Chinese laser purchase/Shenui/Laserworks tips and tricks thread

[Levi Chanowitz]

I have 3 questions:

1. I use laserCut 5.1 and it does not work with windows 7, Rabbit tells me that I would need to switch the electronics to get somthing that is compatible with Windows 7. Is there another way out?

2. for the past few months, somthing must have changed in my computer. When I export to plt and import to laserCut, the letters usually comeout with an extra overlapping wireframe. It doesnt engrave unless I do "Check overlap". How do I change my input file so I dont get the message?

3. I always export to plt (except when I engrave a bitmap). I understand that exporting to .ai would give me a crisper image. The problem is that when I open the .ai file, lots of times there are extra lines that do not belong. How do I export so that I dont have this problem?

[Joshua John Cruz]

Hello guys,

It's me again. Finally able to work with the machine. But encountered some challenges along the way.
But now, my problem is more with alignment and the power/speed settings.

1.
I have a problem aligning the mirrors.
When Mirror #2 is NEAR Mirror #1, the dot is ABOVE
When Mirror #2 is FAR Mirror #1, the dot is BELOW


Does this mean that Mirror #1 & #2 are not at the same level/plane horizontally?
alignment problem.png


2.
I tried to note the speed/power settings for 3mm cast acrylic.
2 weeks ago - it was able to cut at 15/70
Yesterday - it was not able to cut at 15/70. But was able to cut at 10/70
Today - it was not able to cut at 10/70. But was able to cut at 10/80


Is this normal? Because if this is the case, then that means I have to do a sample cut before proceeding with bulk cuts?


3.
At 10/80 setting, the machine can cut at the upper left corner, but not at the upper center. How can I fix this?
cutting problem.png


Thanks in advance ,
Josh

[Dave Sheldrake]

Hi Josh,

1: The tube is at an angle, until it is level with the gantry rails you won't be able to adjust the dot centrally on all mirrors.

2: Cast acrylic varies in thickness by 0.4mm +/- so sheets can be from 2.6mm to 3.4mm for 3mm sheet. Ambient temperature also makes a huge difference (as does alignment)

3: See 1

cheers

Dave

[Joshua John Cruz]

Hi Josh,

1: The tube is at an angle, until it is level with the gantry rails you won't be able to adjust the dot centrally on all mirrors.

2: Cast acrylic varies in thickness by 0.4mm +/- so sheets can be from 2.6mm to 3.4mm for 3mm sheet. Ambient temperature also makes a huge difference (as does alignment)

3: See 1

cheers

Dave

Thanks for the fast reply Dave!

1. So that means that my suspicion that Mirror #1 & #2 are not at the same level/plane horizontally, is not correct?
And the fix for this is just positioning the tube at a correct angle.

2. This is something I need to check. I will buy a thermometer.

3. Alignment is a factor. Could it be that the distance is a factor? For example, at the point where the acrylic is not cut, means that the laser power is sort of decreased because it traveled farther?

Thanks,
Josh

[Dave Sheldrake]

Hi Josh,

The first mirror height may be out (up/down) but unlikely, more likely is the tube is not firing the beam at mirror 1 at an exact plane (45/90 degrees) that would mean no matter what you do you will always be trying to align a beam that starts off at the wrong angle leading to a move in spot position. Until the tube is bang on to the first mirror you will be chasing your tail

Distance does make a difference but not a noticeable one usually,you may lose 1-3% power over distance but as what remains of the beam is focussed down to a tiny spot at the head the losses will be negligible. (also make sure your bed is level to the gantry)

I'll run up a drawing to show the issue with tube angle

cheers

Dave

[Joshua John Cruz]

Thanks again Dave.

I tried the alignment yesterday for 3 hours but still no luck.
Yarde from Shenhui support told me this:

adjust it like this , no matter where the first dot is (2# mirror near) , just keep it there ,then move the 2# mirror far, and the second dot , if it's not at same position as first dot , adjust screw on 1# mirror. then move 2# mirror back to check again, no need must the two dots at center exactly, near center is ok.

But when I adjust mirror # 1, the distance of both 1st & 2nd dots are just the same. It is just that both dots are in a different location (but then again, the same distance).

This is what I did:
1. I adjust the laser tube
2. Did not do anything with mirror # 1
3. Only adjusted mirror # 2 - NEAR or FAR
4. depending on the placment of the NEAR and FAR dots, I put papers below the laser tube.
5. I repeat steps 1 to 4. And this is the only best I get with NEAR and FAR dots in close distance.

dots 1.jpg

laser tube w papers.jpg

The bed might not be parallel to the gantry. I have to check this using a spirit/bubble level. This could also be the reason why it could not cut at the upper center part of the bed.

Thanks in advance for the tube angle illustration Dave

Josh

[Dave Sheldrake]

Hi Josh,

Looking at the burns that's the front to back angle of the tube, gimme 20 mins I'll draw a pic

cheers

Dave

[Joshua John Cruz]

Hi again everyone,


The emergency stop button of my machine got loose.
Pushing it, turning it clockwise/counter-clockwise are probably the causes. Always do this when starting/turning off the machine.


So what I will do starting now, is leave the emergency stop button ON (just power on the machine using the control panel switch).


Talked to shenhui support and he said that this is fine and just use the Emergency button for emgergency (obviously!hehe)

still trying to find a way to fix this as the screw is loose.

$VN294M)HW]20(8`122I9AU.jpg

[Rich Harman]

Hi Josh,

The first mirror height may be out (up/down) but unlikely, more likely is the tube is not firing the beam at mirror 1 at an exact plane (45/90 degrees) that would mean no matter what you do you will always be trying to align a beam that starts off at the wrong angle leading to a move in spot position. Until the tube is bang on to the first mirror you will be chasing your tail

The angle of the tube does not matter at all. As long as the beam is aimed at the center of the first mirror the tube can be at any angle. The first mirror steers the beam toward the second mirror. Since the first mirror is fixed all that matters is that the beam is reflected from the center of that first mirror and steered accurately towards the second.

Reci specifically recommends that one end of the tube be slightly higher than the other, something to do with air bubbles in the cooling system.

[Dave Sheldrake]

The angle of the tube does not matter at all.

Check the geometry in 3D Rich, Tube angle makes a huge difference. The left side (output side) should be higher than the right but can be accomplished by lifting one side of the machine on the adjustable feet.If the emergent beam is not parallel and level with the gantry rail it is impossible to align the spot dead on for the entire bed.

cheers

Dave

[Rich Harman]

Check the geometry in 3D Rich, Tube angle makes a huge difference. The left side (output side) should be higher than the right but can be accomplished by lifting one side of the machine on the adjustable feet.If the emergent beam is not parallel and level with the gantry rail it is impossible to align the spot dead on for the entire bed.

cheers

Dave

I actually have modeled this in 3D a long time ago. Will have to do again to prove my point I guess. Someday when I have nothing else to do...

[Rich Harman]

Nah, we can do this with words...

Can we agree that - if the beam coming from the first mirror is parallel with the Y axis, perpendicular to the X axis and contacts the second mirror in the center - that it does not matter what the beam was doing prior to entering the first mirror?

[Joshua John Cruz]

Hi Rich & Dave,

Your topic is interesting. Been waiting for updates as I am really curious if the angle of the tube would really matter.

According to ShenHui support it matters. If true, then maybe it is the reason why I can't get the 2 dots at the same spot, or even close to 0.5cm. Already cutting acrylic but I am satisfied with the results.

[Dave Sheldrake]

Nah, we can do this with words...

Can we agree that - if the beam coming from the first mirror is parallel with the Y axis, perpendicular to the X axis and contacts the second mirror in the center - that it does not matter what the beam was doing prior to entering the first mirror?

Yup...spot on, the problem for the typical laser owner will be getting it there with a 3 screw system rather than a gimbal mount. It's the main reason large format flatbeds have the tubes mounted in the gantry to prevent trying to make Millrad adjustments over a 3m long bed length. 3 screw has the inherent problem of adjusting one axis also moves the others, on my bigger flying optics machines I have a 532nm laser that fits into the head and runs backward though the optical train (it's a lot easier to adjust a beam you can see) they are also fitted with ThorLabs Gimbals to make life easier

cheers

Dave

[Rich Harman]

Yup...spot on...

Great! Since we agree to the above I will further claim that I can satisfy the requirements in post #147 with the tube in any orientation* - so long as it is aimed at the center of the first mirror.

* except along the path between the first and second mirrors.