Second Laser... new issues...

[Walt Langhans]

Hey guys!

So.... I figured second laser, very much like my first one, so set up should be a piece of cake... yeah... that's not happening.

#1: For the life of me I can't get the mirror that the laser hits first (ie next to the tube) to align with the next mirror (ie, the Y-axis / up - down). I spent all day on this (literally) and couldn't get it done, and I do know how to align a laser. When the Y-axis mirror was close to the 1st mirror, any small movements on the adjustment screws wouldn't move the dot. So to move the dot I have to make large movements on the screws. But when I moved the mirror away from the first mirror (towards the operator) the large movements push the dot way of center. When I adjusted the mirror to compensate it messed up the close alignment too much. In short I could get the dots close (when the second mirror was close t the first mirror, it needed to go up and to the right, and when it was far away it needed to come down and to left) but never overlapping.

Based on my experience and how long it takes to align my shenhui I'm pretty convinced that something else is going on, but I don't know what. I'm thinking something some where isn't square or possible level? I don't know. Thoughts?

#2 The bottom of the nozzle on my shenhui unscrews and holds the lens. On the new machine, when I unscrew the nozzle the lens is still in the tube, so I have to remove the tube from the assemble to get at the lens. Does the amount of the tube that is in the assembly matter?

Meaning, if the distance from the bottom of the assembly to the end was 3 inches, and then when I put it back in I push it up so now it's only 2 inches does it matter? I can't think that it would since when the light hits the top of the lens and and exits out the bottom, it's that distance (from the bottom of the lens to the material) that makes up the focal distance.

Thanks!
Walt

[Rich Harman]

When I adjusted the mirror to compensate it messed up the close alignment too much.

You should only be chasing the far alignment, not the close. You make a mark on the tape when the mirrors are closest, then move the mirrors far apart and steer the laser towards the first mark. If steering it towards the mark puts it off center then that means that you need to move the mirror holder. I had to do that on my machine. At the factory they aligned it only well enough that it worked. It seems that they were not concerned that the laser was not hitting the center of anything.

[Rich Harman]

Does the amount of the tube that is in the assembly matter?

No. I prefer that the tube be up as high as possible but as long as it is doesn't move and is aligned well it won't matter.

[Walt Langhans]

At the factory they aligned it only well enough that it worked. It seems that they were not concerned that the laser was not hitting the center of anything.

I had the same freaking thought, lol! Glad to know it's not just me. But the thing that kills me is that that my first laser I can get them overlapping by about 75%.

Thanks Rich!

[Rich Harman]

...my first laser I can get them overlapping by about 75%

I have to get the marks centered 100% (near as I can tell) or the beam won't hit the lens when at the far corner of the table. Maybe you can get away with it on a smaller machine but I would still strive for a perfect alignment. Anything less means that the beam is hitting the lens in different places depending upon it's location on the table - which means that the beam won't be perpendicular to the work.

[Graham Facer]

I know on mine I would always have some issues until I finally changed the height of the first mirror and leveled the tube slightly so that everything was on the same plane. Basically my centre on the first mirror was too high on the second and third. It worked but the beam was not as perpendicular as I thought it should be and couldn't be adjusted enough at the last mirror because it wasn't centred there.

After the first mirror height adjustment I could get it all in the centre and alignment was a breeze when needed.

[Walt Langhans]

If steering it towards the mark puts it off center then that means that you need to move the mirror holder.

So which direction / way do I move the mirror? When I have it centered close up, the far away alignment is high and to the left. So do I dial in in up close and then get it as close as I can when it's far away with the screws and then move the mirror holder?

And are you saying move the mirror closet to the tube (which is hitting dead center) or move the mounts on the next mirror?

[Rich Harman]

And are you saying move the mirror closet to the tube (which is hitting dead center) or move the mounts on the next mirror?
It really depends. Moving the second mirror may well require moving the third.

Do all your adjusting when the mirror is furthest away. Make the first mark up close, move the mirror away then adjust to try to hit the same spot. Once you get it good tear the tape off and repeat the process. Once you are hitting the same spot on the tape both up close and far away- then you know the beam is parallel. If that spot is off center you would have to decide wether to move the first mirror or the second. You may need to raise the first mirror (and the tube) up, or you may need to move the second mirror down. On mine I did both.

[Walt Langhans]

I'm picking up what your putting down :D Thanks Rich!

[Walt Langhans]

Maybe you can get away with it on a smaller machine but I would still strive for a perfect alignment.

Yeah the stuff I do is mostly cutting with not much precision work and my bed is 1 by 2 foot, so I haven't had any major issues. However, now that I have new machine dialed in almost perfect, I'll go back and see if I can improve upon the Shenhui focus.