Request for two small steel rod-esque lathed part!

[John S]

I make a few bobbins for the rewind industry from time to time and they also have to make non cored coils, not as small as this but similar principle.

What about getting a bar turning part down to 4mm longer than your coil and threaded it M4

The can be any size within reason but the part next to the thread turned down to 9mm as I gather that's just a visual guide on the coil being full ?
This will allow you to wind onto a thin plastic or paper former which can then be removed after.
The ends can have a card washer fitted with a small hole in to locate the wire at the start and then be disposed of after winding. This does away with the tiny drill hole at an angle. not sure why you need two start holes as the end of the wire is going to be on the OD.

Length of coil is controlled by a 9mm diameter 'washer' threaded M4 and held in place by a lock nut to adjust length of coil.

Or am I missing something ?

[HankMcSpank]

Firstly thanks for the comments.

My needs are only to wind copper wire directly onto an Alnico magnet (let's call this magnet the 'core', as essentially that's what it will be - the core of a coil ...essentially a solenoid)....I have no other coil winding requirements (paper /plastic formers etc)

These parts are towards a hobby DIY projectette for a guitar ...therefore I'm constrained to the dimensions of the guitar. So One limiting factor is the core length (ie the magnet you see in my second scribble above), which will be about 8mm max (of 5mm diameter Alnico magnet). This is a very small bit of metal to be turning 150 turns of copper wire onto! Therefore I need all the help I can get at keeping it rigid between those two parts. To help centralize it (since it'll be turning at about 200RPM) & stabilize/rigidize it while turning, I figured I'd need....

1. The parts I'm requesting to be made of steel (bearing in mind I want these parts to 'hold' a magnet...being steel will help them 'click' into & hod in place)

2. The 5mm diameter pocket/recesses at the end of the parts, to be a nice tight fit.

The tiny 'start' holes (I'm thinking 0.5mm!) I mentioned are a 'nice to have', but I can appreciate that it might be a task to get them drilled so small & at an angle. The angle isn't important, but what is important, is that I can thread the wire through the part out of the way - so as I start to wind the coil, the wire isn't a pain to get to start 'biting' (for want of a better word) around the core quickly...to get the coil off to a nice neat start on it's first layer. I need a 'start' hole at both ends, because I anticpate, some coils will be wound starting at the left moving right & other coils wound starting at the right moving left.

The 9mm diameter 'dimension' you picked up on, is both a visual representation (that said, I'm knocking up a PIC based coil winding program which will count the coil turns anyway), but more importantly, to make sure the edges of the coil are nice & perpendicular to the magnet core.

It's all a bit hard to explain in writing,

But in short..the way I'm proposing making the coils perhaps the only way I think it'll be possible to get decent results on a core so small (& I'm sure my mates will probably ask me to make them one too...so I may need to make a good few coils!)

[John S]

Firstly thanks for the comments.


I need a 'start' hole at both ends, because I anticpate, some coils will be wound starting at the left moving right & other coils wound starting at the right moving left.

No just one hole, left to right, right to left can be obtained by reversing the bobbin direction.


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[HankMcSpank]

No just one hole, left to right, right to left can be obtained by reversing the bobbin direction.


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i'm not sure I'm following?

I can't change the parts around from side to side as they have different 'pocket' depths milled into their end bits (this is becuase I need different amounts of magnet core to protrude outside the copper coil at each end). Also each part is held in a different manner ... ie part 1 is held by a drill chuck, whereas part 2 is threaded onto some M8 rod. Therefore if I need to start the coil winding at a different end, then they both need the 'start' holes drilled.

But as Bill helpfully mentioned...the 0.5mm hole wouldn't need to go the whole way, just the last say 0.3mm if drillling from the main rod perimeter down towards the part 1 end surface.