Official Luthiers Forum!

Hello everyone. I have been very much enjoying building my first acoustic OM. What a great hobby! I have been going along pretty good, very happy with my work thus far, until now. I am having problems here and I think I am making it too hard. Surely this shouldn't be a difficult part of the process.

My question is concerning the sides, kerfed linings, tapering, and radiusing. I am hesitant to ask, but I can't find a clear answer in the search forums (at least clear to me anyway )

1. What is the best order in which to perform these tasks? taper, bend, radius, kerfing?

2. I have watched the luthier tips du jour video, but I still have questions. If you taper the sides, then it won't fit into the radius dish correctly right? Is it really as simple as gluing in the neck and heel block, and then tapering down until the sides meet the block?

3. Do you put the sides in the radius dish after the kerfing is in?

I am not really sure how to ask these questions, I hope it even makes sense. ANy advice?

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Always remember you are unique......just like everyone else.

Hi James,
There are many ways to do this that work well.
For me, I taper the sides on the "back" edge but not the "front" edge first. Then, I bend. Then, I install the neck and heel blocks, then the kerfed lining. Then, I radius.
Whichever way you go, here are a couple hints.
First, I like the kerfed lining in place before I radius because I once cracked a side when trying to radius it without the linings. I think the linings give the sides better support to withstand the forces at play as I radius. On the other hand, I have to sand longer. But it doesn't take that long.
Second, once your sides are bent and in the mold, set them in your radius dish to make sure they are pretty close to the right radius. A little sanding is fine, a lot of sanding is a project. If you're way off, use a compass or the equivalent to scribe the sides to the same shape as the radius dish and use a block plane to get the sides closer to the radius before you install the lining.
Good luck!

James: I'll give it a try.
1. I do these tasks in this order,bend,install head and tail blocks,taper, radius roughly, install lining, final radiusing.
2. I taper the sides on the back allowing for a high spot on the sides where the width of the guitar is the least measured from side to side. This will not match the radius dish but will be close enough.
3. I radius roughly ,install lining with small amount left proud of the sides and reradius after glue has set.
Hope that helps a bit. Good luck.
Tom

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A person who has never made a mistake has never made anything!!!

No worries James - this will all make sense for you after you have done it a few times. And.... you will probably find your own sequence too and hopefully help out a noob someday when you are a Master Luthier.

There are lots of ways to do this but here is the order that I do these things in:

1) Leave the top side of the sides flat but follow the tapers in the plans for the back radi on the sides.

2) Bend sides using flat side (top) for alignment in the bender and being sure to note where the waist needs to be.

3) Glue in blocks on bent sides. Some folks glue in the blocks in the mold and I glue the blocks in out of the mold and that is where the flat side (top of the rim) makes for ease of gluing the blocks in as much as it all will sit flat on my bench while gluing the blocks.

4) With sides back in the mold I sand the profiles in the sides in the respective radius dishes. Since we didn't pre-radius the top of the sides that part will take longer....

5) Once the top and back of the rim is radiused in the dishes glue in the kerfed linings.

6) The reason that you sand the rim in the dishes without the kerfed linings installed is that it's far easier to not have to sand though the kerfed linings, blocks, and sides too. When you install the kerfed linings install them about 1/32" proud of the sides and then sand the back and top in the dishes again and Bob's your uncle.

7) You are done when the rim in mold can sit in the radius dish with all kerfed linings and blocks making full contact with the respective dish. Remember too that you may be using two different dishes so be sure to use the one for the top for the top and so on.

Let me know if you have any questions and I am happy to help - always!

I'm a long time beginner, but this is how I do it: (I see others have posted similar methods while I was typing, I'll post this anyway)

1. Bend sides (non-tapered, parallel edges or at least the top side flat). Leaving the top side flat gives you a good reference side for lots of operations before you radius the top.
2. Cut neck and tail blocks to near proper height, allowing just a little extra to be sanded off, glue sides to blocks
3. Use radius dish to scribe the back profile to the sides. This is an old picture, but illustrates the general idea:

The idea is you use two blocks of equal height on the neck and tail block to prop up the dish, then set your compass/scribe to that same size. Instead of using a compass now, I use a little chunk of plywood with a v-groove on one edge where I tape a pencil, it works out to the same size as the blocks. Secure the dish with some tape so it doesn't rock side to side.
4. Use block plane to work the sides down to within about 1/16" or so of the profile line.
5. Install linings, leave slightly proud of the sides.
6. Sand linings with dish till the dish has touched every surface. I use a little section of pipe mounted on my bench that sticks up through a hole in the center of the dish, and then use a crank handle on the dish to turn it round and round. Have to make sure the pipe is positioned along the centerline of the body/mold, which should also be secured to the bench.

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Jonathan Kendall, Siloam Springs AR

Thank you all very much for the help. I greatly appreciate it your willingness to share your ideas knowing that someone somewhere might think you are crazy for doing it that way. I was going about it all wrong. My sides are now too skinny (by about 5mm), so I am deciding whether to glue the lining up a bit more than 1/32" to compensate for my side shortness, just accept a shallower guitar body, or buy new sides and try again. Either way I choose, I have learned something (albeit the hard way).

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Always remember you are unique......just like everyone else.

Before you abandon ship remember theres alot of ways to fix stuff and 5mm is not such a big deal if you can get the plates to fit the sides without torturing the wood too much.....who said guitars all have to be perfectly radiused anyway...if you put a 15' radius on most guitars they will be pretty good up and down and not so good fore and aft...some even build cylinders rather than spheres ....bet you can make it work

Bend sides, top edge flat, back side cut close to profile.
Glue blocks
Profile back with plane close to final, finish with dish
Glue back lining in a tad higher than sides.
Sand back lining until flush with sides AND entire width of lining is sanded.
Glue top lining to sides making it to the radius profile (a la John Mayes DVD)
Sand top lining till flush with sides at the heal and tail, AND all lining surface has been sanded on the entire width.
Done, unless you flatten the upper bout, but thats another topic.

Knowing how to make the lining create the profile takes a few times to get right without having to do too much sanding.

Just glue the back lining up over the side. Remember that the side material that will be missing would have been routed off when you cut the binding channel. Just dont glue it higher than your binding and perf width less the back thickness.

If your guitar ends up being a few mm thin, so what.