Spool for rectangular section cores

  • Last Post 21 August 2019
cd_sharp posted this 12 August 2019

Hey, guys

This is about addressing a practical problem we are facing, making good spools. They are critical for a successful experiment.

I don't have the space to host a 3D printer for now. So I need to make my own bobbins manually. Currently I'm working on a bobbin suitable for my AMCC-200 core with POC setup. It consists of these parts:

I need to make 6 copies of A, 2 of B and 6 of C. The main structure of the spool is formed by the 2 B parts.

Every B part consists of 3 sections corresponding to the 3 POCs. The C parts are kept in place by the longer teeth of the B parts.

Both the B and the C parts are closed down by the 6 A parts which give strength and rigidity to the spool.

I'm not sure I explained it clearly.

The best material I found to be fiberglass laminate sheet with cotton insertion, much like the one used for PCBs. It's an excellent electrical isolator and it's very rigid. I'm using 1 mm sheets.

I'll come back with more details and pictures.


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Chris posted this 13 August 2019

Hey CD,

I often use Acrylic, CNC Cut:



You have seen some of my handy work, dusty all be it:



They work out good! Especially on the end of the Cores, they can be placed and glued inplace.

Another way might be 3D Printing some Formers? Perhaps a bit hard to get on the ends of the MetGlas Cores however.


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cd_sharp posted this 13 August 2019

Hey, man

It looks very good. Is the acrylic one strong enough?

I had previous trouble with glueing pieces at 90 degrees. The side walls did not have enough strength.

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Chris posted this 13 August 2019

Hey CD,

I haven't had any trouble yet. I use 3MM and 5MM, sometimes go up to 10MM. So far I have had no trouble.

I use tight fit, with top and bottom plate recesses, so the sides fit in nice and snug. The MEG Replication is 5MM with a 3MM Recess.


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getreal156 posted this 13 August 2019

Hi Guys,
I'm back from holiday and slowly growing back to the work bench.
Don't forget my offer to print spools if you need some specials. Just material cost and shipping (from EU) for you guys.


Chris posted this 13 August 2019

Hey Jasper,

I hope you had a great holiday!


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Vidura posted this 14 August 2019

That are really nice coil formers, Mine are much more salvage, made of press wood laminations and cardboard peaces, glued with carpenter glue. But they are cheap, and easy to make and quite stiff at the side containment:

Here you can also see the stacked ferrite bar made of 30mm EE coressmile

If I may suggest: sometimes it can be helpful if you are able to move the coils individually to make adjustments of distance.


cd_sharp posted this 20 August 2019

Hey, guys

After a lot, and I mean a lot surprised of manual work, I can show you the results. Here are the parts B and C together:

And parts A also put at their places:

I only need to glue them and I'm done. Exhausting, but I'm pleased with the result.

Fighter posted this 20 August 2019

They looks great Cd_Sharp ! I know how hard is to cut in that material, it's a lot of work to do this...

patrick1 posted this 21 August 2019

wow fantastic work, -

PLEASE NOTE.  any anybody wants square or round spools made, - i am happy too do it for free. -

its more fun than my lathe.,, and can make them any thin'ness ;=).  but i usually stick too 0.3 - 1 mm thick

just draw up the dimensions exactly, and include 1/2 a mm of slack where appropriate, - the accuracy is very good. - last week i made a gear for my newman motor, that fits on a shaft... and dosnt need glue ;=D

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