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| repaired glue joint - - - adhesive peel strength http://www-.luthiersforum.com/forum/viewtopic.php?f=10137&t=55605 |
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| Author: | phavriluk [ Sat Apr 01, 2023 2:34 pm ] |
| Post subject: | repaired glue joint - - - adhesive peel strength |
Seeing as I don't have any information to compare and contrast, I'm asking for comments: I had a wood-to-wood glue joint (new wood, both sides) using epoxy fail - - - the glue could not tolerate the peel stresses I applied. Second attempt, flowed in some 'medium' CA. Same result. I just took the joint apart and scraped it clean of all the old glue I could find, CA and epoxy. What to use to try again? I have five choices: I can make another attempt with epoxy, regular medium CA, Starbond rubberized medium CA, Titebond extend, regular Titebond. Five glues to pick from. (And nonparticipating experts, keep your 'hide glue' mantras to yourselves, please. I've never used the stuff, am not set up to use it and I have exactly two square inches of one joint to reattach. Today. Unless I hear of something I can get from the hardware store today, these five glues are my choices. ) Thanks, folks! |
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| Author: | Chris Pile [ Sat Apr 01, 2023 2:51 pm ] |
| Post subject: | Re: repaired glue joint - - - adhesive peel strength |
Which woods, please? |
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| Author: | phavriluk [ Sat Apr 01, 2023 3:08 pm ] |
| Post subject: | Re: repaired glue joint - - - adhesive peel strength |
Chris, thanks for joining in. Which woods? Mahogany peeled away from mystery wood. |
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| Author: | Barry Daniels [ Sat Apr 01, 2023 3:29 pm ] |
| Post subject: | Re: repaired glue joint - - - adhesive peel strength |
Of your available glues, Titebond Original would be my choice by a long shot. But what kind of stress is this joint getting? |
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| Author: | phavriluk [ Sat Apr 01, 2023 4:40 pm ] |
| Post subject: | Re: repaired glue joint - - - adhesive peel strength |
Thanks, Barry, Stress? Can't measure it, BUT...the bit that departed is one of two support struts under a fingerboard that host a #10 stud each allowing the fingerboard extension to bolt to a neckblock extension. The idea being was that I could take up the odd .050" of air gap between the fingerboard and soundboard, all in service to my allergy to ski-jumps in the fingerboard. One strut stayed glued with its original epoxy, the second got lazy. All this may become moot once the fingerboard gets fretted and the 'compression fretting' on those last six frets may tend to curl the fretboard in the direction I want, anyway. I would, in a perfect world, use threaded fasteners to lock in place a neck that sits where it ought to, and the fasteners' sole job is to make sure it didn't fall off. Meanwhile this building geetars is an adventure unto itself! |
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| Author: | bobgramann [ Sat Apr 01, 2023 4:43 pm ] |
| Post subject: | Re: repaired glue joint - - - adhesive peel strength |
Is one side of the joint end grain? End grain joints can work, but often they’re not as strong as side grain to side grain joints. |
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| Author: | joshnothing [ Sat Apr 01, 2023 4:46 pm ] |
| Post subject: | repaired glue joint - - - adhesive peel strength |
Need a little more information to make a recommendation. Are the surfaces of the joint tightly fitted or are there gaps? Is the mystery wood a hardwood or softwood? Approximately how much force is being applied? Is the load constant or momentary? Edit: I see you answered most of these while I was writing the post. What type of guitar are we talking about here? Why is there an air gap? Having trouble visualising the situation you’re dealing with. |
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| Author: | phavriluk [ Sat Apr 01, 2023 5:06 pm ] |
| Post subject: | Re: repaired glue joint - - - adhesive peel strength |
Bob, no end grain. |
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| Author: | bobgramann [ Sat Apr 01, 2023 6:32 pm ] |
| Post subject: | Re: repaired glue joint - - - adhesive peel strength |
Was there some kind of coating on the mystery wood that prevented a good bond? In other words, when the joint failed was there glue on only one side? Or, was there glue firmly adhered to both sides with the failure in the glue itself? If you can’t make it work with Titebond, nothing else is likely to be superior in this application (ie, not hot and not underwater). |
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| Author: | phavriluk [ Sat Apr 01, 2023 6:42 pm ] |
| Post subject: | Re: repaired glue joint - - - adhesive peel strength |
Bob, no obvious differences between left and right sides. One failed. I'll speak up tomorrow after the glue dries overnight. |
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| Author: | phavriluk [ Sun Apr 02, 2023 11:45 am ] |
| Post subject: | Re: repaired glue joint - - - adhesive peel strength |
Mission accomplished. Anticlimax. Five-minute trial assembly. No force fits. Threads all clean. Geometry good. Very pleased how it worked out. Time for grammar lesson. Today's topic: Complete sentences. And my thanks and appreciation to everyone who spoke up and offered advice and asked questions. Regular Titebond did its assigned task just fine. Next stop, shaping the neck. |
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