#1
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Semroc BT-4, BT/ST-5 fit
If anybody has some pieces of Semroc's BT-4 and BT-5 (ST-5) body tubes, could you slip the BT-4 inside the other and post a picture of it here? Or maybe describe how it "fits" into the other?
I mainly want to know how much "play" (or looseness) there is between the two. I did the math on a piece of paper yesterday, but left it down in the basement. Thanks in advance for your help! Cheers,
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Jay Goemmer "Centuri Guy"/"Tau Zero" YORF Member 28 Semroc SAM #0029 NAR 86131 "I think about organizing things all the time. Never seems to happen. I find something that piques my interest and I'm off on a quest. Or a Centuri. " --Bill Eichelberger, 02/22/2022 “Centuri fret buzz in an updated form.” Bill “Wallyum” Eichelberger re: Estes Flutter-By 03 Sept 2014 |
#2
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If want want to center a BT-4 in a BT-5, you will need some centering rings. The picture shows an Apogee AT-10.5 (BT-4) inside of an Apogee AT-13 (BT-5). The two tubes are close enough in size that you would need a good vernier caliper to tell the difference the Apogee and Semroc tubes.
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'Til next time, Mike Toelle NAR 31692 L1 SAM 0373 |
#3
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Quote:
Quite a bit of gap, Jay. The total gap is .067, which is more than the thickness of a laser-cut centering ring (at 0.05"). Half this (wall thickness dimension) would be .0335"... One method you could try would be several layers of 1/4" wide sticky-back label paper strips, wrapped around the BT-4 in strategic locations. I do this a lot when I'm centering ST-9 into ST-10.
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Craig McGraw BARCLONE Rocketry -- http://barclone.rocketshoppe.com BARCLONE Blogsite -- http://barclone.wordpress.com BARCLONE Forum -- BARCLONE Forum BARs helping BARs SAM 0044 AMA 352635 |
#4
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Besides sticky-back paper, you could cut some grocery sack / kraft paper into 1/2" wide strips, and keep adding wraps until it fits to your satisfaction. Kraft paper should be about 0.007" thick, so it should take 4 or 5 wraps to fit the BT-4 in the BT-5. Doug .
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YORF member #11 |
#5
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Or, take a short section of BT-4 and cut lengthwise once. This sleeve can be slipped over the smaller tube and provide a concentric fit.
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Gravity is a harsh mistress SAM 002 NAR 91005 "The complexity of living is eminently favored to the simplicity of not." |
#6
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Quote:
Doug .
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YORF member #11 |
#7
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I am sure I stole it.
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Gravity is a harsh mistress SAM 002 NAR 91005 "The complexity of living is eminently favored to the simplicity of not." |
#8
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Tubes inside of tubes
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Mike, it wasn't so much a matter of centering, but thanks so much for the A/B comparison photo. Craig, I'm trying to reinforce the ST-5 body tube on my 18mm Prometheus. I was wondering, as jharding58 (John, IIRC) suggested, if I just slit a 3.5" long piece of BT-4 lengthwise, had the builder slather some glue inside the ST-5, and then shoved the BT-4 into the ST-5 (after the BR-510 had been glued in and allowed to dry), if that would do the trick. I asked you guys because you're smart. Quote:
Unless there's some kind of highly advanced technology that you're not mentioning. An interociter, perhaps? (sly look) Cheers,
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Jay Goemmer "Centuri Guy"/"Tau Zero" YORF Member 28 Semroc SAM #0029 NAR 86131 "I think about organizing things all the time. Never seems to happen. I find something that piques my interest and I'm off on a quest. Or a Centuri. " --Bill Eichelberger, 02/22/2022 “Centuri fret buzz in an updated form.” Bill “Wallyum” Eichelberger re: Estes Flutter-By 03 Sept 2014 |
#9
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Quote:
OK, so, maybe not several layers... As such... More or less...
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Craig McGraw BARCLONE Rocketry -- http://barclone.rocketshoppe.com BARCLONE Blogsite -- http://barclone.wordpress.com BARCLONE Forum -- BARCLONE Forum BARs helping BARs SAM 0044 AMA 352635 |
#10
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If you are looking for a stiffer BT-5/ST-5 tube, how about using some Quest T-15 instead? A ST-5 should be able to have a telescoping fit with the T-15. You should also note that the T-15 has a wall thickness of 0.020" instead of 0.013". The main drawback of the MRI/MPC/AVI/Quest tubing is the lack of nose cones and transitions available for it.
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'Til next time, Mike Toelle NAR 31692 L1 SAM 0373 |
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