I have a K40+ and would appreciate some advise on an issue I have when cutting.
Engraving on wood come out very nicely but when I cut lines, the right hand edge of the cut has a heat effected zone or stain about 2 to 3mm wide. This is only present on the right hand side of cuts so not noticable on cuts on the horizonal ie parallel with X axis.
Is this due to a mishaped beam or more likely due to the hot by-products going off to the right side of the cut?
I have sort of ruled out a mishaped beam as the engraved results are very good.
I have gone through the beam alignment process and have it looking good now.
I have checked that it is central to the section where it enters the lens but it still seems to be hitting the edge of the nozzle exit or atleast the charring of the cut surface on the right side of the cut is still present.
I have cleaned the lens and mirrors but this does not seem to have resolved the issue.
I’m thinking that I should check that the lens is sitting flat in the housing or that the bottom of this housing is flat and not having a flaw that cocks the lens a bit. THe retaining collar/nut does not screw all the way down, probably sitting about 2mm up. Not sure if this is normal.
The above pics seem to confirm the beam is hitting the inside edge of the nozzle.
Even though the beam seems to be in the middle of the passage as it enters the lens carrier, I guess it could be at an angle? I had to adjust the final mirror to get the beam into the centre here even though it was in the centre as it entered the final mirror.
Removing the nozzle and lens and putting tape on the open end where the nozzle is, then test firing, will let you know whether the beam is otherwise centered.
Some heads don’t have great adjustment options for the mirror.
I did remove the nozzle and lens assembly then put tape on the open end to adjust the beam steering.
It was off centre ie in the direction of the side of nozzle that the beam was hitting, so I did adjust the last mirror to centre the beam in this assembly.
However, from my basic understanding the lens will invert this ie if beam is centred to the right above the lens, it will be offset to the left below the lens.
Another issue, when I cleaned the lens I struggled to see a side that wasn’t flat. To my eyes both sides looked flat…
I confirmed that the beam is in the centre of the nozzle exit but with the same setttings etc the assymetric scortch mark is still there.
So after watching some instructional videos on importance of airflow and nozzle needing to be close to surface for airflow assist to work well, I made a nozzle add-on for the k40+ and this seems to make a significant difference.
It slides over the std nozzle so the correct focal length can be had while getting the air exit to within 3mm of the surface.
A bigger improvement is made when I run higher flow air through as well.
If you are not cutting in one pass then the smoke has to go somewhere and you have 2 things moving the smoke, the air assist and the exhaust duct(usually to the back of box).
If you are cutting through in one pass and there is smoke on the top of the work piece then our air assist is too weak(usually because of cheap nozzle type air assists which are 20mm above the work piece(air assist nozzle should be sharp stream blowing through the cut so ~5mm or there about from the cut) or the air assist air flow is too weak.
Easiest fix is to apply making material to your work piece so the smoke goes on the masking material instead of onto the work piece. Thus the reason why I created this - Merged Air Nozzle V1 for K40 by DOugL - Thingiverse
Yes all that you say is true and I have only just worked this out.
My nozzle extension thing seeks to achieve the same result as yours. my K40+ has a different arrangement to the K40 but the same logic applies.
My air assist exit is now about 3mm above the cutting surface and it is working much better, although the std internal air source is a little underpowered so looking to have an alternative to that for cutting.
Your thingiverse model looks great!
