Neck pocket tolerance question for the cnc guys.

Discussion in 'Tele Home Depot' started by Bugeater281, Dec 5, 2019.

  1. Bugeater281

    Bugeater281 Tele-Meister

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    Im designing a new guitar, I plan to cnc the first one to check tolerances before making templates. What tolerance do you use when cutting neck pockets? It will be a set neck, the widest point is 2.24in. I was debating doing the actual neck width at 2.23 or 2.22. It would be getting cut out on an x-carve.
     
  2. Freeman Keller

    Freeman Keller Friend of Leo's

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    I build set neck guitars but not with a cnc. I hand fit my necks so that they are snug enough that I can lift the guitar with the neck in the pocket but easily remove it. I seriously doubt that you can do that without doing some finessing by hand. On my dovetails I chalk fit them.

    IMG_1971.JPG

    Also remember that a tele style neck has a very slight taper to the pocket, most set necks do not unless you are trying to lock them (ie a dovetail)
     
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  3. Bugeater281

    Bugeater281 Tele-Meister

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    Currently I’m debating on doing a “dovetail” neck pocket or a straight neck pocket. The shape of the body would make a straight pocket hard to get flush with the angle of the back of the neck pocket. I personally think the straight pocket would look better. Fretboard hiding the neck pocket and all. But a angled pocket would be way easier to make. And if done right wouldn’t look terrible.
    I included a pic of the straight pocket design so far. Haven’t finished the angle pocket design yet.

    D41C1DA1-44CE-4DC9-A4CC-EAF941B096D3.png 01034EE9-79AF-4F4A-BAE1-683534E0B039.png
     
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  4. GunsOfBrixton

    GunsOfBrixton Tele-Afflicted

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    You will probably need to do a few tests on scrap to determine that. An x-carve is not the most accurate of CNC's (mostly due to regidity or lack thereof) So in your CAD / CAM software , set the neck pocket width and the neck width / tenon to the same size. Then tell your CAM routine to cut the neck pocket a few thousandths of an inch bigger. (Very easy to do with most CAM software) Then do a test cut of the neck pocket and neck /heel / tenon. Repeat cutting the neck pocket until you get the fit you are looking for. Oh, use the same wood as you would be using for real if you can.

    If the CNC is accurate enough, you can cut the tenon / neck to fit without any hand finessing. :)
     
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  5. Freeman Keller

    Freeman Keller Friend of Leo's

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    I do standard Gibson style M&T neck joints on all my Gibson inspired guitars (LP, 335....). I try to make the tenon as long as I can extending as far into the body - as in the guitar above it extends all the way into the p/u cavity. I have had to repair SG style guitar with minimum tenon length. That is one of the reasons I like a snug fitting tenon - the sides are glue surfaces but can't be clamped.

    I used traditional dovetails on my first couple of acoustics but have switched to bolted neck joints as long as I have a sound hole to get my hand in. If I don't have a conventional sound hole I use a dovetail but the body has to be deep enough to have bearing surface - I wouldn't use one on a shallow body like yours. I also expect to take the dovetail apart sometime in the future - not something I plan with a set neck electric guitar.

    I'm quite sure that a cnc can make both parts with the necessary geometry to just drop together and be perfect, and I'm quite sure that is how most commercial electric guitars are built today. However I think it is worth remembering that even someone like Taylor with all their cnc experience needs to put the little laser cut shims in their pockets to get the geometry correct.

    I'll look forward to seeing your guitar.
     
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  6. guitarbuilder

    guitarbuilder Telefied Ad Free Member

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    Since my cnc routers aren't $100,000 cnc machine and have some play to them, I normally do rout my mortise first. I draw my nominal size tenon and then use an offset of a couple thousandths to create a new toolpath, then another one to that, and so on. This is done in Rhino and converted by CamBam into Gcode.

    So I set up a series of tenoning gcode sequences which go in increments of a couple thousands on a side. Then I start with the largest tenon and work my way down in increments until the tenon fits in the mortise with just some slight pressure. You need some room for the glue, so don't make it so tight. You don't want to squeeze it all out when you put the neck in. Most of my neck tenons are 3" long and end at the end of the fretboard. The fitting operation is at full tenon depth. While the extended tenon is extra mojo, it isn't necessary as shown by half of Gibson's Les Pauls.

    I assemble the tenon gcode in Notepad with an M0 between them. That way the motion stops and I can measure it. Press enter to continue. This has worked out for me on my K2. I have only done bolt- ons with the x carve. Use a digital micrometer to check it. Use a new router bit too.

    I've found that the x carve with the addition of a cnc4newbies z axis, y axis stiffeners, riser plates, and 9mm belts/pulleys can be pretty accurate but it takes some dialing in.

    Make sure you do the work and glue it without drastic humidity changes.
     
    Last edited: Dec 5, 2019
  7. Jim_in_PA

    Jim_in_PA Tele-Holic Silver Supporter

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    For pocketing where something will be inlaid...which you can certainly fit a neck and pocket situation into...I use about .02mm allowance for the most part. 'Just enough that you can get it in smoothly without pounding on it. This is easier if you are cutting your own necks but certainly possible if you have an accurate digital caliper to measure the actual width of the neck you are going to use if you purchased it, especially if it's already finished. The finish takes up space... ;)
     
  8. Peltogyne

    Peltogyne Tele-Afflicted

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    0.02 millimeter = 0.0007874 inch

    Did you mean .2 mm?

    I've been leaving about .006 inch gap in the design and then dialing it in as I sand the sides of the neck. Measuring one I have here that is fitted the pocket is 15 thousands wider than the neck heal.

    And as already mentioned finish will take up some space.
     
  9. Bugeater281

    Bugeater281 Tele-Meister

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    Set neck, there will be no finish in the pocket. Need just enough room for some glue.
     
  10. Jim_in_PA

    Jim_in_PA Tele-Holic Silver Supporter

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    Yea, mis-typed...I do use .02 for "last pass" allowance however. :)
     
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