How did Gibson cut the bevels on an SG?

Discussion in 'Luthier's Corner' started by Silvertone, Nov 24, 2020.

  1. Silvertone

    Silvertone Well-Known Member

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    For the most part pin routers were used in the early days. CNC didn't really become commercially viable until the late 70's early 80's. I doubt Gibson had CNC until at least the mid 1980s. Doesn't mean they weren't mass producing. The pin router was very similar to CNC only controlled by a human. Cost benefit analysis would've made the decision for them. Was it cheaper to buy computers and computerized machines to do a certain job? Cost of computers VS human wages.

    Cheers Peter.
     
  2. Silvertone

    Silvertone Well-Known Member

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    Interesting. I've never heard that before. I assumed the story about that new design being a Les Paul, makes you think they were all called Les Paul, until 1963 when they changed them to SG. Thanks.

    Cheers Peter.
     
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  3. Silvertone

    Silvertone Well-Known Member

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    Funny that you mention that because I was just drawing up a possible template and pin router bit to cut the bevels. I thought the same thing about the smaller radius on the inner horns but all they had to do was raise the bit slightly and adjust the template accordingly. If they are on the pin router, no need to do work by hand.

    Here is the design I came up with -
    Capture.JPG

    The template is offset about 32mm from the top edge of the bevel. As you move around it will cut the bevel to varying depths because the top edge moves closer and farther from the edge. It would be a very quick method of carving the bevel. It would just require a large diameter bit and a template for the top and the back.

    Regards Peter.
     
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  4. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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    OK Silvertone Peter, I am offended in any way, but I am also not going to make any further attempts to add info as to how Gibson did it, or how a non factory person would do it, or ANY ONE for that matter since it seems you contradict yourself and thus I waste my time trying to help you.

    If anyone reads your posts I quoted, it will illustrate where your very first post says you are trying to figure out how Gib did it but also a DIY way. Then in my posted suggestion of a pantograph, you say you are not really looking for how a DIY person would do it, then bad mouth a pantograph and belittle the device as "silly"

    Good Luck, I will merely watch to see if anyone else but me comes up with HOW OLD SCHOOL GIBSON made SG's back in the day.

    Oh and in my last ditch effort to convey how Gib likely did it, ( not HOW they ACTUALLY did it with 100% Authoratative first person experience or anything)
    I agree with our other member, Permissiontoland, who said it was done by hand. So, Have at it, do it by hand. There are many tools that will make curved and beveled shapes on a block of wood.
     
  5. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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  6. Silvertone

    Silvertone Well-Known Member

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    Sorry, I didn't mean to belittle. Bad form on my part. I apologize. I guess it is a tricky situation as I have done a lot of homework on the way Gibson did things back in the 50's and 60's relating to their other guitars. They used pin routers for most of their operations for an LP body. For instance the pickup routes, neck pocket, control cavity, secondary control cavity route to match the top carve from the underside, as well as switch route, and all covers, as well as the shape of the body were done with templates and jigs on the pin router. I believe they used a duplicarver type machine with a large blade to initially carve the top and then used a slack belt with a paddle to finish the carve. The necks were done with templates and a deadhead sander was used to rough carve the back of the neck profile. Most of the sanding after the fact was finish sanding which, depending on the importance of the functional final shape was done with varying degrees of material being taken.

    When I mentioned DIY, which was a mistake, I was considering buying a similar shaper bit to use in either a pin router or my CNC machine to "do it myself". In my defense regarding the pantograph, which may have just been my ignorance, I have only seen this as a children's toy. I was hoping to hear from someone that may have done research or possibly someone that had worked in the factory whom had first hand knowledge of the process. I realize now that snubbing others posts was quite arrogant and again I apologize.

    Regards Peter.
     
    Last edited: Nov 26, 2020
  7. Silvertone

    Silvertone Well-Known Member

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  8. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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    You're welcome, Silvertone, Peter.

    Most times I try my best to be of some addition of info to the thread or Forums as a whole, even if the OP or someone else might not want the particular info I post, someone may find an answer to a question they may have had.

    Hope you and of course we all get an answer to your original and subsequent queries about Gib's methods etc.
     
  9. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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    Someone I know knows how to make Bevels

    [​IMG]
     
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  10. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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  11. chilipeppermaniac

    chilipeppermaniac Well-Known Member

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  12. SG standard

    SG standard Well-Known Member

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    Ok, I've found the reference - if you want to know how Gibson cut the bevels on SG bodies in the early years, it's briefly described on p104 of Bacon's book. I know you've got that so I won't bother typing out the details here. :)
     
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  13. Silvertone

    Silvertone Well-Known Member

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    Thanks, I just read that passage. It's a little vague but I have heard rumors of a few machines that were basically accidents waiting to happen. The interesting thing is the bevel on the 1962 Standard I had laser scanned is very consistent. Meaning that the body could not have just been pushed through, although he does mention a fixture. This somewhat reinforces what I thought about an angled shaper. Thanks for posting that. Saved me some time reading that book again. ;-)

    Cheers Peter.
     
  14. papagayo

    papagayo Well-Known Member

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    Yess, upgraded 2015 SG Standard Trans Ebony

    SG Standard TBK 233.jpg
     
  15. Silvertone

    Silvertone Well-Known Member

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    Interesting that it has the Les Paul engraved tenon cover. Not sure why? Were they able to charge you an extra couple hundred for that? ;-) Is it a RI?

    Cheers Peter.
     
  16. Reuben

    Reuben New Member

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    I can almost guarantee that every used today is cut with a CNC router. The only way I can think of to manually do make the bevel is to make line on the side that shows the lower edge of the bevel and on the surface trace the inside bevel curves. Using a rasp take out the bulk of the material then move to a finer curve file to get it to where it needs to be... drum sand or hand sand with shaped sanding blocks. I know this is a brute force approach, however try it on a prototype to see if it is feasible with your tools and skills.
    ===
    I just took the plunge and started doing the body design for an SG Custom. I've looked at several PDF draftings that show the drop from the surface of the edge. One shows a surface drop of 7+mm but when I take the drawing and scale it to the dimensions I get about 11mm which is close a third of the thickness of the body (35mm). I'd really like to get the angle º of the bevel so I can calculate the hypotenuse( length)..I just haven't found it anywhere. I'll look at 22º or 25º that was mentioned in the previous posts and use them in my 2-rail sweep as mentioned below.

    I'm able to cut all the surface pockets/holes/body profile, and "rails" by using a feature called a two rail sweep... I select the two vectors that make up the bevels then select a shape that I want to be swept between the rails (this is analogous to the rasp/manual suggestion). This creates a 3D structure that I can cut with a bullnose end mill. I've compared the angle with several pictures and it looks "about right" but without having something physical I can compare it with it's just an educated guess at this point.

    This picture is the result of a profile cut and 4 bevel cuts on the top surface... I haven't started on the neck pocket (will use the same two rail sweep with a 3º ramp), pickup pockets, and other cuts on the surface yet as I'm still trying to figure out the best process to make this happen. All I have to do for the back is "flip it over" along the centerline then replicate the bevels cuts on the back, and cut the wire pocket. More tweaking to yet to come!
    profile.png

    My first attempt at a guitar with my CNC router came out pretty well...of course it took me about 5 months to complete..mostly the lacquer peeping and finishing. It was a Fender 72' spec'd Telecaster
    Good Luck...keep us posted on progress.

    Telecaster.jpg
     
  17. Silvertone

    Silvertone Well-Known Member

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    I do not think there is any debate on how Gibson does it now. See my image on post #17. A quick google search of Gibson shop tours will get you lots of images of current work processes.

    As far as a 3d model or trying to recreate the bevels, there are things to consider. Mainly, how do the bevels move around the body? It is pretty obvious that they change substantially either looking from a plan view or an elevation view. This means the distance between the edge of the bevel and edge of the guitar body on either the horizontal face or the vertical face is not consistent. This is what gives us those curves.

    What I am trying to determine is how they did them in the early - mid 60's to then hypothesize and confirm the design of those bevels. If you look at post #23, you can see that my thought is that the bevels were cut with a shaper / cutter with about a 25 degree angle. If you place a guitar body on a template that is shaped as the outside line it would cut the consistent angled bevel that would get thinner and thicker based on how far the body was away from the cutter.

    Are the angles consistent? Yes, I believe they are. I have two separate models that were based on laser scans of existing guitar bodies. One was a 63 SG JR and the other a 62 SG Standard. Their body shape is slightly different but the bevels are consistent. Except in the cutaways. These are steeper in the early 60s guitars at about 30 degrees. I think they wanted to over emphasize these areas and probably took a pneumatic spindle sander, which was a tool of the day, and deepened those bevels resulting in a steeper angle.

    Capture.JPG

    Again, it would be nice if anyone could find some pics or comments regarding how Gibson did this process in the early 60s. Thanks for all the input.

    Cheers Peter.
     
  18. papagayo

    papagayo Well-Known Member

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    The 2015 SG Ltd Edition is a Les Paul Anniversary model.

    May be I will remove the Les Paul tenon cover for a blank one ...
     
  19. Silvertone

    Silvertone Well-Known Member

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    It's a nice guitar. I've never seen a signed tenon cover that is why I asked about it. I do not know much about the RIs and all the "special" guitars that Gibson built and marketed. I do know there were less than 3 yrs where SGs were called Les Pauls. That was from 1961 - mid-1963 and because they had the crown inlay on the head stock those guitars only had the truss rod cover engraved with the Les Paul name. Les Paul did not like the design and wanted his name taken off them. They actually didn't even tell him that they were slapping his name on it and he had nothing to do with the design. I love the design and it's the guitar that has been in the longest continual production by Gibson, I believe. So obviously lots of other people like them as well. Especially in this forum. ;-)

    Cheers Peter.
     
  20. papagayo

    papagayo Well-Known Member

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    I removed this "strange" engraved tenon cover, the SG looks really better now, really .

    Thank you Peter.

    SG Standard TBK 239.jpg
     
    Last edited: Dec 3, 2020

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