I've heard this reply before and I am puzzled by it. You, the seller, are buying the tubing from a vendor cut to length. A length you specify. Why can't you specify a longer length for a batch of tubes? Is is a minimum order per cut length? I would like it if the carried coupler tubes in longer lengths especially 36" or 48" to use as mandrills for Carbon fiber or fiberglass lay up tubes. True this would be a small market, but it would be a market. Bill Richardson
Yes, usually 1,000 qty. minimum plus a set up charge. Most people don't understand how many that is, until the semi truck pulls up to deliver them. The trucking usually costs 1/3 to 1/2 as much as the tubing. Sure, there is a market, but you'd have to store them for years until they were used up.
Mike Fisher Binder Design
The "popular" length is the standard coupler length. In our case two lengths. Typically 3 and 6 inches or 2 and 4 inches. By adding a third size (length) the mill chartges a new set-up charge, but more to the point, longer tubes have higher minumum shipping cost. So long couplers have very low demand AND about double the cost to the manufacturer. Not necessarily a deal breeaker but if I were to go into the long coupler business I would start-up with a proposed customer list so I could recoup my costs as quickly as practical. I look for 2 year breakevens and smaller vendors look for breakevens measured in weeks or months so it is even less likely a small vendor would do it.
Wanna start a long coupler customer list grouped by tube diameter? I will be glad to order them and have them added to my next shipment.
Good plan on the mandrel. I use standard tubes as a mandrel, lay it up and have custom fiberglass cones made to the slightly thicker wall now.
Neither plan can use stock cones unless you remove the paper from the lay-up which I never do for insulation and fit of standard parts.
Jerry
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P E R S I Z E
May not be that bad. They already make the exact product. It's just a question of what lengths it's cut to by the tube manufacturer.
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!
BRich asked:
I've heard this reply before and I am puzzled by it. You, the seller, are buying the tubing from a vendor cut to length. A length you specify. Why can't you specify a longer length for a batch of tubes?
The "popular" length is the standard coupler length. In our case two lengths. Typically 3 and 6 inches or 2 and 4 inches. By adding a third size (length) the mill charges a new set-up charge, but more to the point, longer tubes have higher minimum shipping cost. So long couplers have very low demand AND about double the cost to the manufacturer. Not necessarily a deal breaker but if I were to go into the long coupler business I would start-up with a proposed customer list so I could recoup my costs as quickly as practical. I look for 2 year break evens and smaller vendors look for break evens measured in weeks or months so it is even less likely a small vendor would do it.
Wanner start a long coupler customer list grouped by tube diameter? I will be glad to order them and have them added to my next shipment.
Is is a minimum order per cut length? I would like it if the carried coupler tubes in longer lengths especially 36" or 48" to use as mandrills for Carbon fiber or fiberglass lay up tubes. True this would be a small market, but it would be a market. Bill Richardson
Good plan on the mandrel. I use standard tubes as a mandrel, lay it up and have custom fiberglass cones made to the slightly thicker wall now.
Neither plan can use stock cones unless you remove the paper from the lay-up which I never do for insulation and fit of standard parts.
Jerry
Jerry & Mike thanks for the reply. That is what i thought as my friend and I have contacted tube makers and they had a $100.00 minimum order for any size. They really would not say how many tubes they would make per size, just that it would cost $100.00.
To make minimum dia 54 mm tubes I use 3 foot mailing tubes from McMaster- Carr. I then cover them with 3M packaging tape and coat them with release compound. When the fiberglass or Carbon fiber is cured I just soak the tube out in the bath tub. Thanks for the info. Bill Richardson
On Sun, 28 Dec 2003 15:06:28 -0800, Jerry Irvine wrote:it is even less likely a small vendor would do it.
I want to buy coupler tubes to use as sacrificial mandrels for rolling my own carbon fiber tubes. Add me to the list but I am going to be a small consumer. I want 38 54 75 and 98mm for starters. But I don't imagine I need more than 10 of each. I would buy more if I *had* to. I am alternately looking for a good mandrel material. If you end up ever doing this, please email me. lennyb at telus dot net.
Thanks!
Len B
What useful purpose does this message serve? Jerry made decent suggestions about the supply of full length coupler tubes. I seldom plonk people but you are now plonked. You don't even offer a hint of useful data as part of your message.
Len B
I don't know anything about rolling Carbon Fiber tubes, but is there a reason that phenolic coupler tube won't work? Just trying to learn something here.
-- Joe Michel NAR 82797 L1
ditto 4 me ...count me in as well
They are much harder to dissolve out and remove than thinner walled simple kraft paper tubes and would cost more.
Koen
Depending on how you make the tube, you may end up sacraficing the tube you wrap the carbon fiber around to get the tube off the mandrel.
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!
Some day I'd like to try the method that I heard about from the Gossamer Condor project: wind/wrap fiber/resin around thin wall aluminum tube, then use alkali solution to eat away the aluminum from inside.
-dave w
May I at least have a priority list ie:
54 75 38 98 ?And a preferred clearance presumably 38mm which is 1.52" airframe and
1.50" motor, you want a 1.50" coupler (typical) or a 1.52" coupler
IIRC the Deadalus project did likewise...
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!
Another good point from Jerry. Minimal diameter HPR rockets are likely under optimum weight. Especially if they use high thrust motors. Any one got an M100? Besides Jerry :-)
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!
Who are you and what have you done with Bob Kaplow?
just fyi, Dave Triano does an excellent job IMO of demonstrating introductory composite techniques in the ShadowAero videos at
- iz
J.A. Michel wrote:
Just ignore the boats going by in the background!
Joel. phx
Other than hybrids, which start with such a mass fraction penalty that RockSim always says the optimum weight for minimum diameter hybrids is 1 oz. :)
I was just reading an online article on rolling tubes from full length coupler tubes. The author wraps the mandrel with mylar before rolling and then the tube just slides off the mandrel no soaking and it's reuseable.
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