Adam Savage Attempts to Make a Tool Collet From Scratch!
Adam Savage attempts to make collets from scratch for his GHA 3A engraving machine using 4140 steel. After multiple failed attempts and learning about proper cutting directions and work hardening, he successfully creates a functional 1/8-inch collet with 1.5 thousandths runout.
Summary
Adam Savage undertakes the challenging project of making collets for his GHA Alexander model 3A engraving machine, which only came with a single 3mm collet. He explains that original collets for these machines are extremely rare, described as 'hen's teeth' or 'unobtanium' online. Using 4140 steel, he decides to make unhardened collets rather than go through the complex hardening and grinding process typically required for dimensional stability.
The project involves multiple complex machining operations: cutting precise tapers to match the original collet geometry, drilling accurate center holes, and creating the characteristic radial slots that allow the collet to grip cutting bits. Savage encounters several setbacks throughout the build, including work hardening the steel, mounting slitting saws in the wrong direction, drilling off-center holes, and breaking drill bits inside workpieces.
After numerous failed attempts and having to remake blanks multiple times, Savage successfully completes one functional 1/8-inch collet. The finished piece demonstrates proper taper geometry and achieves 1.5 thousandths of runout when tested - acceptable performance for his engraving work. He notes that this represents a significant advancement in his machining education, something he wouldn't have attempted five years earlier.
Key Insights
- Savage explains that original GHA collets are so rare they're described online only in metaphors like 'hen's teeth' and 'needle in a haystack'
- Savage decides to use 4140 steel without hardening, explaining that hardening causes warping and requires pre-machining and post-grinding phases
- Savage describes collets as exploiting both steel's hardness and flexibility simultaneously - the radial slices provide flexibility for gripping while dimensional stability provides accuracy
- Savage admits this type of precision collet making would have been 'absolutely not' possible for him five years ago, crediting other machinists like Stefan Gotteswinter for inspiration
- Savage explains his mistake of mounting the slitting saw backwards, noting that while his mill can reverse direction, it's better to mount the blade correctly to avoid accidentally burning it out
Topics
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