[hackerspaces] Epilog laser cutter - focus lens replacement

[Peter Kuhm]

Hi,

Metalab has a 60W EPILOG Legend 36EXT since 2009-08-26
http://metalab.at/wiki/Lazzzor
we bought it as good as new (used only for showroom/fair)

In Sept/Oct 2012 we had the aged laser tube changed and new we
need to replace the focus lens (focus point in 2" distance)

It is sort of consumable, was already not in best condition.
cf http://asset-0.soup.io/asset/3878/2798_0db6.jpeg from last year

But now someone used it w/o checking the lens condition and it
cracked from to heat build-up due to carbon black deposits.


My question: Epilog original spare part via German
distributor costs us something like EUR 220/320 (excl VAT)

Has someone on the list here used a different source and
can share experience?

beside physical dimension the focus length is important

(we want to stick to the 2 inch). 
http://support.epiloglaser.com/article/8205/42831/focus-lens-101

colleagues found much cheaper ones, e.g.
http://www.alibaba.com/product-detail/Co2-Laser-Focus-Lens-Diameter-20mm_708952502.html

Any comment on focus quality (narrowness of the spot) and how
the alterative source can handle 60 Watt in continous service
would be appreciated.

Hack on,
Peter