Since I started building these tools I have wanted to play with a rotary broach. This is the best way to make "hexagonal holes". Traditionally you use a "push broach" - this is slow and, requires a LOT of force to basically push the hexagonal hole into the metal. The rotary broach works by "spinning" the hexagonal shape with a 1 degree "wobble" and then you push the wobbling bit into the metal causing the cutting action around the edges - it is VERY COOL. The current production of the SPDTool uses a Rotary Broach and these tools cost BIG bucks ($800 and up). Much to my amazement, Little Machine Shop started selling one for $99 ! I couldn't order it fast enough and it actually works ! This is going to open up a lot of options for my prototyping !
Also consider the pressure reducing rotary broach holder design from http://www.polygonsolutions.com for broaching blind holes, or applications where alot of coolant is being used.
ReplyDeleteGreat blog. It would be great if you can provide more details about it. Thanks you
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