New wire current contact

I have changed the way current is transferred to the moving wire. In my previous setup I used a carbon brush, which seemed like a nice idea, but the resistance of the brush turned out to be too high (1 ohm) which would introduce large losses and heat dissipation.

Instead, I now use a piece of HSS CO-8 very hard steel from a broken mill bit that I saved after a milling accident (never throw those away, they always come in handy!). The EDM wire drags over the steel making contact. The power is connected to the HSS piece by a silver soldered brass nut. I’ve seen a similar solution in Jaakko Fagerlund’s machine and Mariano also mentioned this solution in a comment on a blog post.


    1. Post

      Hi, that is certainly true. I still want carbide, but buying a pricey carbide mill bit and then chopping it in half is a waste. So whenever I encounter a broken carbide mill, I’ll replace the HSS one.

      1. Jaakko Fagerlund

        Say what size you want and how many and send me an email with your address, I’ll put an envelope coming your way. We have bozes full of broken bits, so doesn’t cost a thing 🙂

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