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| Top Layout Question http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=16584 |
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| Author: | Mike OMelia [ Wed Mar 26, 2008 8:34 am ] |
| Post subject: | Top Layout Question |
The only parts glued in the picture below is the X braces. The rest are just laid out. Please, someone, look carefully and tell me if I have all the braces oriented correctly... I am particularily concerned about the four shortest braces in the lower bout, then the two longer braces in the lower bout. thanks! Mike |
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| Author: | Mike OMelia [ Wed Mar 26, 2008 9:27 am ] |
| Post subject: | Re: Top Layout Question |
Todd, Can do, but I was just following the pattern scribed on the top by J. Hall. I was also concerned about the direction of the finger braces... pointy end in or out. In the end, I spose it does not matter. Mike |
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| Author: | Ken Franklin [ Wed Mar 26, 2008 9:51 am ] |
| Post subject: | Re: Top Layout Question |
Mike, Having the pointy end in will just make it easier to carve, but you would carve both ends any way. I like where you tapered the X brace. I would put a long taper on the four side braces when they are glued. To me that's a lot of support outside the area of greatest stress. You might want to cap the X with some eighth inch spruce at the intersection instead of the cloth piece that many factories use. Of course you will shorten the soundhole braces. Looks fine overall. |
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| Author: | Colin S [ Wed Mar 26, 2008 10:11 am ] |
| Post subject: | Re: Top Layout Question |
slackkey_mike wrote: Todd, Can do, but I was just following the pattern scribed on the top by J. Hall. I was also concerned about the direction of the finger braces... pointy end in or out. In the end, I spose it does not matter. Mike If John Hall scribed the bracing pattern on the top, then I'd stick to his recommendation. Colin |
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| Author: | Howard Klepper [ Wed Mar 26, 2008 10:21 am ] |
| Post subject: | Re: Top Layout Question |
Is that X a full lap joint? Doesn't look like it. |
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| Author: | Daniel M [ Wed Mar 26, 2008 11:27 am ] |
| Post subject: | Re: Top Layout Question |
I am seeing what Howard mentioned. Were the X braces "profiled" before they were notched & joined? It looks like you have an open joint at the top of the X... If this is so, the strength will be seriously impaired, even if you cap over the voids. Otherwise, it looks fine to me, though I would even out the fan brace spacing a bit as was mentioned earlier. |
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| Author: | bluescreek [ Wed Mar 26, 2008 8:46 pm ] |
| Post subject: | Re: Top Layout Question |
you cut the lap joint in the pre shape state. there is nothing wrong with the bracing. All that is needed is a cloth reinforcement. Yes you can influence the tone by moving things around but with the guitar being your first build I do think you need to apply the bracing as plotted. If you move the finger braces you will not create the proper W truss for the control of the rotational forces from the bridge. learn to walk and get your assembly techniques under your belt. There are many different building techniques out there. Don't try and learn them all on the first guitar. Clean joinery and gluing techinques are paramount for successful building. Learning fit and finish can take a lifetime. The bracing is plotted from martin and they have been building guitars a long time. |
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| Author: | Mike OMelia [ Wed Mar 26, 2008 8:47 pm ] |
| Post subject: | Re: Top Layout Question |
Well, as far as the lap joint is concerned, I have no idea. The braces had a subtle curvature to them, but there was no indication anywhere that I was spose to profile them (the back braces came fully profiled at 25'). Lets see what John has to say. Anybody got a drawing or a pic of what the lap joint cover should look like? Mike |
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| Author: | Mike OMelia [ Wed Mar 26, 2008 10:46 pm ] |
| Post subject: | Re: Top Layout Question |
John tells me that it is as it should be. Mike |
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| Author: | bluescreek [ Thu Mar 27, 2008 4:29 am ] |
| Post subject: | Re: Top Layout Question |
http://www.mguitar.com/guitars/features ... index.html this link should be of interest to many here. It shows drawings of the different bracing patterns martin used over the different models The cloth patch that Is referred to in the instructions is about 1 inch round. I use a gun cleaning wad soaked with glue and form it over the joint. This is an efficient to secure the joint. I know many here use a wood overplate. I have seen over plates fail but never saw a cloth one fail. The important part is that your glued surface to the top is secure and cleanly attached without voids. Only them main X and truss rod brace are inlet to the kerf on the top. All other braces are feathered to the top so the flex won't stress the glue joint. All back braces do get inletted hope this helps john |
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| Author: | Mike OMelia [ Thu Mar 27, 2008 9:02 pm ] |
| Post subject: | Re: Top Layout Question |
OK, got some gun barrel cleaning wads, cut a 1" circle out, soaked it in tite bond and tried to affix it. Yuk! That was a mess. Took it off, cleaned up the mess and stopped to think about it. Next try, sprayed a little (very little) scotch glue on the clean cloth to make it tacky. Put it into position then "painted" it with progressively thicker mixes of titebond. Now THAT worked well. Mike 
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| Author: | Kevin Gallagher [ Thu Mar 27, 2008 11:12 pm ] |
| Post subject: | Re: Top Layout Question |
This is obviously a Martin top that was part of a Martin kit. It's easy to tell by the location and jig tabs and holes at the waist and where the fingerboard tongue will lay. I was part of the design group that started that method. There would be no reason for anyone else to incorporate those tabs and holes without having the great aluminum jigs that Martin has. That bracing pattern was traced onto the top at GMC before it was shipped so it is just what is used at Martin.....a pretty safe patter to follow. The lap joint is exactly the way Martin does it and has for a long time. The braces are profiled prior to their being joined. I'd advise sticking with the factory traced bracing lines if you're shooting for a Martin-like result. Shifting the bracing around does affect tone, but it also affects integrity and load bearing and distribution capabilities. Have fun, Kevin Gallagher/Omega Guitars |
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