Speaker Building Tutorial

[Mongrel714]

Hello all, I thought it might be helpful to start a tutorial thread to pass on the knowledge gained here and other places, with the blessing of Sonnie and the other fine folks here!

[Mongrel714]

FLUSH MOUNTING DRIVERS IN MDF

Now, I am not an expert at this, far from it, information presented here
Is gathered from the web and from what experience I have found along the way, and if anyone has a better idea or an easier way, please include it here because this is to help anyone in the same shape as I, looking for information to help them along their journey through this wonderful hobby of DIY audio!

I suppose we will start with a tools list, this is what I used but once again, if anybody has suggestions…..
TOOLS
1. PLUNGE ROUTER. Probably the most important tool for this job, they come in many sizes and prices, my suggestion would be to find one with the smallest diameter body so you can cut some of the smaller mounting hole, with a bigger bodied router you are limited you may not be able to route out a hole for that 4" mid.

2. CIRCLE JIG. Runner up in the important tool list, you just cannot make perfect circles without some kind of jig, there are many commercial units available, Jasper being one of the best known, but making
your own is very simple and quite inexpensive; I will address this in my next tutorial.

3. ROUTER BITS. You will need two different bits for this project, first, a ¼” straight cut up spiral bit, which performs the main cuts and also helps to removes the MDF dust from the groove as it goes, (a regular straight bit will work also)
Second, a ¾” flat bottom bit to cut the recess groove for your drivers, these should be carbide tipped of course, my last non-carbide bit I tried was the ¼” straight cut bit, it lasted for two projects before it was to dull to use.

4. FLAP WHEELS. These little jewels are priceless when finishing the inside edges of your mounting holes.

5. DRILL. For pilot holes mounting holes, and Flap wheels.

6. PIVOT PIN. This is your pivot point for the circle jig, this can be a nail with the head cut off, or even a drill bit, I used a drill bit on my last baffles as the hole you drill for them is exact, so it works well.

ROUTING SOME WOOD!
The first step here is to determine your outside diameter of your driver for the recessed groove, and the through hole diameter, hopefully you can find this information from your retailer or manufacturer, if not, you can use two framing squares to find the diameter by turning your speaker face down, (protect your surround on the speaker) and laying the squares on the outside edges of the driver forming a square, measure the inside edges of the squares to find the diameter. Do the same for the through mounting hole.


Once you have determined your diameters, you must layout your driver placement on the baffles, then mark your centers for each driver, this is where the pivot pin is placed, the picture below shows the drill bit I used and the ¾” flat bottom router bit

Now measure the mounting flange thickness of your driver to determine the depth of your recess, if you want the driver surround recessed include this in your measurement, just don’t go so deep as to weaken the baffle you will be attaching to, for mids, I would keep it at least 3/8” thick.
Take your ¼” straight bit and make a shallow cut the diameter of your recess, then switch to the ¾” flat bottom bit and remove material in several passes down to your pre determined depth as shown in the above illustration.
Now, switch back to the ¼” straight bit, and in several passes, cut out the mounting through hole, many say to leave a small amount of material at the bottom of the groove and cut it with a razor knife afterwards, on small drivers I cut straight through myself as the circle jig will support the router when the plug falls free, use your own judgement on this one. Afterwards, use the flap wheel to finish out the inside of your hole, hopefully you will end up with something similer to this:


I hope you find this helpful! Happy building!!

I'm sorry I could not get the pics in the right place, I need to find a way to upload the word file or host it somewhere.

[Mongrel714]

Heres a short one, a DIY Circle jig, for this project you can use many materials, plastic, wood, masonite, or aluminum, which I made mine from.
Its very simple, just choose the material, cut it wide enough to cover the screw pattern on the router bottom plate, draw a center line down the remainder of the jig to drill your pivot point holes, I measure each driver and drill the holes as I go for each project. I have seen a very clever jig using a sliding pivot point and it had a scale mounted on the side also.
The pictures below include a aproximate drawing for you to follow and a pic of my jig attached to my router. Hope this helps!

[Anthony]

Great writeup.

One thing I would add, is that I have used and love the Jasper Circle jig. Almost identical usage, except it has predrilled for 1/32" increments and a 1/8" pilot hole for the center hole.

I also like the technique of making templates if you are building a run of speakers. Make one for the recess and another for the thru holes. Then you can rough out the center of the holes with a jigsaw (less dust and faster), then make the final pass with the router and template.

Of course, to do this, you must take great care to make the template absolutely perfect.

[Mongrel714]

Anthony wrote:

Great writeup.

One thing I would add, is that I have used and love the Jasper Circle jig. Almost identical usage, except it has predrilled for 1/32" increments and a 1/8" pilot hole for the center hole.

I also like the technique of making templates if you are building a run of speakers. Make one for the recess and another for the thru holes. Then you can rough out the center of the holes with a jigsaw (less dust and faster), then make the final pass with the router and template.

Of course, to do this, you must take great care to make the template absolutely perfect.

Thanks Anthony! What do you make your templates out of, and how do you anchor them to the baffle when cutting??

[Anthony]

I use either Luan plywood or 1/4-1/2" MDF for templates. Usually whatever I have lying around.

As for securing it, if the panel is big enough, I just clamp it in 4 to 6 locations. If it's small, double-sided tape works well (the thin stuff, not the thick puffy stuff to hang pictures and posters). And if I know the holes will be covered (veneer, or the hole location will be cut off later), I use small screws, countersunk so that they won't protrude and affect the router movement.

[Funkmonkey]

Just a tip if you are making a template out of MDF. I know from experience that a router bearing will leave an indention in the MDF and after several passes start to get bumpy, leaving you with imperfect circles. You can minimize this by coating the template surface with C/A glue (basically super glue)[make sure it is the liquid stuff and not the gel version], and then spraying it with "zip kicker." This hardens the edge of the MDF substantially, making it much more durable for repeated use, and only takes a couple of minutes. The MDF is porous enough that it fully absorbs the glue, and the kicker crystalizes the glue on contact so you do not have to wait for it to dry. A very light sanding of the surface will remove any dust particles that got stuck on the edge. You can find C/A glue and "zip kicker" at any model shop, and most art supply stores.

[Brian Bunge]

Actually the Jasper Jig (at least the model 200) has pivot holes in 1/16" increments; not 1/32".

[groundie]

this is great to read for someone who's just thinkin' about
getting into cabinet making; i don't have any tools but
have been reading some, just afraid to jump in i guess.
but i would benefit and enjoy reading more specifics in
building the entire enclosure.

[Mongrel714]

groundie wrote:

this is great to read for someone who's just thinkin' about
getting into cabinet making; i don't have any tools but
have been reading some, just afraid to jump in i guess.
but i would benefit and enjoy reading more specifics in
building the entire enclosure.

Just check out some of the many build threads in this forum, theres nothing more satisfying than shaking the walls with an enclosure you took from the planning stages to reality! It just takes alittle time and effort to complete a really nice project, I hope you do "Jump in", you'll have alot of fun.

[mattnew]

Funkmonkey wrote:

You can find C/A glue and "zip kicker" at any model shop, and most art supply stores.

Just to add on to this... Zip kicker is really just scented water. you can also use a spray mist of water if you don't have the kicker ( kicker is usually pretty $$ ). C/A cures when it comes in contact with moisture.


try it out... put down some c/a glue and mist it with water.. it will cure instantly.

[rodH]

Great thread guys.

I am getting ready to do a sub enclosure. I have a dewalt plunge router and am going to make a jig, seems easy enough.

I actually have a rotozip as well with an adjustable jig, but I am making it out of 1" industrial MDF and a couple test runs I did, the best way I found with the rotozip was to do it multiple depths, but even that gets slightly uneven (not a huge deal, but I am going to build another piece of decorative wood that is going to surround the 2 drivers, and need them to be PERFECT circles and the best/straightest finish possible. My buddy has a dewalt router I am barrowing for the project, it seems to feel more solid and should provide a better cut/hole.

My question is this, you mention to use a straight or upspiral bit. Which one do you prefer? I am planning on buying one, so I can get either one. The upspiral is about $5 more, but that is no big deal if it works better.

Also, if I am going to cut into 1" MDF and 1" plywood, do I have to have a 1" bit, or do I buy something shorter and just keep dropping it lower with the plunge router? If I am JUST using the bit for this project is the 1/4" bit the way to go?

THANKS!!!