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fiberglass mast question
Anyone have suggestions on a method I might try to "twist" and collapse some sections of my telescoping fiberglass mast? I put it up several days ago with perhaps a bit too much "vigor" in making sure it would not collapse on its own and now that I want to stow it away there are a couple of sections I can not unlock. My grip is good, but the sections are really tight. I hate to use something mechanical for fear of cracking the fiberglass and I hate to use a lubricant since the locking requires friction. Thoughts ? Ed K7AAT |
fiberglass mast question
Ed wrote:
Anyone have suggestions on a method I might try to "twist" and collapse some sections of my telescoping fiberglass mast? I put it up several days ago with perhaps a bit too much "vigor" in making sure it would not collapse on its own and now that I want to stow it away there are a couple of sections I can not unlock. My grip is good, but the sections are really tight. I hate to use something mechanical for fear of cracking the fiberglass and I hate to use a lubricant since the locking requires friction. Thoughts ? Ed K7AAT ====== Immerse outer end (only)in hot water. Hopefully it will expand slightly ,but not the inner mast part . Alternatively cover outer end with insulation material and 'cool' inner mast tube with evaporating CO2 'ice' hopefully causing it to shrink slightly. Of course success is not guaranteed but worth trying .....at least it is non-destructive. Frank GM0CSZ / KN6WH |
fiberglass mast question
On 27 Aug 2008 19:04:14 GMT, Ed
wrote: Anyone have suggestions on a method I might try to "twist" and collapse some sections of my telescoping fiberglass mast? I put it up several days ago with perhaps a bit too much "vigor" in making sure it would not collapse on its own and now that I want to stow it away there are a couple of sections I can not unlock. My grip is good, but the sections are really tight. I hate to use something mechanical for fear of cracking the fiberglass and I hate to use a lubricant since the locking requires friction. Let me guess. You extended the pole when the air temperature was cold and are now trying to collapse it when the air temperature is hot? The coefficient of thermal expansion is about the same as glass or 1.1x10^-5 inch/inch/F which is enough to expand the inner tubing into the outer sleeve almost permanently. After a few field days of having exactly the same problem, I sorta learned my lesson. The easiest is to wait until it cools down at night. You can also splash cold water on the joints, which might help. If you want to prevent the problem in the future, I found that ordinary Ivory soap smeared on the joint, makes a decent lube that will not cause premature collapse. If you apply too much, just wash it off. Also, do NOT beat on the ends in an attempt to release the seized joint. The twist type telescoping locks will just lock even harder. If brute force is your forte, you might try a rubber pipe strap wrench as used to remove an automobile spin on oil filter. Wrap the strap around a few times and put something under the gripper teeth to distribute the force. I've never tried this but it seems like it might work. Also, make sure you're turning in the correct direction. I did that once with a window washer pole with predictable results and embarrassment. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
fiberglass mast question
Jeff Liebermann wrote in
: If brute force is your forte, you might try a rubber pipe strap wrench as used to remove an automobile spin on oil filter. Wrap the strap around a few times and put something under the gripper teeth to distribute the force. I've never tried this but it seems like it might work. Those strap wrenches work pretty well, Jeff. - 73 de Mike N3LI - |
fiberglass mast question
On Aug 28, 3:52*am, Mike Coslo wrote:
Jeff Liebermann wrote : If brute force is your forte, you might try a rubber pipe strap wrench as used to remove an automobile spin on oil filter. *Wrap the strap around a few times and put something under the gripper teeth to distribute the force. *I've never tried this but it seems like it might work. Those strap wrenches work pretty well, Jeff. * * * * - 73 de Mike N3LI - You could try holding the pole vertical and let the whole lot drop a few feet so that the base falls onto a hard surface (assuming it has some sort of bump cap on the base). This inertia and rapid deceleration usually releases even the most stubborn joints. UKM |
fiberglass mast question
If brute force is your forte, you might try a rubber pipe strap wrench as used to remove an automobile spin on oil filter. *Wrap the strap around a few times and put something under the gripper teeth to distribute the force. *I've never tried this but it seems like it might work. Those strap wrenches work pretty well, Jeff. * * * * - 73 de Mike N3LI - You could try holding the pole vertical and let the whole lot drop a few feet so that the base falls onto a hard surface (assuming it has some sort of bump cap on the base). This inertia and rapid deceleration usually releases even the most stubborn joints. I have used these poles a lot, and the 'bump' method usually works for me. Start on grass to cushion the blow, and gradually increase the impact force until the joint comes free. Twisting usually does not work, though a little soapy water and heating might help. Be very careful about using any kind of wrench or vice jaws, as these thin-walled poles are VERY vulnerable to crushing. On the other hand, I've never damaged one by end-on impact. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
fiberglass mast question
On Thu, 28 Aug 2008 12:07:01 +0100, Ian White GM3SEK
wrote: On the other hand, I've never damaged one by end-on impact. I have. It split the tubing just below the locking area. The problem is that there are many types of locking mechanisms. You need to know what's inside and how it works before applying the traditional brute force. For example, some poles use external compression or cam type locking mechanisms: http://www.telescopingpoles.com/specs.html http://www.briarwoodproducts.com/newtools.htm These do not jam and will respond properly to the inertial hammer (brute force) disconnect method. However, they add width which is often undesireable. Internal locks, with expanding cores, cams, or wedges are a different story. To prevent collapse, most become tighter when loaded in compression, especiallyl those that take advantage of a slight conical taper in the tubing: http://www.google.com/patents?id=78duAAAAEBAJ http://www.google.com/patents?id=fvc5AAAAEBAJ http://www.google.com/patents?id=i2ZMAAAAEBAJ http://www.google.com/patents?id=_hMBAAAAEBAJ (Look at the drawings). Banging on these internal locks will jam them only worse. I couldn't find a picture of the inside of the common window washer fiberglass pole. It has partial threads molded into the fiberglass. 1/4 turn to lock. Bang on that design, and you'll split the tubing (like I did). -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
fiberglass mast question
This mast is smooth all the way, no cams, locks, etc. The tubes must be "slightly" tapered such that as you pull one out of the other it locks in place by sheer friction. I have tried heat on the outer, cooling the inner tube and considerable twist/pushing force with my hands to get the stuck sections to unlock, all to no avail. Yesterday I resorted to applying some Teflon Lubricant ( Tri-Flo) to a stuck joint but it would still not budge. Maybe today when I go out to the garage the lubricant may have seeped its way down in to the junction.... will try again.... Hate to toss the thing as junk, but its not looking very positive so far. It was a cheap "flag / banner" type import so at least I won't be out as much as a quality unit would have cost me. Ed K7AAT |
fiberglass mast question
On 28 Aug 2008 17:40:08 GMT, Ed
wrote: This mast is smooth all the way, no cams, locks, etc. The tubes must be "slightly" tapered such that as you pull one out of the other it locks in place by sheer friction. I don't think so. Such tapered devices have an irritating habit of collapsing. There's usually some manner of locking mechanism, usually activated by twisting. Any way to look inside and determine the type of mechanism? If you don't have a handy x-ray machine, perhaps a strong light will show something. Could you disclose the maker and model number? If there are any patent numbers listed, that would be helpful to determine the mechanism. I have tried heat on the outer, cooling the inner tube and considerable twist/pushing force with my hands to get the stuck sections to unlock, all to no avail. You don't want to heat the outside. That will cause the outer tube to expand, which will increase its compression on the inner tube. You want to cool both tubes causing both to contract. If you can remove an end cap, pour in some ice water. Yesterday I resorted to applying some Teflon Lubricant ( Tri-Flo) to a stuck joint but it would still not budge. Maybe today when I go out to the garage the lubricant may have seeped its way down in to the junction.... will try again.... Well, that might help if you can get it into the joint. My guess(tm) is that it will cause the uncoated parts of the joint to swell, which might increase its grip. If you must lube the joint, perhaps penetrating oil would be best. Did you try the rubber strap wrench(s) idea? That should give plenty of torque to rotate the sections. Hate to toss the thing as junk, but its not looking very positive so far. It was a cheap "flag / banner" type import so at least I won't be out as much as a quality unit would have cost me. Maker and model number? Photo? -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
fiberglass mast question
Jeff Liebermann wrote:
. . . You don't want to heat the outside. That will cause the outer tube to expand, which will increase its compression on the inner tube. You want to cool both tubes causing both to contract. If you can remove an end cap, pour in some ice water. . . . If you heat a ring of material, both the OD and ID increase in proportion. This loosens, not tightens, its hold on an inner object. I recall from freshman physics that if you heat two concentric rings made of the same material (having a positive coefficient of expansion), all dimensions increase by exactly the same proportion. A little geometry shows that any gap, even microscopic, between them will therefore also increase proportionally. Cooling both objects of course has the opposite effect, reducing the size of any gap and tightening the fit. Heating the outer one and cooling the inner one, as Ed did, gives you the best of both, increasing the ID of the outer tube and decreasing the OD of the inner tube. Roy Lewallen, W7EL |
fiberglass mast question
On Thu, 28 Aug 2008 14:46:23 -0700, Roy Lewallen
wrote: Jeff Liebermann wrote: . . . You don't want to heat the outside. That will cause the outer tube to expand, which will increase its compression on the inner tube. You want to cool both tubes causing both to contract. If you can remove an end cap, pour in some ice water. . . . If you heat a ring of material, both the OD and ID increase in proportion. This loosens, not tightens, its hold on an inner object. I did this with an aluminum torus way back in college daze. You're mostly correct. The O.D. does most of the radial expanding, but there may be a small amount of expansion in the I.D. depending on the compressibility of the material. If the material is soft, the I.D. will shrink slightly. If the material is hard and incompressible, then the I.D. will expand slightly. This illustrates it fairly well (for incompressible materials): http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/thexp2.html What I'm counting on is NOT the change in radius cause by a change in temperature. I'm looking for a slight change in length, which with a taper, has a somewhat similar effect on releasing the jam than a radial change. In that case, the inner taper shrinks, while the outer taper lengthens. I recall from freshman physics that if you heat two concentric rings made of the same material (having a positive coefficient of expansion), all dimensions increase by exactly the same proportion. A little geometry shows that any gap, even microscopic, between them will therefore also increase proportionally. Cooling both objects of course has the opposite effect, reducing the size of any gap and tightening the fit. Apparently, I'm not the only one having problems with the concept. See: http://www.eng-tips.com/viewthread.cfm?qid=99646 Heating the outer one and cooling the inner one, as Ed did, gives you the best of both, increasing the ID of the outer tube and decreasing the OD of the inner tube. Maybe. If the ID of the outer tube does not change with temperature, then heating the outer tube is a waste of effort. If the material is sufficiently incompressible, then it will expand slightly as you suggest. I'm not sure how fiberglass reacts as it depends heavily on the glass weave pattern and composition. If the pole bends, it may have some compressibility. Drivel: If the surface roughness is more than the heated or cooled radial expansion of the tubing, it may still remain stuck. Roy Lewallen, W7EL -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
fiberglass mast question
On 28 Aug 2008 17:40:08 GMT, Ed
wrote: This mast is smooth all the way, no cams, locks, etc. The tubes must be "slightly" tapered such that as you pull one out of the other it locks in place by sheer friction. After stuffing myself with a near-terminally fattening ice cream, I realized that we may be talking about two different types of masts. I'm thinking of a telescoping mast, where each smaller section fits inside a somewhat larger diameter section. Kinda like a telescoping metal whip antenna (i.e. rabbit ears). However, there are also masts made of equal diameter tubing, with some sort of coupler at the ends. Your initial posting clearly said "telescoping" but I'm wondering how one makes a self supporting telescoping mast without an internal or external locking mechanism. Which type to you have? -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
fiberglass mast question
Jeff Liebermann wrote:
On Thu, 28 Aug 2008 12:07:01 +0100, Ian White GM3SEK wrote: On the other hand, I've never damaged one by end-on impact. I have. It split the tubing just below the locking area. The problem is that there are many types of locking mechanisms. You need to know what's inside and how it works before applying the traditional brute force. That's a fair point. From what Ed did (and did not) say, I was assuming his pole had a simplest kind of tapered friction lock... which turns out to be so. These often can be freed by end-on impact when twisting doesn't work and squeezing might crush the thin walls. For example, some poles use external compression or cam type locking mechanisms: http://www.telescopingpoles.com/specs.html http://www.briarwoodproducts.com/newtools.htm These do not jam and will respond properly to the inertial hammer (brute force) disconnect method. However, they add width which is often undesireable. Internal locks, with expanding cores, cams, or wedges are a different story. To prevent collapse, most become tighter when loaded in compression, especiallyl those that take advantage of a slight conical taper in the tubing: http://www.google.com/patents?id=78duAAAAEBAJ http://www.google.com/patents?id=fvc5AAAAEBAJ http://www.google.com/patents?id=i2ZMAAAAEBAJ http://www.google.com/patents?id=_hMBAAAAEBAJ (Look at the drawings). Banging on these internal locks will jam them only worse. I couldn't find a picture of the inside of the common window washer fiberglass pole. It has partial threads molded into the fiberglass. 1/4 turn to lock. Bang on that design, and you'll split the tubing (like I did). But even so... hitting something with a hammer shouldn't always be condemned as "brute" force. Sometimes it *is* the most intelligent thing to do. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
fiberglass mast question
This mast is smooth all the way, no cams, locks, etc. The tubes must be "slightly" tapered such that as you pull one out of the other it locks in place by sheer friction. After stuffing myself with a near-terminally fattening ice cream, I realized that we may be talking about two different types of masts. I'm thinking of a telescoping mast, where each smaller section fits inside a somewhat larger diameter section. Kinda like a telescoping metal whip antenna (i.e. rabbit ears). However, there are also masts made of equal diameter tubing, with some sort of coupler at the ends. Your initial posting clearly said "telescoping" but I'm wondering how one makes a self supporting telescoping mast without an internal or external locking mechanism. Which type to you have? Very cheap plain fiberglass tubes, slightly tapered so that as an inner tube is pulled up in its outer tube, the taper reaches a point of great friction. Incidently, the tubes on the outside are all coated glossy smooth except for a couple inches at the bottom where the inner and outer tubes meet.... raw fiberglass has great friction coeficient, apparently. Also, I suspect my problem is that the extended mast was left out in the rain a week when it rained a bit and water got in the joints causing swelling? There is no make / model number on this. Its a cheap generic made-in- China flag banner pole for RVers, etc. I managed to loosen one of the frozen connections, but the two others, one of which I tried the lubricant are yet to be unfrozen. I have a strong feeling that the use of those rubber type wrenchs would simply apply enough torque to the tubes to fracture them. I am letting the stuck sections sit in my garage in hopes that eventually they will dry out on the inside and then perhaps I can get them unstuck with further application of hand pressure. I may stuff myself with terminally fattening ice cream, too, while waiting..... :^) My thanks to all who have provided suggestions, etc. Ed K7AAT |
fiberglass mast question
That's a fair point. From what Ed did (and did not) say, I was assuming his pole had a simplest kind of tapered friction lock... which turns out to be so. These often can be freed by end-on impact when twisting doesn't work and squeezing might crush the thin walls. I guess if I use a somewhat soft wood as a backstop, I may resort to that. I'm going to give the tubes another week to dry out before resorting to further violence! :^) Ed |
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