Otwin Rhythmus neck problems

[Dave Yelverton]

Just had in a guitar from a customer  who collects European archtop guitars built around the '60's.

The instrument is an Otwin Rhythmus archtop with neck problems which are I believe, common faults with this model.

The neck is beech with no truss rod. Unsurprisingly it has developed a considerable forward bow, giving a profile at the 9th fret of about .080" (2mm)

The neck also requires resetting, having pulled out of its dovetail at the lower end.

I'm assuming the neck removal will be by the normal methods. However, I have never removed an archtop neck. Does it differ from an acoustic dovetail or can it be removed by the same methods?

Once off  I intend to use heat to straighten the neck using a method shown on European Guitars Forum. This involves clamping the fingerboard to a steel  rectangular section bar heated by a fingerboard blanket. The customer is not keen to have a trussrod installed so I need to make sure that he gets a result which leaves him with the profile he wants when the strings are re-tensioned.

Will I need to induce a slight reverse bow to accomplish this? and what would be an appropriate temperature to set my blanket to ? (EGF never specified) I don't want to lift the fingerboard or damage the trim!

After re-setting the straightened neck, I expect that I will need to  need to remove the frets and level the fingerboard slightly followed by a re-fret.

I would greatly appreciate the accumulated wisdom of members of this forum. If anyone has experience of this model or similar European archtops (specifically I have in mind Graham Myers) could you let me know if there are any peculiarities I need to look out for

Oh, and last , but definitely not least.!...what would members regard as a fair price to charge for the work?

Regards

Dave

[Kerry Krishna]

And the CF rods too. I have had good luck with this system, as have many other fine Forum Folk. Go with the CF! 

[Dave Yelverton]

Gosh- I'm overwhelmed by the responses to my query !  Everyone's been amazingly helpful.  Having re-examined the neck join, it seems definitely to be a violin joint- I guess I'll have to do some careful shimming to get it lodged back securely enough to last another 30 years. I'll have to use HHG as titebond may well creep over time.

On reflection, removing the F/B first does seem the way to go; I'm a little worried about the neck extension at the end of the fingerboard which is glued into the end of the neck. I don't want it to be disturbed in the removal or it will add an extra problem.

Can I ask what would be the benefit of pre-injecting vinegar and water? I am conscious from other re-sets that it's not a good idea to get the joint too wet or the dove tail can swell- however, I've never removed a violin joint so I don't know how this would be affected.

The CF inserts seem the best bet. The owner is keen to preserve the authenticity (at least, visually) of his instruments, so a truss rod wouldn't be his first choice. It's been interesting dealing with his collection. There's a fine tradition of archtop making in Europe, particularly in Germany. The instruments are often idiosyncratic in appearance, but great players, in particular those made by Arnold Hoyer.

Well, thanks again to everybody. I'm going to mull over all the advice received until I come up with a plan of action- I'll let you know how it all works out.

Dave

[Eric Steven Johansen]

Vinegar contains acetic acid which helps dissolve the hide glue more quickly, allowing you to use less steam to remove the neck. Don't over saturate the joint. I use a large syringe and inject just enough to keep things moist. A few times throughout the day, 24 hours before removal should do the trick. I wouldn't sweat the extension removal, they usually come off easily.

Best of luck and keep us posted.