Control Cavity Chew Marks - Burst vs Max Vol. II

boogieongtr

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Since the original thread took a left turn and no one posted any pics I thought I'd start a new one. Also I do NOT think the chew marks were made by a router bit. Has anyone ever seen the routing process of a control cavity in person or is everyone just posting what they have read????

Here are the control cavity pics of the 4 Max LP's I use to own.

58 Max


59Max


59Max


59Max



Now for pics of Original 1957/1958/1959/1960 control cavities:







 

RAG7890

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Well, IMHO anything I can learn that furthers my education on Vintage Les Pauls, no matter how little or OCD they seem, I do appreciate. :)

So Jim, thanks again. :thumb: :applause:

It is possible to create these "tool" marks if you know what you are doing & that (unfortunately) can lead to Replicas being passed off as real Bursts by a small handful of dubious characters.

My 2c FWIW.

:cheers:
 

Fletch

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The Max's are close, but not convincing.... although I wonder if you had just posted all these pictures without captioning them and made us guess, if I would have thought the same thing. Sort of like a Pepsi Challenge...

:hmm:



fletch
 

58burst

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Looks to me they're from the chuck of the drill press drilling the control holes, in that case they're drilled from the back (?)
 

Stinky Kitty

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Thanks everyone for this and all the other threads! Not that I'll ever be an expert on much more than making good equipment sound bad, I feel quite fortunate to be able to learn more about these guitars as well as the culture and mystique surrounding them. I do appreciate when the well versed dispel some of the mysteries and make this arcana more assessable to us in the unwashed masses!
 

welland

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The Max chew marks look gratuitous and not convincing enough.

Max should have brushed up on his chewology.
 

Joshabr1

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Looks to me they're from the chuck of the drill press drilling the control holes, in that case they're drilled from the back (?)
That's what I thought when I first seen that. I would say Jim would have a good idea of what caused it.
 

monsterwalley

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For the chew marks to be caused from a drill chuck, they would have to be using an extremely short bit would they not?

Going out on a limb, but what if that was from some sort of plunge router for the angled cavity cut, and as the bit came back out, it was decelerating and snagging the edge instead of cutting the edge?

I only say this because I noticed in some of the pictures there were noticeable ledges were something was momentarily paused?
 

nuance97

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I don't think a router did it. If it was a router it'd be much cleaner. The super high rpm of a router and the sharp bit would leave a clean smooth cut. I think it must have either been a forstner bit or a counterbore/spotfacer. The low rpm of a drill press and relatively dull forstner bit would give that rough cut with the wood fibers being torn and crushed. Counterbore would be somewhat smoother, but not like a router...
 

monsterwalley

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I don't think a router did it. If it was a router it'd be much cleaner. The super high rpm of a router and the sharp bit would leave a clean smooth cut. I think it must have either been a forstner bit or a counterbore/spotfacer. The low rpm of a drill press and relatively dull forstner bit would give that rough cut with the wood fibers being torn and crushed. Counterbore would be somewhat smoother, but not like a router...
I agree with the smooth cut of the router running at high speed, but what if (hypothetical) power was killed to the router on exit and the bit stalled out
against the wood on the way out? I know it sounds far fetched, just throwing it out there.? Seems I've had similar results on an old router many years ago. It had a toggle switch on top and sometimes if I didn't hold it still enough
it would bite before it completely stopped, leaving a chewed edge.
 

nuance97

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I agree with the smooth cut of the router running at high speed, but what if (hypothetical) power was killed to the router on exit and the bit stalled out
against the wood on the way out? I know it sounds far fetched, just throwing it out there.?
IDK...I could see a router bit being extracted while decelerating occasionally nicking the edge, but for it to happen virtually every time they routed the angled cavity floor thousands of times from 1952-1960? I just don't see it...
 

Joshabr1

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I agree with the smooth cut of the router running at high speed, but what if (hypothetical) power was killed to the router on exit and the bit stalled out
against the wood on the way out? I know it sounds far fetched, just throwing it out there.? Seems I've had similar results on an old router many years ago. It had a toggle switch on top and sometimes if I didn't hold it still enough
it would bite before it completely stopped, leaving a chewed edge.
If all the old ones have the chewing. I wouldn't think it would happen everytime pretty uniform like that w a router. But I don't really know enough to even be posting. Just interested in these little details.
 

nuance97

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I also don't think a drill chuck or router collet is the culprit. It's something with a (slightly dull) cutting edge.
 

MiniB

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Here are some thoughts that I quoted from the LPF...

http://www.mylespaul.com/forums/vintage-les-pauls/291572-legitimacy-bursts-marketplace-real-fake-2.html#post5963487

From what I saw when I worked at gibson, the machines used for this production were always table routers, not overhead routers (a pantograph for top carving and an overhead router were used for neck slots and pickup cavities). The chew mark looks like an area where a bit is taking too much wood out at once and it severely slows the machine. These cuts would be very difficult to perform with an overhead router, but pretty simple to perform with a table router.
There is an additional operation. You have to remove the pots in order to see it. I have photos but don't know how to post them.

After the angled rout is done to the cavity floor, an end mill is used to further thin the top so the pots can reach through far enough to attach the washer and nut.

This is done with a 1" end mill with a 3/8" guide extending from the face of the bit. The guide goes into the hole for the pot and the cutting face of the end mill cuts a 1" diameter recess for the pot to sit in.

The plane of the recess is parallel to the face of the top at the point where the pot extends through the top. Consequently, the pot extends from the top at a proper 90 degree angle. In order to get this angle, the bit will hit the wall of the cavity as it enters and leaves the cavity when doing the cutting for the volume pots. Hence, the 'chew mark'.

Noting that the chew marks tend to vary in size and are sometimes completely absent from the area next to the neck volume pot, I would guess that this operation is probably done by hand.
From what I can gather, the bit used for the 'recess' for the pots, which mills out wood straight-on as opposed to on its side like a router bit, is what makes contact with the side wall upon entry on an angle...making the 'tear' or 'chew' mark. A 1-inch end mill bit must be quite a honker.

 

monsterwalley

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IDK...I could see a router bit being extracted while decelerating occasionally nicking the edge, but for it to happen virtually every time they routed the angled cavity floor thousands of times from 1952-1960? I just don't see it...
Yeah, it is pretty far fetched. I envisioned a guy on an assembly line hurriedly
putting it in a fixture for the floor route and when done, killing the pin router or whatever before it comes away clean. What does he care right?, it's the inside of the cavity. I just know when I do my floor route I get similar bites, but they are crisp and clean though. If it were from a forstner bit or spot facer for the pot depth, you would think it would bounce around a lot more doing more damage, unless it was locked in the same jig as the floor route and done with a drill press?
 

monsterwalley

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Here are some thoughts that I quoted from the LPF...

http://www.mylespaul.com/forums/vintage-les-pauls/291572-legitimacy-bursts-marketplace-real-fake-2.html#post5963487





From what I can gather, the bit used for the 'recess' for the pots, which mills out wood straight-on as opposed to o nits side like a router bit, is what makes contact with the side wall upon entry on an angle...making the ;tear' or 'chew' mark.
The spot facer with the guide rod sounds plausible and would explain the small ledges shown in some of the photos of chew marks. Meaning the bit would have stalled out in those spots momentarily because of the guide rod binding on entry or exit.
 

nuance97

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Yeah, it is pretty far fetched. I envisioned a guy on an assembly line hurriedly
putting it in a fixture for the floor route and when done, killing the pin router or whatever before it comes away clean. What does he care right?, it's the inside of the cavity. I just know when I do my floor route I get similar bites, but they are crisp and clean though. If it were from a forstner bit or spot facer for the pot depth, you would think it would bounce around a lot more doing more damage, unless it was locked in the same jig as the floor route and done with a drill press?
Yeah when I've routed my angled portion of the control cavities I too get the bites in the right places, but they are smooth like yours. You and I are both using a router to cut both the round relief for the actual pot and the squarish flattened angled portion of the cavity floor. I don't think they did it like that back in the day. I'm convinced it was a two step process. They cut the squarish angled portion on a pin router in some kind of cradle that held the body at an angle, and then, in a separate operation, cut the round reliefs for the actual pots. Boogieongtr (Jim) has outlined this process in some of his other threads, and Gil Yarron has documented this method in his more recent builds. The only thing about a forstner bit is that they can wander off coarse so maybe a piloted counterbore is more likely? The piloting rod would go into the pot hole guaranteeing the counterbore being centered. Just thinking out loud...
 

MiniB

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Maybe something like this....?






It does look like that one pot is closer to the rout wall than others.
 


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