Chinese laser focal tube and lens question.

[Ken Shea]

Not making a lot of progress with laser power seemingly to be very low so am checking things from the first mirror on, which now is apparent should have been done from the first.

In replacing the lens it was located at the top of the focal tube (not the end where the air nozzle threads on.
Information read seem to locate this lens toward the end of the focal tube where the air nozzle screws on.

Which is the proper location?

Thanks
Ken

[Ian Franks]

Which is the proper location?

Thanks
Ken
Ken
It should be at the bottom. The focal length is from the edge of the lens to the focus point (material).

[paul mott]

The proper location for the lens is in a position where the laser beam can be focussed on to the surface of the work piece with the smallest dot size.

Paul.

[Ken Shea]

Thanks Guys, it had been installed incorrectly to allow for the proper distance.

Apparently it makes no difference where in the tube the lens is as long as it's position will allow for proper height adjustment for a given focal length lens.