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| Help with trimming rims and black fingers! http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=24159 |
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| Author: | matthewrust [ Tue Oct 13, 2009 6:16 am ] |
| Post subject: | Help with trimming rims and black fingers! |
I would ask this in the kit area, but I am building this one from scratch... So, I am to the point where the top is glued on and I am ready to trim the sides so I can attach the back. Cumpiano takes a block plane and sanding board and kind of eyeballs it. Others use radius dishes and sand them that way. I am actually building off of plans from an old J45 and would like to be as close as possible to those plans. Any tips, tricks? Also... every day, my fingertips turn black in the shower. I am not sure if it is glue or dust having a reaction to one of my soaps. I'm not really that worried about it but wonder if you guys have run into this. |
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| Author: | Tim McKnight [ Tue Oct 13, 2009 7:54 am ] |
| Post subject: | Re: Help with trimming rims and black fingers! |
A radius dish is more accurate IMO than using a plane BUT it can be done. I built my first few guitars using a "sanding stick" with a wedge on one end to match the angle of the radius and sandpaper on the other end. It works but neither are as easy as a dish. Are you working with Black Walnut? I have had my fingers get stained from Walnut but that is the only wood that has imparted any pigment to my skin ... yet. |
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| Author: | truckjohn [ Tue Oct 13, 2009 8:08 am ] |
| Post subject: | Re: Help with trimming rims and black fingers! |
Quite a few of the really old Gibsons and many others ran Flat, Unprofiled rims. Old Martins and quite a few others just sanded an arch in with a flat board like Cumpiano. Quite a few newer builders and newer factories use sanding dishes of one sort or another... Hundreds of thousands of good guitars have been built with each of those methods. Each of those methods works out fine, just pick your poison. Remember, with any of these methods, the goal is to sand the rims to a uniform, smooth surface without gaps and lumps... so that the gluing goes smoothly without leaving humps or gaps. I did it Cumpiano's way on my 1st. Worked out fine. I used Dishes on the 2nd. Worked out fine. I believe the Collins J45 print includes a side profile. He drew it off of an actual J45--so it should be as Authentic as it gets.... If you want to really match up his exact side profile -- make a paper template and trace the outline onto your sides. Good luck John |
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| Author: | truckjohn [ Tue Oct 13, 2009 8:32 am ] |
| Post subject: | Re: Help with trimming rims and black fingers! |
Oh, on the Stain thing... Any wood that is high in tannins will do this. The key is Wood high in Tannins + Acid + Iron..... Oak, Walnut, Hickory, Pecan, Cherry, etc... all fall into this category. My hands turn black when working Oak with iron tools (Planes, chisels, etc) If you have Hard water with Iron in it... that will fit the bill pretty well... It will wear off in a couple days. Thanks John |
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| Author: | bluescreek [ Wed Oct 14, 2009 6:30 am ] |
| Post subject: | Re: Help with trimming rims and black fingers! |
Be very careful with profiles as they are designed to match a shape. It will get you close . Eyeballing will work but won't be perfect. Disks and jigs are the way to handle this well but as long as you can see the shape and understand that the back angle is not static you can make it work. You can make yourself a radius template , It should be in the 20 foot range , Use that as a guide to help get the back close. Do not get so worked up that you are exact, as these older guitars had a wider spec range than what is coming out of the factories today. As long as your close you will be fine. Try avoiding a flat area on the kerfing as that will telegraph into the back and top over time. |
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| Author: | Mike Lindstrom [ Wed Oct 14, 2009 6:43 am ] |
| Post subject: | Re: Help with trimming rims and black fingers! |
I've used the sanding dishes which make it harder (but not impossible) to mess it up. If you haven't profiled your sides at all, sanding them to shape will take a while. You can get close in a hurry with a block plane, using the dish as a guide to check progress visually and guide your planing. Then, sand everything smooth and uniform in the dish. On the other hand dishes aren't free and probably don't make sense if you aren't planning on building more guitars later. Mike |
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| Author: | matthewrust [ Wed Oct 14, 2009 7:20 am ] |
| Post subject: | Re: Help with trimming rims and black fingers! |
Thanks guys. Well, I have the top glued on already and it looks great, but I had an issue with my first where I did the sanding stick thing that StewMac recommends and I just wasn't happy with the result. The binding covered up any inconsistency, but I just want to improve with each new build. I took the back down to within 1/8" of where the Collins plans measure to with a block plane and and will use a radius dish to do the fine fitting. As for the black fingers, I don't have them today and I did plenty of planing last night. I have no idea... Oh well. |
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| Author: | Quine [ Wed Oct 14, 2009 12:42 pm ] |
| Post subject: | Re: Help with trimming rims and black fingers! |
I usually eyeball the taper. I rest a level across the rim to make sure they are the same height on each side at each point. Then I use the back plate (unbraced) to make sure I have a nice smooth line. You can transfer the taper off your plans to the rim. Just measure the rim height at a few points on the plans and mark it on the sides. |
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| Author: | Chris Paulick [ Thu Oct 15, 2009 7:05 pm ] |
| Post subject: | Re: Help with trimming rims and black fingers! |
I find that lemon juice removes walnut stains. |
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