# collision issue slic3r **URL:** \ **Category:** Software\ **Created:** [April 23, 2015, 3:24pm UTC](https://forum.lulzbot.com/t/collision-issue-slic3r/1679 "2015-04-23T15:24:14Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![trizik](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@trizik](https://forum.lulzbot.com/u/trizik)\ **Post date:** [April 23, 2015, 3:24pm UTC](https://forum.lulzbot.com/t/collision-issue-slic3r/1679/1 "2015-04-23T15:24:14Z")
I’m wanting to print multiple parts (40) and need to print them as individual objects. The parts are 25mm tall and i’m getting the message “some objects are too tall and cannot be printed without extruder collisions”. I know this is not the case, but can’t bypass it. Does anyone now how to get around this? ---
**Author:** ![edlink](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.lulzbot.com/edlink/32/29_2.png) [@edlink](https://forum.lulzbot.com/u/edlink)\ **Post date:** [April 24, 2015, 10:27am UTC](https://forum.lulzbot.com/t/collision-issue-slic3r/1679/2 "2015-04-24T10:27:33Z")
I assume you’ve selected “sequential printing” and set the extruder radius and height clearance? Hard for me to imagine 40 of anything 1 inch tall on the build plate, and **not** having clearance issues with the extruder head somewhere. What happens when you array 20 parts spaced out more, instead of 40? Do you get the same message? What’s the maximum number of parts you can sequentially print before you get that error message? ---
**Author:** ![trizik](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@trizik](https://forum.lulzbot.com/u/trizik)\ **Post date:** [April 25, 2015, 2:25am UTC](https://forum.lulzbot.com/t/collision-issue-slic3r/1679/3 "2015-04-25T02:25:38Z")
thanks for the reply. i have selected sequential printing and set radius 1 and height of 1. i have only added 2 units to the build table just to try it and it won’t even let me export gcode for two. this is what clued me into the problem, since i can spread the two pieces at opposite ends of the table and it still gives the error. my plan for 40 is to lay them out sequentially, export the gcode, import it into pronterface, look at the tool path, and make sure it is moving from front left corner to back right corner. this will ensure no collision issues. first things first though, i need to get rid of this error message regarding the height, which as i said, i know is truly a false alarm because it won’t even let me export gcode for 2 units. the parts are basically 6mm x 20mm x 25mm cubes. ---
**Author:** ![kcchen\_00](https://avatars.discourse-cdn.com/v4/letter/k/9dc877/32.png) [@kcchen\_00](https://forum.lulzbot.com/u/kcchen_00)\ **Post date:** [April 25, 2015, 6:09am UTC](https://forum.lulzbot.com/t/collision-issue-slic3r/1679/4 "2015-04-25T06:09:46Z")
Do you have the STL of the part? ---
**Author:** ![edlink](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.lulzbot.com/edlink/32/29_2.png) [@edlink](https://forum.lulzbot.com/u/edlink)\ **Post date:** [April 25, 2015, 12:12pm UTC](https://forum.lulzbot.com/t/collision-issue-slic3r/1679/5 "2015-04-25T12:12:57Z")
> [@trizik](#): > > set radius 1 and height of 1. There’s your problem. You can’t build a one inch high part, 1mm away from another one inch high part, sequentially, and not have clearance problems. Change those numbers to 25 and see what happens. Just curious, why do you need to build these sequentially? If you HAVE to print 40 at once, don’t do sequential printing. ---
**Author:** ![trizik](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@trizik](https://forum.lulzbot.com/u/trizik)\ **Post date:** [April 26, 2015, 1:41am UTC](https://forum.lulzbot.com/t/collision-issue-slic3r/1679/6 "2015-04-26T01:41:40Z")
the reason i set radius and height to 1 is because the pop-up not next to the dialog box says “the larger the number, the higher the safety factor” or something like that. for this reason, i set it as low as possible. i just set it to 25 and same message. i’m printing sequentially because these need to be very high quality and i seem to get much better quality with sequential printing. i just printed 10 last night without sequential printing and experienced minor delamination and misalignment of layers (slight). this doesn’t happen with sequential printing. when i just print one it looks perfect. i have a heated enclosure, bed temp 110, extruder 230. black abs. i’ll attach a .stp when i’m back at my main pc. thanks. ---
**Author:** ![edlink](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.lulzbot.com/edlink/32/29_2.png) [@edlink](https://forum.lulzbot.com/u/edlink)\ **Post date:** [April 26, 2015, 12:19pm UTC](https://forum.lulzbot.com/t/collision-issue-slic3r/1679/7 "2015-04-26T12:19:22Z")
The radius and height clearance box numbers are a distance in mm’s around and above the part. After you type in a number, when you go back to the main screen in Slic3r you should see a “clearance” line around the parts that indicate what you’ve typed in. Do you see those lines? They appear blue on my screen when I do this. ---
**Author:** ![edlink](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.lulzbot.com/edlink/32/29_2.png) [@edlink](https://forum.lulzbot.com/u/edlink)\ **Post date:** [April 26, 2015, 12:39pm UTC](https://forum.lulzbot.com/t/collision-issue-slic3r/1679/8 "2015-04-26T12:39:42Z")
[http://manual.slic3r.org/advanced/sequential-printing](http://manual.slic3r.org/advanced/sequential-printing) ---
**Author:** ![trizik](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@trizik](https://forum.lulzbot.com/u/trizik)\ **Post date:** [April 28, 2015, 1:23am UTC](https://forum.lulzbot.com/t/collision-issue-slic3r/1679/9 "2015-04-28T01:23:52Z")
Update: Based on the feedback, I experimented with different clearance numbers and ended up finding that 28 mm seems to be the magic number for these parts. Unfortunately I can only print 12 on the bed, but that’s a lot better than one. I’m not sure I completely understand this setting yet and need to spend some time thinking about it. Thanks for the help!