Mini-Controller + 1v/oct calibrator build blog

[loydb]

I've had pieces of this done for weeks, but managed to give myself a sinus infection from hell in the process of cleaning my woodshop out so I could build. I am finally somewhat better, and thought I'd share my day's progress.

This is going to be my little calibration rig. It combines an MFOS wall wart power supply with an MFOS volts-per-octave calibrator and an MFOS CV mini-controller.


I started out by making a foamcore template for a case bottom. I marked all the mounting holes, installed standoffs, and attached the PCBs.





Now we're out in the shop. I'm using leftovers from other projects to make the case. The body will be built from a 3/4" thick piece of Padauk. It has a beautiful grain pattern, and in the closeup you can get a hint of the final color from the spots where I've sweated on the board The bottom will be 1/4" particle board (essentially pegboard without the holes for pegs), and I've got a piece of 1/4" plywood that I've veneered with curly maple (leftover from a drawer front) that I'm going to use for a top.




After ripping the Paduak in half lengthwise and jointing the edges, I'm left with a couple of long 3.5" wide boards. I'm normally sufficiently OCD that I won't start a project without having done a 3D mockup of it in Max, but this is simple enough that I'm just going to build it on the fly. This will come back to bite me here in a minute.

I start by cutting the Padauk into 13", 10" (two), and 8" pieces based on measurements of the various components and my sketchy plans (I'll scan the 'plan' later). Here's the first rough look at the shape.



In spite of the various joinery options in my 'plan', since the Padauk was a perfect 3/4" thick, I decided to use 1/4" tongue-and-groove joints. I start out by marking the boards where I want to remove wood. I set the blade height to 1/4" using a gauge, and then nibble off the 1/4" channels.

[loydb]

I decide on a 1/4" overlap around the perimeter of the panel. This was a bad decision, as I'll point out later. I set up a 1/4" dado blade on the table saw and cut out the grooves. To get the width perfect, I use the actual panel to set the exact spot for the groove.




I continue this process, cutting tongues and grooves, until the skeleton is assembled. The final picture gives an early glimpse of the final product.

The last picture also shows my miscalculation. Because I used an empty panel (not wanting to expose my actual control-laden panel to sawdust), I didn't account for the width of hardware. You can see how close the wood is to the actual jack if you look at the top right jack hole.

Fortunately, there's plenty of other spots on the panel to move stuff. I might even do a custom one.

[loydb]

I'm done for the day. I got ready to drill a hole for the banana jack for the control wand, and realized I don't actually own any banana jacks. I'm working on an Ultimate + Expander, so I might as well order them now... More next week, I'm off to Mouser.

[loydb]

Here's what I ended up with for the panel design.

edit: got the right image this time

[loydb]

It's been awhile since I could get in the shop. Last weekend I was on vacation, and when I got back:

This is what a bandsaw tire looks like after it has cracked from too many Texas summers in my 100 degree shop, slipped off the flywheel and begun its interaction with Mr. Blade. Fortunately, this all happens inside a metal housing, so all that happened was that my favorite 3/4" resaw blade is now mangled and useless. Plus, I had to order new tires (I'm replacing the top one as well -- it is the same age as the one that cracked). Then I had to actually install the new tires (4 clamps, 3 big screwdrivers, and a pry bar).



During the time I had to wait on parts, I started looking at the last bit of padauk from the original board, and decided to save the maple piece for another project and to use the padauk instead for the top panel.

Resawing a board just means cutting it down the middle. This makes the grain mirror-image itself when the boards are butted together like pages from a book (hence the name 'bookmatching' a board).



After it has been resawed, the surface has to be cleaned up, and the two boards brought down to the same thickness. I use a small drum sander for this. For larger boards, I'd use a jointer and a planer (I wish I had a big wide-belt sander!).



I'm still trying to decide how I want to do the bookmatch. The next two pics show the two different looks I can get based on which edge I make the inside. Also, a sneak peak at the FPE panel that got here this week.

[RF]

Really fun post to see - Thanks!
I'm a tad envious of your woodshop

bruce

[loydb]

Thanks! It started as a 2-car carport. I added another 20'x20' platform next to it and enclosed the whole thing. The first picture shows the original carport -- the double doors lead to the driveway. The door in the back part in the second picture is storage for wood, veneer, and glassblowing supplies.

p.s. I decided to go with the 2nd bookmatch option, and have glued up the panel.

[Skrog Productions]

exellent blog, as with bruce , that's a great workshop there , i have to fight for space with kona & giant mountain bikes in my shed when building , heh

Dave.

[loydb]

Thanks! I spent the last 9 days blowing glass in the woods with no net access. Primitive, but a lot of fun

I hope to finish off the case this coming weekend, I've just got a few rabbets to route and it's ready for glue-up and finishing.

[Captain Biscuits]

I'm with Dave on this - Have to empty the shed of bikes and bales of hay before I start. Takes so long (and gets me so completely covered in hay) that it rarely happens!
Having said that I have a couple of pieces of nice sweet chestnut to rip and plane (all by hand the slow way) so they may just tempt me to battle the hay bales and get stuck in. They should have some nice grain when they're done.
Look forward to seeing more of your project - looks good so far.
Ian

[loydb]

I snuck out and got a little work done over lunch. The next step is to use the router to make slots (rabbets) in the carcase to support the lid. To make sure I got the height right, I used the lid itself to set the height of the 1/4" router bit (pic 1). To get everything to line up, but still leave a space for the "keyboard" bit to protrude, I'm gluing in spacers (pic 2), using a piece of scrap to protect the outside from the clamp (the spacers protrude enough from the surface that they can protect it on the inside -- I'll eventually sand them flush). Once they're dry, I'll trim them flush and cut the lid to fit. After that, there's just a couple more holes to drill and a bottom to deal with.

[loydb]

I got some time in early this morning before it gets ridiculously hot outside. It was 107 yesterday I'm to the point where I'm starting to sand stuff, and nothing screws up a nicely-sanded surface like sweat, so it's pretty much now or in the middle of the night.

Since the bottom will be visible in places, I decided to use solid wood instead of plywood. This was going to be the back of a jewelry chest that went badly wrong -- it will make a good base instead. Rather than rabbeting it in, I plan on drilling and screwing it for easy access.



Time to drill for the banana jack. For those who have forgotten their HS geometry, connect the corners with straight lines, the intersection is the centerpoint.



SAFETY BREAK

Ok, this next picture illustrates why you don't manually hold pieces in drill presses with large drill bits. My initial 5/16" hole drilled fine, but the larger 1/2" bit that I was using for a countersink (the wood is thicker than the jack, so I need a recess for the locking nut) grabbed the part and smashed it into my thumb. The second picture illustrates what I should have done in the first place.




Finally, I'm attaching some Ebony caps to cover the endgrain, and am starting to sand everything down. The belt sander is set up with 120 grit. For the inside faces, this will be the only sanding they get. The outside faces will be sanded *much* finer, but not until after glueup.

[adambee7]

Great workshop. I'm like most UK blokes and I'm sure their sheds are bigger than mine. Having a woodworking cabinet making skill in sdiy is a big bonus and man i wish you lived down the street. Great VCO callibrator and its got great features like the stylus keyboard. Great stuff.

[loydb]

Thanks!

I'm entering the home stretch. I almost forgot to add a hole for a wall wart plug. I got some bad tearout on the inside face (I should have had a support board beneath the case when I drilled), but the pieces glued back in pretty well. I'll probably put a plate around the outside plug socket.


After dealing with the tearout, it was time to get serious about the sanding. I took everything through 80-100-120-150-180-220-320-400 grit sanding belts. Only took about 30 minutes for the whole thing, once you get into the rhythm...


Next, I added a bevel to the ebony pieces using a decorative bit.



Finally, time to start glueup! I'm doing this in two parts, it's going to be easier to keep square. Since I know my tablesaw fence is properly squared to the sliding table, I use them as parallels, then use a machined square to make sure it's true.

[loydb]

I rough cut the bottom, and cut out the lid. You can now start to get a good idea of the final product. The lid hasn't been sanded at all yet -- I'm going to drill a hole in it for a knob first -- right now once it is fitted in it can only be gotten out by poking from the bottom or turning it upside down.

I'm in the home stretch here. Tomorrow I'll try to get the lid drilled and sanded, and drill the holes for the bottom and the faceplate. At that point it will be time to start on the finish.

[loydb]

Worked a bit on this between sets in the gym this morning. I started out by drilling the hole for the knob using a Forstner bit. Note the backing board (used to avoid tearout on the bottom) and the clamps (used to avoid tearout on my hand).



Since I'm using a round marble as a knob, I need to increase the surface area available for adhesive (if the walls of the hole are parallel, the marble will either fall completely through, or only touch it at the rim).

There's a guide bearing on the angled decorative bit I've been using for the bevels on the Ebony. I can "ride" the bearing as I move the piece in a circle, cutting an angle into the side wall of the hole.



I also beveled some more Ebony to use for the wall wart guard plates.



Here's a test fit with a random marble. This one is a little small, it's not making contact with the beveled inside edge. It gives me a good idea of how big to make the real one, however.

[loydb]

It's almost time to move back into the electronic portion of things. I got everything sanded this morning, and just put on the first coat of stain/varnish. I'm using a poly-based gel stain, wiping it on, and wiping it off. I'll decide tomorrow if I'm going to rub the coat out or not.

[Symatic Star]

great visual diary - I really like the woodwork lovely box

[loydb]

Thanks! Hurricane Hermine has parked over me today (well, me and huge chunks of Texas), and the moisture in the air combined with the moisture in the finish has caused the lid to expand juuuuust enough that it doesn't smoothly fit into the recess. Sometime after lunch I'll sand off and refinish a bit of the lid edge to get a fit, then post some more pics.

[loydb]

Ok, here it is with the panel. After looking at it, I think it will benefit greatly from having the finish rubbed out on the outward-facing surfaces, so I'm going to let it cure a few days first.

[loydb]

The stain has cured for 3 days, and is hard enough to rub out. You see arrayed before you the essentials for this job: a rubber mat so things don't slide around while you sand; a soft cotton rag to wipe away sanding dust; lubricant (for the wood) in the form of mineral spirits; lubricant (for the woodworker) in the form of a big glass of Knob Creek; a soft foam sanding block; 600 grit wet/dry sandpaper, and a set of Micromesh sanding cloths (grits 1200-1500-1800-2400-3000-3600-4000-6000-8000-12000).

The Micromesh is the secret to a crazy-good finish. A set only lasts for 3-4 small projects or 1-2 big ones, but they make a huge difference IMO.

Everything is set up so I can watch Monday Night Football and sand



Finally, I topped it all off with a finish of Danish oil (untinted). The reflection of the tape measure kind of shows how smooth it all is. It should all be ready to assemble later this week after the oil has cured.

[Symatic Star]

Looking very Nice, I'm inspired to remake a rough box I have, I have just been given some nice recycled local timber also, good you have a full workshop for this! Next to hear you playing with it!

[loydb]

Next is to calibrate my MFOS vco with it, the impetus behind the build in the first place

So we're almost back to the solder portion of the game. The first pic shows what the final finish looks like. Next, I'm adding the electronic bits that are part of the case itself. I decided to go with a black banana plug instead of a red one -- I think it looks better with the ebony.

In the last pic, you can see the area that is going to have to be covered with a plate. I'll try and get to that this afternoon, then the woodworking portion will be finished!

[loydb]

I worked on the decorative plates this morning. After drilling out access holes, I cut the ebony strips, sanded them, and (in the case of the back strip) began chiseling out a rectangle to fit the plug.

As you can see, in spite of trying to carefully pre-cut the boundries, the ebony still split in half. On the up side, this allowed me to use a scroll saw to square off the corners before gluing the piece back together. The inside plate doesn't need to be squared, it just needed to thread the wires through. I've glued it on, so it will be done by the time the back plate is ready to attach (tomorrow).

I'll clean the glue squeezout up with a small chisel in about 45 minutes after it has set a bit -- a rag would just smear it.

[loydb]

Home stretch time!

I've moved all the hardware from the temp panel to the actual FPD panel. I once again failed to allow sufficient clearance for the jacks at the bottom, so my screw holes are about 1/16" off. I'll drill some new ones tomorrow and fill the old ones with some dark wood paste.



Since the socket for the wall wart is pretty well glued in place now, I don't want to make a permanent solder connection to the motherboard for the power supply, in case the PCB has to be removed, so I'm using crimp connections.



Power supply and v/oct calibrator ready and attached to foamcore.



Before I can screw down the mini-kb, I have to hook up the buss port from the front. I should have done this with a crimp as well, but didn't think about it until too late. Fortunately, there's a lot of slack in the wire, should it be necessary to replace. Red arrow shows the solder location.



Ready to wire!



Wired!



Nearly done. The wiring is complete, and I've calibrated the v/oct portion and verified it is working correctly.