BillFitzmaurice.info

Oooohhhh another Nimrod special - I find it hard to wait......"patience Grasshopper"

hilo4noff,

First, let me say I am impressed by your patient, tidy and accurate work and overall workmanship, as well as the very nice and clear photos of your progress. Keep up the great work.

Now to my concern…
If I understand your idea correctly, the short horizontal bays from the long/vertical slot are optional locking points for the locking bolt, going into the dowel behind the panel.

The location of the locking positions off the center of the dowel, mean that the bolt will be at an angle (relative to the panel) when it is tightened.
This isn’t nice/good practice as it doesn’t allow proper fastening of the bolt and also, tightening the bolt will pull the dowel to the side.

I would suggest an alternative configuration of the slot & bays, in which the locking positions are right on top of the dowel axis and the connecting slot is off to the side (left or right).
This way the bolt is tightened at the shortest distance and perpendicular to the panel surface, thus eliminating the problems mentioned above.

Like so:

Yep, I'm with ya on that... I was just trying to explain both my ideas on the possibilities. If one were going to have the tightening down action of a knob to locate in the main slot and then tighten it down at the desired extension, then then like you say, you want it directly square to the side of the cabinet. Since I'm not really a fan of that idea, my little locator notches off that main branch were if I wasn't going to have a tightening knob, just a cap head bolt sticking out as a little handle. (may pretty that up with drilling out a dice or something for a knob)

The limiting factor here is the tools we have, so the main channel being cut by a 90 degree router with a 6 inch base is the tool for the majority of the cutting. Moving the main channel off directly above the dowel we get into a wonderland of dollar signs about how to route that...85 degree clear through channel? Or do we cut it small and wood file it bigger to the correct pitch...

Ideally, (for super easy operation and construction) I would have put the dowel at the farthest back location and used the side overhang and the rear surface, one for travel and then swing the bolt 90 degrees to the other surface for it's locking positions, through the rear corner and into 1/2" stock ply. But when looking at that, I didn't care for how close it landed to the rear edge of the speaker below. I could angle the path slightly to make it land better but at that point the simplicity in construction goes out the window.

Oh and the reason I moved the center of the E to the other side of the channel was that the wood directly above the slot supports the speaker and keeps the bolt in place, if they are all on the same side, both supporting stops only have just over an inch of structural material to hold the pressured position of the bolt. So by flipping that leg over I theoretically get double the support or strength at least on that end of the bolt. Where as the dowel's ability to hold it perpendicular would probably fail first in either configuration. And what would that take? At least 6 drs above and a portly River-dancer clogging away on top of the stack. It still might hold up.

See you just get stuck some times in your thinking... You are right and I was fixated on the channel being as narrow as possible, when that doesn't matter. The channel even though off set from the ideal clamping location relevant to the dowel can be an inch wide, it doesn't matter as it's only a path of movement.( which gets rid of the need for a precisely routed angle) The resting stops are what have to be precise... Now, with that epiphany I may do both, the static locations and the ability to tighten it down a bit.

Awesome... Thanks!

That's right.

Also, in case you hadn't planned to… a guide for the inner end of the dowel,
and of course the dowel itself long enough to remain in this guide even when fully extended out of the cab.

Dang!

Even after reading though this post i did the same thing. Forgot to cut ducts in one of my DR250s. Luckily ther is a right angle drill in ky work truck i can use. No patching for me. I hate being rushed, stupid stuff like this happens

Wow what a day, I've got all my slots and stops cut on the two lower speakers and the "retracted" and "level" slots cut on the number 2's (flat arrays). Took a bunch of pictures and I'm trying to sort out how post it all. There is a process...Lots of careful steps here, like remove dowel before starting router, don't glue anything until dowel is cut to final length.

First I needed to get some exact measurements on how much lift each leg corner needed to get the front of the cabinet 90 degrees or perfectly perpendicular to the floor.

I thought my wood bench would be close enough, but after I couldn't get to the other side while it was all set up on the spring board and carpenters square, I decided to do it on the table saw which worked out perfectly for getting the pen at the right angle to mark the legs. (on both sides) And I found that the bench must have just enough flex to not get me the exact measurements I needed. That's why in some of the pics you'll notice crossed out measurements once I checked my marks against the iron table saw surface.

The steps I figured out go like this: Draw a center line for the dowel.

Then mark a distance from the bottom of the grab hole so you can be consistent with selector placement over all the cabinets. I tried to go 4 inches down for the first set and the 3 inches on the others to give me more real-estate for the 2 notches needed in the upper cabinets.

That mark now becomes the location for the "stored" position or notch.

From there get needed elevation measurement from dowel leg. Immediately write same measurement on the cabinet. (once it's out on the bench with even one other dowel... They'll start lying to you about who is who, being indistinguishable from the other dowels, all with writing on them)

Measure down from the "stored" mark, the distance written on the dowel and cabinet to make the "level" location, on the center-line mark. Use square from back of cabinet to extend these lines out to where you can label them.

After figuring out through trial and error with the first one how much space I needed, for the lever to engage and travel between the settings I made a guide template quick kind of thing with my router wrench and some masking tape to speed the marking process for what to route out on the following ones.

The two lines we have now horizontal (on the cabinet) mark the tops of the two stops. So I went ahead and drew little circles beneath them so I wouldn't get confused. Using the square, once again from the back surface of the cabinet, I drew the channels from the stops to the travel channel. I chose to leave about 3/8" space so the "level" slot kind of had a keeper wall additionally to hold it in there. But that would be a personal choice to have or not.

Once everything is drawn out...REMOVE Dowel now from cabinet. It all gets very exciting once the router bit box is opened!

I went ahead and predrilled then drilled the stop locations with my drill, and had a back up piece of scrap clamped to the inside to minimize any blow out. (here we need to keep the wood in place as much as possible)

Then on to the router a straitbit starting anywhere in the travel groove getting more precise as you get to the edges and to route the connections to the stops. Then after that, I had a cone shaped bit that's wider at the bottom, (I think usually to do finger joints on drawer corners)... Anyway that gave me some pitch on the one side of the travel groove so the selector doesn't have to move so far out to change positions. This is the only place to use that bit, leave extra material, and like before work carefully toward precision and the desired finish line.

Now that we actually have slots and a travel groove, reinsert dowel to desired or measured setting at "level" and drill starter hole in to dowel in the right position. Remove dowel from cabinet to finish hole so as not to drill into 1/8" horn back.

A note on the distance between the two setting on the lowest cabinets... On one of my speakers( for the level setting) I only needed like 13/16" elevation, so I figured that I could increase the meat over the stop by moving the stored position up to just under 1/2" thick so the dowel, at "stored" would still just barely be inside the 1" hole in the bottom of the cabinet.

Now that we have the hole started in the dowel we can take it out, finish the hole and drill just bigger for the barbed insert.

Mark the width on the same surface you drilled from so you can see it when positioning over table saw. How many times I marked it and then had the marks facing the table saw... Like he'd tell me if I was about to bozo the cut!

Yeah, so a clamp and the table's miter pusher thing to just nibble out, even less than a quarter inch depth, is all that's needed to get the insert's edges clear of the dowel's exterior surface.

Clamp in with piece of scrap protecting other side of dowel from clamp.

Assemble to check fit and extension. I was amazed at how precise this turned out every time. Only once was a leg not exactly where it should have been, but only by a 16th of an inch. So I shortened that up quickly with the miter saw.

Going with N.Webber's idea is REALLY stable. In fact to move the locator out of the "level" position I have to turn the bolt about a quarter of the way out to even move it. So it's a really nice set up. I left my movement channel wider to accommodate a bigger head, whether I glue on a small knob or just find some bigger headed bolts, I've got room in the channel for them.

On the interior brace for the dowel I was thinking about tracing the exact shape I'd need from the bottom of the cabinet and all and really dreading doing more bastard saw work with those curves when it dawned on me that all I needed to worry about were the two angles of a little piece of wood that would trap the dowel in the groove. Much easier!

So with the miter saw I just kept playing around with little pieces until I got to just about as perfect as I could get and it seems that a 20 degree cut on the side edge and a 32 degree cut on the horn curve edge fits in perfectly.

Then I just kept shortening the 20 degree side until I was almost touching the dowel! Less than a 32nds of an inch. And if by chance I cut a hair too much off, it's no biggy just put the edge of the sander right in the travel path of the dowel and remove a bit of the ply where it would touch the dowel. Easy to do, but gets monotonous by the second speaker.

On the bottom speakers, I could mark the top of the little brace on the dowel and cut it off for final length at this point. Reinstall and glue interior brace up, with pins from outside of cabinet (be aware of where fingers are per shoot) and then stack scrap and clamp to get tight clamp on back of horn.

I also discovered by accident last week that PL will not stick to sealed wood. So I had to sand off any paint that would be under the gluing location of the interior brace.

Here's also a picture of where 2nd set is at, as I have yet to locate their "stacked" stop as I haven't put them atop the other ones yet till the glue dries. (on the bottom most ones I mean)

But you can see where the channel will be extended once I get that measurement.

Other experiments that didn't work out

great stuff as an internal brace... Yeah could be done but the little pieces of wood work fine. Now if for some reason the dowel didn't sit nicely in the horn/side of cabinet groove due to crazy paddle bit performance then I could see squirting a line of it in the crease and then clamping wax paper wrapped dowel in stuff to create good track for movement.

And a shot of spray paint to mark extension level of dowel... Nope, the paint absorbed like water into the wood and spread beyond the exposed dowel.

You are the mad professor of speaker experimentation.

Thanks for the compliment but the mad professor is stuck. When I got the second level cabinets on top of the first ones to mark that second notch with the same spring board and such... I discovered that I hate, hate, hate the corners that I bought in bulk from speakerhardware. Not because they aren't fine corners for the t48's but because they are about 3 sizes too big for the drs. Not only that but I'm not sure if I even like the way they lock in a stack to hold the above speakers in place. (even if they were a third the size)

Not to mention the small angle of the bottom of the cabinet kind of screws up the fit anyway.

Hmmm, I'm going to have to do some thinking on this. Maybe the rubber feet and little cup routed in the tops at the correct angle? Along with some of the tiniest little corner protectors...

What does everyone else do about the front edges locking together?

Thanks for the help!

Oh... the back elevators and the length they are already cut to are fine! I had planned on adding whatever thickness in rubber feet or glides to compensate for the front additional lift of the stackers or whatever I end up using.

hilo4noff wrote:Maybe the rubber feet and little cup routed in the tops at the correct angle? Along with some of the tiniest little corner protectors...

I have used exactly this method quite successfully. I built my first cab (not a BFM design) using the same corners as you and I hate the look of them. They are just way to DIY for my taste.

I now use these....

hilo4noff wrote:What does everyone else do about the front edges locking together?

I routed 8 recesses, 4 on the top and 4 on the bottom. The bottom recesses are fitted with HD plastic (Delrin) feet, which mate with the top recesses of the lower cab when stacked.
Even at 8 deg. (Max) splay between the cabs, the feet are well seated inside the recesses and the cabs are firmly engaged.

I made a set of spacer blocks that fit between the sets of back feet of the cabs (also with feet and recesses), with which I can adjust the angle of the whole stack and the angle between the cabs.

This is the top/front recess (the bolt in the center is holding the front grill):