tango Posted May 26, 2021 Report Share Posted May 26, 2021 Hi Some time ago I had some trouble gluing a cello centre joint and don't know what happened because the joint resulted weak. Do you size the joint before gluing? Regards Tango Quote Link to comment Share on other sites More sharing options...
David Burgess Posted May 26, 2021 Report Share Posted May 26, 2021 I do size a center joint prior to gluing, but this is by no means the be-all and end-all, since there are at least ten other things which can go seriously wrong when forming and gluing a center joint. Quote Link to comment Share on other sites More sharing options...
nathan slobodkin Posted May 27, 2021 Report Share Posted May 27, 2021 There have been more than one discussion of joining plates here which you could look up. I personally do not size joints but rely on a carefully planed and checked joint, good glue applied liberally to both surfaces and just the right amount of pressure. Quote Link to comment Share on other sites More sharing options...
tango Posted May 27, 2021 Author Report Share Posted May 27, 2021 David and Nathan. The weak joint mentioned in the previous post looks well. So I was thinking about the way I prepared the glue or the density not the clamping. I don´t know. Regards both Tango Quote Link to comment Share on other sites More sharing options...
David Burgess Posted May 27, 2021 Report Share Posted May 27, 2021 28 minutes ago, tango said: David and Nathan. The weak joint mentioned in the previous post looks well. So I was thinking about the way I prepared the glue or the density not the clamping. I don´t know. Regards both Tango Tango, more details would be helpful for diagnosis, such as how you arrived at the water dilution ratio of the glue you used. Quote Link to comment Share on other sites More sharing options...
tango Posted May 27, 2021 Author Report Share Posted May 27, 2021 Hi I dilute "by eye" the glue Quote Link to comment Share on other sites More sharing options...
tango Posted May 27, 2021 Author Report Share Posted May 27, 2021 How important is the temperature of glue? I know that it must be 72° C approx but surely I heat more . I guess 80° Quote Link to comment Share on other sites More sharing options...
David Burgess Posted May 27, 2021 Report Share Posted May 27, 2021 23 minutes ago, tango said: Hi I dilute "by eye" the glue I haven't had outstanding or consitsent outcomes, via that method. Quote Link to comment Share on other sites More sharing options...
donbarzino Posted May 27, 2021 Report Share Posted May 27, 2021 if your glue was hot and thin and the wood was porous, then the glue might have soaked in and left the joint starved of glue. Quote Link to comment Share on other sites More sharing options...
tango Posted May 28, 2021 Author Report Share Posted May 28, 2021 OK Density and temperature: two points I must control better. Thanks Quote Link to comment Share on other sites More sharing options...
Jim Bress Posted May 28, 2021 Report Share Posted May 28, 2021 I'm not sure how important the precise temperature is. I was taught 140 F (60 C) for temperature and have never deviated from that. I tend to not to try to fix things that are not broken. Although I'm sure there should be an acceptable ideal temperature range. Quote Link to comment Share on other sites More sharing options...
Davide Sora Posted May 29, 2021 Report Share Posted May 29, 2021 On 5/28/2021 at 3:08 AM, Jim Bress said: I'm not sure how important the precise temperature is. I was taught 140 F (60 C) for temperature and have never deviated from that. I tend to not to try to fix things that are not broken. Although I'm sure there should be an acceptable ideal temperature range. 140/145° F (60/62° C) is the ideal glue temperature (Weisshaar). I heat it to 70° C to have a little more open time, if it is the first time that you heat it and you do not leave it at this temperature for a long period of time, I doubt it will be damaged. At least I have no evidence. Quote Link to comment Share on other sites More sharing options...
Davide Sora Posted May 29, 2021 Report Share Posted May 29, 2021 On 5/28/2021 at 2:42 AM, tango said: OK Density and temperature: two points I must control better. Thanks Yes, it doesn't take a lot of effort and if you don't, every time you will have anxiety about whether your joint will hold or not. It's not cool to find out while making the thicknesses Quote Link to comment Share on other sites More sharing options...
Michael K. Posted May 30, 2021 Report Share Posted May 30, 2021 Just wondering how it works to glue a Cello back in a Sauna. Quote Link to comment Share on other sites More sharing options...
tango Posted May 30, 2021 Author Report Share Posted May 30, 2021 Well . I see that underestimate the temperature. About density: I saw when waiting a while for gluing, the glue became dense so I added more water controlling the density with a drop over a piece of paper and spreading with a finger. Does your glue lose water if it takes too long to work? I am guessing that my glue lose a lot of water due to the high temp I used. May be? Quote Link to comment Share on other sites More sharing options...
nathan slobodkin Posted May 30, 2021 Report Share Posted May 30, 2021 3 hours ago, Michael K. said: Just wondering how it works to glue a Cello back in a Sauna. I have been told that some French factories had a "stove room" for gluing . I do pay quite a bit of attention to temperature of both the room and the wood. Quote Link to comment Share on other sites More sharing options...
avandesande Posted May 31, 2021 Report Share Posted May 31, 2021 Way too many variables. I use fresh glue swelling overnight, 4:1 and use it immediately after heating so no chance of it changing. I follow Davide's method of pouring a thick bead in the joint, not only prevents dry joint but the large amount of glue ensure the joint stays hot for a long period and minimizes evaporation. Quote Link to comment Share on other sites More sharing options...
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