Leadin/leadout small problem

I come from a machining background and have a CNC mill and Router so leadin/leadout is quite a common setting to use for me, plus I felt it would give a better finish without any dwell time.
So onto my small problem, I’m making a box to hold an instrument so there are a few holes and tabs, I added leadin/leadout to the cut along with a small length of 1mm and then previewed the cut, the preview showed the leadin/leadout on the outside of the holes (in the part) and some of the outer start points had the leadin/leadout inside the part.
If I disable “Choose best start point” the outer leadin/leadout works correctly but the holes still have them all starting in the part.
It doesn’t seem to make any difference what length or straight/curve etc.
All my holes are round and the artwork was imported as a pdf from Coreldraw.
Obviously the inner leadin/leadout starting in the part is wrong so is this something I’m doing wrong or is it a bug?
The leadin/leadout starting in the part on the outer cut with “Choose best start point” is definitely a bug.

P.S. Just created a box with a circle inside with Lightburn and got the same result.


Can you show a picture of what you mean?

I suspect it’s just that you haven’t made the arc length / diameter small enough to fit in those holes - It doesn’t shrink them if they don’t fit - it merely starts them on the correct side of the line and assumes you have the size set appropriately.

Fir example, with a 60 degree, inside lead, 8mm long:

You can see that it works as expected for the first three circles, but the last is too small for it to fit. Changing it to a 90 degree lead, and shortening it slightly makes it fit:


I’ll try altering the angle but I had the length at 1mm on both curved or straight, I didn’t alter the angle though.


That’ll be it - zero angle means it’s an “in-line lead” - It’ll be going in the same direction as whatever point it’s attached to. Positive angle is outside, and negative angle is inside, but LightBurn will manage that for you a bit. For example, this is a 5mm, 90 degree “outside” lead:


The software figures out that the ‘outside’ of the inner circle is on the opposite side.

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Finally had chance to mess with the leadin/leadout settings, the angle sorts them in circles but I still get problems with some corners when choose best start point is selected.
I’ll sort a screenshot and add it here.

Also I’ve realised I’ve put this post in the wrong forum, I was meaning to put it in the software forum.


I moved it for you.

Thanks Blake.

Screen shot of the preview window showing how the leads start inside on 2 parts, the circles are right now I’ve used the angle setting but it’s not altered the outside leads.

If you’re using ‘choose best start position’ it’s not smart enough yet to check for leads and pick accordingly. I’ll log that as a bug. In the meantime, you can force the starting point to be anywhere you like for a shape by using the start point tool:

That overrides the ‘Choose Best’ behavior, so you would only need to set it on the troublesome shapes.

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That’s what I’ve done, I just wanted to make sure I wasn’t missing something obvious like I had on the inner circles.


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