# Laser cut is oval - mistake or ok? **URL:** \ **Category:** Community Laser Talk\ **Tags:** request\ **Created:** [February 7, 2026, 3:54pm UTC](https://forum.lightburnsoftware.com/t/laser-cut-is-oval-mistake-or-ok/187457 "2026-02-07T15:54:08Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Relleumdesign](https://forum.lightburnsoftware.com/letter_avatar_proxy/v4/letter/r/47e85d/32.png) [@Relleumdesign](https://forum.lightburnsoftware.com/u/Relleumdesign)\ **Post date:** [February 7, 2026, 3:54pm UTC](https://forum.lightburnsoftware.com/t/laser-cut-is-oval-mistake-or-ok/187457/1 "2026-02-07T15:54:08Z")
Hi, I’m currently fumbling around with my yet unused 100W cutting laser. I mounted a carrier for laser diodes and a vac hose, therefore I had to turn the nozzle for 180°: ![IMG_3205](https://forum.lightburnsoftware.com/uploads/default/original/3X/9/f/9fe8e5df84814feea9d7efa0bd9ae57040771744.jpeg) The air assist inlet is now at the back side, was in front. Therefore the vertical nozzle position changed for 1/2 the thread inclination…this should only affect the z laser focus afaik? First check showed that the laser cut is oval - what happened? Did I disasjust something…can’t imagine where as the laser beam should be round at all times. Is it a manufacturing fault? A mirror not plane? I tried this tiny screw in the nozzle without visible change…what is it for? I assume it holds the optics inside? ![IMG_3211](https://forum.lightburnsoftware.com/uploads/default/original/3X/d/d/dd68b98854c9c744c7573084105b7483a9b0f362.jpeg) Havn’t found the correct focus yet, pic just for demonstration. Cheers, Dirk ---
**Author:** ![Relleumdesign](https://forum.lightburnsoftware.com/letter_avatar_proxy/v4/letter/r/47e85d/32.png) [@Relleumdesign](https://forum.lightburnsoftware.com/u/Relleumdesign)\ **Post date:** [February 7, 2026, 4:44pm UTC](https://forum.lightburnsoftware.com/t/laser-cut-is-oval-mistake-or-ok/187457/2 "2026-02-07T16:44:26Z")
Ooookay…beginners mistake, learnt a lot now: it was a manufacturer adjustment mistake. After some thinking I got to the conclusion that it must be a question of focusing the beam to the lens. Too much out of center will produce a distortion in x or y. So I fumbled around with a 5.5mm wrench, a pinpointed pliers and some chilling music. On both mirrors. In the end it’s quite logic: swiveling the beam in y (middle mirror) will produce blurr in y, but it’s the trick to do it at the right mirror. A biiiiit to much and the beam is gone entirely. You will have gone through that… I assume this result is ok, not in focus, just the shape and almost no blurr: ![IMG_3212](https://forum.lightburnsoftware.com/uploads/default/original/3X/5/3/534ae5daaeda90e53e0d3f31fa1f766cc3e53811.jpeg) It’s still a tiny little bit oval in 45° to x, but this might be a result of burning the paper? Any recommendations? Cheers, Dirk ---
**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:** [February 7, 2026, 5:49pm UTC](https://forum.lightburnsoftware.com/t/laser-cut-is-oval-mistake-or-ok/187457/3 "2026-02-07T17:49:37Z")
> [@Relleumdesign](#): > > Any recommendations For all pulsed measurements, set a manual power and pulse duration on the Ruida controller, so that you get a mark rather than torching the paper. For a 6445 controller, I _think_ this works: The Power button sets the pulse power. I generally use about 20%. The pulse duration is (probably) at the Menu button, then `Functions` → `Laser Setting`: - `Laser mode`: pick `Manual` - `Laser time`: about 20 ms works for me The values differ depending on the material and purpose; they will _definitely_ be different for your machine. The point is to have a repeatable pulse that doesn’t depend on your (well, my) reflex time. ---
**Author:** ![Relleumdesign](https://forum.lightburnsoftware.com/letter_avatar_proxy/v4/letter/r/47e85d/32.png) [@Relleumdesign](https://forum.lightburnsoftware.com/u/Relleumdesign)\ **Post date:** [February 7, 2026, 6:03pm UTC](https://forum.lightburnsoftware.com/t/laser-cut-is-oval-mistake-or-ok/187457/4 "2026-02-07T18:03:11Z")
Ah, ok, didn’t know there is a pulse time. Makes it easier. I’m donwn on 5% (less ist not possible), with a short touch I can avoid burning through. But I’m not done yet, despite the first successes. When I move the table down to go deliberately out of focus to check if the laser is vertical (yes, it is) and my crosses still align (works), I see an oval burning in x with some blurrs in x. So I tried to swivel the middel mirror up and down, but this seems to have no effect on that. When I swivel the laserhead mirror the beam wanders out of the center and is no longer vertical - quite logical. I hope I don’t have to fumble around on the first mirror…how do I check if the wide beam is centered to the apertures, looks most important to me? I can’t see the beam on paper, obviously. What’s the trick? There wil be plenty of videos on YT, I guess? Any recommendations? ---
**Author:** ![Relleumdesign](https://forum.lightburnsoftware.com/letter_avatar_proxy/v4/letter/r/47e85d/32.png) [@Relleumdesign](https://forum.lightburnsoftware.com/u/Relleumdesign)\ **Post date:** [February 7, 2026, 6:14pm UTC](https://forum.lightburnsoftware.com/t/laser-cut-is-oval-mistake-or-ok/187457/5 "2026-02-07T18:14:18Z")
Ok, with the next try it will be dark tape and a bit more power to find and adjust the centers. I’m looking forward to find the reason for the oval blurring. I’ve skipped through this video: [![](https://img.youtube.com/vi/G-HhArItCqQ/maxresdefault.jpg "How to align your mirrors on your Chinese / OMTech CO2 laser") ](https://www.youtube.com/watch?v=G-HhArItCqQ) but there are many others. ---
**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:** [February 7, 2026, 6:20pm UTC](https://forum.lightburnsoftware.com/t/laser-cut-is-oval-mistake-or-ok/187457/6 "2026-02-07T18:20:25Z")
> [@Relleumdesign](#): > > can’t see the beam on paper That’s [what those short pulses are for](https://softsolder.com/2024/06/05/laser-cutter-fourth-corner-adjustment/): [![](https://softsolder.com/wp-content/uploads/2024/06/beam-alignment-initial-m1-m2-2024-05-31.jpg) ](https://softsolder.com/wp-content/uploads/2024/06/beam-alignment-initial-m1-m2-2024-05-31.jpg) The [targets are surely over-fancy](https://softsolder.com/2023/09/12/laser-cutter-print-and-cut-alignment-accuracy/), but I like 'em. 😁 The mirror targets mount flat on the mirror at 45° to the beam, so the scorch is elongated horizontally, but they verify the beam is centered on the mirror. You’ll also want targets [mounted perpendicular to the beam](https://softsolder.com/2023/10/03/laser-cutter-beamline-realignment/) to verify its shape at the entry to each mirror: [![](https://softsolder.com/wp-content/uploads/2022/03/pxl_20220322_193755350-omtech-60w-laser-beam-test-mirror-1.jpg) ](https://softsolder.com/wp-content/uploads/2022/03/pxl_20220322_193755350-omtech-60w-laser-beam-test-mirror-1.jpg) If it’s not round at Mirror 1, then there’s definitely a problem upstream of all the optics. ---
**Author:** ![Relleumdesign](https://forum.lightburnsoftware.com/letter_avatar_proxy/v4/letter/r/47e85d/32.png) [@Relleumdesign](https://forum.lightburnsoftware.com/u/Relleumdesign)\ **Post date:** [February 7, 2026, 6:53pm UTC](https://forum.lightburnsoftware.com/t/laser-cut-is-oval-mistake-or-ok/187457/7 "2026-02-07T18:53:33Z")
Seems to be much better than tape bc the adhesive will vapor and settle on the lenses. Same with paper if you burn through it. Will see if I can get those targets cut with the current settings, I won’t need thick material. ---
**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:** [February 7, 2026, 10:17pm UTC](https://forum.lightburnsoftware.com/t/laser-cut-is-oval-mistake-or-ok/187457/8 "2026-02-07T22:17:02Z")
> [@Relleumdesign](#): > > Same with paper if you burn through it Well, then, _don’t do that_. 😁 ---
**Author:** ![Relleumdesign](https://forum.lightburnsoftware.com/letter_avatar_proxy/v4/letter/r/47e85d/32.png) [@Relleumdesign](https://forum.lightburnsoftware.com/u/Relleumdesign)\ **Post date:** [February 7, 2026, 11:06pm UTC](https://forum.lightburnsoftware.com/t/laser-cut-is-oval-mistake-or-ok/187457/9 "2026-02-07T23:06:16Z")
I didn’t see any mark at all yet on paper bc the power was too low, but now I know what to do instead of “poking around in the fog” 😆 ---
**Author:** ![Relleumdesign](https://forum.lightburnsoftware.com/letter_avatar_proxy/v4/letter/r/47e85d/32.png) [@Relleumdesign](https://forum.lightburnsoftware.com/u/Relleumdesign)\ **Post date:** [February 10, 2026, 9:56pm UTC](https://forum.lightburnsoftware.com/t/laser-cut-is-oval-mistake-or-ok/187457/10 "2026-02-10T21:56:48Z")
Ok, I did all this and it came out that the beam is kind of oval all the way before it hits the last mirror and the focusing lens. Then I discovered the beam is not in the center of the nozzle which had the effect that the beam wasn’t perpendicular to the material, so moving out of center with z movement. So I centered the beam everywhere as good as possible. All this corrected it looks now quite round and cuts nicely through plywood.