Lens: which way up?

NickWL · Post by **NickWL** » Mon Apr 21, 2014 9:22 am

After a couple of months of owning a K40, after reading all I can find about it and after doing a successful upgrade to DSP control - I still find myself confused...
Which way up does the focus lens go?
I have it on good authority that the convex side should face UPWARDS ... but I also have it on (equally?) good authority that the convex face should point DOWNWARDS.
What's the betting I'm going to get conflicting answers here as well?

swarm3d · Post by **swarm3d** » Mon Apr 21, 2014 3:05 pm

NickWL wrote:After a couple of months of owning a K40, after reading all I can find about it and after doing a successful upgrade to DSP control - I still find myself confused...
Which way up does the focus lens go?
I have it on good authority that the convex side should face UPWARDS ... but I also have it on (equally?) good authority that the convex face should point DOWNWARDS.
What's the betting I'm going to get conflicting answers here as well?

From what I have read the flat goes toward the table. However I think I run mine the other way and have had no problems. But now I am going to flip it a see if it makes a difference.

swarm3d · Post by **swarm3d** » Mon Apr 21, 2014 3:09 pm

swarm3d wrote:
NickWL wrote:After a couple of months of owning a K40, after reading all I can find about it and after doing a successful upgrade to DSP control - I still find myself confused...
Which way up does the focus lens go?
I have it on good authority that the convex side should face UPWARDS ... but I also have it on (equally?) good authority that the convex face should point DOWNWARDS.
What's the betting I'm going to get conflicting answers here as well?
From what I have read the flat goes toward the table. However I think I run mine the other way and have had no problems. But now I am going to flip it a see if it makes a difference.

https://www.youtube.com/watch?v=v0znprj3xsw this link might help

NickWL · Post by **NickWL** » Tue Apr 22, 2014 4:13 pm

swarm3d - do please keep us posted on your experiment.
I will (eventually) try it myself but just at the moment I'm still trying to eliminate random variables to get my system (DSP'd K40) to a steady starting-point!

ivantandy · Post by **ivantandy** » Mon May 05, 2014 8:55 pm

With the cheap lens from original k40 still installed i can see no real cutting or spot difference whichever way up although I think the convex side up to laser beam is standard. I have not tested engraving to see if resolution affected. All I know is it is worth getting a better lens.

NickWL · Post by **NickWL** » Tue May 06, 2014 9:02 am

From what I can remember of schoolboy physics (a very long time ago) it doesn't make any difference in a single-lens system.

waltfl · Post by **waltfl** » Thu May 08, 2014 12:48 pm

that's right and could be wrong I recommend to test it . I had lenses who would cut concave down much better as reversed but I also had some where it was reversed. I don't know nobody realy can explaine this but that's the way.
greetings
waltfl

NickWL wrote:From what I can remember of schoolboy physics (a very long time ago) it doesn't make any difference in a single-lens system.

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