# Understanding Bit Dimensions (new guy here) **URL:** \ **Category:** Vectric\ **Created:** [December 18, 2021, 8:54pm UTC](https://forum.sienci.com/t/understanding-bit-dimensions-new-guy-here/4616 "2021-12-18T20:54:03Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Abradel](https://forum.sienci.com/letter_avatar_proxy/v4/letter/a/c5a1d2/32.png) [@Abradel](https://forum.sienci.com/u/Abradel)\ **Post date:** [December 18, 2021, 8:54pm UTC](https://forum.sienci.com/t/understanding-bit-dimensions-new-guy-here/4616/1 "2021-12-18T20:54:03Z")
Hey folks, Thanks for the help thus far! It’s been great! New question…I have this bit from lee valley ( [Signmaking Bit - Lee Valley Tools](https://www.leevalley.com/en-ca/shop/tools/power-tool-accessories/router-bits/30212-signmaking-bit?item=16J4901) I am trying to create a profile for it in Aspire but it seems the Lee Valley site doesn’t really give you much in the way of information on it. When they say diameter in the tool profile, I’m assuming that’s not the same as the shank size? The shank size on this particular bit is 1/4". How do I know the diameter that the tool profile wants, and any advice on the rest of the settings? (cutting parameters, feed rates etc. I’m mostly cutting in to 5/8" pine) this is all wicked intimidating for someone who is starting out! Thank you very much for the help. Abe ---
**Author:** ![paullarson](https://forum.sienci.com/user_avatar/forum.sienci.com/paullarson/32/8543_2.png) [@paullarson](https://forum.sienci.com/u/paullarson)\ **Post date:** [December 18, 2021, 9:24pm UTC](https://forum.sienci.com/t/understanding-bit-dimensions-new-guy-here/4616/2 "2021-12-18T21:24:53Z")
From what I see on the website I would enter it as a 3 flute 60 degree vbit with a 13mm diameter. I don’t know about feeds and speeds. Since this is a 3 flute vbit they might be a bit faster (33.3%?) than the normal 2 flute vbits most folks use. ---
**Author:** ![Abradel](https://forum.sienci.com/letter_avatar_proxy/v4/letter/a/c5a1d2/32.png) [@Abradel](https://forum.sienci.com/u/Abradel)\ **Post date:** [December 18, 2021, 9:30pm UTC](https://forum.sienci.com/t/understanding-bit-dimensions-new-guy-here/4616/3 "2021-12-18T21:30:33Z")
Thanks for this. For my own future learning, where did you find the 13mm or how did you arrive at that conclusion. After finding some diagrams of other bits, I THINK it might have a 5/8" diameter? ---
**Author:** ![paullarson](https://forum.sienci.com/user_avatar/forum.sienci.com/paullarson/32/8543_2.png) [@paullarson](https://forum.sienci.com/u/paullarson)\ **Post date:** [December 18, 2021, 9:37pm UTC](https://forum.sienci.com/t/understanding-bit-dimensions-new-guy-here/4616/4 "2021-12-18T21:37:50Z")
The description said it could cut up to 13mm wide so that’s what I used. That’s really close to 5/8". ---
**Author:** ![Abradel](https://forum.sienci.com/letter_avatar_proxy/v4/letter/a/c5a1d2/32.png) [@Abradel](https://forum.sienci.com/u/Abradel)\ **Post date:** [December 18, 2021, 9:39pm UTC](https://forum.sienci.com/t/understanding-bit-dimensions-new-guy-here/4616/5 "2021-12-18T21:39:02Z")
Ahh, ok that makes sense thanks. Now to sort out feed/plunge etc. ---
**Author:** ![Dudley4166](https://forum.sienci.com/user_avatar/forum.sienci.com/dudley4166/32/1823_2.png) [@Dudley4166](https://forum.sienci.com/u/Dudley4166)\ **Post date:** [December 19, 2021, 9:07pm UTC](https://forum.sienci.com/t/understanding-bit-dimensions-new-guy-here/4616/6 "2021-12-19T21:07:31Z")
Garrett Fromme @idcwoodcraft has a pretty good feeds and speed charts to get you started