# Tapered bits seem to be calculated by the shaft diameter and not the tip

**URL:** <https://forum.grid.space/t/tapered-bits-seem-to-be-calculated-by-the-shaft-diameter-and-not-the-tip/3042>\
**Category:** CAM\
**Created:** [August 17, 2026, 4:27pm UTC](https://forum.grid.space/t/tapered-bits-seem-to-be-calculated-by-the-shaft-diameter-and-not-the-tip/3042 "2026-08-17T16:27:29Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![DaBIGOne](https://forum.grid.space/user_avatar/forum.grid.space/dabigone/32/2670_2.png) [@DaBIGOne](https://forum.grid.space/u/DaBIGOne)\
**Post date:** [August 17, 2026, 4:27pm UTC](https://forum.grid.space/t/tapered-bits-seem-to-be-calculated-by-the-shaft-diameter-and-not-the-tip/3042/1 "2026-08-17T16:27:30Z")

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Hi,

When I select a 0.5mm straight corn bit it looks to be working fine, but when I use a tapered bit it looks like it’s calculated from the shaft diameter in stead of the tip diameter.

0.5mm Corn bit:

 ![image](https://forum.grid.space/uploads/default/original/2X/a/a738ef7c325fc439930930c4ac86c9ed4ad28a02.png)

0.5mm tapered ballnose (with 3.175mm shaft):

 ![image](https://forum.grid.space/uploads/default/original/2X/3/348f01a3e73e0e3b40daa3eb6c2d86f2c2f36099.png)

0.1mm 20 degree engraving V-bit:

 ![image](https://forum.grid.space/uploads/default/original/2X/1/175317e3f49ef0f37fc44938f2f5c1657eefce6b.png)

3.175mm flatend bit:

 ![image](https://forum.grid.space/uploads/default/original/2X/1/17769d5275591d0cc1188edc0315f5ba0dd2003f.png)

I’ve about the same with the pocket op:

0.5mm corn bit:

 ![image](https://forum.grid.space/uploads/default/original/2X/9/90754f11acf9a16e195429cd39fe7200fd12db81.png)

0.5mm tapered ballnose:

 ![image](https://forum.grid.space/uploads/default/original/2X/2/264a333b67e93e887dde6780b97984ecb8cfa93d.png)

0.1mm 20 degree engraving V-bit:

 ![image](https://forum.grid.space/uploads/default/original/2X/3/31ec28bdfb4fb2287ba6afb2341d256f663def4c.png)

I’ve seen this on the production server, transferred to the dev-server and got the same.

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<div class="post-metadata">

**Author:** ![stewart](https://forum.grid.space/user_avatar/forum.grid.space/stewart/32/21_2.png) [@stewart](https://forum.grid.space/u/stewart)\
**Post date:** [August 17, 2026, 6:27pm UTC](https://forum.grid.space/t/tapered-bits-seem-to-be-calculated-by-the-shaft-diameter-and-not-the-tip/3042/2 "2026-08-17T18:27:51Z")

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I’ll take a look, but I thought it would use the tip diameter unless that was `0`

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<div class="post-metadata">

**Author:** ![DaBIGOne](https://forum.grid.space/user_avatar/forum.grid.space/dabigone/32/2670_2.png) [@DaBIGOne](https://forum.grid.space/u/DaBIGOne)\
**Post date:** [August 17, 2026, 6:54pm UTC](https://forum.grid.space/t/tapered-bits-seem-to-be-calculated-by-the-shaft-diameter-and-not-the-tip/3042/3 "2026-08-17T18:54:52Z")

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I did a work-around to make a straight ballnose bit of 0.25mm 🙂 and just use the tapered ballnose bit for real, I just needed a 0.2mm deep pocket.

 ![image](https://forum.grid.space/uploads/default/original/2X/6/62fe618cacb38081b103f46320d2153a8f10bb37.png)

Some people call that a needle 😛

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<div class="post-metadata">

**Author:** ![stewart](https://forum.grid.space/user_avatar/forum.grid.space/stewart/32/21_2.png) [@stewart](https://forum.grid.space/u/stewart)\
**Post date:** [August 17, 2026, 8:55pm UTC](https://forum.grid.space/t/tapered-bits-seem-to-be-calculated-by-the-shaft-diameter-and-not-the-tip/3042/4 "2026-08-17T20:55:48Z")

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also called “fake it while you make it”