| Official Luthiers Forum! http://www.luthiersforum.com/forum/ |
|
| gluing bridge http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=34598 |
Page 1 of 1 |
| Author: | Tai Fu [ Sat Dec 17, 2011 7:25 am ] |
| Post subject: | gluing bridge |
How do you glue a bridge on and make sure there are no corner gaps, no glue lines, etc.? I use hot hide glue so I can wipe the glue residue off after it dries, but there are always glue right along the edge that is just a pain to remove. I can imagine it's much more difficult to remove dried glue squeeze out. What about bridges where the corner (like a Taylor bridge) just wants to pop up? I've had to remove that bridge because of this (and thank God for HHG, 5 minutes with an iron and its off) and make several dry runs with various clamping caul to make sure that part stays down. I was able to get it down finally. It seems Taylor doesn't radius the bottom of the bridge to match the top, and there isn't enough material for me to sand that radius in... From my understanding Taylor uses a vacuum clamping fixture anyways. |
|
| Author: | Kim [ Sat Dec 17, 2011 7:46 am ] |
| Post subject: | Re: gluing bridge |
It sounds like you need to bed the bridge down again Tai Fu. In other words the radius of the glue surface of the bridge needs to match that of the top. You can do this by careful taping a sheet of 120 grit sandpaper, abrasive side up, to the top of the guitar and then 'gently' sanding the underside of the bridge on the guitar's surface, at, or close to, where the bridge is to be glued. You do this (gently because you do not want to deform the radius of the top) until the bridge sits evenly across the top with no gaps at the wings. Once the bridge has been properly reseated, clean the underside glue surface with a gentle swipe or two of a sharp scraper or even a fresh razor to reduce the peaks in the scratch pattern and improve the bond surface. A word of caution. You have just 'boiled' that bridge in a pot...When you done that you filled it full of water. It will now need to be allowed to dry out for a while to stabilise before you start removing any wood from anywhere or trying to glue it back on. As to how to remove HHG squeeze, I use a wet stick with a chisel end and then follow up with a point end to push the glue away from the bridge...but only 'after' the glue has had the opertunity to set up or gell quite firmly...you do not want the glue to become hard 'hard' mind..but firm so it will no longer smear. At this stage, softer than a pencil eraser but harder than snot, it should simply roll off like no other glue can and leave an excellent almost invisible glue joint behind. Cheers Kim |
|
| Author: | Tai Fu [ Sat Dec 17, 2011 8:28 am ] |
| Post subject: | Re: gluing bridge |
I can see why the bridge wing popped up in the first place... Taylor did NOT bed the bridge properly at the factory, so when the guitar was exposed to heat that section popped up. Unfortunately I really don't have the space to bed the bridge properly because the bridge itself is rather thin, and it's already glued down... I have until Tuesday at the most to get this fix done and I don't have time to wait around... Now I just managed to get it down without the gap at the corner, with good clamping pressure in the right place I might add. I need to give the guitar owner a stern warning about not leaving this guitar in a hot car... |
|
| Author: | woody b [ Sat Dec 17, 2011 9:41 am ] |
| Post subject: | Re: gluing bridge |
Tai Fu wrote: ................................................ I have until Tuesday at the most to get this fix done and I don't have time to wait around.......................................... That's a big mistake. If you need to make a new bridge, or do whatever needs to be done, and it will take longer make the client wait. It isn't your fault. You didn't make the guitar, you also didn't leave it in a hot car, or do whatever caused the problem. Tell the client the bridge is damaged. A new bridge will need to be made. It will cost (whatever price) and take more time. |
|
| Author: | Tai Fu [ Sat Dec 17, 2011 11:43 am ] |
| Post subject: | Re: gluing bridge |
woody b wrote: Tai Fu wrote: ................................................ I have until Tuesday at the most to get this fix done and I don't have time to wait around.......................................... That's a big mistake. If you need to make a new bridge, or do whatever needs to be done, and it will take longer make the client wait. It isn't your fault. You didn't make the guitar, you also didn't leave it in a hot car, or do whatever caused the problem. Tell the client the bridge is damaged. A new bridge will need to be made. It will cost (whatever price) and take more time. Ok, I lost some sleep, but I finally got the part to fit like they should, but it took me 2 hours of hogging out the middle of the bridge, sanding on the body to get the bridge to finally fit on the body with minimal clamping pressure (last time it took massive clamping pressure, from 3 cam clamps exerting 300lb each). It was worth it. In the process I made some custom clamping caul out of plywood for Taylor bridges. There are still enough height on the bridge, I might have to shim the saddle but if the client wants a new bridge, he can have it made later on, and effortlessly replaced (thank God for HHG). I also discovered it's a lot easier to make the micro ledge so that the bridge fits better with a scraper guided by my thumb, rather than fiddle with routers which can add more hours of work should the cut be too deep. I will take the time to make a bridge clamping fixture so I can do it with one clamp instead of 3. The only thing is, I am trying to figure out where can I get that screw thing that you usually find on clamps? |
|
| Author: | jfmckenna [ Sun Dec 18, 2011 4:40 pm ] |
| Post subject: | Re: gluing bridge |
I don't put an arch in the bridges I make and I've yet to have one come back for repairs in 20 years. So that's not the problem. Leaving the guitar in a hot car is the problem  As for clean up. I don't use hide glue but you could use a similar process: Take a chisel with a rag over it soaked in solvent, in the case of Titebont - water, and get the rag covered edge of the chisel to the edge of the glue joint. |
|
| Author: | Chris Pile [ Sun Dec 18, 2011 4:44 pm ] |
| Post subject: | Re: gluing bridge |
Remember these words of wisdom when repairing guitars... "You can have it repaired fast, or have it repaired well - but not both". |
|
| Author: | Billy T [ Sun Dec 18, 2011 11:18 pm ] |
| Post subject: | Re: gluing bridge |
Number one cause of bridge/soundboard joint failiure is a poor fitted radius on the bridge. |
|
| Page 1 of 1 | All times are UTC - 5 hours |
| Powered by phpBB® Forum Software © phpBB Group http://www.phpbb.com/ |
|