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Old Sep 30, 2010, 12:40 AM
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Originally Posted by Longhorne View Post
That's interesting that .pdf would work. I've worked with three cutters and they've all preferred .dwg or .dxf.

A problem that might be resolved by going to .pdf would be the tendency of CAD generated drawings to cut by the order that the lines were created. This can really kill machine efficiency. It can be resolved with the appropriate software, but most guys I've talked with are on a pretty tight budget and don't have it.

Paul
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Originally Posted by roscoedude View Post
Yeah most of the laser cutters will do DXF files, seems to be fairly standard.

I've been a little busy lately, but I'll get some pics posted here real soon. I got to get back to slicing up the IAR-80 tonight or tomorrow, then I'll set up some cut files and use those for show & tell.

Later,
Dean
Hi,

No worries, we're in no rush here. Paul now that you mention machine efficiency, there was something about making the files in a way that the cutter would not jump around, with using groups or Pedit. Maybe we should try the dxf, if it saves machine time, it saves me a few euros.(and no i'm not cheap, i'm a student )

Here's the pics I mentioned.

talk to you later
raipe
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Old Sep 30, 2010, 12:58 AM
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No worries. I'm cheap.
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Old Sep 30, 2010, 11:31 AM
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Originally Posted by raipe View Post
Hi,

Paul now that you mention machine efficiency, there was something about making the files in a way that the cutter would not jump around, with using groups or Pedit. Maybe we should try the dxf, if it saves machine time, it saves me a few euros.(and no i'm not cheap, i'm a student )

Here's the pics I mentioned.

talk to you later
raipe
Yeah, I've heard the same about the laser jumping around, but I think using DXF's still doesn't change that, not sure.

Anyway, she's looking great Raipe, now for me to get my butt moving.

Dean
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Old Sep 30, 2010, 04:22 PM
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In my experience moving to .dxf definitely won't fix the problem. Now that I've gotten to watch the cutting process a couple of times I've got alot more appreciation for how much time is wasted if the laser has free rein. I'd guess its spending ~30-40% of its time moving over numerous cuts to get to the one that it sees as "next" in the queue. That correlates directly to the cost of the cutting which is often straight machine time.

I'm guessing that converting to .pdf would wipe the slate clean as far as the order that the lines were created in the CAD file. Or maybe I'm just hoping that as it sounds easy.

Paul
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Old Oct 01, 2010, 12:50 AM
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Well I must admit that I know little about these things. Lets just do it the way you prefer Dean.

Raipe
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Old Oct 01, 2010, 09:32 AM
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Originally Posted by Longhorne View Post

I'm guessing that converting to .pdf would wipe the slate clean as far as the order that the lines were created in the CAD file. Or maybe I'm just hoping that as it sounds easy.

Paul
It sounds right; when converting to a DXF file from another CAD format, there's still some, not all, of that hidden info about the lines, poly-lines, etc. that gets transferred also because of the way CAD works, so with using a PDF, PNG, or other similar graphic files, it should basically, as Paul said, wipe the slate clean of that proprietary info, leaving just "dumb" lines, P-lines, etc., which should making cutting them less erratic. It makes sense to me.

Also Raipe, here's a couple things for you, the balsa stats pic from SW that I forgot to post (Doh ) and a PDF on laser cutting that has some good info in it.
And your right about the original Myrsky airfoil and the Clark being different thicknesses, so moving the wing down a tad is a good idea to get it semi-flush with the fuse (like the real one), although it may slightly change the flight characteristic's some, I think it will be just fine.

More later,
Dean
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Old Oct 04, 2010, 01:36 AM
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Hi,

The IAR looks great, you work really fast. If you had all the time I've used on the Myrsky, you'd have done a dozen of these already. Thanks for the info about balsa, I'll add those numbers to my inventor library. And a great pdf about laser cutting.

cheers
Raipe
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Old Oct 04, 2010, 01:39 AM
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No worries. I'm cheap.
OK, so maybe I'm a bit cheap too. I still blame it on being a student though
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Old Oct 04, 2010, 11:26 AM
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I would have but I stopped being a student last year. I guess I just have to embrace it for good now.
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Old Oct 04, 2010, 07:28 PM
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OK, so maybe I'm a bit cheap too. I still blame it on being a student though

The IAR looks great, you work really fast. If you had all the time I've used on the Myrsky, you'd have done a dozen of these already.
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I would have but I stopped being a student last year. I guess I just have to embrace it for good now.
Well I guess that makes 3, but lets just say we're money conscious, you know, all that politically correct crap and all.

And thanks Raipe. But you've really done a great job, even with my fairly vague explanations. I'm looking forward to getting all this squared away, and then see the Myrsky built and flying, now that will be cool. So, do you plan on doing a build thread when all is said and done?

Later,
Dean
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Old Oct 04, 2010, 09:16 PM
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I sure hope a build thread is coming up. This is an interesting and unusual subject and an awful lot of work has gone into it already. It will be fun to see it built up!

Paul
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Old Oct 06, 2010, 01:34 AM
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Thanks guys! I will make a build thread of it for sure, just that it's gonna take a while to get to it. I've got a plane and a boat on the table now so have to get those out of the way first.

Just out of curiosity. When I loft fuselages with inventor, it likes to make "edges" on the lofts. That seems to be caused by the sections (sketches) that are used. i.e. If I start with a round section and go through a pear shape to an oval(or ellipse), the out come is kinda ugly. the circle is made of one line, the pear shape out of maybe 4-6 lines and the oval out of 4 lines. The Inventor is obsessed with the points where those lines meet and attaches them together so that there is a one surface between two lines of two sections. then all the points that are left without a counter part are randomly connected to the lines of the other sections. That causes those surface borders to come out even as a sharp egde sometimes(I know, I had to re read it a few times just to know what I wrote) I can go around it a bit with making the sections with same amount of lines but that is going to work only so far. Am I doing something wrong? Do you guys know a way to avoid this? I'll add a pic to clarify the mess I wrote.

raipe

Edit: might show better. (What didn't fit in the picture description)
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Old Oct 06, 2010, 11:31 AM
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Originally Posted by raipe View Post

Just out of curiosity. When I loft fuselages with inventor, it likes to make "edges" on the lofts. That seems to be caused by the sections (sketches) that are used. i.e. If I start with a round section and go through a pear shape to an oval(or ellipse), the out come is kinda ugly. the circle is made of one line, the pear shape out of maybe 4-6 lines and the oval out of 4 lines. The Inventor is obsessed with the points where those lines meet and attaches them together so that there is a one surface between two lines of two sections. then all the points that are left without a counter part are randomly connected to the lines of the other sections. That causes those surface borders to come out even as a sharp egde sometimes(I know, I had to re read it a few times just to know what I wrote) I can go around it a bit with making the sections with same amount of lines but that is going to work only so far. Am I doing something wrong? Do you guys know a way to avoid this? I'll add a pic to clarify the mess I wrote.

raipe
Hey Raipe, yeah it's a good idea to break up the circle into equal segments to match the others. That way you shouldn't get any funky blends or sharp corners between them.

Dean
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Old Oct 06, 2010, 01:23 PM
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Its not unusual to get the same thing from SW. Making sure that the line segments meet as tangents is key, but every once in awhile not even that is enough.

The equal number of line segments is a good idea.

Paul
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