fEARful™ Part Twelve (12)

[Dekker]

... I cannot use this panel inside out because I cannot remove the braces without seriously damaging the panel (glue is really stronger than I thought). So I guess I'll leave the handle 3cm behind the center instead of 3 cm ahead of the center.

Actually, if you are careful, you can do it with a chisel and hammer. Lay the panel on a hard surface (concrete floor with cardboard to prevent scratches), stand/kneel on the panel and chisel evenly down the brace, going back and forth and on both sides until things loosen up. You will definitely need to cut new braces (not that difficult, if you have the material) and will need to use some extra vinyl spackle to fill the holes (or get creative with PL and sand it down). Not for the faint of heart, but do-able!

Yesterday I noticed I screw up something in my 2 cabs: I made one of the 4 sides (2 per cab) a "mirror image" of the correct side. A really stupid mistake, when I was so picky about minor details!

And here I was thinking I was being unusual for building two cabinets at once! A Invalid Link Removedand [Invalid or Expired Link Removed], but keeping them separated is the key - I'm dreading the thought of glueing the panel from one onto the other/wrong cabinet!

 

[floydman]

Do you have Ace Hardware, Sears hardware, Lowes? Any basic hardware store with a large array of bulk hardware, nuts, bolts, screws drawers will likely have these, and unfortunately they really are simply called rubber stoppers in stores near me. They are 1" tall with varying top and bottom diameters.

it looks like Lowes may have some
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Right now I have my grille removed to add some speaker gasket material around the edge of the grille standoffs to quell grille vibration

Is there a more specific name for those 'rubber stoppers'? I'd like to buy some of those and having the exact name would help. Unfortunately they dont have True Value hardware stores up here in Vancouver Canada.

I'll be looking into getting some of those screw cover things too.

 

[parapentep70]

Actually, if you are careful, you can do it with a chisel and hammer. Lay the panel on a hard surface (concrete floor with cardboard to prevent scratches), stand/kneel on the panel and chisel evenly down the brace, going back and forth and on both sides until things loosen up. You will definitely need to cut new braces (not that difficult, if you have the material) and will need to use some extra vinyl spackle to fill the holes (or get creative with PL and sand it down). Not for the faint of heart, but do-able!
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Thanks a lot!!

I discovered the stupid error yesterday. Then I spent quite a few minutes this morning trying to un-glue the braces. Impossible, one part (brace or panel) will break before.

I could not figure out any saw adequate for this fwork. If I cut some 2 or 3mm high, that's too much sanding.

But I did not think of chisels, I've got 3, one is very wide. I am not bad with them (some recent luthier experience). With chisels at least I can guarantee I am not breaking the main panel.

I've got spare material for the braces, not for the panel. I will try with the small brace (I have 4 in my design), if the panel gets really bad I could leave this side to the inside, so I've got nothing to lose and something to gain if I'm lucky.

I used Aliphatic resin glue for this part (Titebond), I don't know if this makes things better or worse than PU. I guess in both cases glue is stronger and harder than wood, so not much of a difference.

Thanks, I'll try today.

PS As I was writing I googled for "aliphatic unglue" and found that I can weaken joints using a heat gun or better some source of steam (from a steam iron).
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Then I must try a couple of things before I throw the towell.

Internet is great. Thanks!!

 

[Yvarg]

I'd be careful with heatgun and steam; those might start to unglue the laminates on the plywood itself.

 

[floydman]

I just found the same screw covers at speakerhardware for anyone interested
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[masonsjax]

Leave the brace on the outside, maybe start a new fad. Inside-out fEARfuls. Mount the speakers facing inward and the crossovers on the outside where you can get to them easily. That would be sweet. No need for heavy handles, you can grip the cab from any number of external braces.

 

[floydman]

I have seen that most people with a fearful stack have one cab with a reverse baffle so that the midrange drivers line up, is this for aesthetics or functional improvement? Will there be some kind of interference or sound bad if they are not lined up, e.g. I stack a standard 15/6 and a standard 12/6cube?

 

[rpsands]

You should always stack them so the midranges line up. The 12/6 cube and 15/6 are designed to make that easy.

 

[wounded horse]

Thanks a lot. It's cheaper and I could choose colours. And I was already thinking of buying a couple of small pieces from Bluearan (I bought other items from them and I am very happy with their service).

I must reconsider which paint is ideal, I guess it will be "Tuff Cab Paint" instead of Warnex.

Thanks a lot, I enjoyed your pics, there are many interesting details in them.

Yesterday I noticed I screw up something in my 2 cabs: I made one of the 4 sides (2 per cab) a "mirror image" of the correct side. A really stupid mistake, when I was so picky about minor details!



So I have 3 right sides, one left side. The problem is that the handle is moved towards the rear side instead of the front. I cannot use this panel inside out because I cannot remove the braces without seriously damaging the panel (glue is really stronger than I thought). So I guess I'll leave the handle 3cm behind the center instead of 3 cm ahead of the center.

It's awkward, aestheically ugly... but it does not look that bad functionally... I made my mind about it

Out of this incident I am close to finish.

Beg, steal or borrow one of these: A great thing to have when cab building.

 

[KOakley]

Parapentep70, if you have a router you can easily remove the misplaced brace. Place strips of wood on either side of the brace built up slightly higher than the brace. This will give the router a surface to ride on while stradling the brace. By using a flat bottom bit you should be able to cut the brace down flush. Use multiple passes if needed. I've had good results using this method to remove some of my own screw-ups. I hope the instructions make sense. Good luck. Kerry

 

[rpsands]

Dremel with a cutoff disk followed by a chisel.

 

[Foz]

chainsaw + hockey mask

 

[parapentep70]

Thanks for the many options. Including the inside-out version of the cabinet

I tried with the heat gun on a very small piece (intended to align panels in final assembly). Yes, it weakens glue... a little bit when you are close to burn wood! Pulling apart the small piece of wood when it was so hot resulted in wood partially broken instead of completely broken when cold. So glue is weakened... but not enough. And I was sure I could not heat a full length joint at a time, or at least a good section. No way.

I am impressed that Titebond, when clamped properly is times harder than birch plywood. And it resists well over 100ºC without any practical weakening.

Next I tried with chisels. Weakening the brace plywood where I wanted was the way to go. In 30 minutes I removed the 4 braces in a very clean way. I can even re-use 3 of them (mounting the other side that has zero damage). I was able to "erase" all the traces of wood and glue on the panel using the chisel. After sanding it is difficult to see anything.

I also removed the T-nuts. This zone will be covered by the handle, so it will not be not visible. But I will need to work on the area because there was some minor damage, it could result in air leakage in the handle area. I think I will use glue and sanding paper.

I am glad I had the guts to do it, my cab will be good when I finish it !

For final mounting I'll use Poliurethane glue. I think it's much stronger with less than ideal clamping.

Thanks again for all the hints, specially the chisel one.

 

[Dekker]

Parapentep70, if you have a router you can easily remove the misplaced brace. Place strips of wood on either side of the brace built up slightly higher than the brace. This will give the router a surface to ride on while stradling the brace. By using a flat bottom bit you should be able to cut the brace down flush. Use multiple passes if needed. I've had good results using this method to remove some of my own screw-ups. I hope the instructions make sense. Good luck. Kerry

I know Parapentep already removed the braces, but when I read your router suggestion I practically slapped my forehead and cried "Doh!" - it's elegant and gets it down flush, and if done carefully will not leave any damage to the side panel. I'll have to remember that one (for the inevitable).

 

[mikeddd]

I agree w/Dekker. When I read that "use a router like this" description I just smiled and said "That's brilliant!" Router it flat, a little wood putty or bondo if needed and you'll never ever know it was there under the Duratex.

Glad it worked out for you, parapentep70.

 

[tombowlus]

I am impressed that Titebond, when clamped properly is times harder than birch plywood.

+1 We used Titebond III on my fEARful builds. My father-in-law is a big fan, and I trusted his judgment. We did a test butt-joint glued up with the Titebond, and when it was dry, we tried to break it. The 13-ply Baltic birch ply gave way before the glue joint did! Very impressive.

 

[parapentep70]

One question about glues,

For the small pieces I was using Titebond. Mainly because I had it at hand, I had some experience with it and I did not have Poliurethane glue at hand at the time.

Titebond recommends clamping pressures about 150...200 psi. I think I clamped applying pressure similar to the recommendations. Easy for small pieces.

To do the final assembly of panels my plan is to use Poliurethane Glue as recommneded. Now I have it. I read that it works well even filling gaps, so my guess is that clamping is required only to counteract PU glue expansion.

Is this true? Could I do the final assembly with relatively small clamping pressure? I mean some 20...40 Kg total per panel, this would result in just some 4 psi, much smaller than what I used with Titebond.

I'd prefer to avoid buying additional clamps if I don't really need them. Due to the way my panles are cut, I will assemble front, rear and sides applying pressure on top and aligning to 90º using the sides. After, I will glue the sides, I will place the cab on one side and apply again pressure from the other side (now on top), using weights. But I don't know if this would be enough clamping pressure.

Any experience with this? Does my plan look correct?

 

[rpsands]

I have put together cabs with glue and brad nails and no clamps in the past and had no issue.

 

[Dekker]

... clamping is required only to counteract PU glue expansion.

Need? No. Beneficial? Yes. The problem with (most) glues is that until you squeeze down enough, too much glue remains in the joint, causing problems (panels will "float" out of position). Once a joint receives enough pressure, it will be relatively stable. When dealing with hardwood you can starve a joint of glue, but with BB you're pretty safe.

Is this true? Could I do the final assembly with relatively small clamping pressure? I mean some 20...40 Kg total per panel, this would result in just some 4 psi, much smaller than what I used with Titebond.

Yes, you could get by with very little pressure, but make sure your panels don't move around as you continue your assembly (before the glue dries). If you have a brad nailer or use screws, you wouldn't have to worry, and you could speed your assembly process.

 

[parapentep70]

Thanks again. One concern less in my list!

I have already glued some small pieces of wood just to use screws in the main joints. Not enough to force a high joint pressure, but more than enough to hold everything in place. I will dry fit everything before I glue.

I guess I should glue 2 or 3 small pieces of wood to practice before. I never used PU glue.