Tuesday, October 14, 2008

Magically Concentric

I just got some new tools that make it super easy to cut perfectly concentric washers. I've had a disc cutter for a while, and use it all the time, but I have always found it difficult to center the metal to cut washers. After reading this great tutorial from The Mechanical Philosopher, I got myself a set of transfer punches to fit my disc cutter. Basically, a transfer punch is a cylindrical punch with a little spike centered on the end. You can order them in sets or order individual punches in the sizes you need. To use them with your disc cutter, you basically put the metal you want to cut in place in the cutter, then slide the appropriately sized transfer punch into the hole. Tap the transfer punch gently to make a divot in the sheet. Then, being very careful not to shift the metal, cut your disc. You will have a disc with a perfectly centered divot. Then, when you cut the inside diameter of the washer, you can use the smaller transfer punch to align the disc in the cutter. This is just a super quick overview- check out The Mechanical Philosopher's tutorial to see some useful pictures and more detailed instructions. The tutorial shows the use of a press to cut the discs, but I use a hammer and it works just fine.

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