Author Topic: Cutting 90 degrees?  (Read 180 times)

pedwards2932

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Cutting 90 degrees?
« on: January 08, 2017, 10:51:50 AM »
I hope I am not annoying everyone with my questions.  I had to cut a couple of parts today and I noticed the cut thru the balsa isn't exactly 90 degrees.  Is there a method for adjusting?  I am guessing I can make a cut in the x axis and then adjust the gantry beam until the cut is 90 degrees.  I used a framing square to set the beam but it doesn't appear to be working properly.  Not sure there is anyway to adjust the y axis without somehow moving the laser?
« Last Edit: January 08, 2017, 10:55:22 AM by pedwards2932 »

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Re: Cutting 90 degrees?
« Reply #1 on: January 08, 2017, 10:59:51 AM »
I think this condition means your frame isn't exactly 'square'...check it with a 90 degree square (you may have to buy one) and then re-tighten your frame nuts.

You may have to go through some trial and error to find the 'sweet spot' for your specific frame that will result in 90 degree laser lines.

Other users may have some other idea's you can try, but an out of alignment frame is the first thing that comes to my mind.

pedwards2932

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Re: Cutting 90 degrees?
« Reply #2 on: January 08, 2017, 11:48:02 AM »
I used a frame square when I assembled it.  I think the problem is with the gantry cross pieces as this is quite easy to move when you tighten.  I used a square against the edge of the frame and maybe I need to square against the edge of the laser itself.  I am going to cut a thicker piece and see if I can adjust the angle.  Thanks.

pedwards2932

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Re: Cutting 90 degrees?
« Reply #3 on: January 08, 2017, 09:05:22 PM »
I took a square and set the laser so it is square with the waste board as it was off a little.  What I learned is that wasn't the problem.  It was the focus being off.  I need to work on how to get the focus very precise.  I don't think my laser is reducing in power because the focus test seemed to cut the same at 50% and 5%.  Is there any way to see if the power is adjusting? Makes it hard to tell the difference in focus.  I will have to make the focus test run at a faster speed.

I noticed that the with the grain cuts were wider and this is what was causing the angle of the cut.  I was working with medium/hard balsa and the kerf was really large at 3 passes.  When I got the focus correct I was able to make 4 passes and the cut was not angled and the kerf was not much larger than on the first pass.  Guess I'll get better with this as I get experience.

nottingham82

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Re: Cutting 90 degrees?
« Reply #4 on: January 08, 2017, 09:21:23 PM »
T2 uses colors as power settings.  Import this dxf and burn it to see if your laser is ramping up and down or not.
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ggallant571

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Re: Cutting 90 degrees?
« Reply #5 on: January 08, 2017, 10:09:22 PM »
The beam is "V" shaped and I recall 150mm being a good working distance. Is your laser beam vertical? The lens can be off center or loose.

I tried to cut some 5mm balsa tonight and had terrible results. Lots of burning on the slot walls on the later passes.
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Re: Cutting 90 degrees?
« Reply #6 on: January 08, 2017, 10:32:34 PM »
>Is there any way to see if the power is adjusting?

Absolutely...if your laser diode is working, burn a line at 100% power and then burn a line at 20% power...there should be a very noticeable difference in how the two lines look.

If the lines look alike, then your laser isn't working as it should -- or -- in BCL Setup you may not have the correct max laser power value set...see attachment...if you have 255 set, try changing it to 1000 and then do this test again and see if that doesn't make a difference.

If you already have 1000 set and the two lines look about the same, then your laser diode isn't working correctly.

pedwards2932

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Re: Cutting 90 degrees?
« Reply #7 on: January 09, 2017, 04:52:34 AM »
Okay it was set at 1000 and it seems to work somewhat.  I found it hard to tell on balsa so I did it on an index card.  I had to set the speed at 35 in/min or it burned thru the card. I ran it at 100% then 75% then 50% then 25% and finally at 5%.  I got no line at 5% but I am not seeing a big difference in the other lines.  But when I was running at 30 in/min it cut thru at 100% but not at 75%.  So I am assuming it is working properly?   I think the issue I was having on the focus is I have to set the speed higher for balsa so I can see a difference.

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Re: Cutting 90 degrees?
« Reply #8 on: January 09, 2017, 08:36:45 AM »
I don't know about doing this test on other materials but on wood you can clearly and easily see the line burn differences....there is no question when burning wood.

pedwards2932

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Re: Cutting 90 degrees?
« Reply #9 on: January 09, 2017, 09:36:48 AM »
It burns at all the upper settings 100 - 25 % on balsa  it doesn't burn at 5% and light burn at 10% on balsa.  What I was seeing is I had to speed up the laser a lot for balsa because at 200mm and 40% the burn looks the same as at 100% that is why I am saying it looks like it is working somewhat.  Definitely not linear.  But on the card stock at 30 in at 100% it burned thru and 75% it didn't.  I would think card is more consistent than balsa......doesn't have hard spots.

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Re: Cutting 90 degrees?
« Reply #10 on: January 09, 2017, 10:14:34 AM »
You might not get a laser beam on at 5% or 10%...I don't...

pedwards2932

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Re: Cutting 90 degrees?
« Reply #11 on: January 09, 2017, 10:30:00 AM »
I can see the laser beam at 5% and there is some burn at 10%.  I will try to run the focus lines again and take a picture of what it looks like.

pedwards2932

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Re: Cutting 90 degrees?
« Reply #12 on: January 09, 2017, 02:15:08 PM »
Ok had a piece of oak veneer and ran the focus lines.  You can see at 5% is light, then 10% is darker, and 15% darker but then after 50% there isn't a lot of difference.  If I could measure the depth on each there may be a difference.  Just wanted you to be able to see there isn't a big difference visually after 50%

Got to thinking (I know that's dangerous) and I went in on the set up and set max to 255.  The second picture shows what I got.  It looks more linear to me.
« Last Edit: January 09, 2017, 02:46:55 PM by pedwards2932 »

ggallant571

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Re: Cutting 90 degrees?
« Reply #13 on: January 09, 2017, 03:06:33 PM »
Most of have a big unknown with the inner workings of the PWM to Laser current converter board. Agastar is designing a replacement module. With it there is at least a chance of understanding the power delivery system. If you are interested (concerned) you may want to investigate a DIY laser power monitor.
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Re: Cutting 90 degrees?
« Reply #14 on: January 09, 2017, 03:30:02 PM »
Your 255 max setting looks better (more normal) to me than the 1000 setting. I'd stay with 255.

I'm attaching one of my test results on 3mm Plywood just so you can see what I'm getting.

You can clearly see the differences in the line burns at different laser power values. I'm set to 1000 btw.