First speaker starting to come together. Pic with all the internal pieces glued in place.
and with pretty much every clamp I own on it, gluing the other side.
An externally hosted image should be here but it was not working when we last tested it.
and with pretty much every clamp I own on it, gluing the other side.
An externally hosted image should be here but it was not working when we last tested it.
It's a good thing that you are using thick plywood. Otherwise I would say that you were not getting enough clamping force in the middle of the cab. Just remember to drench those middle panels with glue to make sure there is a tight seal.
maybe, I tried a test recently, one with two pieces clamped together, the other I just held the bits together for a minute, supported the two bits so they weren't trying to fall apart then let them dry, both broke by lifting the top layer of plywood in exactly the same fashion. think the gap is more important than the clamping, but i'm no expert.
Right. Squeezing all the glue out (hard as it is) is not a good idea either. Mathias Wandel (YouTube woodworker) did some tests to see the significance of pressure on a joint and found that surprisingly the joint was stronger on the less clamped one.
The problem with larger sheets of ply, or any wood I'd suspect, is that when put under clamping stress it tends to warp in weird ways. Not a lot but enough to make a small unglued crack.
Scottmoose, how would you normally go about doing a large curve like that? Making some kind of compass rig is my first thought. But then it would have to be rather big to do a curve like that. Using string would be too wobbly because the blade is not a point.
Which leaves free handing along a line and then painstakingly trimming to the line with plane or file. Fine for smaller pieces but hell for four large panels like this.
The problem with larger sheets of ply, or any wood I'd suspect, is that when put under clamping stress it tends to warp in weird ways. Not a lot but enough to make a small unglued crack.
Scottmoose, how would you normally go about doing a large curve like that? Making some kind of compass rig is my first thought. But then it would have to be rather big to do a curve like that. Using string would be too wobbly because the blade is not a point.
Which leaves free handing along a line and then painstakingly trimming to the line with plane or file. Fine for smaller pieces but hell for four large panels like this.
Probably the best method for cutting a curve is to make a template and use a top-bearing pattern cutting bit in a router. If you have a router table, a bottom-bearing bit will do.
Another method is to adhere the four side pieces together with some double-sided tape, then freehand cut them all at once on a bandsaw. That's how I did my son's FH3s; for something as large as the Victor you'd definitely need some added support and/or a helper or two. With the sides still taped together, it's quick work to refine/smooth the curve with whatever tools you have or are comfortable using (rasp/file, spokeshave, compass plane, belt sander, random orbit sander, whatever).
Yet another method, if the curve is a simple arc, is indeed to make a large compass consisting of a long piece of wood of the desired radius, with a sturdy pivot at one end and a router with a straight cutting bit (or possibly a jigsaw) mounted at the other end.
Another method is to adhere the four side pieces together with some double-sided tape, then freehand cut them all at once on a bandsaw. That's how I did my son's FH3s; for something as large as the Victor you'd definitely need some added support and/or a helper or two. With the sides still taped together, it's quick work to refine/smooth the curve with whatever tools you have or are comfortable using (rasp/file, spokeshave, compass plane, belt sander, random orbit sander, whatever).
Yet another method, if the curve is a simple arc, is indeed to make a large compass consisting of a long piece of wood of the desired radius, with a sturdy pivot at one end and a router with a straight cutting bit (or possibly a jigsaw) mounted at the other end.
I'd use a template for preference; thin MDF or similar. Various ways of drawing it out; the plans come with metric & Imperial grid-based layout for the side panels. Since I'm far from being the best woodworker on the planet (understatement of the year), I'd simply plot out the XY grid points onto the template, and draw it up with a long steel rule or other suitable straight edge following ye traditional 'straight-line curve' approach. Then if you're not able to create a suitable jig, cut with router or jigsaw to ~'close enough' and use a plane or spokeshave (or both) for the detail finishing to the correct curve. Once that's done, it should be comparatively easy, especially with a router. If that's not an option, it will still make the final planing down a lot quicker / easier.
router all the way.
If the curve is elliptical you could use this method, but with two pegs and a "string" loop instead of a fixed radius. you would just need to find something inelastic, flexible and fairly strong for the "string"
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The cheap painted foam lattice strips at Home Depot work great and are easy to trace around. Just bend them up and carry home in your back seat.
There is a fair bit of tweaking and non obvious calculations with doing a routing template, therefore doing it often seems nearly as much work as the hard way with a jigsaw.
You'd also wear your bit down quite a bit with using it as a saw on many large pieces like that.
Bandsawing is pretty much out of the question with something like this in a normal home workshop.
Maybe if you could get the compass string secured to exactly above (or below!) the rotational axis of the routing bit.
Or with the jigsaw, you could tie the saw with two strings with a common rotational peg, as far apart as possible to the back and front of the saw, maybe even on a stick for extra precision. That would stabilize it and the sole of the saw would take care of verticality.
You'd also wear your bit down quite a bit with using it as a saw on many large pieces like that.
Bandsawing is pretty much out of the question with something like this in a normal home workshop.
Maybe if you could get the compass string secured to exactly above (or below!) the rotational axis of the routing bit.
Or with the jigsaw, you could tie the saw with two strings with a common rotational peg, as far apart as possible to the back and front of the saw, maybe even on a stick for extra precision. That would stabilize it and the sole of the saw would take care of verticality.
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The curves on all the FH and Woden double line horns / labyrinths are simple, but large radius, so it would definitely take a lot of working space to set up a compass jig to machine with router by hand.
The first prototypes I made of all 3 models of FH were done by hand along the method that Scott described above - lots of ways to accurately draw the arc, but cutting is a difference story.
I made 1/4" MDF patterns, rough cut with jigsaw, fine tuned on edge sander. Work pieces were rough cut 1/4" or so oversize with jigsaw, then finished with router and pattern bit.
WTF am I gonna do when I retire and don't have access to a CNC? - build only rectilinear boxes, I guess.
The first prototypes I made of all 3 models of FH were done by hand along the method that Scott described above - lots of ways to accurately draw the arc, but cutting is a difference story.
I made 1/4" MDF patterns, rough cut with jigsaw, fine tuned on edge sander. Work pieces were rough cut 1/4" or so oversize with jigsaw, then finished with router and pattern bit.
WTF am I gonna do when I retire and don't have access to a CNC? - build only rectilinear boxes, I guess.
Squeak:
The beauty of the routing template is you only have to make one. Use scrap plywood, mdf, whatever. Put as much care as you want into making a regular, uniform curve, using the string method (for a circular arc or as oculi pointed out, and ellipsis), the grid method, or blown-up printed pattern. As far as router bit wear, you can prolong your bit life by rough-cutting the curve to within 1/4" of the line.
Like I said, I used the bandsaw (standard 14") on the Frugel Horns, by myself, with excellent results (save for embarrassing human error which I don't wish to go into right now 🙄 ). By my experience, I see no reason why similar results couldn't be achieved on something this size, if one has a helper.
In my opinion, using anything other than a rigid trammel bar for a compass cut will be an exercise in frustration and failure. I laid out the curve for the FH3s using a sturdy, non-stretch string and a pencil. Even under the un-demanding circumstances of scribing a simple pencil line, it was tricky to get it right.
jjcarr:
If at any time you want to bring the speakers up to spec, as determined by Scott, you can always use the template/router method on the already assembled speakers.
The beauty of the routing template is you only have to make one. Use scrap plywood, mdf, whatever. Put as much care as you want into making a regular, uniform curve, using the string method (for a circular arc or as oculi pointed out, and ellipsis), the grid method, or blown-up printed pattern. As far as router bit wear, you can prolong your bit life by rough-cutting the curve to within 1/4" of the line.
Like I said, I used the bandsaw (standard 14") on the Frugel Horns, by myself, with excellent results (save for embarrassing human error which I don't wish to go into right now 🙄 ). By my experience, I see no reason why similar results couldn't be achieved on something this size, if one has a helper.
In my opinion, using anything other than a rigid trammel bar for a compass cut will be an exercise in frustration and failure. I laid out the curve for the FH3s using a sturdy, non-stretch string and a pencil. Even under the un-demanding circumstances of scribing a simple pencil line, it was tricky to get it right.
jjcarr:
If at any time you want to bring the speakers up to spec, as determined by Scott, you can always use the template/router method on the already assembled speakers.
Finished the frame build on one speaker last night. Has one rough sanding on it done.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Plan is to do this set relatively quickly, then play with a v2.0 later, at which time I'll put more time into the back curve.
For me, there's a bit more charm to the aesthetic of this pair than on your FH3 build , and they might work enough to play while you figure out if they really need any improvement.
Did you mention the bottom cavity was to be filled with shot or sand? Otherwise they'll be very tippy
Did you mention the bottom cavity was to be filled with shot or sand? Otherwise they'll be very tippy
Got the Face piece cut. It's 1/4" oversized on each edge, so that there is a slight overlap. As mentioned, it will get a reveal, with the rear portion painted black, and the face piece edged and stained.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
one method I have used
https://youtu.be/RuKYnA6BHKM
this method works just use it in a bigger scale🙂
https://youtu.be/RuKYnA6BHKM
this method works just use it in a bigger scale🙂
kinda hard to smooth sand an inside curve on a disc or belt sander - my patterns for the FH models were sanded on the large diameter end of a stationary wide belt edge sander like this
Got one running. Face is only held on by the 2 clamps, no lining in the main chamber, no break in, only one speaker.
Fired it up briefly. I could feel the face place vibrating a fair amount, so no question that needs to be firmly in place at the very least, not even factoring in break in, acoustic lining, etc....
Thoughts? I think I'm going to like them. A lot of the forward facing horn speakers have a sound that just doesn't work for me, and from what I can tell, these speakers perform as expected, with none of that coloration (again, subjective). The only thing I can really take away from listening to one at this point is that it makes me anxious to finish this and build the 2nd one so I can hear them properly and get them broken in. If my experience with the Frugal Horns tells me anything, it's that they need a good month of break in before the bass reaches it's potential.
An externally hosted image should be here but it was not working when we last tested it.
Fired it up briefly. I could feel the face place vibrating a fair amount, so no question that needs to be firmly in place at the very least, not even factoring in break in, acoustic lining, etc....
Thoughts? I think I'm going to like them. A lot of the forward facing horn speakers have a sound that just doesn't work for me, and from what I can tell, these speakers perform as expected, with none of that coloration (again, subjective). The only thing I can really take away from listening to one at this point is that it makes me anxious to finish this and build the 2nd one so I can hear them properly and get them broken in. If my experience with the Frugal Horns tells me anything, it's that they need a good month of break in before the bass reaches it's potential.
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