Guitar Building Advice – Don’t Cut to Size Until Necessary

Here’s some guitar building advice. Whether you are making a guitar or a cabinet to hang on your wall, always avoid cutting anything to final size until absolutely necessary. Think this is obvious and trivial? Its not. you would be surprised how many people back themselves into a corner by not doing this. Never, ever cut something to final size, or length, or height, until it is safe to do so. Its a basic CYA philosophy shared by most woodworkers and craftspeople. Think ahead. If you cut all your parts to size, then start assembling them chances are some parts are not going to fit perfectly. As you put things together, the last parts to go on will likely be either too short or too small and trimming or shaping will be in order.

Trim to a Known Good Part
For instance, when fitting the guitar’s fingerboard, leave the guitar neck large (width and depth). Trim your fingerboard to a known good template, install it on the neck, then trim the neck to the fingerboard which you know is correct.

If you do this the other way around you may end up cutting the neck too narrow or too shallow, and have to compensate by either making the fingerboard narrower or thicker, neither of which are ideal.

A reader recently asked if he should cut the height of the roughed out heel to dimensions in the drawing before gluing it to the sides. Visualize the next steps before cutting. Since the back is a tilted dome, the height of the heel at the inner edge of the tang is higher than where the heel meets the sides. The back is tilted down toward the neck end of the guitar, so the inner most edge of the tang is the highest part of the heel.

Remember, the tang is glued to the back over its entire surface. This is what locks in the final neck angle. So if you cut the heel too short, you will have to lower the height of the entire perimeter of the guitar to make everything fit right. In doing that you will change the cubic volume inside the box. This should not be an option.

The safest way is to just leave the heel 94mm high. Then trim it with a plane and the sanding disc when you fit the back. You will end up with the heel at the perfect height.

If you are using the side slot cutting sled to cut the side slots in the neck (as in the dvd), the height of the heel should be cut to 94mm before you cut the slots. The sled is designed to cut the slots in the heel at the proper angle with the heel at a height of 94mm. 94mm is still plenty of height for this design, the heel will be too high when fitting the back and need to be trimmed down at this time. This is purposely the order of things so that the body depth will end up at the right dimension after the back is on.

Any other height will produce a different angle in the slots, and hence a different depth, which may not be ok. Nothing can take the wind out of your sails like screwing some aspect of the assembly, requiring you to re-make something, or even start over.

Visualize
The best guitar building advice I can give is to train yourself to visualize things in advance. This applies to woodworking as well. Making furniture I learned to visualize very well. Its absolutely necessary to build furniture especially as it gets more complex. In my book I urged readers to visualize and I wasn’t kidding. I do this every morning before I go into the shop. It works and it is not a waste of time. It’s cheaper to make a mistake in your head than with your wood. Athletes making millions are trained to do this. If you train yourself to do this you will be amazed at how many mistakes you will catch before you make them. Be Mindful.

Blog Comments

Thanks, John, I’ll try standing them up first and see what happens. I did remove material from both faces when thicknessing. Apologies for posting here, will do so in the Forum next time.

Hi John
I am making my first guitar from the video and book. I have made the soundboard and back first but am struggling with the neck. Because of that it’s taking longer than I want and I noticed that the soundboard and back are losing the dome shaping while stored. The edges are lifting up. I am checking humidity to see if it’s too dry but in the meantime can I store the front and back in their moulds to maintain the correct shape? Thanks, Keith.

That happens sometimes. It could be the wood or your environment. For wood to remain stable with the surrounding humidity both faces need to be exposed to the same air. If your top and back were laying flat on another surface with only one face exposed to the air, that may be why they curled. If both faces were exposed to the same air it something with your wood. In any case having both faces exposed is always best. It depends on how bad the curling is. If its slight you may be able to install them without a problem. Understand that the concave face is drier than the other side. The convex face has more moisture content so it is slightly wider, hence the curling. This can be due to a variety of things. Hopefully you removed material from both faces when thicknessing. If not there s your answer. The best thing would be to stand it up so both faces get the same air and let it stay like that until it reaches equilibrium. It may straighten out. If not you’ll have to decide what to do. You can moisten the dry face slightly to get it to straighten out but that is difficult to pull off successfully. In the future please post these types of questions to the forum as this is not the best place for this type of question.

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