20 watt Chinese Fiber Lens size

[Keith Cox]

Looking at the idea of buying a 20 watt fiber what is the best general purpose lens size to get and is it worth getting different sizes

thanks Keith

[Gary Hair]

With 20 watts you are pretty limited with the size lens you can use. I don't know what the max would be, but I can't imagine you should go any bigger than 175mm working area. You might be better off with a 110 just to get the highest power density. You'll lose a bit of working area and maybe some focal range, but you need to use all of the 20 watts and not waste it trying to do something it can't do. FYI - all of this is based on what I have gleaned over the time I have had my two fibers and may be somewhat, or completely, incorrect. If anyone knows better then I'll gladly listen and learn.

[Keith Cox]

With 20 watts you are pretty limited with the size lens you can use. I don't know what the max would be, but I can't imagine you should go any bigger than 175mm working area. You might be better off with a 110 just to get the highest power density. You'll lose a bit of working area and maybe some focal range, but you need to use all of the 20 watts and not waste it trying to do something it can't do. FYI - all of this is based on what I have gleaned over the time I have had my two fibers and may be somewhat, or completely, incorrect. If anyone knows better then I'll gladly listen and learn.

Thank you for your Reply Gary much appreciated

[Kev Williams]

Seems 150mm lenses (just under 6" coverage" are fairly standard with 20 and 30w machines, that's what mine came with.

I'd really like to get a 175 just for marking purposes, since I already do anodized parts that require 3 and 4 setups, a 175 would cut out one of those moves. And I may have a big job of anodized parts with 7-1/2" worth of area to sweep coming down the work pipeline (so I'm told, but not holding my breath), and the 150 could take up to 4 setups

I'd also like to pick up a 110, I'm getting asked for ridiculously deep engraving in hardened steel, and I'm wondering if the tighter lens might be a bit quicker getting there...

Seems I remember someone mentioning they had one they don't use... .... .... ;)

[Rodne Gold]

I use a 110mm and a 220mm for my 20 watt
220 x 220 is best suited for plastics , 110 x 110 for general marking
20w wont get to any "incredible" depth anyway

[Gary Hair]

I'd also like to pick up a 110, I'm getting asked for ridiculously deep engraving in hardened steel, and I'm wondering if the tighter lens might be a bit quicker getting there...

Seems I remember someone mentioning they had one they don't use... .... .... ;)

I recall something like that as well...

[Kenny Davis72]

When I bought my Wisely 20w fiber laser it came with a f-290mm (200mm x 200mm marking area) lens! It is a MOPA laser...I don't know if that makes any difference. It works OK but I always feel i'm missing something with the marking that makes it not quite black enough.

BTW, are you guys talking about focus length or marking area when mentions the measurements? F-150mm is different then 150mm x 150mm. Most manufactures seem to mentions marking area size.

One last thing, how hard is to reset up a fiber laser with a different lens? Is switching setting for different lens difficult.

Kenny

[Kev Williams]

The 'f' thing was explained to me awhile back, works like this--

This is representation of my F210 lens, aka 150mm lens...

http://www.engraver1.com/help/lens-size.jpg


Both squares are identical, the blue is simply rotated 45°, and the circle represents the actual working area of the lens-

I sized the diamond/circle to 210mm, and the red square, aka "working area", measures 'nominally' 150mm...

And just for reference, you are NOT limited to the square working area, my fiber will engrave everywhere within the circled area :)
-- EZcad gives you the option to draw a circular engraving area, but alas, it draws it at 150mm, not 210... go figure!

[matthew knott]

The lenses are specced by there focal length (not working Area)
163mm is the standard go to lens (110mm working area)
254mm is still good on anodised and you can do stainless but can be hit and miss , I would get both as they don't cost much and easy to change , the 330mm lens is not much use on metals and ours doesn't get much use

[Kev Williams]

The focal length IS the working area-- within a circle...

While my lens can only fill a 5.9" x 5.9" square plate from from edge to edge with engraving, It CAN fully engrave a 8.25" diameter circle...

[Keith Cox]

Thanks fellows it has given me some in site into the lens just have to talk the missus in to letting me buy a 30 watt fiber instead of the 20 watt
thanks
keith