Calibrate Focus Rods

[Angus Hines]

So Signwhare house finally made good on their pitiful attempt at keepi ng me a customer, and got me the right lenes.

However, none of the focus rods that they sent are calibrated ( true Signwarehouse service ).

SO the question is how do I measure and calibrate them.I would just e-mail their support department but thats the same department that got me in this mess to begin with.

So with that in mind anyone considering Signwarehouse as a supplier remember < Cavet Emptor >

[Rodne Gold]

Why do the rods have to be calibrated?
Are they anodised rods , blue , purple etc?
Do you have a small hole next to the lens housing , if so , just slip the correct colour rod for the lens (normally matches the anodised fram round the lens) in and the table is focussed when the rod just touches the surface.
Im sure in the machine panel , there is a functiuoin that allows you to specify the lens you use and it adjusts autofocus to suit and there is a "tune autofocus" where you can fine tune it with respect to the rods,

[James Stokes]

I have heard 2 ways. The first 1 is to take a piece of wood and place on the laser bed on an angle vector a line down that piece of wood. The place where the line is smallest is the focus. Second way is by using anodized aluminum the same way and the spot where you have the britest light is the focus.

[Angus Hines]

Rodney,

Because they arn't like the ones with the ZX machine. these are a black rod with a colored knob that slide up and down the rod and gets locked in place by a small set screw.

I'll try the auto tune thing and see if that works.

Can I just measure from the center of the lenes holder down to the material based on which ever lenes Im using?


Why do the rods have to be calibrated?
Are they anodised rods , blue , purple etc?
Do you have a small hole next to the lens housing , if so , just slip the correct colour rod for the lens (normally matches the anodised fram round the lens) in and the table is focussed when the rod just touches the surface.
Im sure in the machine panel , there is a functiuoin that allows you to specify the lens you use and it adjusts autofocus to suit and there is a "tune autofocus" where you can fine tune it with respect to the rods,

[Rodne Gold]

The distance from the exit point of the optic to the focal point = the focal distance - ie 1.5 inches from exit plane of lens would be the focal point. of the 1.5" lens
I find the Autofocus pretty accurate on all my GCC machines , usually just use that.
What lens did you get?
I have 1.5" , 2" , 2.5" and 4" and find just about all barring the 2" pretty much a waste of money.

[Angus Hines]

Thanks Rodney I got the 4" as I sometimes need to cut 1" acrylic and thats the only way to get a semi decent cut.

[Dave Johnson29]

Can I just measure from the center of the lenes holder down to the material based on which ever lenes Im using?


Angus, yes. Well probably near enough. With a 4" the depth of field is going to be maybe 1/2" or more.

If it were me, I would use that to start then use the anodized aluminum method James mentioned to fine tune.

I burn short straight lines then move the line and move the focus 1/8". Then examine with a magnifier for the finest line width. In the pic, the one with the black diamond was the best result.

[Rodne Gold]

I am dubious about cutting 1" pex with a 60 watter , no matter the lens , the 4" will not have good power density at the extremes to get a one pass cut and multiple passes are a b--tch.
We use a cnc for our 1" stuff cos we never get a straight edge with lasers - I have even tried a 120w with a 4" optic and never got good results.
Edge quality on multipasses with a laser is not good, very difficult to get the type of jewel quality polished finish we get with scraping and flame polishing cnc cut.
I don't like the 4" lens even on lesser thicknesses cos of kerf width. I bought mine for a single job , cutting closed cell foam , 3/4" thick , worked a treat cos kerfs were irrelevant.