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| CF glued in neck pops back up http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=37711 |
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| Author: | Mike Lindstrom [ Wed Sep 12, 2012 11:00 pm ] |
| Post subject: | CF glued in neck pops back up |
I meant to ask this quite a while ago. If I did, I can't remember what folks said, and can't find it. When I glue carbon fiber bars in my neck, the epoxy and trapped air conspire to push the CF back up out of the neck. How would a guy avoid that? Am I cutting the slot too tight? Thanks, Mike |
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| Author: | mirage_al [ Thu Sep 13, 2012 6:00 am ] |
| Post subject: | Re: CF glued in neck pops back up |
Eat more slowly...  Seriously, either slide it into the slot from the end to avoid trapping and compressing the air, or clamp it down thus leaving compressed air in there, or else provide some escape path ( a hole somewhere? ) for the air. Those are the tings I'd try, anyway. I'm going to be trying to use CF soon myself so maybe I'll find out.Cheers, Alan |
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| Author: | SteveSmith [ Thu Sep 13, 2012 8:06 am ] |
| Post subject: | Re: CF glued in neck pops back up |
That can happen when gluing things with epoxy. There has to be adequate clearance for squeeze out. I usually make the slot wide enough so the CF rods will just fall out during a dry fit if I turn the neck upside down. When I glue I push the CF into the slot and hold it down while the excess epoxy escapes. Only takes a short time. Other option is to clamp it so it can't move while it sets. Also try not to use too much excess epoxy in the glue up. |
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| Author: | Joe Beaver [ Thu Sep 13, 2012 8:18 am ] |
| Post subject: | Re: CF glued in neck pops back up |
Since my router bits are the same size as the rod I'm cutting the channel for, I just cut the channel a little deep and clamp until cured. |
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| Author: | Terence Kennedy [ Thu Sep 13, 2012 8:34 am ] |
| Post subject: | Re: CF glued in neck pops back up |
I cut the slots with the 1/8" table saw blade and if the rod fits too tight run it through your thickness sander to tweak it. I cut the slots just a hair deep. Clamp it during glue up. I just use 1/8" dowels with wax paper under and spring clamps. I usually mask off the fretboard during installation, it can sure get messy! 
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| Author: | Mike OMelia [ Thu Sep 13, 2012 9:44 am ] |
| Post subject: | Re: CF glued in neck pops back up |
mirage_al wrote: Eat more slowly... AlanLOL!  Mike |
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| Author: | Mike Lindstrom [ Thu Sep 13, 2012 10:00 pm ] |
| Post subject: | Re: CF glued in neck pops back up |
Is there a rule on how much gap epoxy can fill or what's optimal? |
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| Author: | Daniel Minard [ Fri Sep 14, 2012 12:57 pm ] |
| Post subject: | Re: CF glued in neck pops back up |
If the CF rod is too tight in the slot, I just sand it a tiny bit thinner. I like to sand the CF with 220 grit anyway to scratch the surface a bit. The tiny scratches seem to give the epoxy an escape route. Personally, I think the CF should be firmly bedded into the bottom of the slot, without a thick layer of glue underneath. Easing the corners is a good idea, on machined CF rods, which have sharp, square corners. A few quick strokes with 220 sandpaper does the trick. To prepare the neck, I cover the entire surface with masking tape & then cut the tape away from the slots with a sharp x-acto knife. Makes cleanup a snap. |
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| Author: | SteveSmith [ Fri Sep 14, 2012 1:08 pm ] |
| Post subject: | Re: CF glued in neck pops back up |
Daniel Minard wrote: ... To prepare the neck, I cover the entire surface with masking tape & then cut the tape away from the slots with a sharp x-acto knife. Makes cleanup a snap. I do something similar except I just put masking tape on - no cutting. Attachment: CF Install.JPG
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| Author: | Bob Garrish [ Fri Sep 14, 2012 10:36 pm ] |
| Post subject: | Re: CF glued in neck pops back up |
Mike Lindstrom wrote: Is there a rule on how much gap epoxy can fill or what's optimal? You could cast a neck out of epoxy, so there's no issue with gaps. Any trapped air will seep out eventually, so you just need to hold the rod in place until the air pressure leeches out. As others have suggested, I'd clamp down the rod until the epoxy cures. |
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| Author: | Mike OMelia [ Sat Sep 15, 2012 8:09 pm ] |
| Post subject: | Re: CF glued in neck pops back up |
I honestly did not know you needed to glue a CF bar. Assumed that the expoxy used in the FB glue up was enough. I've only done one so far, a uke. Is this something I need to do? Mike |
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| Author: | Dave Stewart [ Sat Sep 15, 2012 9:27 pm ] |
| Post subject: | Re: CF glued in neck pops back up |
Mike, it needs to be securely glued IMO, so if the neck wood trys to bow, the CF will resist it in shear (rather than just slipping in the slot). Ideally, it should be a zero creep glue joint (which is what is in shear). |
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| Author: | Mike OMelia [ Sat Sep 15, 2012 9:38 pm ] |
| Post subject: | Re: CF glued in neck pops back up |
Ok then. I will add that to my process. Is epoxy zero creep? Thanks Dave Mike |
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| Author: | Mike OMelia [ Sun Sep 16, 2012 10:59 am ] |
| Post subject: | Re: CF glued in neck pops back up |
The label begs the question: What is Sticky Ass Glue made from? Mike 
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| Author: | WudWerkr [ Sun Sep 16, 2012 7:52 pm ] |
| Post subject: | Re: CF glued in neck pops back up |
Filippo Morelli wrote: Last many years I've been doing mine with Polyurethane glue. The 1/8" dowel trick is cute. I cut my slot reasonably tight (like a saddle slot), but a smidge deep. Instead of a dowel, I use a hardwood thin, less wide than the slot. This gives me something to clamp the CF down to the bottom. Easy to do glue cleanup while drying as well. When it dries, I simply plane the hardwood thin flat to the neck. With this setup, simply there will be no glue build up or air in the bottom of that slot. It's getting pressed out! The length of the slot can be a smidge longer and it will blow out the ends.  Filippo +1 this works |
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