Les Paul Hollow Body Copy

[gregmary]

I was at the music store today and was looking at some different neck atachments. What type of neck attachments do you like. Some of the necks that I saw looked like the neck was off of a different model as they did not flow into the body at all.

My CAD program has a "shell" command that allows me to create the inside surface as you describe.

I use the router to route out about 85% of the outline as a final operation. The remaining 15% are tabs that connect the body to the waste material that has the tooling holes in it. The tooling holes align the buck to the router table. I use the scroll saw to cut these tabs and seperate the body when everything is done. At this point I can no longer use the router without making a special fixture, this is why it is the final operation.

Greg

[RandMan]

You have to use a mortise and tenon because your neck is angled back to match the carve of the top. You might be interested in comparing the neck joint of a Les Paul (Gibson in general) to that of a Paul Reed Smith. The Gibson body has a block sticking up to mate with the neck which has a matching heel and the tenon that you can't see. The PRS body lines flow continuously without the block area for the mortise. The neck mates with the body along its curves; the mortise is just a hole in the top side. The PRS style is much easier to manufacture because you don't have to accurately align the block with the heel of the neck. Gibson customer expect the traditional design from the handmade era. You can angle the tenon or slant the mortise its your choice. Think about how you'll hold your neck to machine it and how you'll machine the various angles before you choose.

Your approach to machining the body sounds workable to me. I've got LP's if you need a measurement or something.

[turmite]

gergmary,

I am using a .625" layer of balsa as the middle of three layers of wood. Each layer of wood is seperated by an .011" thick layer of carbon 2X2 twill cloth and all this is vacuum bagged together. I then split the body and added a vertical layer between the two halves. I now have carbon going both horizontal and vertical. The neck will be made the same way then carved using my 4th axis to rotate the blank. I will have to do some fixturing to get all the cuts on the neck but I think it is possible. The body will be machine using the same locating system you described. You mentioned "buck". Are you doing this with a manual router or cnc?

I am building this for my niece and she needed a light weight guitar. I will cover the body and neck with carbon fiber so there won't be any pretty wood on this one. It is to be painted purple???? When I build one for myself it will have the nicest piece of wood I can afford.

Mike

[gregmary]

Mike,

Sounds like quite a process. I think it would look pretty cool if you could see the carbon fibre on the finished body. Or even the different layers of wood and carbon fibre inside. It is shame to hide all of that internal structure under a coat of purple paint (I don't have anything against purple, I'm sure my daughter would LOVE it). Is the guitar full size or 3/4? I take it she plans to be play it standing up behind a microphone.

I'm not sure why I used the word 'buck' A buck is a machined prototype that a mold is taken from. Often using a vacumn bag process similiar to what you describe.

I have a three axis router, but I often design my parts using a 4-axis tool path. I then manual flip the part over--my 4th axis is limited to 180 degrees . The way I machine necks is to secure them to a fixture with the back sticking up (the fingerboard covers the holes where the blank is secured to the fixture).

Take care,

Greg

[gregmary]

Randman,

Thanks for the info on the neck. I will search out a Paul Reed Smith. I am not sure how you can help me, unless you have the point data for the contours of the les paul carved top. I am now creating the CAD model for the carved top and am trying to decide how to section it so it is managable from a modeling stand point. I modeled the carved top plate for an f-5 mandolin. This was not too difficult because the shape and profiles of an f-5 mandolin are well documentd since the shape and thickness profiles (as well as tap tuning) are so important to its sound. I was able to find complete profiling for the mandolin from several sources. The Les Paul plans I have simply show the top view outline and the profile view from the side down the middle. I have been visiting a local music store and the guys have been fairly accepting of my repeated caressing of thier les pauls. Using touch is the only way I have to get to know the curves. If I had access to one, I would throw it on cnc machine and run a point probe over it.

Take care,

Greg

[RandMan]

Top carves can be built from offsets of the body curve at various elevations finally with a surface draped over them. The LP has a dip (dish) at about .5" in from the edge that is -1/32". It does not extend north of the waist. The dish rises back to the elevation of the rim at 1" and then rises up to .5" (above rim elevation) at the flat plateau (3" in) that the tailpiece and bridge sits on. That plateau slants back towards the neck joint area which is a 16th or so above the rim elevation. The pickups are on the gradual slant. So at the top of the guitar crosswise it rises towards the fingerboard and then back down the other side. Hopefully I'm making sense and you can relate it to the landmarks in the stewmac drawing. I prefer to understand the classic designs and then take my liberties from there

[turmite]

greg do you not have a cad drawing of one? I have a Rhino file if you would lke it. It is a double cut away but you are welcome to it if you want. I used the Stewmac plans as well as using a copy of a LP by another company to get my starting points. I don't know for sure how true my design is to the original LP but it is nice looking. I will try to attach a jpg so you can see it.

Mike

[turmite]

greg I forgot to mention how I intend to do my neck and you may be able to help me out here. My 4th axis is a full 360 degree so I can reach nearly anywhere I want. I had though I would just mount the neck blank between centers and carve everything I could including the headstock. I had also though of carving the headstock first using fixtures so I could position the holes for the tuners with the cnc. I could then use the top and back surfaces of the head along with the holes to build a fixturefor mounting the blank in the machine. Either way I will have to do either two or three setups with fixtures to completely do the neck on the cnc.

Mike

[gregmary]

Mike,

It would be far out if I get get some CAD data from you. Can you export an IGES file from Rhino? I use Pro-E for CAD and Visualmill for CAM, and use the .igs file format to go between them.

The way I do my necks is I surface the top of the blank where the fingerbord attaches and where the peghead overlay attaches real nice. I then use the corner where the two surface meet as my primary datum when machining the back of the neck. I machine the peghead overlay seperately (a thin piece of ebony), cutting out the holes for the tuners and the pockets for the mother of pearl inlay. I also cut my fingerboard fret slots on the CNC. After I have the neck rough sanded I attach the peghead overlay to the neck, again aligning to the datum at the nut and then use a drill press to drill all the way through the neck for the tuners. I machine the neck in two operations, one with the fingerboard mounted flat to the router table and the second with the peghead flat to the table (the neck sticking up in the air a bit). I have found I only need to machine the neck from the back.

Greg

[gregmary]

Randman,

Thanks for your mesurements. I have printed out your note and I am studing your dimensions. You have given me lots of info and I need to digest it.

Greg

[turmite]

Hi Greg,

Yes to the iges question. If you have particular requirements let me know. Rhino can export many different files.
Send an email to the following address but take out the ihatespam2 before sending. I really do hate spam and looks like I am going to have to shut one of my address down due to the tons of it a day I get there.

Thanks for the hint on machining the neck.

ihatespam2turnercustoms@earthlink.net

That mandolin is nice too. Rand is that yours'?

Mike
ps Greg I don't have the neck finished. Do you need it? Hmmm....carbon fiber F5...now that sounds wild!

[gregmary]

Mike,

Did my email address message get through your spam blocker?

Greg