[kc8apf]

After doing two coats of enamel with roll and tip, I realize I'm just not very good at it.  I was sanding off _way_ too much to smooth it back out.  I needed a different approach.

I've used HVLP before but only outdoors.  I always had trouble with dust and it's getting too cold outside.  I figured I'd give an indoor setup a try.  I built a support structure out of struts and 1/2" threaded rod.  A piece of plywood goes inside the speaker and gets attached to the threaded rod.  That leaves them suspended with all sides accessible.  Suspend a few tarps to contain overspray and voila.





I sprayed a coat of enamel tonight.  I was a bit heavy on the first few sides and two of them ended up with runs.  Other than that, everything looks good.  Hopefully they will stay that way after drying overnight.  Sorry, no pictures of them wet.

[mlundy57]

That's an interesting looking rig. how about some close-ups of how you've attached it to the plywood inside the speaker?

Mike

[kc8apf]

As requested, a few close-ups of how the speaker cabinet hangs on the threaded rods.  It sits against the back wall of the speaker cabinet and the threaded rods pass through the holes for the port and wiring cup. 



The plywood piece is just wide and long enough to fit through the woofer opening.



Hex nuts and flat washers are used on both sides so it can be tightened down a little more than hand-tight.  I tried hand-tight initially but found that they would loosen up overnight. 



Mounting the cabinets on the threaded rod is more challenging than I like.  It's tricky to keep the top washers lined up with the holes in the plywood while positioning the rods to go through them.  Then you need to hold the cabinet up by reaching through the woofer hole and pushing up on the plywood.  While doing that, you need to put on the lower washer and hex nut with the other hand.  Once set up, the cabinets sit well and all faces are easily accessible. 

[mlundy57]

Thanks

I can see how hooking it up would be awkward.

Mike

[kc8apf]

TL;DR: Never sand edges of painted surfaces.  Keep practicing with a spray gun until you get a nearly perfect finish right off the gun.  Use mistakes as an opportunity to improve setup, tools, and technique.

After an excellent brunch and a visit to the local, open-air Weihnachtsmarkt, I had the afternoon free to work on speakers.

I had sprayed on 3 coats of enamel a few days ago and other than a few small drips, they looked pretty good.  Sanding and polishing test strips had gone reasonably well, so I started with 320 grit and worked my way up.  At 400 grit on the first cabinet, I burned through on a sharp corner.  Crap.  It looked repairable so I kept on working and got up to 1000 grit.  The surfaces were starting to be reflective but I had burned through a few more sharp corners.  Using a triangle of thin plastic sheeting, I lightly covered the exposed sections.  I figured I'd let them dry overnight and sand them lightly with 800 grit in the morning.

On to the next cabinet.  Burned through 2 sharp corners with 320 grit.  Now, I had been trying to learn from my earlier mistakes so this was rather annoying.  I was carefully sanding outward from the center so I wouldn't cut hard into the edges.  When I free-handed the roundovers, I ran over the sharp corner where two roundovers meet and instantly burned through.  *sigh* 

Moving on to 400 grit, I burned through next to one of the driver holes.  Touching up the exposed sections wasn't going to work near the driver hole.  It would need to be sanded flat and then worked up to 2000 grit. A thin layer would never hold up.  Time for a new plan.

Spraying a new coat seemed the most reasonable plan.  If I could get it nearly perfect right off the gun, I could skip the whole sanding madness.  Part of the problem had been the Rockler HVLP gun I'd been using.  It works OK but throws globs occasionally and wasn't very consistent.  I'd already purchased a pair of DeVilbiss FinishLine 4s so that part was easy.



The spraying setup using struts to suspend the cabinets had worked out reasonably well but there had been a few areas that could be improved.  For starters, I used the extra sections of strut (it only comes in 10' lengths) to create a lower tier to mount from.  This gives a little more flexibility in positioning as well as stiffens up the whole support structure.



Last time, I had suspended the cabinets such that the front baffle was facing the ground.  Attempting to spray all 6 sides in one pass turned out to be do-able but only barely.  Gravity-fed HVLP guns don't work very well when aimed upward.  This is probably part of the reason I burned through in so many places.  On the other hand, the back of the cabinet (which was facing upward) was considerably smoother and had no issues with burning through.  Ideally, I want to paint the top and sides, then flip the cabinet and paint the top again.  Additionally, attaching the cabinets to the support structure was nearly impossible.  Holding up the cabinet from inside while attaching a washer and nuts through a driver hole ends up being challenging. 

This time, I solved both problems (I hope) by mounting the plywood in the middle of a 4' section of threaded rod.  That way, I can flip the cabinet over and remount it without having to mess with nuts and washers inside the cabinet.  It also means that mounting the cabinet is now just a matter of holding it by the threaded rod and attaching a nut and washer on the top side of the struts.  _Much_ easier.



Finally, there was only a single light mounted in the center of the spray area.  That means that it was pretty hard to see the pattern when working on the far sides of the cabinets.  I added two additional lights on each end of the spray area.  Now I have nearly 200W of fluorescent lighting covering most angles.

Of course, all of this took the entire evening to do.  Painting will need to wait until the morning.

[Peter J]

Two things you might find helpful.

 If you clear coat over your basecoat, you're theoretically sanding the clear and not the color...it does help but the leeway it buys is not going to mitigate an aggressive technique. Sanding the finish is a learning experience in and of itself...

Secondly, rather than sanding contours with sandpaper, you might give Scotchbrite pads a try....probably red.

http://www.tcpglobal.com/3m/3m101-9.aspx

[lacro]

I agree with Peter, building up with with clear will help prevent sand through. I had the same problem on my speakers, but not on my stands because they were stained with India Ink before I applied epoxy which helped seal the color from sand through. On the speakers I had the same sand through problems you had, especially on edges.
 I found what worked for me was skipping all the coarser papers and go directly to 1000 or 1500 wet sanding. Once I did I no longer had any issues with sand through. These soft finishes don't need all the sanding steps unless you are using automotive hard finishes. After the 1500 wet sanding I went directly to compound/polish.

[kc8apf]

Peter:
I did automotive base/clear on my last speaker project.  The clear certainly helps with burning through but I was still having problems.  I'm trying to refine my sanding technique (don't push against the surface, let the paper do the work) but it takes practice.  That's the one positive side of redoing the same surface 4 times.

I think a lot of my problems stem from a fairly rough and inconsistent surface after spraying.  I was having a lot of trouble figuring out the Rockler gun.  It wanted to throw globs and had a fairly narrow fan.  I tried the DeVilbiss today and it was world of difference.  6oz of paint thinned 15% in the Rockler gun was covering all 12 surfaces with some left over.  With the DeVilbiss, I ran through 2 oz thinned 15% on just the two front baffles without any drips.  The wider fan and finer spray seemed to help get good, thick coverage without overdoing it.

lacro:
Good idea on starting at 1000.  I had tried starting at 400 but the paper was clogging pretty quickly.  When I got up to 600, the clogging was immediate so I switched to wet sanding.  If I start with 1000 wet, I can probably work it flat without going so deep.

[kc8apf]

I finished a full coat with the DeVilbiss and it came out as close to perfect as I could expect.  A little dust got on each surface.  I also didn't consider overspray when I did the front baffle in one pass and the rest of the cabinet in another.  It left the front surface with some texture that ended up looking nice.

I only had one major screwup.  I plucked a fiber out of a side and left a smear.  I flooded it to smooth it back out but ended up with a run.  Then I had the bright idea (read dumb) to try to flatten the run by dragging some plastic sheeting across it.  While it did knock the peaks down, it also dug into the rest of the paint and made big, deep lines across the surface.  I went to sand it down today but even after 24h it hadn't quite dried enough.  I'll give it another day, sand it down, and reshoot that one side.

Probably the biggest lesson out of all of this is that satin finishes aren't easy.  They really do need to be done right off the gun.  I finally got there but it took a lot of trial and error.  Of course now when I go back to automotive finishes, they should be much easier to get right.

I'll post some more pictures when I have both speakers assembled.

[kc8apf]

Yesterday, I resprayed the side I messed up.  It went very smoothly.  I've finally gotten the hang of the setup, paint, and gun.  I'm still having trouble with dust.  Some plastic sheeting overhead would probably do wonders.

Today, I did final assembly.  I had forgotten to mask off the tweeter hole during painting.  The paint had built up enough that the baffle wouldn't go into the recess.  While I was really careful with the knife blade, I didn't notice that the handle was scraping along the face along the hole.  There's no good way to fix the scrapes without repainting the face.  My sister already knows there will be a few imperfections.  Hopefully she won't mind those scrapes.





Excuse the poor photos.  The lighting in my office is terrible.

[Danny Richie]

A sharpie can make nice touch ups.

[kc8apf]

I tried that on a scraped spot that isn't visible. The sharpie is a slightly different shade of black. I couldn't decide if it was better than the scrape so I left it. I'll let my sister decide if she wants to try it.

[kc8apf]

This story has come to an end.  I packed and shipped them off to my sister today.  While the speakers are for her birthday, she's getting a NAD D3020 and Blue Jeans speaker cables for Christmas.  I wasn't willing to pay for fast enough shipping (ground was already $90, yikes!) for the speakers to arrive on time so she'll have to wait a week to try the whole setup.  She'll just need to borrow our brother's Pioneer's that he doesn't know he's getting.

A fun side-story: I took the speakers, a Schiit Modi, a Virtue One.2, and my MacBook Air to work to show them off.  I share an office with three others and I was the first to arrive.  I set everything up on top of a bookshelf and put some Crosby, Stills, and Nash on at a low volume.  One by one, my office mates arrived and didn't say anything.  After the last one arrived, I mentioned that the setup was a one-day affair and they were welcome to change the music or turn it off.  They asked why I had brought it all in just for one day.  When I explained that those were the speakers I had been building (they knew from prior conversations), they were in complete awe.

Throughout the rest of the day, there was a steady stream of people stopping by just to take a look/listen.  Most of them came in, looked around, and asked where my speakers were.  When I pointed to them, they could scarcely believe that I had built them.  They were expecting bare wood or something less finished.  Even my director (my boss's boss) came by to take a look.

[Captainhemo]

Cool story     
It's pretty awesome finishing off  a speaker project then being able to listen  to them and  share the resutls with ohers .

I'm sure your sister is going  to love them   

-jay

[bdp24]

I just visited my sister for Thanksgiving. While I was at her house I heard her talking about Bose speakers, saying "They're the best". Is it TV advertising that gives non-enthusiast people that idea? I mean, it was a long time ago, but she heard my Magneplanars. I'll bet she thinks that about Bose without ever having heard them. The good doctor may not have been much of an engineer, but he's proved to be good at advertising. Like the old saying goes "If you lie long enough, it becomes the truth".

[lacro]

Yesterday, I resprayed the side I messed up.  It went very smoothly.  I've finally gotten the hang of the setup, paint, and gun.  I'm still having trouble with dust.  Some plastic sheeting overhead would probably do wonders.

I know your all done now, and your speakers came out awesome!!
 
But, here are my thoughts regarding dust.... I struggled with it when I was building strip kayaks in my basement. 

Here is some of what I did:

Sweep floor, walls, ceiling
Vacuum overhead lights (florescent tubes)
Put a fan in my basement window facing out. Close entrance door to room.
Turn on fan, use a hand held leaf blower to loosen every bit of loose dust from all surfaces.
The out facing fan in the window with door closed creates a negative in the room
The dust the leaf blower picks up becomes airborne, and is sucked out the window
I made a fine dust collector using furnace filters which I ran for an hour after stopping the window fan.
I then mopped the floor and left it wet.
Sanding between each brushed coat (6-12) on the kayaks was done outside
Before applying each coat, the surfaces were vacuumed, wiped down with damp paper towels, and finally tack ragged.

 After all that prep, I still got DUST I then started looking at the finish material itself. I decided to strain each and every batch with fine paint strainers. WOW.... hardly any dust at all I now sand, vacuum, wipe with damp paper towel, and most of all TACK RAG, and STRAIN THE Finish material whether brushing or spraying.

 I am now convinced that MOST dust/dirt is not airborne, it's in the finish material.....

 

[kc8apf]

Interesting.  I'll pick up some strainers and give that a try on the next set.  They're already glued up and getting epoxied so it won't be a long wait.