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Resophonic

Need help removing "The Heritage" H-40 mandolin neck

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As far as X-Rays, I went to a veterinarian and they were happy to do it for the cost of the  "film", as I recall roughly 35 dollars.

YMMV

1954xray.jpg

 

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18 hours ago, TalismanRich said:

If your guitar was old enough for Medicare, it probably would have gone through.   Unfortunately,  it's going to have to wait another 20 years or so!

That brought a smile to my face...

 

Heritage responded today with this response:

"We believe it should be a dovetail. Regarding the glue, it would have been traditional/standard wood glue (white glue) and not hide.  For the steam hole, unfortunately we're unable to recommend a place as we would need to have the mandolin in our possession to evaluate. Our repair tech said he would likely do it by removing the fretboard or back which requires a bit more work."

 

I also made contact with Steve Cowles at Aaron's Music Service. He was actually out of town but responded:

"Going by the pictures it should be a tenon.  Probably built by my dad for Heritage. He would have used Titebond I'm sure.

 I would be tempted to force glue into the joint with a needle and clamp it good. Can respond more in depth if you like but I'm at Cedar Point today...

 

I emailed back that would like to revisit this discussion when he returned and had the minutes to do so. At least I know what kind of glue was used...

 

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Hi Jim,

Funny, I was thinking a vet clinic might be a better angle to try than the very large, protocol driven, hospital megalopolis where I live. Thanks for your input.

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Steve Cowles got back to me today,  with my feeling around in the neck heel separation using a thin blade and his input, I am convinced that the joint is a tenon.

 

This from Steve: "As to the neck joint, I know that modern Gibson F-5s made here by my dad had tenon necks, and I think so did the Heritage ones.  I’m unsure if he was doing that however with his personal builds.  I’d have to see a few up close.  The easiest way to know on an F style is to see if the portion of the neck that’s over the body is a separate piece of wood or not.  Dovetail necks have an extra piece underneath the fingerboard, tenon joints don’t.  I drew a line on this one to indicate where that line would be on your mandolin if it were a dovetail"

image001.png.59ccdafd4c6a1a142b4b12a13bcdb88d.png

I checked under strong light with magnification, no parting line. The neck and fingerboard extension support are one piece of wood. Removing the finger board in this case would reveal nothing but a continuation of neck wood. The only plausible way I see is to maybe pull this thing apart is to remove the heel cap, drill a hole at a bit of a downward angle, through the heel and into the center of the joint with a heating rod ( https://www.stewmac.com/Luthier_Tools/Tools_by_Job/StewMac_HeatStick_for_Neck_Removal.html ) to soften the glue. This could still be iffy and fraught with problems. My recommendation will be to do some cosmetic work to help hide the neck heel separation and the chipped finish there and then give it a proper set up the way it is.

 

My thanks to those who responded here, for your help and input.

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Steve Cowles very graciously took the time to send me these images. thought I would also post them here for posterity...

 

An unfinished F model with a tenon joint, either Gibson or Heritage.

image001.jpg.bc648a2883407fafca31b3fa9c166486.jpg

image002.jpg.e91e3dd9783369597e8d788fa5030280.jpg

image003.jpg.21b1733fc13ee524f6497bb0d47d0fe1.jpg

image004.jpg.b11e9dde639ba4cdedf36812a5da8606.jpg

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Great photos!

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fascinating stuff, I always wondered about the mandolin construction

si I guess it's best to just squirt some glue in there, and clamp?

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would that we all take our babies to a luthier as concerned as you about doing their homework and gathering as much info as possible before proceeding. Kudos to you @resophonic 

Where's your shop?

 

 

Edited by kidsmoke
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On 9/2/2019 at 8:43 PM, bolero said:

fascinating stuff, I always wondered about the mandolin construction

si I guess it's best to just squirt some glue in there, and clamp?

Yes, that is tempting for many to "just squirt some glue in". I have done several projects to reverse such impulses. I call them helpful Henry's. They mean well but often create more problems than they solve.

 

Thanks for the kind words kidsmoke. I am in East Central Illinois, Champaign. I own and operate a cabinet business and have been doing instrument repair as a part time passion since 2000. I used to go fishing on the weekends but now spend them in my shop improving things with strings that are musical.

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well, I was responding to this

"I would be tempted to force glue into the joint with a needle and clamp it good."

bad choice of words, I suppose...are you not going to glue it?

 

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Sorry, didn't mean to come off as demeaning.

 

I mentioned earlier in the thread that I clamped across the back of the mandolin from the neck heel, to the tail block. I applied as much force as I thought I could get away with and not dent the neck heel, I couldn't budge it at all. No, glue would help the lifted neck heel without first removing the neck completely and re-setting it. The decision was made to leave it alone for now and just do a good set up. I told the owner to keep an eye on the neck heel for any change but I am rather confident that it won't budge. I suspect that the lifting was caused from the mandolin being left in a hot car but don't know for sure.

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I have read that is one of the advantages of hide glue over yellow/titebond: more resistant to heat from being left in cars, for example

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Yes, that is true, Titebond will start to creep around 120 degrees. Elmers White glue starts going South around 110 degrees. Cars easily reach temperatures this high. Couple that with either of the mentioned glues, high heat and around 200 lbs. string pull force an a guitar and it doesn't take long for glue creep to cause a bridge or neck heel to lift.

 

I did an experiment with dry granules of hide glue, which is the same state hide glue would be in after drying in wood joinery. I placed the dry hide glue granules on a 3/4" thick bar of Aluminum and heated the bar on a hot plate. I placed a bi-metallic thermometer on the Aluminum bar to monitor temperature. The hide glue never changed state until 400 degrees, at which point it started smoking. At 400 degrees, your wood instrument would be smoking too. I am confident that wood creep would absolutely not happen in a hot car if hide glue was used. However, if you live in a tropical rain forest, the high humidity could be a problem for an instrument put together with hide glue, not a problem around here.

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Interesting. Thank you for the information.

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