"Pro" tip - triple check your stupid bit size

I’ve been playing around a lot lately, with a bunch of little issues that I hadn’t been able to track down, mostly cut out parts not being exactly what I swear they SHOULD be based on the vector I imported…

Now, I bought my bits from drillman1 on ebay - good prices, but odd sizes… 0.0945, 0.063…

Dyslexia (and stupidity) has hit me hard. I’ve been carving using the 0.0945 mill, THINKING is was the 0.063 mill, but looking at the last numbers and putting in 0.0645 as my size.

Been cutting oddly for TWO days. It wasn’t until I started a nice 12x23 project that it started missing details that should have been there based on the previewed path.

I was using a mill almost 50% larger than what I generated toolpaths for…and that toolpath number wasn’t even the correct size for the bit I was planning on using.

Lots of pain, wasted wood…only to find out it was my own basic error.

When using odd sizes (well, ones that don’t match standard American sizes like 1/8 or 1/16) — TRIPLE check that bit size. Will prevent lots of wasted wood and useless time on your machine.

Was 45 minutes into this cut before I even noticed.


nods I have done that on my old CNC.
At one point I considered color coding them :wink:

In the early days I bought so many different bits. In the end I wound up just defaulting to a favored few.
Adjusting my projects to work with the bits I used rather than trying to get a new bit to fit the project.

I always try to use standard sizes makes operating a lot easier unless you setup tool libraries in programs such as aspire. That way you can can your odd size bits odd names. It also helps to put nail polish on the tip that goes into the Chuck and label your tool library the color.

I ruined a piece a few week ago when I used a 90 deg vbit for a tool path that was expecting a 60 deg bit. Turns out that size really does matter.

also helps to double check that a 1/4" bit actually measures 0.25" and 1/8" is really 0.125"

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Yup. I bought a cheap Chinese v-bit on ebay labeled as 1/8" but it was actually a different (but close) metric size.

I only ever mess this up myself when I only have enough material left to do it once. :smile:

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The tools I bought from Drillman on Ebay all have little color-coded collars on them with the size stamped into them. I’m not sure if those numbers are accurate, but the collars are great for setting the bit depth in the spindle and being able to change bits quickly without touching a hot or sharp bit with your fingers.