Cutting Acrylic???

[Rob_hoppe]

I'm doing test setting on the new DSP upgraded K40. X7 board (AWC708) I have a small test part I want to cut out of .210 (5.3mm) clear acrylic. I've tried multiple setting as seen from the test cuts and the settings for each are in the table attached. You can see from the photo that it can do a pretty clean cut, but I get bubbles. I varied PPI, with and without Air assist (it DOES make a difference!!), speed, power (min and max) and it's not what I would expect. Looks like I'm stuck at 1mm speed and 100% power to cut through it, even then it's not very good... Seems like I've seen faster cutting and better results from others? The photo is taken from the backside of the sheet so it's easier to see depth of cut. Far right of each row, you can see the test fire of laser (quick click of button) and it seems to be going all the way through in just a microsecond! What am I doing wrong here, any ideas? What setting are others using to get good clean cuts?

Also, having issues with the manual order: Per the manual I place the cutting start point in LaserCAD in the bottom right of each part, save the file, open it and it's right where I put it. But when I send to the machine it puts it wherever it wants it (Laser does not fire where I told it too in lower right of each part) and it also changes the start point in the Laser CAD. How do I get the machine to start where I want it it to start cutting on each part?

Rob

[Rob_hoppe]

Just wondering if anyone can see my posts. No replies at all after 4 days. How does the forum work?

Rob

[Tech_Marco]

I am here .....
Sorry I missed your post... busy busy...

For K40, the max deep you can cut with stock 32W laser tube is 4mm with speed 2~3mm/s. Since the acrylic you have is 5.3mm so I won't be surprise to see slow speed like 1~2mm/s with Air-assisted. If you upgrade the focus lens to a better one, the performance could be improved say 20~30%. You also need to make good alignment on mirrors/lens. Make sure beam target matched at all four corner when you fire up a laser (low power enough to burn a dot on a piece of paper).

By the way, not all acrylics are the same. Some with better quality but some is hard to cut.

Marco

[Rob_hoppe]

Thanks, Marco. Laser is aligned perfectly at all 4 points if bed and currently using new 38mm focus lens. Also have a new 50mm lens. No difference. I'll try a different acyrylic.

Any input on my question on laserCAD manual order no starting cut where I put it?

Rob

[Tech_Marco]

What current was you running when doing those cutting?
38.5mm is good for engraving or 2~3mm cutting. You shouldn't use 38.5mm for 4mm or above height as the beam is going to diverse out and make terrible cut
For 5mm, minimum is 50.8mm and better with 63.5 or 68.5mm but K40 stock tube is lack of power to drive a longer focus lens. Try 50.8mm (if you already have one), and set the speed to 1.5mm/s see how it goes

If you use 16mA, you may get 30W at most. If you drive by 18mA you can get 32~35W but the life span of tube affected as well
Make sure air is ON and honeycomb is used. Otherwise the hot steam from the acrylic cutting may ruins the job

"Any input on my question on laserCAD manual order no starting cut where I put it? "
It is origin issue. Use LCD panel to set the origin mode you prefer. Usually we use "Key" to set the origin. In your case, you may want to use "Software" instead


Marco

[Rob_hoppe]

Marco,

To answer your question about "What current I am running", all settings appear in the chart above the photo. Max_Power setting in the MANUFACTURER PARAMETERS is set to 75. With MAX POWER set to 75, and each layer set to 100 power, that means max power is actually 75, right? if true, my ammeter is showing 21 mA. So 75% power is driving 21mA? How can that be right?

I've attached the file which corresponds to row "E" in the photo. Each part is on a different layer, each layer is set to the same power and speed (100 and 1mm). The only difference between the parts (layers) is the PPI setting. (All 5 layers cut through in 2 passes.)

Now, if you open the file I've attached and choose TOOL>MANUAL ORDER you will see that each of the 5 parts has the red dot in the lower right of each piece. Per the manual, this is where the laser starts cutting, and the arrows show which direction it cuts, right? At least, that is the way I understand the manual. If wrong, please let me know! Now, with the file saved and uploaded to the machine, the laser starts cutting in the middle of the left side of the part (not the lower right corner as I have set in the MANUAL ORDER. However, it does not start in the same place on each part when it's actually cutting and ignores where I have told it to start!

The way I understand it, the origin is different than where the laser starts cutting, that is indicated by the blue dot, both in the file in laserCAD and on the LCD display. If that is true, how can this be an "origin issue." Mine is set to "key" as well and has been since I set the machine up. I just don't understand how to get the part to start cutting where I tell the machine start cutting in the MANUAL ORDER screen.

Rob

[Tech_Marco]

HI Rob:

That's why I asked you about "What current you're running". The % doesn't mean anything but it is just sorted of measurement scale that allow us to interprate the difference of power output. The Max_current is used to limit current at the ceiling. No current can go over that limit. But, it is using % instead of true current level so it may be a little confuse. If setting of 75% get you 18mA maximum outpout, then 37.5% should get you 9mA idealy but it is not true because of non-linear issue. When you set 100% for a cutting (on the layer setting), it will drop to 75% automatically because the Max_current (ceiling) is limited to 75% here
So, a current meter should be installed to monitor the job


Marco

[Tech_Marco]

Where is your physical limit switches installed at? Which corner?
Then, go through the User Parameters and make sure that both Page zero and machine zero match the true home location
There is also a button on the manual bar name "Position Relatives", again make sure it matches the home location
After this all set properly, the cutting should be started from Left to Right unless you manually change the direction

Marco

[Rob_hoppe]

Marco,

Page Zero, Machine Zero, Base Position and Position Relative settings are all set to "LEFT_UP" (I just verified all.) No matter where I select as the start laser point for cutting using MANUAL ORDER, it still starts wherever it wants too. I do have 2 other settings for each X and Y in the Manufacturer Parameters that state DATUM and KEY DIRECTION. What are they and what are they used for?

On the machine, I have 4 limit switches installed X-X+Y-Y+. All are tested and work perfectly. When the machine is resetting or powering on, carriage goes to upper left of machine (Closest to Mirror #1) and beeps letting me know it reached proper origin or "home" position.

Lastly, what is the maximum PPI the machine can handle?

Rob

[NickWL]

You ARE using the origin button, aren't you?

[Rob_hoppe]

Yes, I am. But the origin button just places the relative origin of the laser head over the bed which is different than machine origin ( the max travel of the gantry controlled by limit switches.) I'm talking about using MANUAL ORDER to start the laser firing on each and every object within the graphic. As previously described in great detail, when I use manual order to move the starting point of the firing of laser, save the file and upload, the machine does not start firing where I want it to... Per the manual on page 40;

"3.13.1 Manual Order
User can use [Manual Order] to set cutting serial number for each object, cutting start point and finish point.
Click [Tool]/ [Manual Order], then [Manual Order] window will show at the left side of main interface shown below:

◆ Change serial number of object
（1）Drag items in the [Manual Order] with mouse, allow to change the item to top of cursor.
（2）Double click the item in the [Manual Order], will move it to the top
(3) Click [Rev-Order] will reverse all items.
Note: Items listed in the [Manual Order] window is related to the serial number of the corresponding objects. The closer to the top the item is, the more prior the corresponding object is to be processed.
◆ Change cutting start point of object
Cutting start point shown as “
”, click the object and change the cutting start point.
◆ Change cutting direction of object
Cutting direction is shown as “
”.The direction of arrow shows the cutting direction. Click [Manual Order]/ [Rev-Order] allows reversing the cutting direction.