# Simulate 4mm endmill cut for laser?

**URL:** <https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614>\
**Category:** LightBurn Software Questions\
**Created:** [November 1, 2026, 9:37am UTC](https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614 "2026-11-01T09:37:45Z")\
**Posts on this page:** 13\
**Page:** 1

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**Author:** ![BaronPork](https://forum.lightburnsoftware.com/letter_avatar_proxy/v4/letter/b/c6cbf5/32.png) [@BaronPork](https://forum.lightburnsoftware.com/u/BaronPork)\
**Post date:** [November 1, 2026, 9:37am UTC](https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614/1 "2026-11-01T09:37:45Z")

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I have a situation where i need to simulate radius tools on cnc (4mm endmill) for sample cutting on a laser.

It’s a map, where there are thousands upon thousands of elements and i would need to add fillets to every one of them in the vector file to do this.

Any way to autogenerate paths as if laser beam/kerf is 4mm thick with radiused internal corners ?

Pic below shows two 500x500mm squars i need to do as a sample for much bigger panel that will not fit my laser and will need cut with a cnc later on (actual cnc tests coming later). If i were to cut it as is it would have sharp corners of, well, laser cut (0.1-0.2mm ?) and not drop elements that 4mm bit wont fit.

All of what i’m doing here is an experiment trying to prototype things at home where i dont have access to a cnc. Finish panel will be much larger (about 1x3m 12mm thick panel).

 ![image](https://forum.lightburnsoftware.com/uploads/default/original/3X/0/4/04e01b41d72ed1567deff13d4cba1efa01ab3838.png)

Any words of wisdom here ? Working in Autocad/Coreldraw/Vcarve. Laser is 100w 900x600, cnc is 5x10’ gantry machine with 9kw spindle and 20 tool atc.

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**Author:** ![ednisley](https://forum.lightburnsoftware.com/user_avatar/forum.lightburnsoftware.com/ednisley/32/40455_2.png) [@ednisley](https://forum.lightburnsoftware.com/u/ednisley)\
**Post date:** [November 1, 2026, 2:16pm UTC](https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614/2 "2026-11-01T14:16:35Z")

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> [@BaronPork](#):
>
> simulate radius tools on cnc (4mm endmill)

As a quick first approximation:

- Import an image square into LightBurn
- Scale it to 500×500 mm
- Trace the image

 ![LightBurn - City Streets - trace bitmap](https://forum.lightburnsoftware.com/uploads/default/original/3X/3/9/39d63405af57901379492b5f793a9c961c4dd7e8.jpeg)

To simulate a cutter following the lines:

- Set the `Image` layer `Show` = **Off**
- Set the traced layer to `Line` mode
- Select everything in that layer

Then apply an `Offset`:

- `Outward` by 2.0 mm = cutter radius
- `Round` to simulate a cutter
- `Outer shapes only` to avoid internal paths

Which looks like this before you hit OK:

 ![LightBurn - City Streets - offset on trace](https://forum.lightburnsoftware.com/uploads/default/original/3X/0/d/0da72f09a97299ab52d07f480e7e680ee06013b3.jpeg)

The result will run the laser along the outside of the path the cutter would follow:

 ![LightBurn - City Streets - laser path](https://forum.lightburnsoftware.com/uploads/default/original/3X/d/9/d949d2a8cadf1057c5b0266b6cdc5e3a3ea1e8ee.jpeg)

Depending on how fussy you are with the laser-cut version, the image will require cleanup _before_ tracing:

- Closing building outlines crossing the outer border
- Closing open shapes
- Removing other anomalies as needed

But that should get the ball most of the way to the goal …

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**Author:** ![NicholasL](https://forum.lightburnsoftware.com/user_avatar/forum.lightburnsoftware.com/nicholasl/32/40942_2.png) [@NicholasL](https://forum.lightburnsoftware.com/u/NicholasL)\
**Post date:** [November 1, 2026, 4:46pm UTC](https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614/3 "2026-11-01T16:46:06Z")

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You could try the new ‘Center line trace’;

 ![image](https://forum.lightburnsoftware.com/uploads/default/original/3X/7/8/78d7ad551e5387c1703bebb98f37d8bd1825b793.png)

Offset that trace line outward then inward if you are cutting on the outside:

 ![image](https://forum.lightburnsoftware.com/uploads/default/original/3X/1/9/197a5318310aa77cccb3ce2d4cbb71052a4fd637.png)  
 ![image](https://forum.lightburnsoftware.com/uploads/default/original/3X/f/b/fb78834a041cd9ec24c995bea41cb0e176f34a58.png)

 ![image](https://forum.lightburnsoftware.com/uploads/default/original/3X/7/a/7ab8202ebcbc70c25f29f6ac317702436718a6a2.png)

Or inward first and then outward if the cutter will be on the inside:

 ![image](https://forum.lightburnsoftware.com/uploads/default/original/3X/e/8/e81f5501b06eceacc0db07d835f0f33e6562b6f2.png)

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**Author:** ![ednisley](https://forum.lightburnsoftware.com/user_avatar/forum.lightburnsoftware.com/ednisley/32/40455_2.png) [@ednisley](https://forum.lightburnsoftware.com/u/ednisley)\
**Post date:** [November 1, 2026, 5:00pm UTC](https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614/4 "2026-11-01T17:00:24Z")

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> [@NicholasL](#):
>
> the new ‘Center line trace’

That introduces some peculiarities:

 ![LightBurn - City Streets - centerline trace oddities](https://forum.lightburnsoftware.com/uploads/default/original/3X/8/c/8cffc457a93e1a0e0cff4a526f66c5937fd9d21a.jpeg)

Finding & fixing those may be somewhat less awful than what I suggested, but AFAICT the original image has enough oddities to stonker any automated approach. 😁

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<div class="post-metadata">

**Author:** ![BaronPork](https://forum.lightburnsoftware.com/letter_avatar_proxy/v4/letter/b/c6cbf5/32.png) [@BaronPork](https://forum.lightburnsoftware.com/u/BaronPork)\
**Post date:** [November 1, 2026, 7:00pm UTC](https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614/5 "2026-11-01T19:00:16Z")

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I wasn’t clear at the beginning - the graphics are already a vector, i just posted a screenshot from Coreldraw for illustration. No tracing is needed as such.

I cannot change anything in original vectors as i need to keep scale for tooling, so no ofsetting of any kind can be made. Using the same svg export for both laser and cnc. Cutting inside only, black stays, white falls out. All i need is to somehow fillet all the corners r2mm and discard anything what 4mm endmill wont fit into.

 ![image](https://forum.lightburnsoftware.com/uploads/default/original/3X/0/3/035d46137bbc3f7017f610a41e4cbe4dbd46ee6c.png)

Ran a sim/toolpath using vcarve, this is what i’m trying to do but in LB.

 ![image](https://forum.lightburnsoftware.com/uploads/default/original/3X/5/e/5eaf0eb5ba53bea10eadf25c59677b7eacd1e284.png)

Any way to tell lightburn to cut with “fat laser” ? 😃

Cheers

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**Author:** ![ednisley](https://forum.lightburnsoftware.com/user_avatar/forum.lightburnsoftware.com/ednisley/32/40455_2.png) [@ednisley](https://forum.lightburnsoftware.com/u/ednisley)\
**Post date:** [November 1, 2026, 7:12pm UTC](https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614/6 "2026-11-01T19:12:22Z")

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> [@BaronPork](#):
>
> Using the same svg export for both laser and cnc

Not a problem: you modify the SVG layout _in LightBurn_ to make it work for lasering, leaving the original SVG file unchanged.

> [@BaronPork](#):
>
> graphics are already a vector

Try this:

- Apply a 2 mm `Offset` to the layer
  - `Inward` and `Corner` to get the cutter / spindle path
  - `Delete original shapes`

- Apply a 2 mm `Offset` to the result
  - `Outward` and `Round` to simulate the cutter
  - `Delete original shapes`

The result will look a lot like a 4 mm cutter run around the inside of the original shape. Very small shapes will have problems, but that’s just a preview of what the CNC cutter will do. 😁

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<div class="post-metadata">

**Author:** ![BaronPork](https://forum.lightburnsoftware.com/letter_avatar_proxy/v4/letter/b/c6cbf5/32.png) [@BaronPork](https://forum.lightburnsoftware.com/u/BaronPork)\
**Post date:** [November 1, 2026, 7:26pm UTC](https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614/7 "2026-11-01T19:26:09Z")

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That was the whole idea, to simulate what it would look like if cut with 4mm endmill, but also losing any detail that 4mm endmill wouldnt fit into. Perfect.

Also, the whole experiment is now moot as apparently cutting 13mm veneered mdf is a bit too much for 100w co3 laser 😃 5mmps at 24mA in one pass -4mm focus, +0.25s dwelltime on start - FIRE 😃 Well there was no fire on tests, but i will not risk it…It kind of cut through but barely. Also one 500x500 panel would take an hour to cut… Might redo this experiment if customer agrees to go to 9mm which i cut before.

 ![image](https://forum.lightburnsoftware.com/uploads/default/original/3X/e/a/ead10d1d257272d77f8922fb03a7f998db1ec9f7.jpeg)

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<div class="post-metadata">

**Author:** ![ednisley](https://forum.lightburnsoftware.com/user_avatar/forum.lightburnsoftware.com/ednisley/32/40455_2.png) [@ednisley](https://forum.lightburnsoftware.com/u/ednisley)\
**Post date:** [November 1, 2026, 9:47pm UTC](https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614/8 "2026-11-01T21:47:15Z")

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> [@BaronPork](#):
>
> 5mmps

This is likely [below the controller’s `Start Speed`](https://forum.lightburnsoftware.com/t/why-ruida-doesnt-light-the-laser-below-10mm-s-80w/120353/2), so it will reduce the power to the layer’s `Min` setting. Depending on all those settings, the machine may be producing well under the power you expect.

A few years ago, I knocked the `Start Speed` down to 2 mm/s and watched a 60 W laser [having trouble with various woods](https://softsolder.com/2022/05/17/omtech-60-w-laser-wood-cutting/) over maybe 6 mm:

[![](https://softsolder.com/wp-content/uploads/2022/05/pxl_20220504_184105094-laser-cut-wood-samples.jpg) ](https://softsolder.com/wp-content/uploads/2022/05/pxl_20220504_184105094-laser-cut-wood-samples.jpg)

Your veneered MDF may combine the worst of both worlds: an interior full of random chemicals and a textured exterior perfectly holding the soot. ☹

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<div class="post-metadata">

**Author:** ![BaronPork](https://forum.lightburnsoftware.com/letter_avatar_proxy/v4/letter/b/c6cbf5/32.png) [@BaronPork](https://forum.lightburnsoftware.com/u/BaronPork)\
**Post date:** [November 1, 2026, 10:11pm UTC](https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614/9 "2026-11-01T22:11:51Z")

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Well, i was watching BOTH (digital and analogue) meters show 24mA while test cutting, so i’d say its 100% limit for this tube (EFR F4, 100w sustained, 1.4m long). Actually tried 2 pass cut which made it worse for soot and made me worried of setting things on fire. Tried one pass at 4.5mmps, probably slowest i ever went…nope…

Focus is an issue as this is 2.5" lens i believe. I can cut 10mm acrylic fairly well with focus way down, but mdf just too much thermal damage for this thick of a material. I wish i could find a cone for 4mm lens for this head with no luck. Yellow one still on machine. Got the black one but might pose rigidity problems for its weight and rubbish gantry engineering (skinny gantry, skinny belts, direct drive nema17 motor, big head is a no).

 ![image](https://forum.lightburnsoftware.com/uploads/default/original/3X/a/1/a17310d85dd802f9cb8f838181efa297e93902cd.jpeg)

I also have 9" lens off of old industrial multi-kilowatt class laser, may fit it for giggles at some point just to see 😃 (left 18mm 2.5FL, right II-VI 9.5FL)

 ![image](https://forum.lightburnsoftware.com/uploads/default/original/3X/c/8/c88a7dc187597208ee3a99dbf55f592a0cfb7adf.jpeg)

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**Author:** ![jkwilborn](https://forum.lightburnsoftware.com/user_avatar/forum.lightburnsoftware.com/jkwilborn/32/63089_2.png) [@jkwilborn](https://forum.lightburnsoftware.com/u/jkwilborn)\
**Post date:** [November 1, 2026, 10:58pm UTC](https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614/10 "2026-11-01T22:58:04Z")

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You can use the spot size/depth of focus (dof) [on-line calculator to figure out dof](https://lasercalculator.com/laser-spot-size-calculator/).

I believe I figured my 2" lens has a dof of ~2.7mm, so yes you need at least a 4" for this task.

I replaced my head with this lightweight head designed by Russ Sadler. It weighs about 100g. It can easily outrun the lps response time.

 ![head-left-crop](https://forum.lightburnsoftware.com/uploads/default/original/3X/d/d/dde9d1ddbe7f5c9c969a28879799de9c23e5f36d.jpeg)

Might want to check the head/mirror position. My mirror was not aligned with the mirror.

 ![Resized_20210713_105351(1)](https://forum.lightburnsoftware.com/uploads/default/original/3X/c/9/c93355d5396a67f811288f2e86e7e958f7c7d300.jpeg)

😺

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<div class="post-metadata">

**Author:** ![BaronPork](https://forum.lightburnsoftware.com/letter_avatar_proxy/v4/letter/b/c6cbf5/32.png) [@BaronPork](https://forum.lightburnsoftware.com/u/BaronPork)\
**Post date:** [November 1, 2026, 11:16pm UTC](https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614/11 "2026-11-01T23:16:39Z")

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Where do i get Russ superlight head ? Does he sell online ?

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<div class="post-metadata">

**Author:** ![jkwilborn](https://forum.lightburnsoftware.com/user_avatar/forum.lightburnsoftware.com/jkwilborn/32/63089_2.png) [@jkwilborn](https://forum.lightburnsoftware.com/u/jkwilborn)\
**Post date:** [November 2, 2026, 12:46am UTC](https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614/12 "2026-11-02T00:46:00Z")

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Check out his [youtube channel and videos](https://www.youtube.com/@SarbarMultimedia/search?query=lightweight%20head).

[![](https://img.youtube.com/vi/W55YVMokjEM/maxresdefault.jpg "RDWorks Learning Lab 184 Lightweight Head News") ](https://www.youtube.com/watch?v=W55YVMokjEM)

[![](https://img.youtube.com/vi/3lZ2Ttdwrdc/maxresdefault.jpg "RDWorks Learning Lab 185 Lightweight head update") ](https://www.youtube.com/watch?v=3lZ2Ttdwrdc)

😺

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<div class="post-metadata">

**Author:** ![system](https://forum.lightburnsoftware.com/user_avatar/forum.lightburnsoftware.com/system/32/64335_2.png) [@system](https://forum.lightburnsoftware.com/u/system)\
**Post date:** [November 4, 2026, 12:46am UTC](https://forum.lightburnsoftware.com/t/simulate-4mm-endmill-cut-for-laser/193614/13 "2026-11-04T00:46:28Z")

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Closed on November 4, 2026, 12:46am UTC

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