Different Focus Lenses

Hardware settings, adjustments and fixes and other hardware discussion. This includes the "doHICky" Laser Power measurement system by Russ.
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Colin Krebbers
Posts: 5
Joined: Tue May 29, 2018
Location: Haelen
Country: Nederland
Laser Machine Make or Type: Jd1630
Laser Power: 150
Laser Bed Size: 63"x118"
Home Position: BR
RDWorks Version: 0
Windows Version: 10
Accessories: Rotary clamp

Hi all,

While trying to cut 12 mm thick poplar wood I've noticed different results with various lenses.

Standard, I'm using a 3" ZnSe lens giving me clear and fairly straight cutting edges, getting through the material at a nice pace.
Once we are using a 4" or 5" ZnSe lens, while setting its focus accordingly, we are not able to cut through the same material with equal laser settings.

We are using the laser head tube, height adjustment rings, and 4"/5" lenses from Master Laser.

Looking forward to your reply!

Colin
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Gene Uselman
Posts: 2180
Joined: Thu Jul 07, 2016
Location: Suburban Minneapolis, Minnesota, US
Country: USA
Nickname: Gene
Laser Machine Make or Type: QC
Laser Power: 130W
Laser Bed Size: 900x1300
Home Position: TR
Control Software: LIGHTBURN
RDWorks Version: RDw .19 & Lightburn
LightBurn Version: Latest
Ruida Controller: RDC6442
Windows Version: Win 10 Pro
Accessories: I have a combining lenses, pin tables [homebuilt], honeycomb tables , wireless remote, Modifed Ultimate Air Assist, home built non-powered rotary device, PrusaMK4 and Mini Prusa printers.

Colin you may want to watch Russ' videos on lenses [there is an index of his videos on the forum] Most machines I have seen are either 1.5 or 2.0 lenses and that is what I have experience with. I just googled your laser and it looks like a pretty substantial machine- is it a cabinet or flatbed?
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Colin Krebbers
Posts: 5
Joined: Tue May 29, 2018
Location: Haelen
Country: Nederland
Laser Machine Make or Type: Jd1630
Laser Power: 150
Laser Bed Size: 63"x118"
Home Position: BR
RDWorks Version: 0
Windows Version: 10
Accessories: Rotary clamp

Hi Gene,

Thank you for the reply and advice, I will have a look at the videos!

Indeed, it's a flatbed laser with quite large dimensions !

Kind regards,
Colin
Colin Krebbers
Posts: 5
Joined: Tue May 29, 2018
Location: Haelen
Country: Nederland
Laser Machine Make or Type: Jd1630
Laser Power: 150
Laser Bed Size: 63"x118"
Home Position: BR
RDWorks Version: 0
Windows Version: 10
Accessories: Rotary clamp

Hi,

From the following video I might have find the answer to what I've observed.
Quite obviously, the spot size of the laser with a larger focal distance lens increases, simply reducing the power per square mm/inch.

Link to the video: https://www.youtube.com/watch?v=K_dKUsY05jY

A nice side note, within the video the reasoning for me using a large focal distance lens is being presented.
You might have observed in some sense tapered edges cutting thicker material, this gradually decreases using lenses with higher FD.

A summary of the correct lenses specified for different types/thickness of material can be found from the table provided by Trotec:
https://www.troteclaser.com/en-us/knowl ... ight-lens/

Kind regards,
Colin
Dave Vigness
Posts: 526
Joined: Sun Dec 15, 2019
Location: Kansas City - Rural
Country: USA
Nickname: Dave
Laser Machine Make or Type: Chine Red and Black
Laser Power: EF RF2 80W
Laser Bed Size: 20 x 26
Home Position: TR
Control Software: RDWORKS
RDWorks Version: 8.01.54
Ruida Controller: RDC6445
Windows Version: 7
Accessories: Power Switch for air assist / exhaust blower, Ma meter with switch for external digital, dual digital temp gauge, LED lights under gantry and and and.

Pics and a list here. https://drive.google.com/drive/folders/ ... sp=sharing

Something else I discovered in emailing with Russ, the difference between cutting and engraving setups. I didn't realize mine was set for engraving, with a more than 19mm gap tip to work surface. Not getting enough airflow to keep the cut clear for good cutting. Getting a set of tips to get my gap down in the 5mm to 6mm range. I'f you're not close to the work you're fighting yourself.
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