Early magneto coupling needed- see pictures

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Just an update for folks,


Using the patent drawings and measurements of a few surviving parts we were able to "reverse engineer" the Milbarth Magneto coupling

as Mike has on his engine. From what we can tell these were proprietary to Wisconsin Motor Manufacturing since Milbarth was one of the

founding partners. These coupling would have been used on the T-head Wisconsin Model "A" (Stutz, FWD, etc.) as well on the model "L", "G" and "J" engines

and their marine variants (AM, LM, GM & JM)


First we modeled each component in 3D. Using these, we assembled a complete 3D model and generated the 2D shop drawings that will

be used for machining the castings etc. We also generated the 3D models for the patterns. We will use Fusion 360 to generate the tool paths

and post process to PathPilot for our Tormach CNC milling machine. I have some nice mahogany all laminated up so next week we can mill out the patterns.


The disk is actually leather which I thought was a neat feature.







Interestingly we recently finished the core boxes and patterns for the valve covers for the same series of Wisconsin engines. Below is a batch just out of the foundry.



I love this stuff!




Edited by Terry Harper (see edit history)

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The original splines appear to be square, but drawing shows tapered or involute splines. Will you wire EDM them in. And I am wondering why if you are only making one coupler why would you cast it, probably much cheaper to just machine it. 

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Yes, it appears that way and yet the patent states that they "... are preferably ordinary gear teeth" We will be doing a number of sets - thus the castings. In this case theWire EDM would indeed be the way to go to cut the teeth. The patent states that this design would provide for fine adjustment of the magneto timing. I guess we will see!

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We finished the shop drawings and 3D printed a mockup (just for fun) We also started milling out the patterns.

We should.... key word.... should have the patterns all done next week. We had to set it aside for a bit so we could mill out some parts for our

UMO steam engine project. The patterns will be setup on a match plate with the runners and gates and shrink bob and allow two sets at once to be cast.

I usually mill my patterns out of pine but since these are small and fragile I decided to use some mahogany I had on hand. Since this is a rather open grain wood

I will have to fill the grain before applying the shellac.







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Well since other projects got in the way it took a bit longer than planned but here are the patterns for the Milbrath magneto. I setup the coupling halves as a match plate

so four complete couplings can be cast at once. I also included the runner and gates as part of the pattern. After machining the halves can be split using a slitting saw. The spyder pieces are just a simple one sided pattern. Since I didn't have a drive gear to measure it would be best to hob a new one to match the coupling. This was a fun project which I enjoyed tremendously.


These were sized for casting in aluminum but can be cast in iron as well  - the difference in shrinkage rate would make them just a tad bigger which shouldn't be much of an issue with the parts.

Mike I know you don't need a set now but if anyone wants still wants or needs a set please let me know. I also have a shop drawing to go with it.


Best regards,








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