Length of XY Head trying to find focal point.

[shanet94]

I am using the head that comes with the XY 900x600 stage ( http://www.lightobject.com/XLE-900600-X ... -P762.aspx )

I have a 68.5mm focus lense. Does anyone know the distance from the focus lens to the bottom of the tip so i can figure out how far from the tip to the object. Been playing around all day not gaining much ground

[shanet94]

I tried to do it the suggested way and set a block about 1.5 inch tall and a board diangle. Marked the thinnest point that i saw and measured. Was right at 24.5mm from tip to the board. The performance is still very very bad. My 30watt Epilog cuts much better and its only a 30watt vs this one is 100watt. So i know something is still not right.

I have the power set to 60% and on my gauge I am showing 25.2ma or so so that should be close to the full 100watts correct? My tube (http://www.lightobject.com/SPT-C100-100 ... -P873.aspx) says Current: 28mA, 30mA max
I am trying to cut a thin piece of plexiglass. On my 30watt Epilog i can cut it at 100% power and 10% speed and it cuts nice and easily. Tried cutting with this machine at 60% (should be close full power) and 5% speed and it takes 2 passes to cut it. I also noticed that the cut is not perfectly straight. Seems to be a bit of a angle. See images below. Frustration is setting in I am pretty sure the mirror alignment if correct, even pulled the focus mirror and cleaned it to make sure I had no condensation on it since its been hot and cold here.

Thanks for the advise!

[Techgraphix]

To find the right focuspoint for a lens, I made a block of wood with a partial ramp of 100mm length. On one side it is 5mm lower and on the other side it is 5mm higher.

FocusBlock.JPG (76.46 KiB) Viewed 3205 times

Now you focus on the horizontal part and let the laser draw a line of 100mm over the paper with very low power and a reasonable speed.... It just has to mark the paper.
You also see the mm markers on the ramp: is the thinnest part of the line is near the third maker from the middle, you know that your focuspoint is 3mm higher or lower so you have to adjust your autofocussensor mechanically or enter the appropriate value in the controller for Z-offset.

The angle of cutting is a matter of proper alignment. I have seen quite a few that had an angle on three sides. After aligning the lasertube itself.... and all the mirrors ofcourse, it was solved..

The cut of a 68mm lens is much wider than one of a 38mm, but a high quality lens and mirrors also give you a better cut.

Kees

[Tech_Marco]

FYI，RF is more efficiency than a CO2 laser. A 10W RF output is equivalent to a 30W CO2 laser. So, no surprise that a 30W performance is similar to a 100W CO2 tube.


If you use a 68.5mm focus lens on the XY stage, you need to get an adapter for the lens because the default size for the standard laser head is 50.8mm. You can test the power without the laser tip


Marco

[shanet94]

To find the right focuspoint for a lens, I made a block of wood with a partial ramp of 100mm length. On one side it is 5mm lower and on the other side it is 5mm higher.

FocusBlock.JPG

Now you focus on the horizontal part and let the laser draw a line of 100mm over the paper with very low power and a reasonable speed.... It just has to mark the paper.
You also see the mm markers on the ramp: is the thinnest part of the line is near the third maker from the middle, you know that your focuspoint is 3mm higher or lower so you have to adjust your autofocussensor mechanically or enter the appropriate value in the controller for Z-offset.

The angle of cutting is a matter of proper alignment. I have seen quite a few that had an angle on three sides. After aligning the lasertube itself.... and all the mirrors ofcourse, it was solved..

The cut of a 68mm lens is much wider than one of a 38mm, but a high quality lens and mirrors also give you a better cut.

Kees

Thank you will try that.
Shane