[belin]

Im having a few problems with the loss of laser power the further the X & Y axis move away from the top left of the machine..

meaning...for example...if i set the machine at 50% power and when it starts at the origin point at top left of machine which places the laser head closer to the laser tube output beam...the engraving is good and fine...but as the laser head moves further away to the right side or bottom left or bottom right the power seems to drop off considerably...

i have the K40 laser with a workspace of 300mmm x 200m but its really at present only good for about a half of that space closer to the top left of the machine.

is this normal or do i have a problem?

Anyone got any ideas on the problem?????

[KipLawson]

Sounds like an alignment issue. Have you tested the alignment of the mirrors?

[belin]

Well Yes...i think so....i simply use a piece of paper to be sure that the beam is hitting all mirrors centrally...

unless there is a more precise way..

Please help if i need it....LOL

[belin]

Sounds like an alignment issue. Have you tested the alignment of the mirrors?

if you are able to assist me with a exact alignment setting i would be greatly appreciative..

[KipLawson]

I'm somewhat new to this laser stuff but I found a technique of placing tape over the mirrors to work better than paper. It gives you a perfectly accurate depiction of where the beam is hitting. Afterwards you will want to wipe the mirrors clean. IMO it works better than trying to hold a piece of paper. But I'm sure there a a bunch of people on here that know more than me though.

[KipLawson]

Test each mirror though. Just because it looks good on the final turn before the material does not mean its accurate on the previous mirror. Move the head of the laser to each corner of your platform and you want the beam to hit in the same place on that tape in each corner. I'm willing to bet that if you do that right now you will see the beam hitting in a few different places, thus causing your lack of power in some places.

[belin]

I'm somewhat new to this laser stuff but I found a technique of placing tape over the mirrors to work better than paper. It gives you a perfectly accurate depiction of where the beam is hitting. Afterwards you will want to wipe the mirrors clean. IMO it works better than trying to hold a piece of paper. But I'm sure there a a bunch of people on here that know more than me though.

good idea...i will give that a try this morning when i get to the workshop...

[belin]

Test each mirror though. Just because it looks good on the final turn before the material does not mean its accurate on the previous mirror. Move the head of the laser to each corner of your platform and you want the beam to hit in the same place on that tape in each corner. I'm willing to bet that if you do that right now you will see the beam hitting in a few different places, thus causing your lack of power in some places.

You will excuse me if i dont take you up on your BET....LOL

my bet is your Bet is accurate..

I will be testing this out within the hour

Thank You

[18111]

Have you check the focal distance on all corners of the table, top right, top left, down right and down left? My k40 table was 3 mm off at bottom right form the top left when I had similar problem like yours. You may need to adjust table hight of each conner all equal distance from tip of the laser corn if not. Mirror arraignment alone won't work if table is not parallel to the laser lens.

[sky1]

If you get enough power in any area of your bed to cut through your laser tube should be OK. Although you will loose power over long distances this will not be the case as your machine is fairly small. Just also remember you will loose power on every lens or reflective surface. Make sure that all lenses are spotless clean as well as the laser tube outer lens.
1. Make sure that the beam is 100% parallel to the X-axis and Y-axis rail. No exceptions. Use a piece of masking tape and make sure the power and laser on time is just enough to make a mark and not burning too much otherwise you will have to clean all the mirrors again. Always mark the tape first on the closest position to the laser tube and the second position away from the laser tube is the adjustment position. Switch off the red dot laser indicator if it is from the rear of the machine as it can confuse you with your adjustments.
Attachment 216394
2. Make sure that the beam enter the hole of the nozzle or top in the center of the mirror 3. If not, then adjust the laser tube only, not the mirrors. This adjustment is for up/down and front/back. Look at he image below to see what will happen if you move the laser tube to the front/rear.
Attachment 216396
3. Adjust the downward beam to exit the bottom of the nozzle in the center. Make sure the dot is round and not oval.
Attachment 216398
4. Adjust the bed level to the nozzle by using a piece of wood between the nozzle and the bed. Distance should not vary more than 0.5mm on all areas of the bed.

[belin]

you guys are just great

whenever a poor little aussie girl is in distress , i can count on you guys to help me out...

absolutely fantastic...

[ozstockman]

As suggested by others I would check beam alignment plus check that focal distance is equal all over your laser table. If your table is tilted that's when you get problems similar to what you are experiencing.

[belin]

As suggested by others I would check beam alignment plus check that focal distance is equal all over your laser table. If your table is tilted that's when you get problems similar to what you are experiencing.

i have reset the mirror alignments to the best of my ability...it may not be 100% perfect but it is sure extremely close...

I will take a look at the table hieght...thanks for that

[Dean448]

If you use a nozzle that looks like a rocket nose cone and have a long focal length where the beam is wide as it passes out of the tip of the nose cone, part of the beam could be hitting the inside of the nose cone. You can see if this is happening by putting tape right on the tip and insuring that the beam is central to the hole in the nose cone. Point is that you will never see that the beam is hitting the cone but the cutting power will be reduced

Also if you are trying to cut something accurate like a circle. And notice that the disk cut out of the material doesn't quite rotate in the cut, I believe that's also from beam alignment. As the stage moves around if the beam isn't perfectly in the center of the lens it will deviate from where the machine thinks it is.




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[belin]

i have aligned my mirrors to almost perfect...it is a very tedious job...but i think im extremely close...

I tested it out and did a cut through 4mm perspex and at the top left it cuts straight throw ar 5mm/per/s @ 60% power...no problems

i then moved it to the bottom right (furtherest distance apart and at the same setting it ALMOST cut through...which is a huge improvement..

what i think my problem is....that a couple of months ago i damage one of the Guide Wheels and had to "dicky" it up a little while i await new wheels from lightobject (they are on the way...

When i dickied it up the right hand wheel (when looking at the machine) is a little lower putting the laser head on a very slight angle and not exactly at 905 to the carriageway...

once the new wheels arrive and i replace both front guide wheels everything should be back in alignment...i hope...

While im talking about these guide wheels...it may be important to note that these wheels and the small brass fitting they attach to via a tiny screw going into a tiny delicate brass threaded sleeve are very easily broken by just a little downward pressure that i inadvertedly applied when i was tightening a few screws on top...it just gave way....please take extreme care with not puting any pressure on the laser head carriage...

[belin]

here is 2 roughly drawn diagrams...

the first one is how it was before i broke the guide wheel (perfect)

The 2nd is showing how the laserhead is a bit offline

i think this is certainly a problem i have

[sky1]

You will have to correct the nozzle aliment so that the beam move straight down the center of the tube and hit the center of the lens otherwise the deflection through the lens will cause the beam to deflect at a greater angle and causing skew cuts.
Attachment 216668
Should you have a problem when cutting a circle and the cut does not finish at the same point, look for anything loose like rail bearings, lenses, laser tube or even mirrors as movement in the laser beam will cause a different start point than end point. Beam alignment won't cause such a problem.