Request for two small steel rod-esque lathed part!

[Ross77]

you can then have a slight quiescent pull on the string

Isnt that going to give you tuning and intonation problems like when a Pup is set to high? :surprised:

Where dose this go then? since it looks like a single coil are u lossing a pickup to use it?

[HankMcSpank]

Isnt that going to give you tuning and intonation problems like when a Pup is set to high? :surprised:

Where dose this go then? since it looks like a single coil are u lossing a pickup to use it?

Well this is how the commercial ones work too!

in practise I don't see how it could it would cause much in the way of problems (if your guitar's intonation is setup up right, then it'll cause no impact whatsoever. After all, that's what setting up intonation is about....so the tuning isn't knocked out of whack no matter where you fret the string) ...& we're talking minimal quiescent pull. Where you have to be careful is on the guitar's natural sustain (ie no sustainer active)...if the sustianer coil magnets have too strong a pull on the string when inactive, it actually kills the guitar's natural sustain.

re mounting....well, the commerical ones, you have to sacrifice a pickup...but I'm trying to get a surface mount one to work (hence the low height). These sustainers aren't suitable for all guitars as normally they do radiate a lot of magnetic interference, which alas is the very thing a guitar pickup senses! Therefore it certainly needs some physical distance from the next nearest nearest pickup.

[Ross77]

Ah. I see. sounds like a good project.

Is it the no.of turns and length of wire that makes it work? If so you could use a small square bobbin to reduce the wasted space between the coils and then you can drill them to suit the size of the magnet. no need for a fancy holder and hopfully reduce the height.

Just my 2 peneth

[HankMcSpank]

It's a combination of the current through the coils, coupled with the number of turns (ampere turns in fact). It's a fine balancing act at that too.

Too many coil windings = too high an inductance, which means the coil presents resistance to higher frequencies feeding into it. The higher frequencies are the thinner strings, less ferrous material in them, so they actually need more drive

Too few windings = not enough magnetic force presented at the strings...only way to compensate is to cranck the current up, but that saps the battery.

Re round vs square coils. Square would be better (as it goes, I'd already considered them...in fact, you wouldn't believe the amount of McSpank Grey Matter processor 'cycles' I've dedicated to this little project!), but my simple coil winder (a drill chuck) cant cater for winding anything other than circular shapes! In fact longer rectangular coils would be better still...slightly overlapping one another so no dead spots when bending strings etc.

Ah. I see. sounds like a good project.
Is it the no.of turns and length of wire that makes it work? If so you could use a small square bobbin to reduce the wasted space between the coils and then you can drill them to suit the size of the magnet. no need for a fancy holder and hopfully reduce the height.

Not sure I fully grasp what you're getting at when you say (re square bobbins) "drill them to suit the size of the magnet" nor how could this proposale "reduce the height" .....I'm all ears, could you put more meat on the bone?

[HankMcSpank]

Over the weekend I had a bit of a play with my homemade CNC - I made a lot of simple mistakes, like forgetting to zero the tool after a tool change, only to watch the drill bit plunge right down through my material & a little into the table- eeek!), here's what I've been on with (rather than six little coils - one per string - becuase I don't have those parts I need, I had a opo at a larger coil.....



(I'm not sure if you'll notice, the bit marked 'bottom' part has a slight chip at the top left corner, this is because when changed cutting bits ,I had the feed rate too high, the machine went ballistic & gouged into the part a little! But since this is just a protoype, I couldn't be bothered to re-run the cut! The other two parts turned out well though...particularly happy with that middle bit - that's just 1mm between the edge holes & the bobbin edge at each end - remember my leadscrews are just M8 rod, & my drive nuts are badly homemade delrin ones!

The colour scheme(!) wouldn't be of my choosing, but I was limited to those colours because of the thickness of the acrylic (I needed 2mm thickness which I only had as clear acrylic & also 4.5mm which I only had in translucent royal blue!). Here it is as a temporary 'push fit'



those poles sticking up are actually 20mm lengths of Alnico magnets ...they obviously need trimming...they were an *extremely* tight fit. I screwed up with the middle part too! Basically, I read somewhere to get rid of the cutter marks that acrylic can be flame polished along the edge ...apparently, all you need to do is run a butane torch gas flame along the edge - I'm sure it normally works well, but not when the part so small....the acrylic heated the small part up & distorted the acrylic! (shrunk it a fraction...hence a couple of the poles not being bolt upright)

Here it is ready to be wound (I've not glued the top to the middle, because, after the coil is potted, I'd like to see how it looks without the top, hence the large washers clamping the top to the middle for while it's being wound)...



(the square edging makes it look somewhat utlitarian & of "East European circa 1970!" design ...but it's just a prototype so I have expended much effort giving it bevelled/rounded edges!

So then, next I wound 150 turns of 0.235mm wire (which is actually 0.27mm if you include the enamel coating!), this gauge is much thicker than I'm used to & is quite a bugger to 'control' while winding on to the bobbin....

....those two large screws atop are simply holding the top part to the remainder (pending potting - after which, the screws will come out & the magnets will go in)