# Print head scratching bed during levelling **URL:** \ **Category:** Snapmaker 2.0 (3-in-1)\ **Created:** [July 26, 2021, 4:58pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106 "2021-07-26T16:58:33Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Mattuk](https://avatars.discourse-cdn.com/v4/letter/m/46a35a/32.png) [@Mattuk](https://forum.snapmaker.com/u/Mattuk)\ **Post date:** [July 26, 2021, 4:58pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/1 "2021-07-26T16:58:33Z")
Hi Everyone, I’ve just put my a350 together and turned on for the initial calibration with the 3d print head and bed installed, When the machine starts to calibrate the print head, it moves it to the top of the linear supports, moves up and down a bit, and then moves to the front left part of the bed and comes down. However it does not stop and hits the bed and scratches it as it moves right… I’ve checked the cables and everything seems to be in the right place. The linear modules look like they are seated properly… Andy ideas? Thanks! ---
**Author:** ![Mattuk](https://avatars.discourse-cdn.com/v4/letter/m/46a35a/32.png) [@Mattuk](https://forum.snapmaker.com/u/Mattuk)\ **Post date:** [July 26, 2021, 5:08pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/3 "2021-07-26T17:08:32Z")
Thanks William, yes I started the machine without a print head, connected it to the wifi and tried the auto update - it didn’t update though ---
**Author:** ![Mattuk](https://avatars.discourse-cdn.com/v4/letter/m/46a35a/32.png) [@Mattuk](https://forum.snapmaker.com/u/Mattuk)\ **Post date:** [July 26, 2021, 5:15pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/5 "2021-07-26T17:15:28Z")
Thanks again - will give it a go! ---
**Author:** ![Mattuk](https://avatars.discourse-cdn.com/v4/letter/m/46a35a/32.png) [@Mattuk](https://forum.snapmaker.com/u/Mattuk)\ **Post date:** [July 26, 2021, 5:53pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/6 "2021-07-26T17:53:48Z")
I’ve updated the software, however it’s still colliding with the bed, this time on the back left corner instead of the front left? ---
**Author:** ![brent113](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.snapmaker.com/brent113/32/11114_2.png) [@brent113](https://forum.snapmaker.com/u/brent113)\ **Post date:** [July 26, 2021, 5:58pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/7 "2021-07-26T17:58:26Z")
Post a picture of the machine clearly showing the linear modules and how they are attached to the base plate, and also a photo showing the platform from the side - there’s a couple easy to make assembly errors that can cause that. ---
**Author:** ![brvdboss](https://avatars.discourse-cdn.com/v4/letter/b/9f8e36/32.png) [@brvdboss](https://forum.snapmaker.com/u/brvdboss)\ **Post date:** [July 26, 2021, 6:02pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/8 "2021-07-26T18:02:28Z")
Aside from the questions already asked: - Can you confirm the magnet bed sheet (the floppy one) is on top of the print bed? - When you take that of and hold it against the print head, on the right there is a small sensor that should show a little (faint!) red light. (The sensor is a dark slightly transparent plastic thingy that sticks out on the back right). Can you see that light turning on? ---
**Author:** ![Mattuk](https://avatars.discourse-cdn.com/v4/letter/m/46a35a/32.png) [@Mattuk](https://forum.snapmaker.com/u/Mattuk)\ **Post date:** [July 26, 2021, 6:10pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/9 "2021-07-26T18:10:14Z")
Thanks brvdboss, yes the mat was on the bed, when I hold it up under the print head the red light comes on. Here are some photos of the machine ![image](https://us1.discourse-cdn.com/flex022/uploads/snapmaker/original/2X/a/a40e31522ba2ae43768d8d9ed013c67317a94345.jpeg) ![image](https://us1.discourse-cdn.com/flex022/uploads/snapmaker/original/2X/4/486bbf367b572860a60d31de91a19588fff8645e.jpeg) ![image](https://us1.discourse-cdn.com/flex022/uploads/snapmaker/original/2X/2/270ca531e3f5ee57eb12d0428c0ace5baa47d6c1.jpeg) ![image](https://us1.discourse-cdn.com/flex022/uploads/snapmaker/original/2X/1/1141d42b048345c4a9b03ece43a9a13c1e1daa7a.jpeg) ---
**Author:** ![brent113](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.snapmaker.com/brent113/32/11114_2.png) [@brent113](https://forum.snapmaker.com/u/brent113)\ **Post date:** [July 26, 2021, 6:20pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/10 "2021-07-26T18:20:01Z")
Unfortunately, it looks correctly assembled, so no easy fixes there. If you jog the toolhead down to the platform so the nozzle is just about touching the surface does the red light illuminate on the sensor? Could be the sensor is slightly too high and needs to be adjusted closer to the table. ---
**Author:** ![edf](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@edf](https://forum.snapmaker.com/u/edf)\ **Post date:** [July 26, 2021, 6:23pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/11 "2021-07-26T18:23:46Z")
> [@brent113](#): > > Unfortunately, it looks correctly assembled, so no easy fixes there. “Unfortunately” heh Check the position of the proximity sensor. That’s unlikely to be problem straight out of the box but it burned me the first time I replaced a hot end. With the novel touching the calibration card on the bed, the proximity sensor should be about 1mm (the thickness of a credit card in the docs) higher than the nozzle. ---
**Author:** ![Mattuk](https://avatars.discourse-cdn.com/v4/letter/m/46a35a/32.png) [@Mattuk](https://forum.snapmaker.com/u/Mattuk)\ **Post date:** [July 26, 2021, 6:40pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/13 "2021-07-26T18:40:18Z")
It looks to be about 1mm from the sensor when I tried it with a drill bit, but by adjusting the top module when the machine is turned off it appears to be a few mill for the sensor and about half a mill for the head tip ![image](https://us1.discourse-cdn.com/flex022/uploads/snapmaker/original/2X/8/833b634c0a0264ea8b8c1fd43971f0b44663531b.jpeg) ![image](https://us1.discourse-cdn.com/flex022/uploads/snapmaker/original/2X/0/0c2bab2d4da078e8f82953a3c7bdd5e927c0e187.jpeg) ---
**Author:** ![Mattuk](https://avatars.discourse-cdn.com/v4/letter/m/46a35a/32.png) [@Mattuk](https://forum.snapmaker.com/u/Mattuk)\ **Post date:** [July 26, 2021, 7:02pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/15 "2021-07-26T19:02:01Z")
Many thanks everyone for your help, I tried the pallet knife test… and it just keeps going! [https://youtube.com/shorts/SgOh6hMjems?feature=share](https://youtube.com/shorts/SgOh6hMjems?feature=share) I’m guessing that’s a fault module? ---
**Author:** ![albutch](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.snapmaker.com/albutch/32/16397_2.png) [@albutch](https://forum.snapmaker.com/u/albutch)\ **Post date:** [July 26, 2021, 7:25pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/17 "2021-07-26T19:25:40Z")
Have you checked that you have the aluminium frame in the correct orientation, i.e. nuts down? Also check the positioning of the sensor on the print head, it may be set too high. ---
**Author:** ![Mattuk](https://avatars.discourse-cdn.com/v4/letter/m/46a35a/32.png) [@Mattuk](https://forum.snapmaker.com/u/Mattuk)\ **Post date:** [July 26, 2021, 7:33pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/18 "2021-07-26T19:33:00Z")
Thanks albutch, yes the nuts are down (photo in the thread) and the sensor being triggered does not stop the head (as video above). Looks like a faulty head / controller. ---
**Author:** ![albutch](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.snapmaker.com/albutch/32/16397_2.png) [@albutch](https://forum.snapmaker.com/u/albutch)\ **Post date:** [July 26, 2021, 7:37pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/19 "2021-07-26T19:37:08Z")
Sorry, it looks like I didn’t read the whole thread… that’s because I didn’t, for some reason it opened at your last post, I didn’t realise there were posts above. 😄 ---
**Author:** ![Mattuk](https://avatars.discourse-cdn.com/v4/letter/m/46a35a/32.png) [@Mattuk](https://forum.snapmaker.com/u/Mattuk)\ **Post date:** [July 26, 2021, 7:42pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/20 "2021-07-26T19:42:37Z")
Hehe no worries - all help and suggestions greatly appreciated 👍😁 ---
**Author:** ![MooseJuice](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.snapmaker.com/moosejuice/32/10684_2.png) [@MooseJuice](https://forum.snapmaker.com/u/MooseJuice)\ **Post date:** [July 26, 2021, 11:25pm UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/21 "2021-07-26T23:25:35Z")
Hello Granted this is a photo, but… It looks to me like the linear modules are leaning forward. Got a square? It also looks like there is a bow in your main base to me ![image](https://us1.discourse-cdn.com/flex022/uploads/snapmaker/original/2X/0/050fedf21734556cf17ce641e639d4a8f499bc4b.jpeg) The blue is a straight 90 degree, the green is about 88 ---
**Author:** ![Artezio](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.snapmaker.com/artezio/32/15834_2.png) [@Artezio](https://forum.snapmaker.com/u/Artezio)\ **Post date:** [July 27, 2021, 1:05am UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/22 "2021-07-27T01:05:28Z")
@MooseJuice It looks square to the bed, the camera itself was a bit crooked, also notice the raised part of the table at the front. ---
**Author:** ![Mattuk](https://avatars.discourse-cdn.com/v4/letter/m/46a35a/32.png) [@Mattuk](https://forum.snapmaker.com/u/Mattuk)\ **Post date:** [July 27, 2021, 5:53am UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/23 "2021-07-27T05:53:30Z")
Thanks, I’ll check the square. I was moving it about to get the photos and it is bridging 2 units which are not quite the same height so that may account for some of it, but good thing to check as well. Support are advising that cables are round the wrong way and the print head should home to the top of the machine…. Which it already does… ---
**Author:** ![Artezio](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.snapmaker.com/artezio/32/15834_2.png) [@Artezio](https://forum.snapmaker.com/u/Artezio)\ **Post date:** [July 27, 2021, 7:06am UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/24 "2021-07-27T07:06:11Z")
@Mattuk which homes first? The x axis and head? Or the bed? Also, that wouldn’t account for the z probe not working. You put a spatula to it and no red light came on, right? ---
**Author:** ![Mattuk](https://avatars.discourse-cdn.com/v4/letter/m/46a35a/32.png) [@Mattuk](https://forum.snapmaker.com/u/Mattuk)\ **Post date:** [July 27, 2021, 7:08am UTC](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106/25 "2021-07-27T07:08:29Z")
Yes I did, it was a cable issue - I needed to invert the z & y axis and the bed should move last. All is working now, thanks everyone for you help! Matt [Next page](https://forum.snapmaker.com/t/print-head-scratching-bed-during-levelling/20106.md?page=2)