stunthanger.com
General control line discussion => Open Forum => Topic started by: Bob Reeves on August 12, 2010, 01:24:31 AM
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I'm drawing a set of ribs that will be laser cut and have a few questions. Trying to make it as easy as possible for whoever does the import from an AutoCAD drawing into the cutting software. A few things I already know...
Ribs need to be completely joined polylines to keep the laser from excess starting and stopping.
Make a cut sheet that fits the stock being cut.
Scale parts up 0.006 to compensate for the kerf.
I was told at one time to save each part in a separate file before adding it to the cut sheet. Not sure why..
Now the question: I need to add building tabs to the botton of the ribs (see drawing). What is needed to cut slots so the building tabs can easily be removed? Can I just break the line at say 1/8 inch segments between the tab and the rib? Any tips on the easiest way to do this with multiple ribs in AutoCAD?
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Guess it is too early in the morn. The ribs I have gotten that were laser cut had a peice of wood at each end of the tabs that was not cut. About an 1/8 inch wide/long. They snap off easily when wing is framed up. Maybe Mike and Walter will jump on this. H^^
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I believe that Eric Rule uses two colors on his files, one cuts through, the other just leaves markings. You could do that as a guide for final trimming.
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Shame Larry Cunningham never got his StuntRib program converted to Windows. Gave .dxf output and calculated all the ribs. Very cool, but only the old DOS version is around.
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I have used this guy. Some good info.
http://ak-models.com/lasercutservices.htm
But, profilie2 does all the ribs for me now. It includes tabs and all that.
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I'm drawing a set of ribs that will be laser cut and have a few questions. Trying to make it as easy as possible for whoever does the import from an AutoCAD drawing into the cutting software. A few things I already know...
Ribs need to be completely joined polylines to keep the laser from excess starting and stopping.
Make a cut sheet that fits the stock being cut.
Scale parts up 0.006 to compensate for the kerf.
I was told at one time to save each part in a separate file before adding it to the cut sheet. Not sure why..
Now the question: I need to add building tabs to the botton of the ribs (see drawing). What is needed to cut slots so the building tabs can easily be removed? Can I just break the line at say 1/8 inch segments between the tab and the rib? Any tips on the easiest way to do this with multiple ribs in AutoCAD?
Bob, yes, most of your info is correct. One thing to consider is making "laser breaks" so the parts stay attached to the sheets ratther than falling out and getting lost or broken.
Making laser breaks is simple, I draw a line across the parts, then offset 1/8'. Next copy, using multiple copy, and place thse lines at loctions where you want the laser breaks.
Laser breaks seem to work best at 1/8" for balsa. and 1/16' or 1/32" for plywood.
Now use the trim command, and highlight all these lines you just created.
Zoom in and trim the line segments from between the highlighted lines. after you've done this, erase the cut lines.
As for the tabs, I use the break command, and insert several breaks on the part line b etween the uprights of the tabs.
Many modern airfoil programs will set up the tabs, but i know of none that will set up the line breaks for them.
I personally use Compufoil 3D, and though it was not free, it has prooven to be a good value, and does all I need it to do.
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Thanks John, that will make it fairly painless...
I purchased Profilie a couple years ago and was going to use it for this project but it died with an old computer. I tried to get in touch with the Profilie guy to get a new registration number but after sending 3 emails and 3 days of waiting with no response I gave up and drew the ribs the hard way. Still haven't heard back from the guy..
Thankfully it was only 6 ribs HB~>
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Bob, I do not use Profili that often—like you, I have been using Compufoil for quite a while, but then again, I also use Winfoil.
I am surprised that you have difficulty with Stephano at Profili. I have found his customer service absolutely exemplarary.
Maybe he is having problems, or may be it's because it is mid-summer and he is on holiday.
Don't give up on Stephano.
Cheers, Geoff
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Hey Geoff, thought of you when I was drawing ribs, remembered the great help you were when I was drawing the TwistMaster. Haven't given up on Stephano, figured he was on holliday or something.
Just couldn't wait, this project has a good chance of being kitted and wanted to get the ball rolling.
Thanks,
Bob