sandpaper after I cut them, but didn't notice an appreciable difference in appearance or texture. So how do I avoid sanding too much? If I only need to sand a little, then I can just use my sanding block... but if significant elbow grease is involved, maybe I should get a small orbital sander next time I'm at HF.

Thanks for the pointer on priming. I was going to paint my piezo horns as well so I'll just pick up an extra can of blank paint.

DJPhatman wrote:allow drying to take place in a warm (80+ F), dry place.

This is DC. We either get warm, or dry, but not both.

ian wrote:, maybe I should get a small orbital sander next time I'm at HF.

Random Orbital Sander......only way to go. You'll wonder why you never had one before.

Bruce Weldy wrote:

ian wrote:, maybe I should get a small orbital sander next time I'm at HF.

Random Orbital Sander......only way to go. You'll wonder why you never had one before.

+1 - The little cheapy one from Harbor Freight works great - I've had mine going strong for over 2 years and I think I paid $9.99 for it on sale.

ian wrote:

DJPhatman wrote:allow drying to take place in a warm (80+ F), dry place.

This is DC. We either get warm, or dry, but not both.

Then make a "dry box" out of a large cardboard box and a heater. Use common sense while using the heater. You can also bring the cabs indoors to dry and cure.

Back of the horn is primed for eventual painting, and glued to the bottom panel. Mouth panels are cut and beveled, and are clamped together since they warped a little. I also cut the phase plug with my router.



Tomorrow I should be able to attach the mouth panels! Duratex will also be arriving Monday... we are warm today but pouring rain. If spring actually happens then there'll be some good painting days in there. If not, it'll be time to cut and glue up the melded array and build the crossover.

... and the mouth panels are installed. To correct for plywood warpage, the mouth panels are clamped so terrifyingly, so horrifically to their respective places of rest that they cannot be pictorially depicted in a family forum. Let's just say Richelieu would have been proud.

Oh and the phase plug since it was sitting right there.

My vote: post clamp pics anyway. There is no such thing as too many clamps. Just impossible. Many clamps is good, yet more clamps is always better.

AntonZ wrote: Many clamps is good, yet more clamps is always better.

Nooo!
In my world you have to say "more better"

I stand corrected.
Many clamps is good, more clamps is more better.