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| Clamping Compression Mark? http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=19380 |
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| Author: | George L [ Tue Oct 28, 2008 5:48 pm ] |
| Post subject: | Clamping Compression Mark? |
Hi. I'm currently working on my second build, so, I'm very inexperienced. I recently glued the braces on my top and back using my Go-bar deck--everything seemed fine. Last night I was working on fitting the back to the sides and I noticed that I can feel a variation in the surface where one of the braces is attached beneath. It's very slight and not readily visible, but it's there. Was this caused by too much clamping pressure? I have a feeling that sanding the back will just make it worse. Is there a remedy to this situation? Any advice will be greatly appreciated. Thanks, George :-) |
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| Author: | Kent Chasson [ Tue Oct 28, 2008 6:08 pm ] |
| Post subject: | Re: Clamping Compression Mark? |
Unlikely you could get too much clamping pressure with a go-bar deck, particularly on a back. I would suspect a change in humidity from when you glued it to now. Are you controlling humidity? |
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| Author: | George L [ Tue Oct 28, 2008 7:02 pm ] |
| Post subject: | Re: Clamping Compression Mark? |
Kent Chasson wrote: Are you controlling humidity? Hmm... Interesting thought. For a time I was quite attentive to RH in my home but never recorded an instance where it left the 40% - 50% range, so I stopped worrying about it. I have a couple of digital sensors in place. I'll take a look tonight and see what they say. Thanks for your reply. I appreciate it. George :-) |
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| Author: | John Hale [ Tue Oct 28, 2008 7:40 pm ] |
| Post subject: | Re: Clamping Compression Mark? |
I've had similar problems in relativly stable humidity too, but you couldn't of got more slab sawn cupped wood than I was given and I've fought it all along and lost several times never gonna be pretty but I;m the one ending up winning also I think radius dishes are the way to go as well to get 100% conformity of parts only my thoughts though |
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| Author: | George L [ Tue Oct 28, 2008 11:49 pm ] |
| Post subject: | Re: Clamping Compression Mark? |
Well, for what it's worth I have two Planet Waves digital hydrometers in my house (not the best, I know) that currently read 42% & 43% RH. They have a setting that is supposed to indicate when the RH has varied outside a proscribed "safe" zone as well and neither has been triggered. The weather station at the school three blocks away shows the RH outside as 71%, so general dryness isn't an issue. Maybe it's too humid? I don't know. Anyway, regardless of the cause for this slight indentation, protuberance, or whatever it may be called, does anyone have any advice on how I might go about rectifying the situation? Humidification? Sanding? Scraping? Leave it alone? It's not a huge deal. I'm just kind of curious and like to use these little mysteries that come up during a build as learning opportunities. Thanks, George :-) |
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| Author: | Todd Rose [ Wed Oct 29, 2008 4:59 am ] |
| Post subject: | Re: Clamping Compression Mark? |
I wonder if the plate(s) may be too thin. Another thought is if you used excessive glue, the swelling of the wood from the water in the glue could be a culprit. If that's the case, it may correct itself as the wood fully dries out again. In any case, I wouldn't worry about it right now. Your final sanding before finishing should correct it, not make it worse, as long as you use a sanding block. If I were you, I would also take steps to accurately measure and control the humidity in your workshop. |
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| Author: | George L [ Wed Oct 29, 2008 8:51 am ] |
| Post subject: | Re: Clamping Compression Mark? |
Thanks for the replies. I'll continue to monitor this as the build progresses and will definitely take steps to address any humidity problems. I was hoping that final sanding would help not hinder, so it's good to know I'm not alone in my thinking. Thanks again for the help. George :-) |
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| Author: | Michael Dale Payne [ Thu Oct 30, 2008 9:14 am ] |
| Post subject: | Re: Clamping Compression Mark? |
On steel strings guitars if this happens there are 2 main culprits, all have been mentioned. Warp-age in the plate due to humidity and moisture from glue. There is on other culprit I have seen. In my early building days I once use and anti slit foam pad under the plate between the back plate and dome dish and got this same result. This could have been a combination of to much Titebond and the pad. |
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