How did you get your faceplate 'true'?

[David King]

Having a perfect faceplate is certainly nice but don't let the better get in the way of the good. I make my faceplates from the baltic birch plywood scraps i have left over from other projects. I drill the hole first to fit a drill stop or collar using a cheap forstner bit on the drill press. I generally drill them all 5/8" to fit on a table saw arbor. (In UK and Europe the standard might be 20mm) I cut outside of the disk as close to round as I can on the bandsaw or with a jigsaw and then spin them on the tablesaw or lathe while i file them with a sharp file. It takes a little patience and you need to hold the file just so for it to give you a perfectly round disk. I use the file and sanding blocks to round the edges and then soak the edges in shellac or superglue. It's not dangerous and the results are 100% useable for turning pickup bobbins at 2000rpm.

If you need to make a custom collar for going from 5/8" (or 20mm) to 8mm then that's what your little lathe is good at. Do all the turning operations on a 3/4" or 25mm bar in a three jaw chuck without releasing the jaws until you are ready to face off the back side (after cutoff operation). That way the all-important ID and OD will stay concentric. I have about 10 faceplates to fit different bobbins and can make up new ones as needed in a matter of minutes. I also use similar faceplates on the tailstock but a "live center" might be even better.

[peskywinnets]

A hearty thanks to you all for taking the time to give me the benefit of your experience.

My determination to get a completely true faceplate is a result of ongoing 'negative experience' with my homemade coil winding rig!

Let me put a bit more meat on the bone.....

I'm trying to wind a 'surface mount' (ie sit on the guitar surface - no routing) sustainer.

I'm going to have to talk metric in my post here ...so sorry to all those over the pond! (I worked in both imperial & metric for the first 10 years of my life...but then our schooling system discarded imperial ...just as well, base 32 was never a strong point of mine!).

To surface mount a sustainer, certainly for my intended guitar, there's only 6.8mm 'space' between the strings & the guitar body (this allows for a little bit of headroom for when the stings are vibrating hard). BTW I'm designing/cutting my own custom bobbins out of acrylic.

Ok, so now I've only got 6.8mm to work with including the bobbin edges - but they need to be about 1.5mm thick (else the bobbin edges are too flimsy & prone to snapping), So now I'm down to just 3.8mm bobbin 'winding space'. The thing is with sustainers, they use wire which is about 5 times thicker than guitar pickups. This doesn't leave a whole lot of space for winding the wire onto! Thankfully, sustainers only need a 100-200 turns.

I've been trying to squeeze every last 0.01mm winding space out of that remaining small area of bobbin recess. This means starting right at the bobbin edge...but what I've found is that for all the wire aligned on one side of the bobbin, it's out by a small margin on the other side...this typically results in the wire it 'catching' over the bobbin edge....necessitating me having to start over (& due to the very high tension needed - to ensure my sustainer winds without massive bulging along the bobbin flats - starting over involves an elaborate time consuming sequence of setting up!)

In short it it taking me ages to align the wire to get a good wind - I reckon if my faceplate is totally true, then this will go some way (in part) to helping me save a little bit of time winding sustainers.

[David King]

Well peskywinnets,
A couple of thing come to mind here right away. First is; what wattage are you needing to drive the string and can you possible get away with thinner wire?

Second; there is no need for a bobbin at all if you don't mind encapsulating the driver/pickup in an epoxy matrix using mold/mould.
You'll need face plates that are very shiny and coated with a mold release agent of some sort. Stick your core between the plates, wind the full 6mm (1/4") width and then squirt the windings with CA glue to hold them together.
Prepare a plug that's a full height 6.7mm with radiused ends and corners etc.
Figure out a way to suspend the armature in your silicone mold that you made from the plug and pour you epoxy in slowly from a great height (1-2 feet according to jonson?) so that it stays more or less free of bubbles.

[peskywinnets]

Well peskywinnets,
A couple of thing come to mind here right away. First is; what wattage are you needing to drive the string and can you possible get away with thinner wire?

Second; there is no need for a bobbin at all if you don't mind encapsulating the driver/pickup in an epoxy matrix using mold/mould.
You'll need face plates that are very shiny and coated with a mold release agent of some sort. Stick your core between the plates, wind the full 6mm (1/4") width and then squirt the windings with CA glue to hold them together.
Prepare a plug that's a full height 6.7mm with radiused ends and corners etc.
Figure out a way to suspend the armature in your silicone mold that you made from the plug and pour you epoxy in slowly from a great height (1-2 feet according to jonson?) so that it stays more or less free of bubbles.

It's a fairly convoluted calculation to arrive at the optimum wire size ...but wire size is mainly decided by the supply rail of the supporting circuit. It's actually possible to get a string to sustain using a normal pickup...but you need about 100V for your circuit (the current needed through a pickup would only be about 4mA....so the thin gaue wire ought to be able to handle that). For a 9V supply, the coil needs to be about 8 ohms, for 5V about 4 ohms.

I'm making a 5V supply coil - therefore I'm pretty much tied to 4 ohms. The only way to get 4 ohms with sufficient 'turns' is to use thicker wire.

In short it's not possible to go thinner!

I know it's possible to make a coil without a bobbin, but using epoxy is a pain/mess & also the looks of a bobbinless coil aren't to everyone's taste (I reckon guitarists - by & large - are a little bit old fashioned in their tastes...eg they want a guitar to be strat-esque shape & have pickups that llook like pickups!)


So for now at least...I'll pursue a bobbin solution - but thanks for your ideas though - they are always welcome/appreciated.

[Bruce Johnson]

I don't know if you saw this on another thread, but here's a portion of my web site showing all the processes that I use to build my pickups:

Building Scroll Basses- Pickups 1

On the second page, you'll see how I solved the problem of the wire catching on the bobbin flanges. I machined up two round aluminum disks which go on either side of the bobbin, and the disks have recesses machined into them which the flanges sink in to. The outer edges of the disks are beveled and polished. It almost guarantees that the wire can't catch and loop. When I set up the stops, I try not to let the wire rub against the aluminum disks, but it doesn't really matter if it does.

Along the lines of what David was suggesting, you could also design your bobbin so it's slightly squashable. Wind it a little looser with the flanges apart, then squash it down in a vise or something, and apply CA glue to pot it.

[peskywinnets]

Hi Bruce - wow, what can I say?!

Firstly, it's great to be among like minded people ...& for all I'm way, *way* behind we're your already at - it sometimes a lonely path I'm trodding! (ie making my own CNC machine, making my own CNC winder, making my own bobbins etc etc). Seeing your manafacturing process both inspires me & reafirims I've pitched up my trailer at the right forum so to speak! I'm confident that whatever hiccup I hit, there'll be an answer from someone on here!

To your proposal - I'd actually considered cutting a recess into the faceplate myself - not sure how well my homemade CNC would cope milling aluminium though - as you'll see in my pic above, my homemade winder presently has am acrylic faceplate, but I want to go aluminiium which is where this thread came in!

Re winding the bobbins loose & squishing them down...that sounds a little erhmm 'kludgey' ....but that said, therein lies another one of my probelms - because I'm using much, much thicker wire, I'm having to wind incredibly tight (else the wire bulges terribly along the bobbin long flats). The problem with winding tightly, is that it puts immense pressure on the bobbin ends - this is splaying out my bobbin (ie bobbin end are thicker than the middle two thirds)...it's just the final 1/3" - but nevertheless it's got to be resolved. I may have a go at a loose wind & then squish it! I don't mine apparent kludges if the end results justify the means!!

thanks once again.


Anyway, a great set of pictorials there - well done!

[peskywinnets]

Well peskywinnets,

Second; there is no need for a bobbin at all if you don't mind encapsulating the driver/pickup in an epoxy matrix using mold/mould.
You'll need face plates that are very shiny and coated with a mold release agent of some sort. Stick your core between the plates, wind the full 6mm (1/4") width and then squirt the windings with CA glue to hold them together.
Prepare a plug that's a full height 6.7mm with radiused ends and corners etc.
Figure out a way to suspend the armature in your silicone mold that you made from the plug and pour you epoxy in slowly from a great height (1-2 feet according to jonson?) so that it stays more or less free of bubbles.

Having just tested my latest sustainer driver...alas, it looks like I'm going to have to go with even thicker wire (so much for my calculations! Actually, my driver does sustain, but I'd like a little more power in reservce on the top two thinnest stings). It's getting to the point now where, due to the thickness of wire needed & the lack of space if surface mounting, then I may be forced to go bobbinless...that prospect brought me back to your post David. I particularly curious about this bit...

Stick your core between the plates, wind the full 6mm (1/4") width and then squirt the windings with CA glue to hold them together.

Did you mean 'squirt the windings' on each successive coil winding 'layer' as the coil winds ...or just apply CA the final layer? If just the final layer, there must be a danger that the first few (&/or middle) copper wire layers will 'spring out' when removed from the faceplates?

But also, if you mean spray with CA while the coil is winding...then can the CA dry ok once covered with other windings (I'm no expert on CA, but doesn't it need air to 'set'). I'd have thought epoxy would be the thing to apply...but I'm all ears to the possiblity of winding a bobbinless coil in any way proposed!

[David King]

Having just tested my latest sustainer driver...alas, it looks like I'm going to have to go with even thicker wire (so much for my calculations! Actually, my driver does sustain, but I'd like a little more power in reservce on the top two thinnest stings). It's getting to the point now where, due to the thickness of wire needed & the lack of space if surface mounting, then I may be forced to go bobbinless...that prospect brought me back to your post David. I particularly curious about this bit...



Did you mean 'squirt the windings' on each successive coil winding 'layer' as the coil winds ...or just apply CA the final layer? If just the final layer, there must be a danger that the first few (&/or middle) copper wire layers will 'spring out' when removed from the faceplates?

But also, if you mean spray with CA while the coil is winding...then can the CA dry ok once covered with other windings (I'm no expert on CA, but doesn't it need air to 'set'). I'd have thought epoxy would be the thing to apply...but I'm all ears to the possiblity of winding a bobbinless coil in any way proposed!

I think just the final layer if you are using the thin CA glue as it will quickly flow via capilary action all the way through the coil. You can use an "accelerator" spray to speed the set up but you are right it needs some time to gas off completely. Mostly you want the CA to bind the edges enough so you can pop the coil off your plates and have it stay rigid long enough to encapsulate it. Generally folks use black epoxy or polyester so that it looks presentable in the end. A rough mold will work as you can sand the exterior to your heart's content (provided you don't sand through to the copper).