# Linear rail alignment for better precision **URL:** \ **Category:** Build Logs\ **Created:** [April 21, 2023, 1:35pm UTC](https://forum.avidcnc.com/t/linear-rail-alignment-for-better-precision/1987 "2023-04-21T13:35:10Z")\ **Posts on this page:** 6\ **Page:** 2
**Author:** ![double0jimb0](https://avatars.discourse-cdn.com/v4/letter/d/f08c70/32.png) [@double0jimb0](https://forum.avidcnc.com/u/double0jimb0)\ **Post date:** [April 26, 2023, 2:27am UTC](https://forum.avidcnc.com/t/linear-rail-alignment-for-better-precision/1987/21 "2023-04-26T02:27:20Z")
Will do! Thanks for posting that video. Going to do similar approach when mounting and leveling the linear rails. One thing I am going to do differently is only level the upper linear rail on the gantry. Will then drive the gantry carriage (with 2 upper and only 1 lower linear bearings installed) down the length and tighten the lower linear rail as I go along. I found this procedure from hiwin install guide. This procedure uses the linear bearings as an alignment jig. One weird things I noticed so far, while the steel of the linear rails is the same “height”, the “height” at which the linear bearing actually rides is a 0.002” difference between the two y-axis linear rails. ---
**Author:** ![greg.obj](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/greg.obj/32/2807_2.png) [@greg.obj](https://forum.avidcnc.com/u/greg.obj)\ **Post date:** [May 27, 2025, 4:01pm UTC](https://forum.avidcnc.com/t/linear-rail-alignment-for-better-precision/1987/22 "2025-05-27T16:01:28Z")
@tinkeringtechie This laser/webcam method you shared is working great so far! Made a 3d printed jig to mount it directly to a bearing. ![IMG_6233](https://canada1.discourse-cdn.com/flex027/uploads/avidcnc/original/2X/7/7897623904a87f00ee3a8cb1d09c4ec0c305528b.jpeg) ---
**Author:** ![corbin](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/corbin/32/2800_2.png) [@corbin](https://forum.avidcnc.com/u/corbin)\ **Post date:** [May 27, 2025, 4:13pm UTC](https://forum.avidcnc.com/t/linear-rail-alignment-for-better-precision/1987/23 "2025-05-27T16:13:18Z")
Whoa, sweet! Did you find stuff was a bit off? ---
**Author:** ![greg.obj](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/greg.obj/32/2807_2.png) [@greg.obj](https://forum.avidcnc.com/u/greg.obj)\ **Post date:** [May 27, 2025, 5:17pm UTC](https://forum.avidcnc.com/t/linear-rail-alignment-for-better-precision/1987/24 "2025-05-27T17:17:17Z")
@corbin Definitely - I just moved my cnc so things were clearly very warped to begin with. I have only had time to do one rail so far, but one can really see and address tiny variations in the rail mounting height. I believe I have the one rail leveled to within .002" or so. I put some washers under avid’s leveling jig to use as a point to clamp against and slid it along with the webcam sensor, loosening a few screws, moving the rail to the correct position by clamping off of the rail/jig(up) or rail/gear rack (down), and re-tightening the bolts. I don’t think moving the laser up and doing the same for the y-axis rails will really guarantee its in the same plane as the x-axis rails as I don’t trust this cheap laser’s “level” being 100% consistent, but it will certainly be better than it was previously. For the cost of an old webcam and $2 in 3dp resin it appears to be working exceptionally well. ---
**Author:** ![Eric](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/eric/32/3220_2.png) [@Eric](https://forum.avidcnc.com/u/Eric)\ **Post date:** [May 27, 2025, 5:31pm UTC](https://forum.avidcnc.com/t/linear-rail-alignment-for-better-precision/1987/25 "2025-05-27T17:31:43Z")
What is this setup? Is there any information about it posted anywhere? ---
**Author:** ![greg.obj](https://yyz1.discourse-cdn.com/flex027/user_avatar/forum.avidcnc.com/greg.obj/32/2807_2.png) [@greg.obj](https://forum.avidcnc.com/u/greg.obj)\ **Post date:** [May 27, 2025, 5:44pm UTC](https://forum.avidcnc.com/t/linear-rail-alignment-for-better-precision/1987/26 "2025-05-27T17:44:57Z")
Tinkeringtechie shared the link above: > [@tinkeringtechie](#): > > [Measuring flatness](https://www.youtube.com/watch?v=hnHjrz_inQU) [Previous page](https://forum.avidcnc.com/t/linear-rail-alignment-for-better-precision/1987.md?page=1)