#11
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Would you mind posting a link to one, I'm not familiar with what you speak of! I went today to get a piece of steel angle but the Builders Station hardware place didn't have a way to cut it down to a managable size and neither do I! But I'd love to know more about T angles. Quote:
? Do you know of a link to an example of these tips? I've got a plan for a scratch build that will have some little tubes on the end of the fins and if this would help me to insure they are properly parallel to the body that would be fantastic! |
#12
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http://forums.rocketshoppe.com/show...rs+lander+build At least you can get an idea of what it looks like. Mine is 11inches long (no wise cracks Bill )but you can get them longer. It also doubles as a straight edge when I have trouble finding my steel ruler (well, too lazy to get up and get it.......yes, I even have my wife bring me a beer when she's in a good mood ). I think you might even find these in an Office Max, Office Depot, Staples type store, probably around the templates or engineering supplies.
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Don NAR 53455 "Carpe Diem" |
#13
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MUCH appreciated... that looks very useful and will indeed go on the pick up soon list... thanks a ton!
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#14
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I find the plastic one that comes with the Estes fin alignment kit often dents balsa wood fins. I don't use it anymore. There is a really fancy one designed by Art Rose in Handbook of Model Rocketry (7th edition). There is also a home-made one "Kuhn" style that can be made from a piece of angle wood and rubber bands. When I get a chance, I'll scan a pic of it. I haven't tried the Kuhn, but it seems like it would be about as effective as the Estes one.
Re: Metal Angle for fin marking I got this tip from the aforementioned book and strongly agree. I bought a 4' piece of aluminum angle at Lowe's or Home Depot (can't remember). Cut it into 2'6", 1', and 6" lengths. Aluminum is easy to cut with a hack saw too. File down the edges so you don't scratch your body tubes! |
#15
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Yep... dented my Big Bertha fin a bit, and I thought the same thing of the Kuhn jig. I Googled the Art Rose machine a few weeks ago and couldnt find it anywhere. |
#16
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I would think you could go to any store that sells home improvement store or lumber yard that sells moulding and buy some corner moulding. I know I have some lying around the house. Use a table saw to cut a grove in one end and you are done. I might just make a fin alignment jig tonight.
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#17
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I bought some aluminum angle in 3 ft lengths from either Home Depot or Lowes. It works well for extending the lines on the tube. I couldn't find it on their websites, but the UPC code turned up this link you can navigate to "Aluminum shapes" to see other extrusions available. If 3 ft is too long, you can cut it with a hack saw.
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#18
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You ought to be able find aluminum angle in a variety of sizes at just about any hardware store, and they aren't at all expensive. I have three sizes that I use for "standard" sizes of tubes, and I even have a couple of sizes of K&S brass angle that I use for micromaxx tubes. For alignment, I get good results from the eyeball method. I hold the empty body tube horizontally and adjust my hold so that when I look through the tube, the opening at the far end is exactly centered in the opening at the end closest to me, with the fin in question pointing straight up. Then, without moving the tube or my head, I glance up at the fin. I want to be able to see only the trailing edge - nothing more. If I can see even a sliver of either side of the fin, I know that it is not exactly parallel to the tube, and needs to be adjusted. To check to see if the fin is projecting straight out from the tube, I hold the tube as previously described, but hold it so that I can see a vertical line (e.g., a door frame, the edge of a cabinet, etc.) through it. I line up the tube so that the vertical line exactly bisects the opening at the far end of the tube (and the far end opening is exactly centered in the near end opening), and then, without moving, glance up at the fin, to see if the vertical line of the fin matches my reference line. Once you've practiced these techniques a couple of times, they get to be pretty easy, and become "second nature." A trained eye is a really sensitive instrument, and can detect very minute angle differences with stunning accuracy, even at great distances. I learned these techniques many, many years ago while pursuing an art minor (painting, drawing and graphic design) in college. It should be mentioned that you should have good lighting for this. In situations where you are using a distant object for alignment reference, you should also have good contrast between your tube and fin, and good contrast between the two of them and the distant reference object. Mark
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Mark S. Kulka NAR #86134 L1,_ASTRE #471_Adirondack Mountains, NY
Opinions Unfettered by Logic • Advice Unsullied by Erudition • Rocketry Without Pity
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#19
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MARKII, I'm doing exactly what you're doing and getting some super results. First I had the Estes yellow body marking / fin jig set and it just gave all kinds of fits, then I got ahold of one of the older plastic fin jigs that was modeled after the metal ones everyone screams for, and it just had to much "give" in too many places to be as accurate as I would like, and it was too tough to see what was happening to make adjustments.
Doing the eyeball down the tube thing really works well... when you look into the tube and see the fin through what's something like a peripheral vision, it seems like your brain activates some special nodes or something and you can pick up on some very subtle qualities and make the adjustments in plenty of time before yellow glue dries it permanently into place! As I'm eyeballing, mainly from the back, and some from the front, I gently "roll" the tube around in a circular motion... very subtly... this allows me to study the alignment on both sides of the fin, looking for the slightest difference in when the opposite part of the fin becomes visable. I wrap the line that I've drawn on the tube around to the back edge and fatten it up a little, so I can check both the line coming out from under the front of the fin and the line just up under the back... get em just right and then all you've got to worry about is the vertical angle straightness. Last night using this method I got the fins on a new Bertha straighter than any I have done before... I doubt I will be bothering with tools again, unless they come out with something that leaves much less margine of "give". |
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