Here is the promised drawing. It is kind of hokey, I know. I've discovered in moving to my present version of OS X I have left my drawing software behind and have had to use what is offered in Word. I had to take it into PowerPoint and make a slide of it and store it as a JPG. There it is. I think it is clear enough for you to get the idea. The measurement for the set back of the baffle face from the outer edge of the nose is not clear for some reason; it is 3/4".
I have a couple of questions about the solid walnut moulding that makes up the nose as Dave is calling it. How did you hide the seam between it and the walnut veneered sides? How did you make the moulding?Originally Posted by riessen
A couple of years back I was going to build some 4355s and when it came time to make the moulding, I ripped some strips on the table saw and most of it warped pretty significantly due to inner stress that was released during all of the wood removal... I thought I might glue rectilinear blocks on the cabs and rout them in place, but I never finished the project so my problem went away.
Widget
Hi Mr. Widget: I attached a pic that should show the two different ways that I have done the trim molding on the Pro monitors.
The dwg. labeled "A" is how JBL attached the front trim. The trim was glued to the face of the finished cabinet and the visible seam was on the top, side, etc. The exposed top edge of the trim varies from near nothing to maybe 1/8". JBL was very good at blending the trim wood and veneer colors and the seam was barely visible. I have sometimes bleached the trim to match the veneer and had good results. You have to keep in mind that their cabinet shop had all the goodies and craftsmen on hand to make this problem go away.
The dwg. labeled "B" is how I do it (most of the time). I attach the trim (before the bevel is cut) to the bare cabinet and veneer over the trim. I then cut my beveled face and cut thru the trim and veneer at the same time. Since I'm a glue and hot iron veneer guy this gives me great results. 90% of my work is with 10 mil. paperback veneer so the exposed edge of the veneer is barely visible after the bevel is cut. I have a few colored permanent markers (made by Sharpie) that are intended for furniture touchup. With the wood not oiled the seam is usually not visible. After oiling is when you'll see it. Before applying oil I run a damp cloth across the edge to see what shows and about what shade the wood will be when oiled. I then take the appropriate marker and run it along the edge where the veneer meets the trim. Let it dry and then apply oil. Since the veneer is only 10 mil. I rarely see the seam and that's upon close inspection. From a foot away you'll likely not see anything.
If you're using phenolic backed or other types of veneer that are real thick, you need to use the method in Dwg. "A". With thick veneer I have had little luck hiding the edge seam that will show on the beveled face.
If I was using a vacuum bag and epoxy the thicker veneers would be easier to apply. Laying it down with wood glue and heat is a nightmare. I consequently always try to use 10 mil paperback.
Most of the pro cabinets I have seen have a face trim that is only 3/8" to 7/16" thick with a width coinciding to the thickness of the cabinet walls. It's very hard to cut this thin trim accurately and even harder to cut the bevel on it. Then try to clamp the beveled piece to the face of the cabinet without it rolling over under the clamp jaws. When restoring a pair of 4350B's some time back, I was cutting off the old face trim with a router and edge guide. I found myself cutting thru small trim nails. It appears that on some cabinets they did more than just glue it on.
Cutting the face bevel after the trim is applied and after the cabinet is veneered is a bit risky but gives the best results. I use a clamped edge guide in addition to the pilot bearing on the router bit, to keep the router from going anywhere it's not supposed to go. Along a 4 foot edge I may take 8 cuts before reaching the final depth. The first couple of passes will tell you if you're running "with" or "against the grain. If I'm running against the grain I usually take lighter cuts and pull the router instead of pushing. Having said all that I'll keep my fingers crosses. I haven't splintered a piece of trim yet but the risk is there. If that happens - cut it all off and go to Dwg. "A".
When doing this trim cutting I use my big 3HP porter cable router in-hand and a 1/2" shank bit - plenty of ass. The 30 degree bevel bit is expensive, maybe $30 to $40, and make sure it's sharp with no burned edges. If you mess up at this point
Hope this helps - It's worked good for me on many cabinets.
Rick
Good ways to apply trim, for someone making a set of these speakers at home, but I'm puzzled by the fact that the inside of the nosing on my 4333A's is sprayed baffle blue. Why? When? I doubt they would do any spraying after the trim and veneer were applied just so the inside of the trim would be blue.
Dave: I'm not sure what you're asking. All the monitors I have seen have the inside of the trim painted to match the baffle. I assume JBL masked off the exposed walnut front edge and the rest of the cabinet (maybe with a mask frame sized for the cabinet) and shot everything blue, including a lot of the interior insulation. I'm only copy catting what they have done. The inside of my face trim is always blue too. I just don't spray the cabinet interior in the process.
From what I have seen, the baffle was without a doubt painted after the trim was installed. I have seen cabinets with no evidence of a seam between the trim and cabinet where painted (no line, no crack, nothing). I would suggest that they either used a rigid frame type shield sized for the cabinet and then finish taped it in place or a paper masking frame taped in place. I have seen both methods used in cabinet shop production painting. Small amounts of overspray (if they encountered any) could easily be sanded off prior to applying oil.
It's just that the masking would be unnecessary if they were sprayed before the veneer and trim went on. I would think the spraying would be done in a special room. If the cabinets are veneered and trimmed when they are sprayed they would have to be taken into the room one at a time, masked off, handled by someone not into the paint, etc. It's not important; just wondering. I've looked at the brochures for the large monitor series, and they all seem to be that way as far as I can tell.
You're forgetting that JBL wasn't a small time cabinet maker like I am. I quite often veneer after the cabinet is built - but JBL DID NOT. Their cabinets were made from pre-veneered stock. It's not likely they rolled their own veneer either (possibly) as they could easily order veneered stock, to their specifications, from the mill that supplied their material. The process of applying veneer on a large scale operation would have required a lot of expensive equipment, most likely cheaper to buy it already veneered. Somebody out there should be able to ask JBL to verify one way or another. Since their cabinets were assembled already veneered, they would have to mask the cabinet prior to painting the baffle - trim or no trim. So why not mask and paint after the trim was installed.
Dave: You are correct. I have either owned, had possession of or closely inspected every 43XX series monitor. ALL have their face trim painted on the inside surface - black on studio grays and blue on walnut models.
Here's some info that should get you started. My notebook drawings were too busy with misc notes so I cleaned them up a bit.
If you're trying to closely duplicate the factory cabinet these will get you there. Keep in mind that there may be minor differences between cabinets made early and late in production. The information here was taken from a pair of factory 4331's that I had completely gutted for restoration some years back.
I am missing some info on the cabinet back panel drawings so I will try to post it later. Check with SPEAKERDAVE for the length of the port tube since he has a pair. I seem to have lost that info and I don't have a pair anymore to measure the length.
Hope this helps - Rick
Here's a couple more pics. One shows a little closer view of the saddle that supports the 2420 mid driver. It is integral to the rear access cover. I can hopefully post some details of this assembly later. Also there's a pic that shows the internal metal "L" brackets that are provided for support when hanging the enclosure. One is visible in Dave's pics too.
Rick,
Thank you. You are truly a gentleman and a scholar.
These are exactly what I was looking for.
Speakerdave? Can you assist with the port length?
Thanks to everyone who helped. All excellent information.
Cheers,
James.
This is exactly the kind of stuff we've been looking for with respect to various JBL systems since the forum first started.
Thanks Speakerdave and Rick!
Post # 8
Your frame dimension should be made to work with your actual box (things happen). Mine is 28 3/16 by 21 15/16 measured over the cloth.
The part of the frame that fits against the baffle is cut from one piece of 5/8" particle board; it is cut square on the outer edge.
The depth of the frame is 2 11/16", consisting of the particle board, short corner blocks and intermediate struts, and the outer rails which are made of 1/2" softwood and fastened to the ends of the corner blocks and struts. The bevel of the frame sides is achieved by cutting a 5 degree bevel on the outside lateral surfaces of the corner blocks, intermediate struts and outer rails. There is a cross piece reinforcing the outer rails in the long dimension. It is made of 3/4" solid softwood and fitted to the rails with a lap joint so that it's front surface is held back from the plane of the cloth. It is positioned to fit above the woofer and below the 2308. In addition, there are four small metal L brackets screwed to the outer rails to provide anchors for the tie tacks that mount the long metal badges to the front of the grille cloth, one pair for horizontal and one for vertical orientation.
These photographs may help:
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