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Low spots on sides
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Low spots on sides
Im going to be starting my 6th acoustic build soon. One issue I continue to have is low spots on the sides. I use an LMI bender with the spring steel slats that LMI provided (they are pretty stout).
One observation, sometimes there is a bit of rebound in the sides as I take them out of the bender. I sort of force them into the mold to glue the neck and tail blocks. I’m wondering if that may be where the issue is occurring.
After removing from the mold, I use a rolling pin sander attachment to level the sides, then install bindings and once again level the sides with the pin sander.
The end result looks good, but I’d like to see if I can improve the process and not sand as much to get to level sides.
Any advice is greatly appreciated.
Thanks,
James
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9 Replies
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You’re almost always going to have spring back unless you make a side bender mold that overbends the sides. If you’ve seen the benders at Collings they overbend quite a bit for this reason. There is a video out there somewhere…
What shape is this? Dreadnought?
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Hi, yes this has happened to me with dreadnought and 000 size guitars. Do you think the rebound and resulting pushing to get the side into the guitar mold is what could be causing the low spots?
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I think the truth about building guitars is the amount of sanding that goes into them. I feel like you will always have to deal with low spots. Some bends/woods perform better than others. Now sanding the sides flat pre-bind is crucial for final shape and uniformity of the binding. I always mark the sides with a crayon and then hit the belt sander. I take it as far as I feel comfortable on the belt sander and then finish up by hand, especially in the waist. Here’s a video I found from a quick google search that demonstrates it pretty well.
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Thanks, Peter. My belt sander broke a couple of months back so I replaced it with a felder edge sander. The edge sander is great, but it’s quite powerful and I’m hesitant to attempt leveling sides on it. I’ve been debating getting another 6” belt: disc combo sander, if I do I will definitely give this method a try.
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The more radius you bend into a side the less likely it will end up having a dip. The problem with the Drednought is that area from the lower bout to the middle of the waist is almost flat and prone to dip. The Taylor Grand Auditorium (GA, most popular size) even has a flat spot in that area that is prone as well. A guitar side with 100% radius over the entire surface will more than likely stay flat without issue. Side braces are always a cure. Or changing the design to always have some kind of curve and no flat areas. (when I worked with Andy Powers at Taylor this was one of his biggest pet peeves, his designs are all curve) I just looked at 5 Martin drednoughts I have in the shop right now, 3 out of 5 have a dip. 2 are rather minimal one is very bad. Not sure how they keep them flat for the most part at Martin, I’m curious to know. Also, sometimes it’s not there when the guitar is first built but over time they appear. Regardless, you don’t want to oversand to remove them, that is certain. Having seen thousands of guitars in the Taylor Repair Dept. I don’t recall anyone complaining about it. And we built hundreds of 610’s with quilted maple that ended up looking like a roller coaster (mostly because it was flat sawn)
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Thanks Dave, that’s really informative and makes me feel better about the issue. Maybe I’ll try a model with similar internal volume as a dreadnought but more curvature on the sides (grand auditorium or something similar).
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I find that I get better results, meaning less springback if I let the sides sit in the fox style bender overnight. Also side splints can help as well.
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I usually do that as well. I’m not sure if rebound is what has contributed to the issue or if it is something else.
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The spring back is fine, not part of the dip issue.
Some people leave in the bender overnight then cook again the next day and leave it in another night.
Even at Taylor they spring back. They get bent for maybe 15 minutes? then go in a cooling rack which is basically a board with 8-10 1/2″ dowels stinking out perpendicular that hold it in shape. Then they are put in a mold and blocked/kerfed within .5-1 hour later. Maybe even sooner…
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