Todd, you’ve been a great buddy through this and other efforts, thanks very much.
It is nice to have your own equipment.
I wanted to cut a top from acrylic for a speaker A/B/X box I devised and my only method of measurement was a tape measure. So I cut a piece of cardboard exactly to size, but the tape is too crude to get an accurate measurement.
I asked the tech if they had anything that could accurately measure my cardboard (within 1 mm), but all they had were “tape measures.” (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-yell.gif)
I spent almost 2 hours trying to get the laser to trace the cardboard exactly while continually modifying the program.
Once I finally got it about perfect, I has to get it to fit on my only piece of acrylic, which is ~1 mm bigger along one axis than the top needs to be. So the “home position” had to be damn near perfect to get the cut in the right place to work.
After about 2 hours of futsing with it, and not getting it right, I had to let the next person on the laser and will try again on Friday. (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-frown.gif)
Bummer Todd, you were so close!
Interesting that you used the laser to measure the cardboard, I can see that it would be time consuming.
Do you have software to make your pattern beforehand, based on the raw dimensions?
Yes.
I did the pattern in DesignSpark and imported that as a dxf into CorelDraw on the laser’s computer. I initially set the size at 430 mm x 240 mm (simple rectangle), in DesignSpark based on my tape measure measurement. I figured better a bit big than small because I can sand big too small, but would loose my clear edge and would prefer to just get it right. I can’t sand small too big.
The 240 mm was about spot on, and is not so critical.
The 430 mm was too big (actually traced out at 428.8 mm and is critical).
But now the drawing is in Corel, which I only use at the facility so don’t have great skills with nor knowlege of the intracacies. I would try to shorten the horizontal lines (fractions of a millimeter), but saw no difference in the tracings on the laser. Based on the small distances involved, it was difficult to tell if the tracing was getting smaller or not, so this took a few trys until I said, “hmmm,” and tried a big difference and saw no difference in the tracing.
Then it hit me. Corel disassociated the horizontal from the vertical lines and in addition to shortening the horizontal lines I would have to move the vertical lines in to meet them, cause they were still out at 430 mm. Gotta be a better/easier way.
So…, as another way to “skin a cat,” I just told CorelDraw to make a rectangle and set the dimensions at 430 x 240 mm and went from there making the rectangle smaller across until I got the tracing. (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-embarassed.gif)
Then I had to get it onto my scrap piece of acrylic with a “clear” area that is just a hair larger than the pattern. So in Corel I had to designate the home and get the sizing of the workspace just so to start the cut in the ~exact spot, and …
…and there goes 2 hours.
Now I know the size and can put this into DesignSpark. When that imports into CorelDraw I can set the size of the piece being imported to the size of the workspace and the size of the working piece of material, set this as “Home” when positioning the laser, and it will start its cut right in the upper left corner of the piece. Then I don’t have to Dick with CorelDraw…, so much at least.
I got back on the laser today. This time I knew the size and it was just a matter of getting the “home” and “piece” in the right positions. NAILED IT! (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)
Then I peeled back paper in the the corners so I could see through the piece, set it in place and marked the screw holes from above with a marker. I set Corel to make a 0.15" circle and it was just a matter of repositioning the piece time after time to get it to center with the circles. BULL’S EYE!
This is a speaker A/B/X switching box with wireless remote. The user can choose speaker A, speaker B, or let the unit select the speaker at random, in which case, the user tries to determine which set is playing (i.e., is there an audible difference and if so, what). It can also mute the speakers. This is of my own conception/design and there are no commercial units on the market that do what this does. (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)
Because a louder speaker will always sound better, the user has the ability to attenuate one, or both sets at the speakers using stereo Lpads, or at the source using stereo pots, or both. All tapers are logrithmic to accomodate the way we hear things.
Cool!
It almost sounds like you used the laser as a drill press: lining the head on the center of your mark, and then cutting a pre-drawn circle around that point.
That’s what I did. This is the best way to “drill” acrylic, and you will quickly catch on to all the things you can do with a little thought.
When I was there, I also took the pattern for the top step of the landing for the gallows and enlarged it a bit in Corel. (I was done with the case top in less than 1/2 hour this time.) I run “cut lines” for the boards at 35 - 50 speed so they don’t go all the way through. Then I remove the center lines in Corel without moving the piece and run the exterior lines at 8 speed so they do cut.
Then using the pattern that was used to cut the square hole in the gallows deck for the pole, I cut the same hole here for another pole. Again, its just a matter of watching the tracer beam and determining where I want the hole to be before letting it cut the acrylic. This will serve as the pinata hanger for the kids so that the man at the gallows can still hang via thrown balls.
Very cool Todd.
I need to calibrate the red LED pointer to make it useful like that. Up til this point I haven’t needed to be very accurate on the starting point; I just used the “pulse” button to make a mini hole in the material to check if that was good enough. Lots of room for improvement there.
Interesting how you describe your engraving vs. cutting process. My software (“RDWorks”) lets you make layers of linework, and assign speeds / power levels / etc. to each layer. They’re easy to see, since each layer has a different color. You set the order of these, so that engraving is dome first and cutting last. You can save the file, with all that info preserved for the next time. Maybe your software as similar abilities?
Corel has “raster,” “vector,” and “both.” When specifing both, the raster work is always done before the vector work.
In Corel you tell it to cut or raster by the size of the line in your drawing. If you designate it as “hairline” it will cut. Any other line width setting will raster, as will any jpeg image.
Definately get your pointer aligned. It is a whole lot easier to draw a line on the computer, watch where that line ends up via the pointer, and place your piece to be cut in that position. I see people do this all the time.