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#1
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Bent Laminations
"alexy" wrote in message ... I am getting ready to do a bent lamination, and have questions about adhesives and springback. I have heard that urea formaldehyde or plastic resin glue is the best to use for this application because of the long open time and lack of creep once set. I am having a hard time finding it, though. I can get a gallon from Highland Woodworking but because of its relatively short shelf life, I would end up throwing away 95% of it. Anyone know a good source for small quantities (Atlanta area desired, but online source okay, too) or whether another type of glue would work as well. My application is not load-bearing, and in fact will be "captured" by another structure. I'm laminating 4 pieces of 1/8" thick poplar for edge banding of the inside of an elliptical arch cut in plywood. I have a form for bending my lamination, that I made slightly undersize, anticipating that there will be some "springback" when the lamination is removed from the form. Anyone have any ideas or formulas for estimating how much that will be in advance, or is it just a case of trial and error? -- Alex -- Alex, For the project you describe above, I would use polyurethane glue. Its has sufficient open time for your project. I only use plastic resin glue when I need + 20 minutes to get the project clamped up. Dave |
#2
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Bent Laminations
"Teamcasa" wrote:
"alexy" wrote in message .. . I am getting ready to do a bent lamination, and have questions about adhesives and springback. I have heard that urea formaldehyde or plastic resin glue is the best to use for this application because of the long open time and lack of creep once set. I am having a hard time finding it, though. I can get a gallon from Highland Woodworking but because of its relatively short shelf life, I would end up throwing away 95% of it. Anyone know a good source for small quantities (Atlanta area desired, but online source okay, too) or whether another type of glue would work as well. My application is not load-bearing, and in fact will be "captured" by another structure. I'm laminating 4 pieces of 1/8" thick poplar for edge banding of the inside of an elliptical arch cut in plywood. I have a form for bending my lamination, that I made slightly undersize, anticipating that there will be some "springback" when the lamination is removed from the form. Anyone have any ideas or formulas for estimating how much that will be in advance, or is it just a case of trial and error? -- Alex -- Alex, For the project you describe above, I would use polyurethane glue. Its has sufficient open time for your project. I only use plastic resin glue when I need + 20 minutes to get the project clamped up. Dave I've thought about that, but how is it for creep? My impression is that UF and epoxy are better in this regard. But maybe that's academic in my relatively low-stress project? -- Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently. |
#3
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Bent Laminations
snip
Alex, For the project you describe above, I would use polyurethane glue. Its has sufficient open time for your project. I only use plastic resin glue when I need + 20 minutes to get the project clamped up. Dave I've thought about that, but how is it for creep? My impression is that UF and epoxy are better in this regard. But maybe that's academic in my relatively low-stress project? -- Alex I use blue tape to stop creep. Its really not much of an issue unless the bend is severe. Just make sure you wear nitrile (blue) gloves. Dave |
#4
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Bent Laminations
alexy wrote:
I've thought about that, but how is it for creep? My impression is that UF and epoxy are better in this regard. But maybe that's academic in my relatively low-stress project? SFWIW, For the price of Gorilla Glue or equal, you can add maybe 10% and get epoxy. There is no comparison between epoxy and Gorilla Glue. Lew |
#5
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Bent Laminations
Lew Hodgett wrote:
alexy wrote: I've thought about that, but how is it for creep? My impression is that UF and epoxy are better in this regard. But maybe that's academic in my relatively low-stress project? SFWIW, For the price of Gorilla Glue or equal, you can add maybe 10% and get epoxy. There is no comparison between epoxy and Gorilla Glue. Thanks, Lew. I wonder what the trade-offs are between UF and epoxy? Sounds like you are a "fan" of epoxy, but there are always tradeoffs. -- Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently. |
#6
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Bent Laminations
"Teamcasa" wrote:
I use blue tape to stop creep. Either I am misusing the term "creep", or I don't understand what you are doing with the blue tape to stop it. I thought that creep in a glue joint referred to movement in response to sheer forces. -- Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently. |
#7
Posted to rec.woodworking
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Bent Laminations
"alexy" wrote in message ... Lew Hodgett wrote: alexy wrote: I've thought about that, but how is it for creep? My impression is that UF and epoxy are better in this regard. But maybe that's academic in my relatively low-stress project? SFWIW, For the price of Gorilla Glue or equal, you can add maybe 10% and get epoxy. There is no comparison between epoxy and Gorilla Glue. Thanks, Lew. I wonder what the trade-offs are between UF and epoxy? Sounds like you are a "fan" of epoxy, but there are always tradeoffs. Lew LOVES epoxy (and must have stock WestSystems). He suggests it for virtually every fix where an adhesive is used. Since he works on boats, its a natural choice. For the rest of us, we get to use several diffrent glues. Dave |
#8
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Bent Laminations
"alexy" wrote in message ... "Teamcasa" wrote: I use blue tape to stop creep. Either I am misusing the term "creep", or I don't understand what you are doing with the blue tape to stop it. I thought that creep in a glue joint referred to movement in response to sheer forces. You are not. Creep is what happens to the wood sandwich as clamping pressures are applied. Blue tape will hold it most of the time for flat stock glue ups, it has a hard time when the form includes a bend and twist. Unless your bending form incorporates a twist as well as a bend, you should not have a problem with creep. If you do, and blue tape will not hold, (try it without glue first) apply clamps and cauls to prevent severe creep. Use clear packing tape on the cauls to prevent the adhesive from sticking to it. Dave |
#9
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Bent Laminations
Teamcasa wrote:
Lew LOVES epoxy (and must have stock WestSystems). Actually, I don't use any West Systems. They are not competitive for my applications. The reason I suggest them is that they offer small quantities, are readily available almost every place, and they offer very good tech service. Lew |
#10
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Bent Laminations
"Lew Hodgett" wrote in message hlink.net... Teamcasa wrote: Lew LOVES epoxy (and must have stock WestSystems). Actually, I don't use any West Systems. They are not competitive for my applications. The reason I suggest them is that they offer small quantities, are readily available almost every place, and they offer very good tech service. Lew What do you use? Dave |
#11
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Bent Laminations
Teamcasa wrote:
What do you use? I work with Diversified Materials in San Diego. They use several different suppliers based on price and availability. Laminating epoxy is strictly a commodity, IMHO. Lew |
#12
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Bent Laminations
"Teamcasa" wrote:
"alexy" wrote in message .. . "Teamcasa" wrote: I use blue tape to stop creep. Either I am misusing the term "creep", or I don't understand what you are doing with the blue tape to stop it. I thought that creep in a glue joint referred to movement in response to sheer forces. You are not. Creep is what happens to the wood sandwich as clamping pressures are applied. Blue tape will hold it most of the time for flat stock glue ups, it has a hard time when the form includes a bend and twist. Unless your bending form incorporates a twist as well as a bend, you should not have a problem with creep. If you do, and blue tape will not hold, (try it without glue first) apply clamps and cauls to prevent severe creep. Use clear packing tape on the cauls to prevent the adhesive from sticking to it. Okay. That's not my understanding of the term. I think it refers to a property of the cured glue line. From an engineering dictionary: :Creep :the dimensional change with time of a material under load. and from the Franklin Global web site: :What is creep in an adhesive bond? :Creep or cold-flow in an adhesive bond is the deformation of :the bond line under a stress or load over a period of time -- Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently. |
#13
Posted to rec.woodworking
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Bent Laminations
"Teamcasa" wrote:
"alexy" wrote in message .. . Lew Hodgett wrote: alexy wrote: I've thought about that, but how is it for creep? My impression is that UF and epoxy are better in this regard. But maybe that's academic in my relatively low-stress project? SFWIW, For the price of Gorilla Glue or equal, you can add maybe 10% and get epoxy. There is no comparison between epoxy and Gorilla Glue. Thanks, Lew. I wonder what the trade-offs are between UF and epoxy? Sounds like you are a "fan" of epoxy, but there are always tradeoffs. Lew LOVES epoxy (and must have stock WestSystems). He suggests it for virtually every fix where an adhesive is used. Since he works on boats, its a natural choice. For the rest of us, we get to use several diffrent glues. And his love of epoxy may be well founded--in its many formulations it is wonderfully flexible. But I still believe that there are tradeoffs in selection of any construction material or technique, and I'd like to see some discussion to form the basis of an informed choice. -- Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently. |
#14
Posted to rec.woodworking
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Bent Laminations
"alexy" wrote in message ... "Teamcasa" wrote: "alexy" wrote in message . .. Lew Hodgett wrote: alexy wrote: I've thought about that, but how is it for creep? My impression is that UF and epoxy are better in this regard. But maybe that's academic in my relatively low-stress project? SFWIW, For the price of Gorilla Glue or equal, you can add maybe 10% and get epoxy. There is no comparison between epoxy and Gorilla Glue. Thanks, Lew. I wonder what the trade-offs are between UF and epoxy? Sounds like you are a "fan" of epoxy, but there are always tradeoffs. Lew LOVES epoxy (and must have stock WestSystems). He suggests it for virtually every fix where an adhesive is used. Since he works on boats, its a natural choice. For the rest of us, we get to use several diffrent glues. And his love of epoxy may be well founded--in its many formulations it is wonderfully flexible. But I still believe that there are tradeoffs in selection of any construction material or technique, and I'd like to see some discussion to form the basis of an informed choice. Cagle, in "Handbook of Adhesive Bonding", a well known engineering reference, recommends UF or RF over epoxy for wood-to-wood joints exposed to weather. I don't remember why now and my copy is not readily accessible. However he was writing over 30 years ago and the available epoxy formulations may have improved since then. Personally I generally use Titebond or PU for the convenience, but if it's mission-critical indoor and I've got a good fit I go for the UF and mission-critical outdoor the RF. OTOH, I've got an assembly I'm going to glue up with T88 epoxy tomorrow, the reason being that it's outdoors, the temperature right now is going down into the high 30s at night, and T88 will cure at that temperature (eventually) while UF and RF aren't rated to cure below 70 and the rest not below 50. |
#15
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Bent Laminations
"Teamcasa"
You are not. Creep is what happens to the wood sandwich as clamping pressures are applied. Blue tape will hold it most of the time for flat stock glue ups, it has a hard time when the form includes a bend and twist. Unless your bending form incorporates a twist as well as a bend, you should not have a problem with creep. If you do, and blue tape will not hold, (try it without glue first) apply clamps and cauls to prevent severe creep. Use clear packing tape on the cauls to prevent the adhesive from sticking to it. Alex Okay. That's not my understanding of the term. I think it refers to a property of the cured glue line. From an engineering dictionary: :Creep :the dimensional change with time of a material under load. and from the Franklin Global web site: :What is creep in an adhesive bond? :Creep or cold-flow in an adhesive bond is the deformation of :the bond line under a stress or load over a period of time Alex, I don't think that applies to furniture making. Structural materials, subject to significant pressures and/or vibration and large temperature fluctuations, maybe. If you are making a glue lamination beam (GLB), that may have to hold during a fire, then I'd worry about that type of creep. Dave |
#16
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Bent Laminations
Teamcasa wrote:
: :What is creep in an adhesive bond? : :Creep or cold-flow in an adhesive bond is the deformation of : :the bond line under a stress or load over a period of time : : Alex, I don't think that applies to furniture making. Structural materials, : subject to significant pressures and/or vibration and large temperature : fluctuations, maybe. If you are making a glue lamination beam (GLB), that : may have to hold during a fire, then I'd worry about that type of creep. The most common sense of "glue creep" in woodworking is pretty much Alex's, but perhaps with 'time' replacing 'load'. Concretely, it's the phenomenon of having two pieces glued together become non-flush with one another at the glue line. Most common with white and yellow glues. - Andy Barss |
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